Do releases of the mirid predator Macrolophus basicornis (Hemiptera: Miridae) together with the egg parasitoid Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) improve biological control of Tuta absoluta (Lepidoptera: Gelechiidae) in tomato?

During the past decade, the use of predatory mirids alone or combined with releases of egg parasitoids of the genus Trichogramma have been tested in Europe for biological control of the worldwide invasive pest, Tuta absoluta (Meyrick). Here, we evaluated the control of this pest by the release of the Neotropical mirid Macrolophus basicornis (Stal), the Neotropic/Nearctic parasitoid Trichogramma pretiosum Riley, and by combined releases of the predator and the parasitoid. Tests were conducted in greenhouse compartments during the summer and fall season. Each compartment contained 10 tomato plants in which only the pest was released or the pest with 1 or 2 natural enemies. Plant damage, and pest and natural enemy densities were checked weekly on one apical, medium, and bottom leaf of 5 plants. Both M. basicornis and T. pretiosum significantly reduced T. absoluta density when released alone. Combined releases resulted in a 10% higher reduction during the summer season, but not during the fall season. The damage caused by T. absoluta was significantly higher in control treatments than in all natural enemy treatments: at the end of the summer trial leaves were completely damaged in the control treatment, whereas only up to 25% leaf damage occurred in the natural enemy treatments. Combined releases did not result in lower damage than with releases of either M. basicornis or T. pretiosum. Practical aspects of single and combined releases are discussed.

The pest kill rate of thirteen natural enemies as aggregate evaluation criterion of their biological control potential of Tuta absoluta.

Ecologists study how populations are regulated, while scientists studying biological pest control apply population regulation processes to reduce numbers of harmful organisms: an organism (a natural enemy) is used to reduce the population density of another organism (a pest). Finding an effective biological control agent among the tens to hundreds of natural enemies of a pest is a daunting task. Evaluation criteria help in a first selection to remove clearly ineffective or risky species from the list of candidates. Next, we propose to use an aggregate evaluation criterion, the pest kill rate, to compare the pest population reduction capacity of species not eliminated during the first selection. The pest kill rate is the average daily lifetime killing of the pest by the natural enemy under consideration. Pest kill rates of six species of predators and seven species of parasitoids of Tuta absoluta were calculated and compared. Several natural enemies had pest kill rates that were too low to be able to theoretically reduce the pest population below crop damaging densities. Other species showed a high pest reduction capacity and their potential for practical application can now be tested under commercial crop production conditions.

Attraction of Three Mirid Predators to Tomato Infested by Both the Tomato Leaf Mining Moth Tuta absoluta and the Whitefly Bemisia tabaci.

Plants emit volatile compounds in response to insect herbivory, which may play multiple roles as defensive compounds and mediators of interactions with other plants, microorganisms and animals. Herbivore-induced plant volatiles (HIPVs) may act as indirect plant defenses by attracting natural enemies of the attacking herbivore. We report here the first evidence of the attraction of three Neotropical mirid predators (Macrolophus basicornis, Engytatus varians and Campyloneuropsis infumatus) toward plants emitting volatiles induced upon feeding by two tomato pests, the leaf miner Tuta absoluta and the phloem feeder Bemisia tabaci, in olfactometer bioassays. Subsequently, we compared the composition of volatile blends emitted by insect-infested tomato plants by collecting headspace samples and analyzing them with GC-FID and GC-MS. Egg deposition by T. absoluta did not make tomato plants more attractive to the mirid predators than uninfested tomato plants. Macrolophus basicornis is attracted to tomato plants infested with either T. absoluta larvae or by a mixture of B. tabaci eggs, nymphs and adults. Engytatus varians and C. infumatus responded to volatile blends released by tomato plants infested with T. absoluta larvae over uninfested plants. Also, multiple herbivory by T. absoluta and B. tabaci did not increase the attraction of the mirids compared to infestation with T. absoluta alone. Terpenoids represented the most important class of compounds in the volatile blends and there were significant differences between the volatile blends emitted by tomato plants in response to attack by T. absoluta, B. tabaci, or by both insects. We, therefore, conclude that all three mirids use tomato plant volatiles to find T. absoluta larvae. Multiple herbivory did neither increase, nor decrease attraction of C. infumatus, E. varians and M. basicornis. By breeding for higher rates of emission of selected terpenes, increased attractiveness of tomato plants to natural enemies may improve the effectiveness of biological control.

Qualitative and Quantitative Differences in Herbivore-Induced Plant Volatile Blends from Tomato Plants Infested by Either Tuta absoluta or Bemisia tabaci.

Plants release a variety of volatile organic compounds that play multiple roles in the interactions with other plants and animals. Natural enemies of plant-feeding insects use these volatiles as cues to find their prey or host. Here, we report differences between the volatile blends of tomato plants infested with the whitefly Bemisia tabaci or the tomato borer Tuta absoluta. We compared the volatile emission of: (1) clean tomato plants; (2) tomato plants infested with T. absoluta larvae; and (3) tomato plants infested with B. tabaci adults, nymphs, and eggs. A total of 80 volatiles were recorded of which 10 occurred consistently only in the headspace of T. absoluta-infested plants. Many of the compounds detected in the headspace of the two herbivory treatments were emitted at different rates. Plants damaged by T. absoluta emitted at least 10 times higher levels of many compounds compared to plants damaged by B. tabaci and intact plants. The multivariate separation of T. absoluta-infested plants from those infested with B. tabaci was due largely to the chorismate-derived compounds as well as volatile metabolites of C18-fatty acids and branched chain amino acids that had higher emission rates from T. absoluta-infested plants, whereas the cyclic sesquiterpenes α- and ß-copaene, valencene, and aristolochene were emitted at significantly higher levels from B. tabaci-infested plants. Our findings imply that feeding by T. absoluta and B. tabaci induced emission of volatile blends that differ quantitatively and qualitatively, providing a chemical basis for the recently documented behavioral discrimination by two generalist predatory mirid species, natural enemies of T. absoluta and B. tabaci employed in biological control.

Functional Responses of Three Neotropical Mirid Predators to Eggs of Tuta absoluta on Tomato.

Tuta absoluta (Meyrick) has quickly developed into a significant tomato pest worldwide. While the recently found mirid predators Macrolophus basicornis (Stal), Engytatus varians (Distant) and Campyloneuropsis infumatus (Carvalho) of this pest are able to establish and reproduce on tomato, biological knowledge of these mirids is still limited. Here we describe the functional response of the three mirid predators of the tomato pest T. absoluta when offered a range of prey densities (four, eight, 16, 32, 64, 128 and 256 eggs) during a 24 h period inside cylindrical plastic cages in the laboratory. Engytatus varians and M. basicornis showed a type III functional response, whereas C. infumatus showed a type II functional response. At the highest prey densities, C. infumatus consumed an average of 51.0 eggs, E. varians 91.1 eggs, and M. basicornis 100.8 eggs. Taking all information into account that we have collected of these three Neotropical mirid species, we predict that M. basicornis might be the best candidate for control of the tomato borer in Brazil: it has the highest fecundity, the largest maximum predation capacity, and it reacts in a density-dependent way to the widest prey range.

[Quality of different aphids species as hosts for the parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae: Aphidiinae)]. / Qualidade de diferentes espécies de pulgões como hospedeiros do parasitóide Aphidius ervi Haliday (Hymenoptera: Braconidae: Aphidiinae).

The suitability of Macrosiphum euphorbiae (Thomas), Aulacorthum solani (Kaltenbach) and Acyrthosiphon kondoi Shinji (Hemiptera: Aphididae) as hosts for the aphid parasitoid Aphidius ervi Haliday was evaluated by assessing host size, host preference, and host quality. Tests were carried out in an environmental chamber at 22±1ºC, 70±10% RH and 12h photophase. Replicates (11) consisted of one 24h-old mated female of A. ervi without a previous oviposition experience. Female was released into a Petri dish (5 cm) with 20 2nd and 3rd instars of one of each aphid species tested on a leaf disc of the host plant onto a 1% water-agar layer. Parasitoid emergency was lower in A. kondoi (78.7%) compared to M. euphorbiae (92.2%) and A. solani (91.7%). Acyrthosiphon kondoi (0.36 mm) was the smallest host. The parasitoid showed preference (74.0% parasitism) for M. euphorbiae, the largest host (hind tibia length=0.73 mm), which in turn yielded larger A. ervi females (0.75 mm).

Qualidade de diferentes espécies de pulgões como hospedeiros do parasitóide Aphidius ervi Haliday (Hymenoptera: Braconidae: Aphidiinae) / Quality of different aphids species as hosts for the parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae: Aphidiinae)

The suitability of Macrosiphum euphorbiae (Thomas), Aulacorthum solani (Kaltenbach) and Acyrthosiphon kondoi Shinji (Hemiptera: Aphididae) as hosts for the aphid parasitoid Aphidius ervi Haliday was evaluated by assessing host size, host preference, and host quality. Tests were carried out in an environmental chamber at 22 ± 1ºC, 70 ± 10 percent RH and 12h photophase. Replicates (11) consisted of one 24h-old mated female of A. ervi without a previous oviposition experience. Female was released into a Petri dish (5 cm) with 20 2nd and 3rd instars of one of each aphid species tested on a leaf disc of the host plant onto a 1 percent water-agar layer. Parasitoid emergency was lower in A. kondoi (78.7 percent) compared to M. euphorbiae (92.2 percent) and A. solani (91.7 percent). Acyrthosiphon kondoi (0.36 mm) was the smallest host. The parasitoid showed preference (74.0 percent parasitism) for M. euphorbiae, the largest host (hind tibia length = 0.73 mm), which in turn yielded larger A. ervi females (0.75 mm).

Avaliação de substratos de oviposição para Orius insidiosus (Say) (Hemiptera, Anthocoridae) / Evaluation of oviposition substrates for Orius insidiosus (Say) (Hemiptera, Anthocoridae)

Avaliação de substratos de oviposição para Orius insidiosus (Say) (Hemiptera, Anthocoridae). Fêmeas do predador O. insidiosus usam tecidos de plantas para colocação de seus ovos, o que caracteriza a oviposição endofítica. Este trabalho teve por objetivo avaliar diferentes substratos de oviposição para este predador. O estudo foi conduzido em sala climatizada a 25 ± 2ºC, UR de 70 ± 10 por cento e fotofase de 12 horas. Os substratos de oviposição utilizados foram brotos de feijão (Phaselus vulgaris L.), brotos de soja [Glycine max (L.) Merr.], brotos de batata (Solanum tuberosum L.), vagem de feijão (Phaselus vulgaris L.) e inflorescências de picão-preto (Bidens pilosa L.). Foram avaliados os números médio diário e total de ovos por um período de 15 dias, o número de adultos vivos em cada recipiente e a viabilidade na produção dos adultos. Todos os substratos testados foram aceitos pelas fêmeas. Entretanto, foi observado um número significativamente maior de ovos de O. insidiosus em brotos de feijão (4,3 ovos por dia) e brotos de soja (3,9 ovos por dia), comparado aos demais substratos avaliados. As menores (p< 0,05) viabilidades na produção de adultos de O. insidiosus (75,1 e 71,7 por cento) foram verificadas a partir dos ovos colocados em brotos de batata e vagem de feijão, respectivamente. Brotos de feijão e brotos de soja foram adequados para a utilização na criação de O. insidiosus em laboratório, com vantagens de poderem ser produzidos durante todo o ano sem necessitar de grandes áreas para isso, reduzindo assim os custos e o trabalho com a sua obtenção e preparo para uso no sistema de criação do predador. Esses resultados poderão auxiliar na criação massal de O. insidiosus em laboratório, visando à liberação do mesmo em programas de controle biológico de tripes.

Females of O. insidiosus deposit their eggs in the plant tissue. This study aimed to evaluate oviposition substrates for this predator. The study was conducted in an air-conditioned room at 25 ± 2ºC, 70 ± 10 percent RH, and a 12 h photophase. The oviposition substrates used consisted of bean sprouts (Phaseolus vulgaris L.), soybean sprouts [Glycine max (L.) Merr.], potato sprouts (Solanum tuberosum L.), bean pods (Phaseolus vulgaris L.), and farmer's friend inflorescences (Bidens pilosa L.). Evaluations included the daily mean and total numbers of eggs per female during a 15-day period, the number of live adults in each container, and adult production viability. All substrates tested were accepted by the females. However, a significantly higher number of O. insidiosus eggs was found on bean sprouts (4.3 eggs per day) and soybean sprouts (3.9 eggs per day), when compared with the other substrates evaluated. The lowest (p<0,05) viability values in the production of O. insidiosus adults (75.1 and 71.7 percent) were observed from eggs laid on potato sprouts and bean pods, respectively. Bean and soybean sprouts were suitable to rear O. insidiosus in the laboratory; these substrates have the additional advantages of being produced throughout the year without requiring large areas for its production, thus reducing the costs and labor necessary to obtain and prepare them to be use on the mass-rearing system. These results may be useful in the mass rearing of O. insidiosus in the laboratory, with the objective of releasing the predator in biological control programs against thrips.

[Quality of different aphids as hosts of the parasitoid Lysiphlebus testaceipes (Cresson) (Hymenoptera: Braconidae, Aphidiinae)]. / Qualidade de diferentes espécies de pulgões como hospedeiros do parasitóide Lysiphlebus testaceipes (Cresson) (Hymenoptera: Braconidae, Aphidiinae).

Lysiphlebus testaceipes (Cresson) has a broad aphid host range; however the quality of these preys may interfere in its biological feature. This study aimed to evaluate the quality of three Macrosiphini, Brevicoryne brassicae (L.), Lipaphis erysimi (Kaltenbach) and Myzus persicae (Sulzer), and three Aphidini Schizaphis graminum (Rondani) Rhopalosiphum maidis (Fitch) and Aphis gossypii Glover as hosts to L. testaceipes and to determine the relation possible of host preference, of size and quality of the host. The tests were carried out in climatic chamber at 25 +/- 1 degrees C, RH 70 +/- 10% and 12h photophase. The parasitoid did not oviposite in B. brassicae and L. erysimi, while the other species were nutritionally suitable to the parasitoid. L. testaceipes showed preference for aphids from tribe Aphidini and these hosts presented better quality to the parasitoid when compared to Macrosiphini. Interactions among size, preference and quality between the Aphidini were found. L testaceipes showed preference (parasitism rate 76.7%) for R. maidis, the bigger host (hind tibia with 0.281 mm). This host provided bigger size (hind tibia with 0.49 mm) and higher emergence rate (95.6%) to the parasitoid when compared to A. gossypii (parasitism rate of 55.7%). Also the smaller host A. gossypii (0.266 mm) provided smaller size hind tibia (0.45 mm) and higher mortality of the parasitoid (emergence rate 72.1%). However, the development time was shorter and the longevity was higher in A. gossypii (6.3 and 5.4 days, respectively) when compared to the host R. maidis (6.7 and 3.8 days, respectively), and not been related to host size.

Qualidade de diferentes espécies de pulgões como hospedeiros do parasitóide Lysiphlebus testaceipes (Cresson) (Hymenoptera: Braconidae, Aphidiinae) / Quality of different aphids as hosts of the parasitoid Lysiphlebus testaceipes (Cresson) (Hymenoptera: Braconidae, Aphidiinae)

O endoparasitóide solitário Lysiphlebus testaceipes (Cresson) tem uma ampla faixa de afídeos hospedeiros e a qualidade desses afídeos pode interferir nos parâmetros biológicos do mesmo. Este trabalho teve como objetivo avaliar a qualidade de três Macrosiphini, Brevicoryne brassicae (L.), Lipaphis erysimi (Kaltenbach) e Myzus persicae (Sulzer), e três Aphidini, Schizaphis graminum (Rondani), Rhopalosiphum maidis (Fitch) e Aphis gossypii Glover, como hospedeiros de L. testaceipes e determinar a possível relação da preferência do parasitóide com o tamanho e a qualidade do hospedeiro. Os testes foram conduzidos em câmara climática a 25 ± 1°C, 70 ± 10 por cento UR e 12h fotofase. O parasitóide não ovipositou em B. brassicae e L. erysimi e as demais espécies foram adequadas nutricionalmente ao parasitóide. L. testaceipes apresentou preferência por pulgões da tribo Aphidini e esses hospedeiros apresentaram maior qualidade para o parasitóide quando comparados aos Macrosiphini. Foi encontrada relação entre tamanho, preferência e qualidade entre os Aphidini. O parasitóide apresentou preferência (76,7 por cento de parasitismo) por R. maidis, o maior hospedeiro (tíbia posterior de 0,281 mm), e este proporcionou maior tamanho (tíbia posterior de 0,49 mm) e emergência (95,6 por cento) ao parasitóide quando comparado a A. gossypii (55,7 por cento de parasitismo), hospedeiro menor (0,266 mm) e que proporcionou menor tamanho (0,45 mm) e maior mortalidade ao parasitóide (72,1 por cento de emergência). Contudo, o desenvolvimento de ovo a múmia foi menor e a longevidade foi maior em A. gossypii (6,3 e 5,4 dias respectivamente) do que em R. maidis (6,7 e 3,8 dias respectivamente), não estando relacionados ao tamanho do hospedeiro.

Lysiphlebus testaceipes (Cresson) has a broad aphid host range; however the quality of these preys may interfere in its biological feature. This study aimed to evaluate the quality of three Macrosiphini, Brevicoryne brassicae (L.), Lipaphis erysimi (Kaltenbach) and Myzus persicae (Sulzer), and three Aphidini Schizaphis graminum (Rondani) Rhopalosiphum maidis (Fitch) and Aphis gossypii Glover as hosts to L. testaceipes and to determine the relation possible of host preference, of size and quality of the host. The tests were carried out in climatic chamber at 25 ± 1°C, RH 70 ± 10 percent and 12h photophase. The parasitoid did not oviposite in B. brassicae and L. erysimi, while the other species were nutritionally suitable to the parasitoid. L. testaceipes showed preference for aphids from tribe Aphidini and these hosts presented better quality to the parasitoid when compared to Macrosiphini. Interactions among size, preference and quality between the Aphidini were found. L testaceipes showed preference (parasitism rate 76.7 percent) for R. maidis, the bigger host (hind tibia with 0.281 mm). This host provided bigger size (hind tibia with 0.49 mm) and higher emergence rate (95.6 percent) to the parasitoid when compared to A. gossypii (parasitism rate of 55.7 percent). Also the smaller host A. gossypii (0.266 mm) provided smaller size hind tibia (0.45 mm) and higher mortality of the parasitoid (emergence rate 72.1 percent). However, the development time was shorter and the longevity was higher in A. gossypii (6.3 and 5.4 days, respectively) when compared to the host R. maidis (6.7 and 3.8 days, respectively), and not been related to host size.

[Fertility life table of Aphidius colemani Viereck (Hymenoptera: Braconidae, Aphidiinae) on Aphis gossypii Glover (Hemiptera: Aphididae)]. / Tabela de vida de fertilidade de Aphidius colemani Viereck (Hymenoptera: Braconidae, Aphidiinae) em Aphis gossypii Glover (Hemiptera: Aphididae).

The intrinsic rate of increase of a parasitoid related to its hosts play an important role in biological control programs. In this work, fertility of the parasitoid Aphidius colemani Viereck was evaluated on Aphis gossypii Glover by means of a fertility life table. To determine the immature mortality, the development time and the sex ratio, 12 mated females of A. colemani (24h old), and 240 nymphs of A. gossypii (3 days old) were used. To evaluate fertility 15 mated females (24h old) were used. For each parasitoid female, 300 nymphs were offered in the 1st day, 250 nymphs in the 2nd day, 200 nymphs in the 3rd day, 150 nymphs in the 4th day, 100 nymphs in the 5th day and 50 nymphs in the other days. Immature mortality of A. colemani was 22.1%, development time of males and females were 12.0 and 11.8 days, respectively, and sex ratio was 0.6. The females of A. colemani laid 420 eggs and had longevity of 5.9 days. The net reproduction rate (R(o)) was 194.81 females and the intrinsic rate of increase (r(m)) was 0.384 females/females/day. The finite rate of increase (lambda) was 1.48 females/day, the mean length of a generation (T) was 13.74 days and the time to duplication the population (TD) was 12.60 days. The parasitoid A. colemani had a great potential of population growth on A. gossypii as a host and could be an effective biological control agent of this aphid.

[Development of Aphidius colemani Viereck (Hym.: Braconidae, Aphidiinae) and alterations caused by the parasitism in the host Aphis gossypii Glover (Hem.: Aphididae) in different temperatures]. / Desenvolvimento de Aphidius colemani Viereck (Hymenoptera: Braconidae, Aphidiinae) e alterações causadas pelo parasitismo no hospedeiro Aphis gossypii Glover (Hemiptera: Aphididae) em diferentes temperaturas.

Aphidius colemani Viereck is among the main natural enemies used for biological control of Aphis gossypii Glover. The objective of the present study was to evaluate the development of A. colemani and the alterations caused by the parasitism in the host A. gossypii in different temperatures and to estimate the thermal requirements of the parasitoid. The experiments were carried out in controlled environmental chambers at 16, 19, 22, 25, 28 and 31 +/- 1 degrees C, 70 +/- 10% RH, and 12h photophase. Second-instar nymphs of A. gossypii were parasitized once and kept individually in glass tubes (2.5 cm x 8.5 cm), containing leaf disc of cucumber (2 cm) and 1% water/agar solution. The development time of A. colemani, from oviposition to mummies (11.9, 9.8, 7.7, 6.4 and 6.4 days) and from oviposition to adult (19.4, 16.2, 12.6, 10.5 and 10.7 days) decreased with the increase of the temperature from 16 degrees C to 25 degrees C. The rates of mummies and the emergence of the parasitoid, and its longevity also decreased with the increase of the temperature. Mummies were not produced at 31 degrees C. The lower temperature threshold of A. colemani was 5.94 degrees C and its thermal constant was 200 degrees-day. The alterations caused by the parasitoid in the A. gossypii host were minimized at 31 degrees C, where 98% of the host did not show symptoms of parasitism and produced nymphs. The temperature of 22 degrees C was optimal for the development time of A. colemani.

Tabela de vida de fertilidade de Aphidius colemani Viereck (Hymenoptera: Braconidae, Aphidiinae) em Aphis gossypii Glover (Hemiptera: Aphididae) / Fertility life table of Aphidius colemani Viereck (Hymenoptera: Braconidae, Aphidiinae) on Aphis gossypii Glover (Hemiptera: Aphididae)

A taxa intrínseca de crescimento populacional de um parasitóide relacionada ao hospedeiro tem papel importante em programas de controle biológico. Este trabalho avaliou a fertilidade de Aphidius colemani Viereck sobre Aphis gossypii Glover, por meio de tabela de vida de fertilidade. Na avaliação da mortalidade de imaturos, desenvolvimento e razão sexual de A. colemani foram utilizadas 12 fêmeas, acasaladas, com 24h de idade e 240 ninfas de A. gossypii (com três dias de idade). Na avaliação da fertilidade foram utilizadas 15 fêmeas. O número de ninfas do pulgão oferecidas durante o ciclo de vida do parasitóide foram oferecidas: 300 ninfas no 1° dia, 250 ninfas no 2°, 200 ninfas no 3°, 150 ninfas no 4°, 100 ninfas no 5° dia, e 50 ninfas nos dias subseqüentes. A mortalidade de imaturos de A. colemani foi de 22,1 por cento. O desenvolvimento de machos e fêmeas foi de 12,0 e 11,8 dias, respectivamente e a razão sexual de 0,6. As fêmeas de A. colemani depositaram 420 ovos e tiveram longevidade de 5,9 dias. A taxa líquida de reprodução (Ro) foi de 194,81 fêmeas, a taxa intrínseca de crescimento populacional (r m) de 0,384 fêmeas/fêmea/dia, a razão finita de aumento (lambda) de 1,48 fêmeas/dia, tempo médio entre gerações (T) de 13,74 dias e o tempo de duplicação da população (TD) de 12,60 dias. A. colemani apresenta alto potencial de crescimento populacional, tendo como hospedeiro A. gossypii, podendo ser um agente efetivo de controle biológico deste afídeo.

The intrinsic rate of increase of a parasitoid related to its hosts play an important role in biological control programs. In this work, fertility of the parasitoid Aphidius colemani Viereck was evaluated on Aphis gossypii Glover by means of a fertility life table. To determine the immature mortality, the development time and the sex ratio, 12 mated females of A. colemani (24h old), and 240 nymphs of A. gossypii (3 days old) were used. To evaluate fertility 15 mated females (24h old) were used. For each parasitoid female, 300 nymphs were offered in the 1st day, 250 nymphs in the 2nd day, 200 nymphs in the 3rd day, 150 nymphs in the 4th day, 100 nymphs in the 5th day and 50 nymphs in the other days. Immature mortality of A. colemani was 22.1 percent, development time of males and females were 12.0 and 11.8 days, respectively, and sex ratio was 0.6. The females of A. colemani laid 420 eggs and had longevity of 5.9 days. The net reproduction rate (Ro) was 194.81 females and the intrinsic rate of increase (r m) was 0.384 females/females/day. The finite rate of increase (lambda) was 1.48 females/day, the mean length of a generation (T) was 13.74 days and the time to duplication the population (TD) was 12.60 days. The parasitoid A. colemani had a great potential of population growth on A. gossypii as a host and could be an effective biological control agent of this aphid.

Desenvolvimento de Aphidius colemani Viereck (Hymenoptera: Braconidae, Aphidiinae) e alterações causadas pelo parasitismo no hospedeiro Aphis gossypii Glover (Hemiptera: Aphididae) em diferentes temperaturas / Development of Aphidius colemani Viereck (Hym.: Braconidae, Aphidiinae) and alterations caused by the parasitism in the host Aphis gossypii Glover (Hem.: Aphididae) in different temperatures

Aphidius colemani Viereck está entre os principais inimigos naturais utilizados no controle biológico de Aphis gossypii Glover. Os objetivos deste trabalho foram avaliar o desenvolvimento de A. colemani e as alterações causadas pelo parasitismo no hospedeiro A. gossypii em diferentes temperaturas e estimar as exigências térmicas do parasitóide. O experimento foi conduzido em câmaras climatizadas a 16, 19, 22, 25, 28 e 31 ± 1°C, com 70 ± 10 por cento U.R. e fotofase de 12h. Ninfas de 2° instar de A. gossypii foram parasitadas uma vez e individualizadas em tubos de vidro (2,5 cm x 8,5 cm), contendo disco foliar de pepino (2 cm) e solução agar/água a 1 por cento. O período da oviposição à formação da múmia (11,9; 9,8; 7,7; 6,4 e 6,4 dias) e o da oviposição ao adulto de A. colemani (19,4; 16,2; 12,6; 10,5 e 10,7 dias) diminuíram com o aumento da temperatura no intervalo de 16°C e 25°C. A porcentagem de múmias formadas e a de emergência do parasitóide, assim como a longevidade diminuíram com o incremento da temperatura. Não houve formação de múmias a 31°C. O parasitóide A. colemani apresentou temperatura base inferior de desenvolvimento de 5,94°C e constante térmica de 200 GD. As alterações ocasionadas no hospedeiro A. gossypii pelo parasitismo foram minimizadas na temperatura de 31°C, sendo que 98 por cento dos hospedeiros não apresentaram sintomas de parasitismo e produziram ninfas. A temperatura de 22°C foi a mais adequada para o desenvolvimento de A. colemani.

Aphidius colemani Viereck is among the main natural enemies used for biological control of Aphis gossypii Glover. The objective of the present study was to evaluate the development of A. colemani and the alterations caused by the parasitism in the host A. gossypii in different temperatures and to estimate the thermal requirements of the parasitoid. The experiments were carried out in controlled environmental chambers at 16, 19, 22, 25, 28 and 31 ± 1°C, 70 ± 10 percent RH, and 12h photophase. Second-instar nymphs of A. gossypii were parasitized once and kept individually in glass tubes (2.5 cm x 8.5 cm), containing leaf disc of cucumber (2 cm) and 1 percent water/agar solution. The development time of A. colemani, from oviposition to mummies (11.9, 9.8, 7.7, 6.4 and 6.4 days) and from oviposition to adult (19.4, 16.2, 12.6, 10.5 and 10.7 days) decreased with the increase of the temperature from 16°C to 25°C. The rates of mummies and the emergence of the parasitoid, and its longevity also decreased with the increase of the temperature. Mummies were not produced at 31°C. The lower temperature threshold of A. colemani was 5.94°C and its thermal constant was 200 degrees-day. The alterations caused by the parasitoid in the A. gossypii host were minimized at 31°C, where 98 percent of the host did not show symptoms of parasitism and produced nymphs. The temperature of 22°C was optimal for the development time of A. colemani.

Influence of photoperiod on Orius thyestes Herring (Hemiptera: Anthocoridae) reproduction and longevity.

Several species of Orius Wolff are used in biological control of thrips in protected cultivations in temperate regions, but some of them show reproductive diapause, compromising the efficiency of these agents of biological control. There are no reports on the biology of the neotropical species Orius thyestes Herring under different environmental conditions. The purpose of this work was to investigate the influence of photoperiod on reproduction and longevity of this predator. Nymphs were kept in petri dishes in climatic chambers at 28+/-1 degree C, 70+/-10% RH and under the photoperiods of 12L:12D, 11L:13D, 10 L:14D e 09L:15D. The mating adults were kept in petri dishes with Bidens pilosa L. Asteraceae inflorescences as oviposition substracts and eggs of Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) as food. The pre-oviposition and oviposition periods, fecundity and longevity were evaluated and O. thyestes did not show reprodutive diapause in all photoperiod conditions established. The mean number of eggs obtained per female decreased with the reduction of the photophase, with a difference (P < 0.05) between the values obtained in 12h and 9h of photophase. Longevity of females and males under 9h photophase was shorter (P < 0.05) than in all other photoperiods tested. The knowledge of the biology of the natural enemy under different conditions allows to optimise the mass rearing and to predict the performance of the predator in different photoperiods which may occur along the year and in greenhouses.

Influence of photoperiod on Orius thyestes Herring (Hemiptera: Anthocoridae) reproduction and longevity

Several species of Orius Wolff are used in biological control of thrips in protected cultivations in temperate regions, but some of them show reproductive diapause, compromising the efficiency of these agents of biological control. There are no reports on the biology of the neotropical species Orius thyestes Herring under different environmental conditions. The purpose of this work was to investigate the influence of photoperiod on reproduction and longevity of this predator. Nymphs were kept in petri dishes in climatic chambers at 28 ± 1°C, 70 ± 10 percent RH and under the photoperiods of 12L:12D, 11L:13D, 10L:14D e 09L:15D. The mating adults were kept in petri dishes with Bidens pilosa L. Asteraceae inflorescences as oviposition substracts and eggs of Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) as food. The pre-oviposition and oviposition periods, fecundity and longevity were evaluated and O. thyestes did not show reprodutive diapause in all photoperiod conditions established. The mean number of eggs obtained per female decreased with the reduction of the photophase, with a difference (P < 0.05) between the values obtained in 12h and 9h of photophase. Longevity of females and males under 9h photophase was shorter (P < 0.05) than in all other photoperiods tested. The knowledge of the biology of the natural enemy under different conditions allows to optimise the mass rearing and to predict the performance of the predator in different photoperiods which may occur along the year and in greenhouses.

Várias espécies de Orius Wolff são utilizadas no controle biológico de tripes em cultivos protegidos em regiões temperadas, entretanto algumas delas apresentam diapausa reprodutiva, comprometendo a atuação desses agentes de controle biológico. Não existem relatos sobre a biologia da espécie neotropical Orius thyestes Herring em diferentes condições ambientais. Este trabalho objetivou verificar a influência do fotoperíodo na reprodução e longevidade desse predador. Ninfas foram individualizadas em placas de Petri e mantidas em câmaras climatizadas a 28 ± 1°C, UR de 70 ± 10 por cento e nos fotoperíodos de 12L:12E, 11L:13E, 10L:14E e 09L:15E. Os adultos foram acasalados em placas de Petri contendo inflorescência de Bidens pilosa L. Asteraceae como substrato de oviposição e ovos de Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) como alimento. Foram avaliados os períodos de pré-oviposição e oviposição, fecundidade e longevidade de fêmeas e machos. Em nenhuma das condições de fotoperíodos avaliadas O. thyestes apresentou diapausa reprodutiva. O número médio de ovos por fêmea diminuiu proporcionalmente ao número de horas de luz, com diferença (P < 0,05) entre os valores obtidos em 12h e 9h de luz. A longevidade de fêmeas e machos do predador sob fotofase de 9h foi menor (P < 0,05) que as longevidades observadas nos demais fotoperíodos testados. O conhecimento sobre a biologia do inimigo natural em diferentes condições permite otimizar a criação massal e prever o desempenho do predador em diferentes fotoperíodos que podem ocorrer ao longo do ano e no interior das casas de vegetação.

Desenvolvimento e parasitismo de Lysiphlebus testaceipes (Cresson) e Aphidius colemani Viereck (Hymenoptera: Braconidae) em Aphis gossypii Glover (Hemiptera: Aphididae) em duas cultivares de crisântemo / Development and parasitism of Lysiphlebus testaceipes (Cresson) and Aphidius colemani Viereck (Hymenoptera: Braconidae) on Aphis gossypii Glover (Hemiptera: Aphididae) on two chrysanthemum cultivars

Os parasitóides Lysiphlebus testaceipes (Cresson) e Aphidius colemani Viereck desempenham importante papel na regulação das populações de afídeos que atacam crisântemo em ambientes protegidos. O objetivo deste estudo foi avaliar a interação controle biológico e resistência de plantas, por meio do desenvolvimento e parasitismo de L. testaceipes e A. colemani no pulgão Aphis gossypii Glover mantido nas cultivares comerciais de crisântemo suscetível Yellow Snowdon (YS) e resistente White Reagan (WR). O experimento foi conduzido em câmara climática à temperatura de 22 ± 1°C, UR de 70 ± 10 por cento e fotofase de 12h, utilizando ninfas de 2° e 3° ínstares de A. gossypii atacadas apenas uma vez pelos parasitóides. O desenvolvimento foi de 15,0 e 12,9 dias, para L. testaceipes e de 17,0 e 16,3 dias para A. colemani em A. gossypii nas cvs. YS e WR, respectivamente. O parasitismo por L. testaceipes foi maior em A. gossypii na cv. YS (68,4 por cento), quando comparado com WR (50,0 por cento), sendo que para A. colemani não houve diferença significativa (46,8 e 35,0 por cento para YS e WR, respectivamente). As porcentagens de emergência de L. testaceipes e A. colemani em A. gossypii mantido em YS e WR foram, respectivamente 91,6 por cento e 85,3 por cento e 78,1 por cento e 100,0 por cento. A longevidade de A. colemani e a taxa de parasitismo de L. testaceipes foram influenciadas negativamente pela cultivar WR. Os resultados indicam uma interação positiva entre controle biológico com parasitóides e a cultivar resistente WR no controle de A. gossypii em crisântemo em sistema protegido.

The parasitoids Lysiphlebus testaceipes (Cresson) and Aphidius colemani Viereck play an important role on the regulation of aphid populations on chrysanthemum grown in greenhouses. This study evaluated the interaction of biological control and plant resistance by the development and the parasitism of L. testaceipes and A. colemani on Aphis gossypii Glover. The aphid host was kept on commercial cultivars of chrysanthemum susceptible Yellow Snowdon (YS) and resistant White Reagan (WR). The experiment was carried out in climatic chamber at 22 ± 1°C, 70 ± 10 percent RH, and photophase 12h. Nymphs of 2nd and 3rd instars of A. gossypii attacked only once by the parasitoids were used in the experiment. The development time was 15.0 and 12.9 days for L. testaceipes and 17.0 and 16.3 days for A. colemani kept on A gossypii on cvs. YS and WR, respectively. The parasitoid L. testaceipes showed greater parasitism rate (68.4 percent) on A. gossypii on cv. YS than on WR (50 percent), and for A. colemani was not found significative difference on parasitism (46.8 and 35 percent to YS and WR, respectively). The emergence rates of L. testaceipes and A. colemani were 91.6 percent and 85.3 percent on A gossypii reared on YS, and 78.1 percent and 100 percent on WR, respectively. The longevity of A colemani and the parasitism rate of L. testaceipes were affected in a negative way by the cv. WR. The results indicated a positive interaction of biological control with parasitoids and the resistant cv. WR on A. gossypii control in protected cultivation.

[Development and parasitism of Lysiphlebus testaceipes (Cresson) and Aphidius colemani Viereck (Hymenoptera: Braconidae) on Aphis gossypii Glover (Hemiptera: Aphididae) on two chrysanthemum cultivars]. / Desenvolvimento e parasitismo de Lysiphlebus testaceipes (Cresson) e Aphidius colemani Viereck (Hymenoptera: Braconidae) em Aphis gossypii Glover (Hemiptera: Aphididae) em duas cultivares de crisântemo.

The parasitoids Lysiphlebus testaceipes (Cresson) and Aphidius colemani Viereck play an important role on the regulation of aphid populations on chrysanthemum grown in greenhouses. This study evaluated the interaction of biological control and plant resistance by the development and the parasitism of L. testaceipes and A. colemani on Aphis gossypii Glover. The aphid host was kept on commercial cultivars of chrysanthemum susceptible Yellow Snowdon (YS) and resistant White Reagan (WR). The experiment was carried out in climatic chamber at 22 +/- 1 masculineC, 70 +/- 10% RH, and photophase 12h. Nymphs of 2nd and 3rd instars of A. gossypii attacked only once by the parasitoids were used in the experiment. The development time was 15.0 and 12.9 days for L. testaceipes and 17.0 and 16.3 days for A. colemani kept on A gossypii on cvs. YS and WR, respectively. The parasitoid L. testaceipes showed greater parasitism rate (68.4%) on A. gossypii on cv. YS than on WR (50%), and for A. colemani was not found significative difference on parasitism (46.8 and 35% to YS and WR, respectively). The emergence rates of L. testaceipes and A. colemani were 91.6% and 85.3% on A gossypii reared on YS, and 78.1% and 100% on WR, respectively. The longevity of A colemani and the parasitism rate of L. testaceipes were affected in a negative way by the cv. WR. The results indicated a positive interaction of biological control with parasitoids and the resistant cv. WR on A. gossypii control in protected cultivation.

Desenvolvimento, consumo ninfal e exigências térmicas de Orius thyestes Herring (Hemiptera: Anthocoridae) / Development, nymphal consumption and thermal requirements of Orius thyestes Herring (Hemiptera: Anthocoridae)

A temperatura e o alimento têm um importante papel no desenvolvimento e nas atividades de adultos de espécies de Orius, e esses parâmetros biológicos são fundamentais para propósitos de criação massal de inimigos naturais e seu uso em programas de controle biológico. O objetivo deste trabalho foi avaliar a influência de diferentes temperaturas no desenvolvimento ninfal do predador Orius thyestes Herring alimentado com ovos de Anagasta kuehniella (Zeller). Também foram determinadas as exigências térmicas e o consumo ninfal. O experimento foi conduzido em câmaras climáticas a 16, 19, 22, 25, 28 e 31 ± 1°C, UR de 70 ± 10 por cento e fotofase de 12h. O. thyestes apresentou cinco ínstares. O período ninfal foi cerca de seis vezes maior a 31°C (9,8 dias) do que a 16°C (58,2 dias). A menor sobrevivência ninfal do predador foi a 16°C, com somente 40 por cento das ninfas atingindo a fase adulta. Maiores percentagens de sobrevivência das ninfas foram observadas a 22°C (96,4 por cento), 25°C (94,5 por cento) e 28°C (100 por cento). Cada ninfa de O. thyestes consumiu 39,4 ovos de A. kuehniella. O predador apresentou temperatura base e constante térmica para a fase ninfal de 12,8°C e 173,82 graus-dia, respectivamente. O intervalo mais adequado para o desenvolvimento de O. thyestes situa-se entre 22°C e 28°C. O. thyestes provavelmente encontra melhores chances de colonização e estabelecimento em regiões tropicais e subtropicais.

Temperature and food play an important part in the development time and adult activities of Orius species, and these biological parameters are important for purpose of mass rearing of natural enemies for use on biological control programs. The objective of this research was to evaluate the influence of different temperatures on nymphal development of Orius thyestes Herring when fed with Anagasta kuehniella (Zeller) eggs in climatic chambers at 16, 19, 22, 25, 28 and 31 ± 1°C, 70 ± 10 percent RH and 12h photophase. The thermal requirements and nymphal consumption were also determined. O. thyestes presented five instars. The nymphal period was about six times shorter at 31°C (9.8 days) than at 16°C (58.2 days). Nymph survival was lowest at 16°C, with only 40 percent of the nymphs reaching adult stage. The higher nymph survival were found at 22°C (96.4 percent), 25°C (94.5 percent) and 28°C (100 percent). Each nymph of O. thyestes consumed 39.4 eggs of A. kuehniella. The lower temperature threshold and thermal constant for the nymphal development of O. thyestes were 12.8°C and 173.82 day-degrees, respectively. The interval from 22°C to 28°C is more suitable for nymphal development of O. thyestes. O. thyestes finds probably better chance for colonization and establishment in tropical and subtropical regions.

Adequabilidade de diferentes substratos à oviposição do predador Orius insidiosus ( Say ) ( Hemiptera: Anthocoridae ) / Suitability of different substrates for oviposition of the predator Orius insidiosus ( Say ) ( Hemiptera: Anthocoridae )

Fêmeas de Orius insidiosus (Say) colocam seus ovos endofíticamente, em diversas plantas, e um obstáculo para a criação massal desse predador é a seleção de um substrato de oviposição que seja de fácil obtenção e aceito pelo inseto. O objetivo deste estudo foi avaliar a preferência e a adeqüabilidade de diferentes substratos de oviposição para O. insidiosus. Os testes foram conduzidos em câmaras climatizadas reguladas a 25 ± 1°C, UR de 70 ±10 por cento e fotofase de 12h. Os substratos avaliados quanto à preferência e adequabilidade foram caule de caruru (Amaranthus viridis L.), caule e vagem de feijão (Phaseolus vulgaris L.), vagem de feijão-de-vagem (Phaseolus vulgaris L.) e inflorescências de picão-preto (Bidens pilosa L.). Na adequabilidade também foi avaliado o caule de poaia-do-campo (Spermacoce latifola Aubl.). Fêmeas submetidas aos testes com e sem chance de escolha preferiram ovipositar em inflorescências de picão-preto. O período de pré-oviposição foi influenciado pelo tipo de substrato, sendo menor na presença da inflorescência de picão-preto (3,0 dias) e no feijão, tanto no caule (3,1dias) como na vagem (3,7 dias) comparado aos demais substratos. O período de oviposição, bem como a longevidade foram cerca de três a quatro vezes menores na presença do caule de poaia-do-campo (8,9 dias). O número total de ovos/fêmea de O. insidiosus foi maior em inflorescências de picão-preto (163,3 ovos). Os resultados indicam a adeqüabilidade das inflorescências de picão-preto como substrato de oviposição para O. insidiosus, sendo o preferido nos testes, com e sem chance de escolha, e onde as fêmeas apresentaram melhor performance reprodutiva.