Resistance and behavioural response of Plutella xylostella (Lepidoptera: Plutellidae) populations to Bacillus thuringiensis formulations.

BACKGROUND: Insecticide resistance is probably the major cause of control failure of Plutella xylostella (L.) in Brazil. In most production regions, the use of chemicals has been the prevalent method of control, with reduced efficacy through cropping seasons, even for the most recent use of products based on Bacillus thuringiensis (Bt). The current status of the resistance to these products was assessed, as well as the behavioural response of P. xylostella populations to Bt sprays. RESULTS: Most populations of P. xylostella were resistant to Bt products, particularly to Xentari®WDG (2-54-fold). Differences in walking characteristics of larvae were variable for most populations, for both Dipel®WP and Xentari®WDG, but not associated with resistance. Most females preferred to lay eggs on untreated surfaces and showed a reduced proportion of oviposition on treated surfaces that only correlated with resistance to Dipel®WP (r = -0.74, P = 0.02). CONCLUSION: Broad and indiscriminate use of Bt-based products has selected Brazilian P. xylostella populations to resistance. Larval movement appears to be a resistance-independent mechanism. Most populations of P. xylostella preferred to lay eggs on Bt-free surfaces, which might be a result of growers' practice of spraying the cabbage head. Reduced oviposition on treated surfaces correlated with physiological resistance, suggesting a behavioural response among the Bt-resistant colonies to Dipel®WP.

New records of natural enemies of Plutella xylostella (L.) (Lepidoptera: Plutellidae) in Pernambuco, Brazil.

We report the occurrence of natural enemies of Plutella xylostela (L.) in organically farmed kale in Pernambuco, Brazil. Seven natural enemies were observed parasitizing or preying on larvae and pupae of P. xylostella--three parasitoids: Cotesia plutellae Kurdjumov (Hym.: Braconidae), Conura pseudofulvovariegata (Becker) (Hym.: Chalcididae) and Tetrastichus howardi (Olliff) (Hym.: Eulophidae), and four predators: Cheiracanthium inclusum (Hentz) (Araneae: Miturgidae), Pheidole sp.Westwood (Hym.: Formicidae), nymphs and adults of Podisus nigrispinus (Dallas) (Hem.: Pentatomidae), and one unidentified species of solitary wasp. Beyond recording these natural enemies, data on predation of P. xylostella larvae in the field and laboratory by C. inclusum are presented.

New records of natural enemies of Plutella xylostella (L.) (Lepidoptera: Plutellidae) in Pernambuco, Brazil

We report the occurrence of natural enemies of Plutella xylostela (L.) in organically farmed kale in Pernambuco, Brazil. Seven natural enemies were observed parasitizing or preying on larvae and pupae of P. xylostella - three parasitoids: Cotesia plutellae Kurdjumov (Hym.: Braconidae), Conura pseudofulvovariegata (Becker) (Hym.: Chalcididae) and Tetrastichus howardi (Olliff) (Hym.: Eulophidae), and four predators: Cheiracanthium inclusum (Hentz) (Araneae: Miturgidae), Pheidole sp.Westwood (Hym.: Formicidae), nymphs and adults of Podisus nigrispinus (Dallas) (Hem.: Pentatomidae), and one unidentified species of solitary wasp. Beyond recording these natural enemies, data on predation of P. xylostella larvae in the field and laboratory by C. inclusum are presented.

Hypertrophied myocardium is more dependent on extracellular calcium than the normal cardiac muscle.

BACKGROUND: The aim of this study was to analyze stable hypertrophied myocardial function and its response to inotropic maneuvers in rats submitted to renovascular hypertension for a 10-week period (RHT group, n=10). MATERIAL/METHODS: Myocardial performance was studied in isolated left ventricle papillary muscles in isometric contraction under the following conditions: at postrest contraction of 30 seconds (PRC), at extracellular calcium (ECa2+) chloride concentration of 1.25 and 5.20 mM, and after beta-adrenergic stimulation with 10-6 M isoproterenol (ISOP). RESULTS: The results were compared with normotensive Wistar controls rats (C group, n=10). In basal condition, resting tension, and contraction time (TPT) were greater, while relaxation time (RT50) tended to be longer in RHT than C group. PRC and ISOP promoted a similar change in muscle function response intensity (delta) in both groups. ECa2+ shift did not change TPT in the C group and decreased TPT in the RHT animals; delta was different between these groups. RT50 increased in C and decreased in RHT, both without statistical significance; however, delta was different. CONCLUSIONS: These results suggest that hypertrophied myocardial dysfunction may be attributed to changes in intracellular calcium cycling.

[Thermal requirements of the coconut pest Atheloca subrufella (Hulst) (Lepidoptera: Phycitidae)]. / Exigências térmicas da praga do coqueiro Atheloca subrufella (Hulst)(Lepidoptera: Phycitidae).

Among the important pests of coconut, the coconut moth Atheloca subrufella (Hulst) is a significant pest of flowers and fruits, and is found across all coconut-producing regions in Brazil. We investigated the thermal requirements of A. subrufella and estimated the number of generations for two different growing coconut regions in Pernambuco State. The developmental time of all immature stages reduced as the temperature increased. The egg to adult period ranged from 19.3 to 59.8 days from 32 degrees C to 18 degrees C, respectively. The survival of the period from egg to adult was 25% at extreme temperatures (18 degrees C and 32 degreesC), while at the intermediate temperatures it was over 72%. Based on the thermal requirements determined for A. subrufella and the average temperatures determined for "Zona da Mata" and "Sertão" of Pernambuco State, it was estimated that A. subrufella is able to complete up to 13 generations per year in both areas. These results indicate that A. subrufella exhibited development and reproduction limited by temperatures higher than 32 degrees C and lower than 18 degrees C. However, based on the thermal requirements of A. subrufella and the mean temperatures of the "Zona da Mata" and "Sertão" of Pernambuco State, this pest can develop throughout the entire year.

[Egg distribution of Plutella xylostella (L.) (Lepidoptera: Plutellidae) and the parasitism by Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae)]. / Distribuição de ovos de Plutella xylostella (L.) (Lepidoptera: Plutellidae) e o parasitismo por Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae).

Oviposition site preference of Plutella xylostella (L.) and the parasitism by Trichogramma pretiosum Riley on cabbage plants at pre- and post-head formation were investigated in commercial cabbage field. Groups of six plants were randomly caged. In each cage three pairs of 24h-old P. xylostella moths were released, followed by 1,200 T. pretiosum females released 12h later. After 48 h from parasitoid release, plants were harvested and fully inspected with the oviposition mapped according to the leaf position and their parts (basal, median and border) and upper and bellow leaf surfaces. Moth oviposition and egg parasitism were equally distributed across the plant leaves at the pre-head formation stage. At this stage, the basal part and the upper leaf surface were the preferred places for oviposition and egg parasitism, respectively. Cabbage plants at the post-head formation stage exhibited greater oviposition and egg parasitism in the inner leaf attached to the head. At this stage, the leaf border and the upper leaf surface were the preferred places for oviposition and egg parasitism, respectively. The infestation of P. xylostella on cabbage can be determined by egg counting at the pre- and post-head formation stages at the basal part of the leaves or at the border of the leaf attached to the head, respectively. And, in both plant stages parasitized eggs by T. pretiosum are more likely to be found at the upper leaf surface.

Exigências térmicas da praga do coqueiro Atheloca subrufella (Hulst)(Lepidoptera: Phycitidae) / Thermal requirements of the coconut pest Atheloca subrufella (Hulst) (Lepidoptera: Phycitidae)

Among the important pests of coconut, the coconut moth Atheloca subrufella (Hulst) is a significant pest of flowers and fruits, and is found across all coconut-producing regions in Brazil. We investigated the thermal requirements of A. subrufella and estimated the number of generations for two different growing coconut regions in Pernambuco State. The developmental time of all immature stages reduced as the temperature increased. The egg to adult period ranged from 19.3 to 59.8 days from 32ºC to 18ºC, respectively. The survival of the period from egg to adult was 25 percent at extreme temperatures (18ºC and 32ºC), while at the intermediate temperatures it was over 72 percent. Based on the thermal requirements determined for A. subrufella and the average temperatures determined for "Zona da Mata" and "Sertão" of Pernambuco State, it was estimated that A. subrufella is able to complete up to 13 generations per year in both areas. These results indicate that A. subrufella exhibited development and reproduction limited by temperatures higher than 32ºC and lower than 18ºC. However, based on the thermal requirements of A. subrufella and the mean temperatures of the "Zona da Mata" and "Sertão" of Pernambuco State, this pest can develop throughout the entire year.

Distribuição de ovos de Plutella xylostella (L. ) (Lepidoptera: Plutellidae) e o parasitismo por Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) / Egg distribution of Plutella xylostella (L. ) (Lepidoptera: Plutellidae) and the parasitism by Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae)

Oviposition site preference of Plutella xylostella (L.) and the parasitism by Trichogramma pretiosum Riley on cabbage plants at pre- and post-head formation were investigated in commercial cabbage field. Groups of six plants were randomly caged. In each cage three pairs of 24h-old P. xylostella moths were released, followed by 1,200 T. pretiosum females released 12h later. After 48h from parasitoid release, plants were harvested and fully inspected with the oviposition mapped according to the leaf position and their parts (basal, median and border) and upper and bellow leaf surfaces. Moth oviposition and egg parasitism were equally distributed across the plant leaves at the pre-head formation stage. At this stage, the basal part and the upper leaf surface were the preferred places for oviposition and egg parasitism, respectively. Cabbage plants at the post-head formation stage exhibited greater oviposition and egg parasitism in the inner leaf attached to the head. At this stage, the leaf border and the upper leaf surface were the preferred places for oviposition and egg parasitism, respectively. The infestation of P. xylostella on cabbage can be determined by egg counting at the pre- and post-head formation stages at the basal part of the leaves or at the border of the leaf attached to the head, respectively. And, in both plant stages parasitized eggs by T. pretiosum are more likely to be found at the upper leaf surface.

[Effect of age, photoperiod and host availability on the parasitism behavior of Oomyzus sokolowskii Kurdjumov (Hymenoptera: Eulophidae)]. / Efeito da idade, fotoperíodo e disponibilidade de hospedeiro no comportamento de parasitismo de Oomyzus sokolowskii Kurdjumov (Hymenoptera: Eulophidae).

The high reproduction rate, potential to cause damage, wide geographic distribution and resistance to insecticides of Plutella xylostella (L.) makes difficult its efficient control. However, larvae and pupae of this pest are naturally parasitized by Oomyzus sokolowskii (Kurdjumov), providing opportunities to improve the natural parasitism. This study investigated the effects of the age of adult parasitoids, host availability and time of exposure on O. sokolowskii parasitism behavior. The number of larvae encounters by parasitoid females and the parasitism rate increased with parasitoid age up to 96h. The parasitization was higher when wasps received a constant number of hosts daily in comparison with a random number (13.3 versus 8.9 larvae parasitized). Female parasitization activity was maintained up to the age of 20 days in both treatments and exhibited similar longevity (constant host = 33.5 d; and random host = 34.7 d). The progeny produced per female and the number of parasitoids emerged per host significantly decreased as wasps aged. There was no significant effect of the light regime (12h darkness or 12h light exposure) on the parasitization, although parasitoid was more active after 3h of light exposure. Therefore, further studies on field application of O. sokolowskii should consider the release of 48 h- to 72 h-old parasitoids at dawn as a way to increase the success of host parasitization.

Efeito da idade, fotoperíodo e disponibilidade de hospedeiro no comportamento de parasitismo de Oomyzus sokolowskii Kurdjumov (Hymenoptera: Eulophidae) / Effect of age, photoperiod and host availability on the parasitism behavior of Oomyzus sokolowskii Kurdjumov (Hymenoptera: Eulophidae)

Plutella xylostella (L.) é uma praga de difícil controle em virtude de seu alto potencial reprodutivo e de causar danos, e ampla distribuição geográfica, além de apresentar resistência a inseticidas. No entanto, as fases de larva e pupa dessa praga são naturalmente parasitadas por Oomyzus sokolowskii (Kurdjumov), favorecendo o incremento do parasitismo natural. Este estudo investigou o efeito da idade do parasitóide, disponibilidade de hospedeiro e fotoperíodo no comportamento reprodutivo de O. sokolowskii. O número de encontros entre parasitóide e hospedeiro e a taxa de parasitismo aumentaram com a idade das fêmeas até 96h. O parasitismo foi maior quando fêmeas do parasitóide receberam diariamente um número constante de hospedeiros comparado à disponibilidade randômica (13,3 versus 8,9 lagartas). A atividade de parasitismo ocorreu até 20 dias de idade e com longevidade semelhante entre os tratamentos (constante = 33,5 d; randômico = 34,7 d). O número de descendentes por fêmea, no entanto, decresceu com a sua idade, sendo o mesmo observado para o número de parasitóides emergidos por lagarta parasitada. A exposição contínua do hospedeiro à luz ou ao escuro por 12h não afetou a taxa de parasitismo; porém, parasitóides apresentaram maior atividade após 3h de exposição à luz. Assim, futuros estudos e possível utilização de O. sokolowskii, em campo, devem considerar a liberações de parasitóides com idade entre 48h e 72h e, preferencialmente, na madrugada para maiores chances de sucesso de parasitismo.

The high reproduction rate, potential to cause damage, wide geographic distribution and resistance to insecticides of Plutella xylostella (L.) makes difficult its efficient control. However, larvae and pupae of this pest are naturally parasitized by Oomyzus sokolowskii (Kurdjumov), providing opportunities to improve the natural parasitism. This study investigated the effects of the age of adult parasitoids, host availability and time of exposure on O. sokolowskii parasitism behavior. The number of larvae encounters by parasitoid females and the parasitism rate increased with parasitoid age up to 96h. The parasitization was higher when wasps received a constant number of hosts daily in comparison with a random number (13.3 versus 8.9 larvae parasitized). Female parasitization activity was maintained up to the age of 20 days in both treatments and exhibited similar longevity (constant host = 33.5 d; and random host = 34.7 d). The progeny produced per female and the number of parasitoids emerged per host significantly decreased as wasps aged. There was no significant effect of the light regime (12h darkness or 12h light exposure) on the parasitization, although parasitoid was more active after 3h of light exposure. Therefore, further studies on field application of O. sokolowskii should consider the release of 48h- to 72h-old parasitoids at dawn as a way to increase the success of host parasitization.

Biologia de Ceraeochrysa claveri Navás (Neuroptera: Chrysopidae) predando Plutella xylostella (L. ) (Lepidoptera: Plutellidae) / Biology of Ceraeochrysa claveri Navás (Neuroptera: Chrysopidae) Preying on Plutella x ylostella (L. ) (Lepidoptera: Plutellidae)

Ceraeochrysa claveri Navás (Neuroptera: Chrysopidae) é um predador encontrado em vários agroecossistemas, predando insetos pequenos e de tegumento mole. Seu alto potencial reprodutivo e elevada capacidade de busca o tornam capazes de predar ovos e larvas de Plutella xylostella (L.) (Lepidoptera: Plutellidae) nas partes mais internas da cabeça do repolho, onde outros inimigos naturais não conseguem. Essas características podem favorecer a utilização desse predador no controle biológico dessa praga. Neste trabalho, o objetivo é avaliar o desenvolvimento, reprodução e capacidade de predação de C. claveri, quando ovos e larvas de P. xylostella foram ofertados em condições de laboratório. Foram avaliadas as seguintes dietas: 1) ovos; 2) larvas de segundo ínstar; 3) ovos + larvas de segundo ínstar. O desenvolvimento e a viabilidade das formas imaturas de C. claveri foi melhor nas dietas que continham ovos da presa. A oviposição e longevidade também foram maiores nessas dietas, independentemente da presença de larvas. Contudo, o tipo de dieta não afetou a razão sexual e o peso das larvas no oitavo dia de vida. Em média, cada larva de C. claveri foi capaz de predar 1611 ovos ou 135 larvas de segundo ínstar de P. xylostella durante seu desenvolvimento. O predador foi capaz de aumentar a população 218 vezes a cada 42 dias, alimentando-se, exclusivamente, de ovos da presa. Concluiu-se que o predador apresenta potencial para ser utilizado no controle biológico de P. xylostella.

Ceraeochrysa claveri Navás (Neuroptera: Chrysopidae) is a predator found in several agricultural ecosystems and it preys on small and soft body insects. Its high reproductive potential and forage capacity makes it able of preying eggs and larvae of Plutella xylostella (L.) (Lepidoptera: Plutellidae) internally hidden on cabbage head, where other natural enemies usually do not reach. These characteristics are important when choosing this predator to be used within biological control programs. This search evaluated the C. claveri development, reproduction, as well as the consumption of P. xylostella eggs and larvae under laboratory conditions. Therefore, it was evaluated the following diets: 1) eggs; 2) larvae of second ínstar; 3) eggs + larvae of second ínstar. The development and the viability of the immature forms of C. claveri were better in the diets containing eggs of P. xylostella. Also, the egg laying and adult longevity were greater with these diets, independently of the larvae presence. However, the diet type did not affect the sexual rate and the weight of the larvae after eight days of living. On average, each C. claveri larva was able of preying 1611 eggs or 135 second-ínstar larvae of P. xylostella during its development. The predator was able to increase its population 218 times after 42 days, feeding exclusively on P. xylostella eggs. Based on these results, this predator presents a great potential of being used within biological control programs of P. xylostella.

Population dynamics of Aceria guerreronis Keifer (Acari: Eriophyidae) and associated predators on coconut fruits in Northeastern Brazil.

Aceria guerreronis Keifer can cause severe damage to coconuts in several countries around the world. Rare studies have been conducted to determine the predatory mites associated with A. guerreronis in Brazil. The study evaluated the prevalence of A. guerreronis and associated predators on the bracts and on the surface of the fruits underneath the bracts, for 12 months, on coconut palms grown along the coast of the States of Alagoas, Paraíba and Pernambuco, Northeastern Brazil. Mites of 10 families were found, but by far the most abundant species was A. guerreronis, corresponding to 99.5% of the mites collected. The prevailing species amongst the predators were the Phytoseiidae mites Neoseiulus baraki (Athias-Henriot) and Neoseiulus paspalivorus (De Leon). These are flat mites that have short limbs, characteristics that allow them to invade the main habitat occupied by A. guerreronis. Other predators were found, but in low numbers, due mainly to their difficulty in reaching the fruit areas most inhabited by A. guerreronis. However, these mites could prey on that pest when it leaves its preferred habitat to disperse. No significant correlations were observed between the levels of abiotic factors and the population levels of A. guerreronis or of the phytoseiids associated with it. This probably occurred due to the simultaneous and conflicting effects of those factors on the mites in the field, or to significant differences between the climatic factors measured in the environment and those prevailing in the habitat occupied by A. guerreronis.

Tabela de vida de fertilidade de Trichogramma pratissolii Querino & Zucchi, 2003 (Hymenoptera: Trichogrammatidae) em hospedeiros alternativos, sob diferentes temperaturas / Fertility life table of Trichogramma pratissolii Querino & Zucchi, 2003 (Hymenoptera: Trichogrammatidae) in alternative hosts, under different temperatures

A espécie, Trichogramma pratissolii Querino & Zucchi (Hymenoptera: Trichogrammatidae) foi recentemente coletada em plantios de abacate, Persea americana Mill. (Lauraceae), e pode representar uma alternativa no controle biológico de lepidópteros pragas dessa cultura. Assim, objetivou-se neste trabalho avaliar o desempenho de T. pratissolii criado em ovos de Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) e Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae),sob diferentes temperaturas utilizando tabelas de vida de fertilidade. A criação de A. kuehniella foi mantida com dieta à base de farinha de trigo integral, milho e levedura de cerveja, enquanto para C. cephalonica foi utilizada dieta à base de farelo de arroz, levedura de cerveja e açúcar. T. pratissolii foi criado nos hospedeiros, utilizando-se a técnica de colagem de ovos em cartolina azul. Foram determinadas a duração média da geração (T), taxa líquida de reprodução (Ro), razão infinitesimal de aumento (r m) e razão infinita de aumento (λ) para as temperaturas de 15; 21; 24; 27; 30 e 33 ±1ºC, com 70±10 por cento de umidade relativa e fotofase de 14 horas. A melhor condição térmica para desenvolvimento de T. pratissolii em A. kuehniella e C. cephalonica foi a 27ºC, enquanto o melhor hospedeiro nessa temperatura é C. cephalonica.

The specie, Trichogramma pratissolii Querino & Zucchi (Hymenoptera: Trichogrammatidae) was recently collected in avocado plantations, Persea americana Mill. (Lauraceae), and therefore might be an alternative biological control agent for lepidopteran pests in this crop. Thus, this work evaluated the performance of T. pratissolii parasitizing eggs of Anagasta kuehniella Zeller (Lepidoptera: Pyralidae) and Corcyra cephalonica Stainton (Lepidoptera: Pyralidae), under different temperature regimes through fertility life table method. The host A. kuehniella was reared using diet constituted of whole wheat meal, corn meal and yeast, while C. cephalonica was reared with rice meal, yeast and sugar. Eggs of both hosts were offered to T. pratissolii pasted in blue cards. Mean generation time (T), net reproductive rate (Ro), intrinsic rate of population increase (r m) and finite rate of increase (λ) were estimated for parasitoid reared under 15; 21; 24; 27; 30 and 33 ±1ºC, 70±10 percent relative humidity and 14 hours of photoperiod. The best thermal conditions to T. pratissolii develop parasitizing A. kuehniella and C. cephalonica was 27ºC, and under this temperature eggs of the later host produced the better results.

Population dynamics of Aceria guerreronis Keifer (Acari: Eriophyidae) and associated predators on coconut fruits in Northeastern Brazil / Dinâmica populacional de Aceria guerreronis Keifer (Acari: Eriophyidae) e predadores associados em frutos de coqueiro no Nordeste do Brasil

Aceria guerreronis Keifer can cause severe damage to coconuts in several countries around the world. Rare studies have been conducted to determine the predatory mites associated with A. guerreronis in Brazil. The study evaluated the prevalence of A. guerreronis and associated predators on the bracts and on the surface of the fruits underneath the bracts, for 12 months, on coconut palms grown along the coast of the States of Alagoas, Paraíba and Pernambuco, Northeastern Brazil. Mites of 10 families were found, but by far the most abundant species was A. guerreronis, corresponding to 99.5 percent of the mites collected. The prevailing species amongst the predators were the Phytoseiidae mites Neoseiulus baraki (Athias-Henriot) and Neoseiulus paspalivorus (De Leon). These are flat mites that have short limbs, characteristics that allow them to invade the main habitat occupied by A. guerreronis. Other predators were found, but in low numbers, due mainly to their difficulty in reaching the fruit areas most inhabited by A. guerreronis. However, these mites could prey on that pest when it leaves its preferred habitat to disperse. No significant correlations were observed between the levels of abiotic factors and the population levels of A. guerreronis or of the phytoseiids associated with it. This probably occurred due to the simultaneous and conflicting effects of those factors on the mites in the field, or to significant differences between the climatic factors measured in the environment and those prevailing in the habitat occupied by A. guerreronis.

Aceria guerreronis Keifer pode causar danos severos em coqueiro em vários países ao redor do mundo. Raros estudos têm sido conduzidos para determinar os ácaros predadores associados com A. guerreronis no Brasil. O objetivo deste estudo foi avaliar a prevalência de A. guerreronis e dos predadores associados nas brácteas e na superfície dos frutos abaixo delas, durante 12 meses, em frutos de coqueiro adulto ao longo da costa de Alagoas, Paraíba e Pernambuco, no Nordeste do Brasil. Ácaros de 10 famílias foram encontrados, contudo a espécie mais abundante foi A. guerreronis, correspondendo a 99,5 por cento dos ácaros coletados. Dentre as espécies predadoras prevaleceram os ácaros Phytoseiidae Neoseiulus baraki (Athias-Henriot) e Neoseiulus paspalivorus (De Leon). Estes são achatados e possuem pernas curtas, características que lhes permitem invadir o habitat ocupado por A. guerreronis. Outros predadores foram encontrados, mas em número bem menor, provavelmente pela dificuldade que têm em penetrar nas áreas comumente habitadas por A. guerreronis. Contudo, essas espécies têm potencial de predação sobre o ácaro quando este sai de seu habitat preferido para se dispersar. Não se observaram correlações significativas entre os níveis de fatores abióticos e os níveis populacionais de A. guerreronis ou dos fitoseídeos associados a essa espécie. Isso provavelmente se deu devido aos efeitos simultâneo e conflitante daqueles fatores sobre os ácaros no campo, ou a diferenças significativas entre os fatores climáticos medidos no ambiente e aqueles prevalentes no habitat ocupado por A. guerreronis.

Effect of Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok. on Biological Characteristics of Diatraea saccharalis F. (Lepidoptera: Crambidae) - DOI: 10.4025/actascibiolsci.v30i2.3627 / Efeito de Beauveria bassiana (Bals.) Vuill. e Metarhizium anisopliae (Metsch.) Sorok. sobre características biológicas de Diatraea saccharalis F. (Lepidoptera: Crambidae) - DOI: 10.4025/actascibiolsci.v30i2.3627

The sugarcane borer Diatraea saccharalis F. is considered one of the major sugarcane pests in the American continent. Among control methods, the use of entomopathogenic fungi has been broadly recommended to manage sugarcane pests, including other sugarcane borers. Therefore, this study investigated the effects of different concentrations of Beauveria bassiana (Bals.) Vuill and Metarhizium anisopliae (Metch.) Sorok on biological characteristics of the sugarcane borer. Third-instar larvae of D. saccharalis were fungi-treated using the concentrations of 103, 104 and 105 conidia mL-1. Larvae treated with 105 conidia mL-1 of B. bassiana showed lower survival (56.6%) compared to untreated larvae (90%). Adults originated from treated larvae laid a lower number of eggs and exhibited lower viability, and lived less compared to adults of untreated larvae. Also, larvae treated with 105 conidia mL-1 of M. anisopliae and adults originated from those larvae presented reduced performance compared to untreated larvae. Results indicate that B. bassiana and M. anisopliae are pathogenic to D. saccharalis larvae and affect its biology. Hence, they have potential to be used against this pest.

A broca da cana-de-açúcar Diatraea saccharalis F. é considerada uma das principais pragas nas Américas. Entre os métodos de controle, o uso de fungos entomopatogênicos tem sido amplamente recomendado no manejo das pragas da cana-de-açúcar, incluindo outras lepidobrocas. Assim sendo, este estudo investigou os efeitos de diferentes concentrações de Beauveria bassiana (Bals.) Vuill. e Metarhizium anisopliae (Metsch.) Sorok. sobre parâmetros biológicos da broca da cana-de-açúcar. Larvas de terceiro instar de D. saccharalis foram tratadas com os fungos usando as concentrações de 103, 104 e 105 conídios mL-1. Larvas tratadas com 105 conídios mL-1 de B. bassiana tiveram menor sobrevivência (56,6%), comparadas com lagartas não-tratadas (90%). Adultos originados de larvas tratadas colocaram menor número de ovos, com menor viabilidade, e viveram menos, comparados com adultos originados de larvas não-tratadas. Larvas tratadas com M. anisopliae na concentração de 105 conídios mL-1 e adultos originados destas larvas também exibiram redução no desempenho, comparados aos insetos não-tratados. Os resultados indicam que B. bassiana e M. anisopliae, além de patogênicos às larvas de D. saccharalis, também interferem negativamente na sua biologia, mostrando potencial de uso contra esta praga.

[Biology and thermal requirements of Trichogramma atopovirilia Oatman & Platner (Hymenoptera: Trichogrammatidae) parasitizing eggs of Diaphania hyalinata L. (Lepidoptera: Pyralidae)]. / Biologia e exigências térmicas de Trichogramma atopovirilia Oatman & Platner (Hymenoptera: Trichogrammatidae) em ovos de Diaphania hyalinata L. (Lepidoptera: Pyralidae).

The development and parasitism of Diaphania hyalinata L. eggs by Trichogramma atopovirilia Oatman & Platner and its thermal requirements were studied at the temperatures of 18, 21, 24, 27, 30 and 33 degrees C. Thirty eggs of D. hyalinata were exposed to three females of T. atopovirilia for 5h at 25 degrees C and incubated at the different temperatures. The developmental time from egg exposure to adult, parasitism viability, number of adults per parasitized host egg and progeny sex ratio were monitored. The developmental time from egg to adult emergence of the parasitoid exhibited inverse relationship to the temperature, lasting 24.12 days at 18 degrees C and 7.36 days at 33 degrees C. Parasitism viability at 24, 27 and 30 degrees C was higher than 90%. The ratio of T. atapovirilia adult produced per egg and its sex ratio were not affected when using D. hialynata as host. The lowest threshold temperature (Tb) and estimated degree-days over Tb required by T. atopovirilia to develop on eggs of D. hyalinata was 11.99 degrees C and 130.42 masculine C, respectively. Considering the temperature regimes of two areas where cucurbitaces are cultivated in Bahia State (Rio Real and Inhambupe County) it was estimated that T. atopovirilia can achieve more than 32 generation per year. The results suggest that T. atopovirilia has potential to control D. hyalinata eggs with better chance of success under temperature regimes ranging from 24 to 27 degrees C that meets the suitable field conditions for cropping cucurbitaces.

Biologia e exigências térmicas de Trichogramma atopovirilia Oatman & Platner (Hymenoptera: Trichogrammatidae) em ovos de Diaphania hyalinata L. (Lepidoptera: Pyralidae) / Biology and thermal requirements of Trichogramma atopovirilia Oatman & Platner (Hymenoptera: Trichogrammatidae) parasitizing eggs of Diaphania hyalinata L. (Lepidoptera: Pyralidae)

A biologia de Trichogramma atopovirilia Oatman & Platner parasitando ovos de Diaphania hyalinata L. foi estudada nas temperaturas de 18, 21, 24, 27, 30 e 33°C e suas exigências térmicas foram determinadas. Trinta ovos do hospedeiro foram submetidos ao parasitismo na proporção de uma fêmea do parasitóide para 10 ovos, durante 5h, a 25°C e incubados nas diferentes temperaturas. Os parâmetros avaliados foram duração do ciclo ovo-adulto, viabilidade, número de indivíduos emergidos por ovo e razão sexual. A duração do período de desenvolvimento ovo-adulto apresentou relação inversa à temperatura e foi de 24,12 dias a 18°C e 7,36 dias a 33°C. A viabilidade do parasitismo a 24, 27 e 30°C foi superior a 90 por cento. O número de indivíduos emergidos por ovo hospedeiro e a razão sexual não sofreram influência da temperatura. A temperatura base (Tb) e a constante térmica (K) requerida por T. atopovirilia criados em ovos de D. hyalinata foi de 11,99°C e 130,42°C, respectivamente. Baseado nas médias térmicas de duas localidades de cultivo de cucurbitáceas da Bahia (Rio Real e Inhambupe) estimou-se que T. atopovirilia pode completar mais do que 32 gerações ao longo do ano. Estes resultados indicam que T. atopovirilia possui potencial de utilização para o controle de D. hyalinata com maiores chances de sucesso entre as temperaturas de 24°C e 27°C as quais também são apropriadas para o cultivo de cucurbitáceas.

The development and parasitism of Diaphania hyalinata L. eggs by Trichogramma atopovirilia Oatman & Platner and its thermal requirements were studied at the temperatures of 18, 21, 24, 27, 30 and 33°C. Thirty eggs of D. hyalinata were exposed to three females of T. atopovirilia for 5h at 25°C and incubated at the different temperatures. The developmental time from egg exposure to adult, parasitism viability, number of adults per parasitized host egg and progeny sex ratio were monitored. The developmental time from egg to adult emergence of the parasitoid exhibited inverse relationship to the temperature, lasting 24.12 days at 18°C and 7.36 days at 33°C. Parasitism viability at 24, 27 and 30°C was higher than 90 percent. The ratio of T. atapovirilia adult produced per egg and its sex ratio were not affected when using D. hialynata as host. The lowest threshold temperature (Tb) and estimated degree-days over Tb required by T. atopovirilia to develop on eggs of D. hyalinata was 11.99°C and 130.42°C, respectively. Considering the temperature regimes of two areas where cucurbitaces are cultivated in Bahia State (Rio Real and Inhambupe County) it was estimated that T. atopovirilia can achieve more than 32 generation per year. The results suggest that T. atopovirilia has potential to control D. hyalinata eggs with better chance of success under temperature regimes ranging from 24 to 27°C that meets the suitable field conditions for cropping cucurbitaces.

[Parasitism capacity of Trichogramma pratissolii Querino & Zucchi (Hymenoptera: Trichogrammatidae) on alternative hosts, under different temperatures]. / Capacidade de parasitismo de Trichogramma pratissolii Querino & Zucchi (Hymenoptera: Trichogrammatidae) em hospedeiros alternativos, sob diferentes temperaturas.

The successful use of Trichogramma as biocontrol agent depends on its mass production in laboratory, a fundamental step for any biological control program among other factors. This work investigated the parasitism capacity of Trichogramma pratissolii Querino & Zuchi (Hymenoptera: Trichogrammatidae), a new recorded Trichogramma species, parasitizing eggs of Anagasta kuehniella (Zeller) and Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) under the temperatures of 15, 18, 21, 24, 27, 30 and 33 degree Celsius. Eggs of these hosts were offered to newly emerged females during 24h. This procedure was repeated daily for each female and each temperature up to female death, in order to estimate daily and accumulated parasitism, and female longevity. On both hosts, the daily parasitism decreased as function of the female age. Under all temperatures studied and both hosts the highest rate of parasitism was observed during the first 24h of host exposure, and reached 80% of total parasitism in the 4th and 3rd days when parasitizing A. kuehniella and C. cephalonica, respectively. On both hosts, the highest parasitism rate was observed under temperatures from 21 degree Celsius to 27 degree Celsius. Average longevities of T. pratissolii females deprived of food emerging from A. kuehniella and C. cephalonica lived for 1.0 and 8.9 days when reared at 15 degree Celsius e 33 degree Celsius, respectively. The results indicate that eggs of A. kuehniella and C. cephalonica and temperatures from 21 degree Celsius to 27 degree Celsius were appropriate to rear T. pratissolii.

Capacidade de parasitismo de Trichogramma exiguum Pinto & Platner, 1978 (Hymenoptera: Trichogrammatidae) em ovos de Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae) em diferentes temperaturas / Parasitism capacity of Trichogramma exiguum Pinto & Platner, 1978 (Hymenoptera: Trichogrammatidae) on different temperatures on Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae) eggs

Estudou-se a capacidade de parasitismo de Trichogramma exiguum Pinto & Platner, 1978 (Hymenoptera: Trichogrammatidae) em ovos de Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae) nas temperaturas de 18, 20, 22, 25, 28, 30 e 32°C, avaliando-se o número de ovos parasitados diariamente, a porcentagem acumulada de parasitismo, o número total de ovos parasitados por fêmea e a longevidade de fêmeas. O ritmo de parasitismo, durante as primeiras 24 horas, oscilou de 1,5 a 11,7 ovos parasitados por fêmeas de T. exiguum, nas temperaturas entre 18 e 32°C. O parasitismo acumulado de ovos de P. xylostella, nas temperaturas de 18, 20, 22, 25, 28, 30 e 32°C, atingiu 80 por cento, respectivamente, aos 10, 7, 8, 5, 5, 4 e 5 dias, por T. exiguum. As maiores taxas de parasitismo obtidas por T. exiguum ocorreram nas faixas térmicas de 25, 30 e 32°C. A longevidade de fêmeas de T. exiguum, nas faixas térmicas compreendidas entre 18 e 32°C, variou de 4,2 a 7,4 dias.

The parasitism capacity of Trichogramma exiguum Pinto & Platner, 1978 (Hymenoptera: Trichogrammatidae) on eggs of Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae) was studied, under temperatures of 18, 20, 22, 25, 28, 30 and 32°C aiming at evaluating the number of days with parasitism, cumulated parasitism, total number of eggs parasited per female and their longevity. Parasitism during the first 24 hours ranged from 1.5 to 11.7 eggs of P. xylostella per T. exiguum female in the range of 18 to 32°C. Cumulated egg parasitism of P. xylostella by T. exiguum reached 80 percent after 10, 7, 8, 5, 5, 4 and 5 days at 18, 20, 22, 25, 28, 30 and 32°C. Higher parasitism rates were recorded at 25, 30 and 32°C while longevity of T. exiguum females varied from 4.2 to 7.4 days under temperatures of 18 to 32°C.

Capacidade de parasitismo de Trichogramma pratissolii Querino & Zucchi (Hymenoptera: Trichogrammatidae) em hospedeiros alternativos, sob diferentes temperaturas / Parasitism capacity of Trichogramma pratissolii Querino & Zucchi (Hymenoptera: Trichogrammatidae) on alternative hosts, under different temperatures

O sucesso no uso de Trichogramma como agente de controle biológico depende de sua produção em laboratório que é etapa fundamental, entre outras, em qualquer programa de controle biológico. Este trabalho investigou a capacidade de parasitismo de Trichogramma pratissolii Querino & Zuchi, uma nova espécie encontrada, parasitando ovos de Anagasta kuehniella (Zeller) e Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) submetidos a 15, 18, 21, 24, 27, 30 e 33°C. Ovos desses hospedeiros foram oferecidos para fêmeas recém-emergidas por 24h. Esse procedimento foi repetido para cada fêmea e temperatura até a morte das fêmeas do parasitóide, para estimar o parasitismo diário, acumulado e a longevidade das fêmeas. Em ambos hospedeiros, o parasitismo diário decresceu em função da idade da fêmea. Em todas as temperaturas estudadas e ambos hospedeiros, o maior parasitismo ocorreu durante as primeiras 24h e, atingiu 80 por cento do total no quarto e terceiro dias quando parasitou A. kuehniella e C. cephalonica, respectivamente. Para ambos os hospedeiros os maiores índices de parasitismo foram observados entre 21°C e 27°C. A longevidade média de fêmeas de T. pratissolii sem alimento e provenientes de ovos de A. kuehniella e C. cephalonica sobreviveram de 1,0 a 8,9 dias, quando criadas a 15°C e 33°C, respectivamente. Os resultados encontrados indicam que ovos de A. kuehniella e C. cephalonica e temperaturas de 21°C a 27°C foram apropriados para criação de T. pratissolii.

The successful use of Trichogramma as biocontrol agent depends on its mass production in laboratory, a fundamental step for any biological control program among other factors. This work investigated the parasitism capacity of Trichogramma pratissolii Querino & Zuchi (Hymenoptera: Trichogrammatidae), a new recorded Trichogramma species, parasitizing eggs of Anagasta kuehniella (Zeller) and Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) under the temperatures of 15, 18, 21, 24, 27, 30 and 33°C. Eggs of these hosts were offered to newly emerged females during 24h. This procedure was repeated daily for each female and each temperature up to female death, in order to estimate daily and accumulated parasitism, and female longevity. On both hosts, the daily parasitism decreased as function of the female age. Under all temperatures studied and both hosts the highest rate of parasitism was observed during the first 24h of host exposure, and reached 80 percent of total parasitism in the 4th and 3rd days when parasitizing A. kuehniella and C. cephalonica, respectively. On both hosts, the highest parasitism rate was observed under temperatures from 21°C to 27°C. Average longevities of T. pratissolii females deprived of food emerging from A. kuehniella and C. cephalonica lived for 1.0 and 8.9 days when reared at 15°C e 33°C, respectively. The results indicate that eggs of A. kuehniella and C. cephalonica and temperatures from 21°C to 27°C were appropriate to rear T. pratissolii.