Bt Soybean Cry1Ac Does Not Affect Development, Reproduction, or Feeding Behavior of Red-Banded Stink Bug Piezodorus guildinii (Hemiptera: Pentatomidae).

Bt soybean cultivation is increasing worldwide. The Cry1Ac protein expressed in Bt soybean efficiently controls several lepidopteran pests. The stink bug, Piezodorus guildinii (Westwood), a major pest for soybean in the Americas, is not controlled by Bt crops, although possible sub-lethal effects may occur. Even if there were no negative effects for sting bug, ingesting toxins could affect its bio-controllers. We tested through ELISA detection if P. guildinii ingests Cry1Ac from Bt soybean and possible effects on its development, reproduction, survival, and feeding behavior. Biological traits were evaluated under controlled conditions of nymphs and adults feeding on pods of near-isogenic cultivars DM5958iPRO (Bt) and DM59i (non-Bt). Feeding behavior was recorded using an AC-DC electropenetrography (EPG) device. Results indicated that P. guildinii ingested the Cry1Ac protein; however, nymphal period and accumulated survival percentage did not differ between cultivars. Feeding on Bt soybean pods did not affect fecundity (i.e., number of egg masses and eggs/female) nor egg viability. Different feeding behaviors were only detected on the pathway phase (stylet penetration into plant tissue), which was more pronounced in the Bt cultivar. However, the total duration of the feeding activities on seeds was numerically higher (ca. 2X) on Bt plants compared to non-Bt. This is the first study to demonstrate that P. guildinii does ingest the Cry1Ac protein and excrete it without being absorbed, probably explaining the lack of direct adverse effects on its biological parameters. EPG could indicate that Bt soybean plants might be less palatable than non-Bt to red-banded stink bug.

Nymph development and adult feeding on, and damage to, immature siliquae of canola by different species of stink bugs.

Studies were conducted in the laboratory and in the greenhouse with the objective of evaluating nymph development, adult body weight gain, and damage of different species of pentatomids feeding on fruit (hereafter referred to as siliqua) of canola, Brassica napus (L.) var. oleifera. Nymphs of Nezara viridula (L.) were able to reach adulthood feeding on siliquae (93.3% survivorship), while nymphs feeding on siliquae that had their seeds removed showed arrested development, only reaching the 4th instar and did not complete development to adulthood. Adults of N. viridula gained body weight feeding on canola siliquae, particularly during the first two weeks of adult life, dropping weight thereafter. Adults of another species of pentatomid, Diceraeus furcatus (F.), also gained body weight, while adults of Euschistus heros (F.) lost weight. N. viridula adults caused significantly greater damage to seeds (shrunken and with rotten aspect) within siliqua and to the siliqua walls (whitish spots with lesions in the form of starbursts, called rosettes) compared to D. furcatus and to E. heros. The amount of damaged seeds caused by N. viridula adults during the first week of adult life was greater (ca. 60%) compared to those of older females 32 days of age (27%). Damage symptons caused by the feeding activity on siliqua walls (commonly known as rosettes) reached up to 10% of the total area with similar injury rates for N. viridula adults of different ages. The majority of N. viridula (70%) caused rosette, while only 20% of E. heros and 5% of D. furcatus produced similar damage.

Historical and Contemporary Perspectives on the Biological Control of Aphids on Winter Cereals by Parasitoids in South America.

Aphids are worldwide pests, and in South America, they harm many crops including winter cereals. In the 1970s, the rapid expansion of the wheat crop area in the subtropical region of South America led to growth of aphid populations. The wide availability of food, associated with the low effectiveness of natural biological control, put the aphid populations out of balance, requiring intensive use of insecticides. At the end of the decade, biological control programs of aphids were initiated in Argentina, Brazil, and Chile, including the importation of natural enemies (mainly parasitoids), followed by their laboratory rearing and field release. With decreased use of highly hazardous pesticides, biological control by introduced and already-present parasitoid species was enhanced. The program was very successful and aphid populations have been kept at low levels. This review article explores the history of this program and its current status. In modern day agriculture, with intense multiple cropping systems, adoption of several conservation practices, and increased cultivation of wheat in tropical regions, we discuss ways to keep this program effective to maintain aphid populations on cereal crops at low acceptable levels through employing biological control agents.

Dynamics in Pest Status of Phytophagous Stink Bugs in the Neotropics.

In this review article, we present and discuss the main factors influencing the change in pest status of phytophagous stink bugs (Hemiptera: Heteroptera: Pentatomidae) in the Neotropics. We have surveyed the published records over the past 50 years and divided this timeframe into decades. This was done to rank in time the relative abundance (percentage) of the following species, known pests of commodities, in the Neotropical Region: the Neotropical brown stink bug, Euschistus heros (F.); the green-bellied stink bugs, Diceraeus melacanthus Dallas and D. furcatus (F.); the redbanded stink bug, Piezodorus guildinii (Westwood); the southern green stink bug, Nezara viridula (L.); and the brown-winged stink bug, Edessa meditabunda (F.). The analysis showed that E. heros, D. melacanthus, and D. furcatus, formerly minor pests, in the last decade (2010s) became major pests. The once most important pest species, N. viridula and P. guildinii, decreased their pest status in the last decade. Edessa meditabunda, which never achieved high populations, showed a tendency to increase in abundance in the last two decades (2000s and 2010s). Major factors believed to influence the dynamics of pest populations of stink bugs in the Neotropics include cropping systems (no-tillage replacing conventional soil plowing, and crop rotation); genetically modified (GM) plants (mostly plants expressing insecticidal crystalline proteins derived from Bacillus thuringiensis Berliner - Bt); change in availability of host and associated plants in the new landscape scenario; increased usage of chemicals (insecticides, fungicides, and herbicides); and change in the role of natural enemies in modern day agriculture.

Diceraeus melacanthus (Dallas) (Hemiptera: Pentatomidae) development, preference for feeding and oviposition related to different food sources

ABSTRACT The dispersion of Diceraeus melacanthus (Dallas) from soybean (first crop season) to maize (second crop season) is facilitated by the presence of weeds (e.g. Commelina benghalensis) and soybean grains on the ground. Understanding insect development and behavior on different food sources is important to develop pest management strategies. Thus, three independent experiments were conducted to study D. melacanthus nymph development, and adult preference for feeding and oviposition in different food source scenarios in the field. The first two trials studied development and food preference of D. melacanthus related to different food sources (C. benghalensis branches, moistened soybean grain + soybean seedlings, maize seedlings + C. benghalensis branches, moistened soybean grains + maize seedlings, moistened soybean grains + C. benghalensis branches, maize seedlings, as well as a standard diet). The third trial evaluated D. melacanthus oviposition preferences between the aforementioned plants. Overall, moistened soybean grains resulted in better nutritional quality, thus being crucial for D. melacanthus development, triggering faster nymph development as well as better overall adult fitness. The combination of soybean grains and maize seedlings or C. benghalensis branches showed great potential to benefit D. melacanthus, since these complementary food sources improved stink bug fitness, increasing mainly adult longevity, fecundity and egg viability. Therefore, it can be concluded that in order to reduce D. melacanthus outbreaks in second season maize, it is important to reduce soybean harvest loss (reducing, therefore, moistened soybean grain on the ground) and eliminate stink bug associated plants like C. benghalensis.

Intrinsic Interspecific Competition Between Telenomus podisi and Trissolcus teretis (Hymenoptera: Scelionidae).

The competition between Telenomus podisi Ashmead and Trissolcus teretis (Johnson) parasitizing eggs of Diceraeus melacanthus (Dallas) and Euschistus heros (Fabricius) was studied in three different laboratory bioassays to gather knowledge in order to improve stink bug management and to strengthen the preservation of naturally occurring parasitoid species. The impact of parasitoid sequence and time intervals (4 to 192 h) between parasitoid species was evaluated. Competition of Te. podisi and Tr. teretis for the same host favored the parasitoid encountering the egg host first, as it usually outcompetes the second parasitoid. We conclude that it is unwarranted in a short-term goal to release both species together in augmentative biological control programs since the repeated release of Te. podisi led to higher parasitism than any other studied variation of parasitoid sequence. However, simultaneous release of multiple species could be important to help the preservation of the diversity of scelionids in the agroecosystem, a hypothesis that needs to be further investigated in future research.

Feeding Behavior of Collaria scenica (Stål) (Hemiptera: Miridae) on Wheat Plants: an EPG Waveform Characterization.

In this study, we use for the first time the electropenetrography (EPG) technique to characterize and describe the feeding activities of Collaria scenica (Stål) adults and their respective waveforms on wheat, Triticum aestivum L. plants. It comprised of four waveforms, two related to non-feeding (Np and R) and two with feeding activities (CR and I). The Np wave represents the insect resting or walking on the plant surface (75% of the recording time). R wave was associated to sensory evaluation of leaf surface with the tip of the labium (labial dabbing activity-ca. 1% of the recording time). Feeding activities were of relative short duration; cell rupture waveform (CR-ca. 49 min-ca. 15% of the recording time) was highly irregular due to constant movement of the stylets internally in the plant tissue. The waveform I (ca. 28 min-ca. 9% of the recording time) showed stereotypical and repetitive pattern and represents ingestion of the cell contents previously degraded via cell-rupturing activities. The damage caused by C. scenica in wheat leaflets is a result of cell-rupturing activities, generated by action of digestive enzymes plus mechanical action of serrated mandibular stylets. This results in whitish streaks, dots, or spots on the leaflet of wheat plants which cause significant damage and eventually plants' death.

Biological characteristics of Trissolcus urichi (Crawford) (Hymenoptera: Scelionidae) on Euschistus heros (Fabricius) and Dichelops melacanthus (Dallas) (Hemiptera: Pentatomidae) Eggs.

Species of the genus Trissolcus are effective as egg parasitoids of Euschistus heros and can potentially be used in a multispecies pest management approach. However, in order to successfully use those biocontrol agents in the field, previous detailed knowledge about their life history are necessary. Therefore, we evaluate some biological characteristics of Trissolcus urichi on Euschistus heros and Dichelops melacanthus eggs. Three independent experiments were performed: (1) T. urichi host preference between E. heros and D. melacanthus eggs. (2) T. urichi eggs-adult period (days), number of parasitized eggs in 24 h, emergence rate (%) and sex ratio of the parasitoid in E. heros and D. melacanthus eggs. (3) Morphometric characteristics of T. urichi grown on E. heros and D. melacanthus eggs. Trissolcus urichi preferred to parasitize E. heros eggs, exhibiting a higher number of parasitized eggs, higher rate of emergence (%) and faster development, as well as producing progeny of larger size than the parasitoids emerged from eggs of D. melacanthus in relation to body length, wing length and width. Thus, it can be concluded that T. urichi had better performance on E. heros eggs, although the parasitoid had also acceptable parasitism capacity and development in D. melacanthus eggs.

Stink Bugs Nymph and Adult Biology and Adult Preference on Cultivated Crop Plants in the Southern Brazilian Neotropics.

Laboratory studies were conducted with Dichelops furcatus (F.), Euschistus heros (F.), and Nezara viridula (L.) (Heteroptera: Pentatomidae) aiming to evaluate nymph and adult biology and adult preference for immature reproductive structures of the cultivated plants, soybean, Glycine max (L.) Merrill (Fabaceae), wheat, Triticum aestivum L. (Poaceae), and canola, Brassica napus L. var. oleifera (Brassicaceae). Considering the survivorship for D. furcatus nymphs, it was greater on soybean and wheat, for E. heros nymphs it was greater on soybean compared to canola and wheat, and for N. viridula nymphs the survivorship was greater on soybean and canola. Dichelops furcatus nymphs developed faster on soybean and wheat, and E. heros and N. viridula nymphs developed faster on soybean and canola. Body weight at adult emergency for D. furcatus was greater on soybean and wheat, and for E. heros and N. viridula, it was greater on soybean. Adult survivorship and longevity were similar on soybean/wheat/canola for D. furcatus and N. viridula, and greater on soybean for E. heros. Reproduction and weight gain of adults were greater on soybean and wheat for D. furcatus, and on soybean for E. heros; N. viridula reproduced only on soybean and tended to gain greater body weight in this food source. As expected, soybean considering its superior nutritional quality was, in general, the best food. These laboratory studies coupled with field observations allow to conclude that the sequence of soybean/wheat/canola crops in the area studied forms a 'green bridge' that favor stink bug populations abundance in southern Brazilian neotropics.

Feeding activity, salivary amylase activity, and superficial damage to soybean seed by adult Edessa meditabunda (F.) and Euschistus heros (F.) (Hemiptera: Pentatomidae).

Greenhouse and laboratory studies were conducted to evaluate feeding activity and superficial damage to soybean seed by the brown-winged stink bug, Edessa meditabunda (F.), and the Neotropical brown stink bug, Euschistus heros (F.). Soybean plants (cv. BRS 282), at R6 stage of development were used. Thirty pairs of each species were used individually for 48 h. Two daily observations (9:00 AM and 3:00 PM) were taken to record the number of bugs (feeding/resting) on plant parts. Harvested seeds imbibed in tetrazolium solution were photographed for measurement of the damaged surface. Adult E. meditabunda significantly preferred soybean stems (19.7 bugs) to pods (2.7). Feeding/resting was similar at 9:00 AM (mean number of 28.0 bugs) and 3:00 PM (24.3). Euschistus heros equally fed/stayed on stems (7.3 bugs) and pods (6.9), although most bugs (12.3) remained on the cage net; feeding/resting on all plant structures amounted to 13.7 bugs at 9:00 AM and 17.7 bugs at 3:00 PM. Amylase activity was greater for E. heros (41.61 ± 0.89 U/mg) and almost none for E. meditabunda (2.35 ± 0.14 U/mg). The superficial damage to seeds was significantly greater for E. meditabunda (22. 9 mm(2)) compared to E. heros (12.5 mm(2)). However, E. meditabunda caused less shrinkage of the seed tegument, while E. heros damage was deeper and seeds showed reduction in size.

Injúrias de quatro espécies de percevejos pentatomídeos em plântulas de milho / Injuries of four species of stink bugs to corn seedlings

Neste estudo, foram caracterizadas as injúrias causadas pelos percevejos Dichelops furcatus (F.), Nezara viridula (L.) e Euschistus heros (F.), em comparação com D. melacanthus (Dallas), em plântulas de milho (Zea mays L.). O experimento foi realizado em vasos, em ambiente de telado, em delineamento inteiramente casualizado, com cinco tratamentos (infestação com percevejos de quatro espécies e testemunha, sem infestação) em oito repetições. Na fase vegetativa do milho (estádio V1 até V3), D. melacanthus, na densidade de um adulto/planta, provocou redução na altura, no número de folhas expandidas, na massa seca das raízes e provocou injúrias no cartucho e/ou enrolamento das folhas centrais da planta. D. furcatus, E. heros e N. viridula causaram injúrias, porém, em intensidades diferentes. As injúrias causadas por D. furcatus e N. viridula foram semelhantes na forma e intensidade às de D. melacanthus e as injúrias causadas por E. heros foram menos intensas que as dos demais percevejos estudados.

Injuries caused by the stink bugs Dichelops furcatus (F.), Nezara viridula (L.) and Euschistus heros (F.), compared with Dichelops melacanthus (Dallas), to corn (Zea mays L.) seedlings were studied. The experiment was conducted in a greenhouse in a completely randomized design with five treatments (four species of stink bugs and control, without infestation) using eight replications. In the vegetative stage (V1 to V3) D. melacanthus, at the density of one adult/plant, caused reduction in height, in the number of expanded leaves, in root dry matter, and caused injuries and winding of the central leaves. D. furcatus, E. heros and N. viridula caused injuries, but at different intensities. Injuries caused by D. furcatus and N. viridula were similar in intensity to those by D. melacanthus and the injuries caused by E. heros were less intense than those of the other species.

Danos do percevejo barriga-verde Dichelops melacanthus (Dallas) (Heteroptera: Pentatomidae) em trigo / Damage of the green belly stink bug Dichelops melacanthus (Dallas) (Heteroptera: Pentatomidae) to wheat

O objetivo deste estudo foi avaliar a reação de dois cultivares de trigo aos danos causados por percevejos adultos de Dichelops melacanthus (Dallas), confinados sobre a cultura a partir do início do perfilhamento. Foram comparados os efeitos de diferentes níveis de infestação (0, 2, 4, 8 e 16 percevejos m-2) sobre o número de perfilhos m-2, número de espigas m-2, peso de mil sementes (g) e rendimento (kg ha-1) das cultivares æBR 18' e æBRS 193' de trigo, em Londrina, PR. O número de perfilhos m-2 cresceu linearmente para a cv. æBR 18' e de forma quadrática para a cv. æBRS 193' com o aumento do número de percevejos m-2; o número de espigas m-2, o peso de mil sementes, e o rendimento decresceram de forma linear com o aumento do nível de infestação para as duas cultivares. æAcv.BRS 193' foi mais suscetível ao ataque de D. melacanthus, apresentando uma redução de 254,4kg para cada unidade de aumento no número de percevejos m-2.

Morphology of olfactory sensilla and its role in host plant recognition by Neomegalotomus parvus (Westwood) (Heteroptera: Alydidae)

A morfologia externa dos sensilos de adultos de Neomegalotomus parvus (Westw.) (Het.: Alydidae), incluindo poros e pontos permeáveis na cutícula, foi estudada em microscópio eletrônico de varredura, em relação à função olfativa. A evidência comportamental do olfato e a importância dos diferentes segmentos antenais na localização do hospedeiro, em condições de ausência de movimentação do ar, foram também estudados. Sensilos mecanoreceptores foram observados nos quatro segmentos da antena de N. parvus, sendo no entanto, a densidade maior no quarto segmento. Nos segmentos apicais, foram observados sensilos com características morfológicas olfativas. Percevejos com antenas intactas localizaram o alimento com mais freqüência e rapidez do que aqueles com antenas bloqueadas ou amputadas. Adultos de N. parvus preferiram sementes intactas do que aquelas vedadas com Parafilm®, mas não apresentaram preferência quando o último segmento da antena foi bloqueado. Em túnel de vento, os percevejos foram atraídos para sementes e vagens maduras, e para extrato hexânico de vagens maduras de guandu, Cajanus cajan (L.) Millsp.; não houve resposta para panículas de arroz, Oryza sativa L. (planta não hospedeira) ou para feromônio extraído de machos.

Responses of Neomegalotomus parvus (Hemiptera: Alydidae) to color and male-lured traps

Em 1998, as respostas relativas de Neomegalotomus parvus (Westwood) (Hemiptera: Alydidae) a cores em armadilhas foram avaliadas no campo. As cores foram impressas (preto, verde, amarelo, vermelho e azul), em papel alcalino branco e coberto com plástico transparente. Também se incluiu papel branco e folha de alumínio, como tratamentos. Armadilhas verdes capturaram mais insetos que outras armadilhas (exceto amarelo). Armadilhas amarelas capturaram significativamente mais machos de N. parvus do que armadilhas azuis, pretas e alumínio. Armadilhas brancas, vermelhas e azuis capturaram significativamente mais machos de N. parvus do que armadilhas pretas. Em 1999, os mesmos tratamentos foram usados e também se incluiu fator presença (X ausência) de machos em gaiolas nas armadilhas. Quatro machos foram confinados nas gaiolas junto com sementes de guandu e água. Testemunhas receberam somente sementes de guandu e água. Não foram obtidas respostas significativas à cores. Armadilhas com machos capturaram significativamente mais machos que armadilhas testemunhas.

Population dynamics, gregarious behavior and oviposition preference of Neomegalotomus parvus (Westwood) (Hemiptera: Heteroptera: Alydidae)

Interactions between Neomegalotomus parvus (Westwood) (Coreoidea: Heteroptera: Alydidae) and host plants were investigated including population monitoring throughout the year, gregarious behavior in the field, and oviposition preference among host plants and one non-host plant in field cages. Cowpea, Vigna unguiculata (L.) Walp., soybean, Glycine max (L.) Mill. cv. BR 37, pigeon pea, Cajanus cajan (L.) Mill., pigeon pea cv. Anäo, and lablab, Dolichos lablab L. were monitored in the field. N. parvus was found on host plants during 11 months. The shortest period of occurrence was observed on soybean and the longest on lablab. Insects were found mostly on mature pods. Contagious distribution (negative bionomial) was detected, characterizing the aggregation. Greater number of eggs were observed on pigeon pea, followed by soybean and lablab. Eggs were not found on cowpea, on common bean Phaseolus vulgaris L., and on rice, Oryza sativa L