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.

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.

Effects of parasitoid and host age on the parasitism of Trichogramma pretiosum on eggs of Anticarsia gemmatalis

Abstract The ages of parasitoid females and their hosts can have substantial effects on parasitism and parasitoid efficacy. This relationship has been investigated over the last few decades and found to vary among species. To our knowledge, it was virtually unknown for Trichogramma pretiosum wasps that parasitize Anticarsia gemmatalis eggs. Therefore, the influence of parasitoid and host age on the parasitism of T. pretiosum on eggs of A. gemmatalis was here evaluated in three independent bioassays. Neither the number of parasitized eggs nor that of emerged parasitoids differed between T. pretiosum females of different age. The number of parasitoids per egg and the sex ratio were higher for 5-day-old females. Regarding host age, the number of parasitized eggs was highest for A. gemmatalis eggs aged 24 h (9.60), followed by eggs aged 48 h (1.00), while no parasitism was observed for eggs aged 72 h. The number of parasitoids per egg and sex ratio were not influenced by host age. Preference was significantly higher for host eggs aged 24 h (79.67%), followed by eggs aged 48 h (16.99%) and 72 h (3.33%). Accordingly to these results, the key challenge for a successful T. pretiosum release to control A. gemmatalis in the field is to synchronize the presence of up to 5-day-old adults with the most susceptible phase of the host eggs (1 day).

Selectivity of different biological products to the egg parasitoid Telenomus remus (Hymenoptera: Platygastridae)

ABSTRACT The selectivity of five entomopathogens and a chemical insecticide (positive control) to pupae and adults of the egg parasitoid Telenomus remus (Nixon) was evaluated in the laboratory under controlled environmental conditions according to protocols established by the International Organization for Biological Control. Baculovirus anticarsia (Baculovirus AEE®), Bacillus thuringiensis var. kurstaki (Thuricide®), Bacillus thuringiensis var. aizawai (Agree®), Beauveria bassiana (Boveril®), Metarhizium anisopliae (Metarril®) and Trichoderma harzianum (Trichodermil®) are harmless to T. remus pupae, and adults. Thus, our results suggest that the insect control strategies applied here are compatible since entomopathogens were classified as harmless to T. remus in most examined cases and therefore facilitate a joint application to control different pests. Bacillus thuringiensis var. kurstaki (Dipel®), despite being classified as slightly harmful in some of the evaluations, can still be considered compatible for use together with T. remus, especially when compared with chemical insecticides such as chlorpyrifos that might be considered harmful to the parasitoid survival.

Biology and reproductive capacity of Spodoptera eridania (Cramer) (Lepidoptera, Noctuidae) in different soybean cultivars

This study aimed to evaluate the development, survival and reproductive capacity of Spodoptera eridania in four soybean cultivars. The experiment was conducted in the laboratory, in a climatic chamber at 25 °C ± 1 °C, 70 ± 10% relative humidity and 12 h photophase. The cultivars used were: FMT Tabarana, BRS/MT Pintado, FMT Tucunaré and Monsoy 8757, all conventional cultivars with medium cycles. All cultivars tested allowed the development of S. eridania. However, Monsoy 8757 was the cultivar that most affected the prolonged in the duration larval, pupal and total cycle, showed lower pupal weight as well as reduction in the intrinsic rate increase. These results contribute to the management of this species in regions of outbreaks in soybean areas.

Natural parasitism of Hexacladia smithii Ashmead (Hymenoptera: Encyrtidae) on Euschistus heros (F. ) (Hemiptera: Pentatomidae): new record from Mato Grosso State, Brazil / Parasitismo natural de Hexacladia smithii Ashmead (Hymenoptera: Encyrtidae) sobre Euschistus heros (F. ) (Hemiptera: Pentatomidae): novo registro no estado do Mato Grosso

The neotropical stink brown bug, Euschistus heros (F.) (Hemiptera: Pentatomidae), is an insect pest to soybean crops in Mato Grosso State, Brazil. In this region, synthetic insecticides are frequently used for insect control. An alternative to the indiscriminate use of insecticides is the biological control with parasitoids. Thus, the objective of this study was to conduct the survey of parasitoids that use E. heros adults as hosts. Random samples were conducted during the harvests of 2009/10 and 2010/11 in two farms that produce soybean (conventional system) in Tangará da Serra, Mato Grosso State, Brazil. The total number of collected E. heros was: 297 (Field 1) and 293 (Field 2) in 2009/10 and 295 (Field 1) and 376 (Field 2) in 2010/11. Of these, 1.50 (Field 1) and 13.99% (Field 2) were parasitized in 2009/10 and 8.47 (Field 1) and 7.45% (Field 2) in 2010/11. The parasitoids found were Hexacladia smithii Ashmead (Hymenoptera: Encyrtidae) in both fields. This is the first record of parasitism in E. heros adults in the state of Mato Grosso, Brazil.(AU)

O percevejo marrom, Euschistus heros (Hemiptera: Pentatomidae), é um inseto praga na cultura da soja no estado do Mato Grosso, Brasil. Nesta região, inseticidas sintéticos são frequentemente utilizados ao controle de insetos. Uma alternativa para o uso indiscriminado de inseticidas é o controle biológico com parasitoides. Assim, o objetivo deste estudo foi realizar o levantamento dos parasitoides que utilizam adultos de E. heros como hospedeiros. Para isso, amostras aleatórias foram conduzidas durante as safras de 2009/10 e 2010/11, em duas fazendas produtoras de soja (sistema convencional) em Tangará da Serra, Mato Grosso, Brasil. O número total de E. heros coletados foi: 297 (Área 1) e 293 (Área 2) em 2009/10 e 295 (Área 1) e 376 (Área 2) em 2010/11. Destes percevejos 1,50 (Área 1) e 13,99% (Área 2) encontravam-se parasitados em 2009/10 e 8,47 (Área 1) e 7,45% (Área 2) em 2010/11. Nas duas áreas, o parasitoide encontrado foi Hexacladia smithii Ashmead (Hymenoptera: Encyrtidae). Este é o primeiro registro de parasitismo em adultos de E. heros no estado do Mato Grosso, Brasil.(AU)

Oviposition preference of the neotropical brown stink bug Euschistus heros on artificial substrates of different colors / Preferência de oviposição do percevejo marrom Euschistus heros em substratos artificiais de diferentes cores

This study aimed to evaluate the oviposition preference of the Neotropical brown stink bug, Euschistus heros (F.) on artificial substrates of different colors (felt woven). For this, ten pairs of stink bugs were transferred into plastic pots. Each pot contained seven felts of 6x20 cm (100% polyester-atoxic) of different colors (white, black, blue, green, red, yellow and brown). The pots were evaluated daily for three weeks (21 days) being counted the number of eggs, clutches and eggs per clutch for each color of felt. The choice test was set in a completely randomized design. Data obtained was submitted to the analysis of variance and means were compared by Scott-Knott test at 5% probability. During the evaluation were produced 7074 eggs distributed in 977 clutches, accounting a mean of 7.06±0.67 eggs per clutch. Results indicated that females laid a significantly greater number of eggs (2380 and 1686) and a greater number of clutches (319 and 233) on the yellow and white felts, respectively, than on the remaining substrates. The substrates in color red, black and brown were the least preferred, and the colors blue and green were intermediate when compared with others. Therefore, the substrates colored yellow and white are suggested to be used in rearing E. heros in the laboratory.

Este estudo teve como objetivo avaliar a preferência para oviposição do percevejo marrom Euschistus heros (F.) em substratos artificiais de diferentes cores (feltros). Para isso, dez casais de percevejos foram transferidos para potes plásticos que continham sete feltros de 6x20 cm (100% poliéster atóxico) de cores diferentes (branco, preto, azul, verde, vermelho, amarelo e marrom). Os potes foram avaliados diariamente durante três semanas (21 dias), sendo contado o número de ovos, posturas e de ovos por postura para cada cor de feltro. O teste de preferência foi montado em um delineamento experimental inteiramente casualizado. Os dados obtidos foram submetidos à análise de variância e as médias comparadas pelo teste Scott-Knott a 5% de probabilidade. Durante a avaliação, foram produzidos 7.074 ovos, distribuídos em 977 posturas, contabilizando uma média de 7,06±0,67 ovos por posturas. Os resultados indicaram que as fêmeas ovipositaram um número significativamente maior de ovos (2380 e 1686) e de posturas (319 e 233) sobre os substratos de cores amarela e branca, respectivamente, do que nos demais substratos coloridos. Os feltros das cores vermelha, preta e marrom foram os menos preferidos, e as cores azul e verde foram intermediários, quando comparados aos demais. Assim, os substratos de cor amarela e branca são sugeridos para utilização na produção de ovos e criação de E. heros em laboratório.