This study examined the dispersal capacity of the parasitoid Telenomus remus Nixon (Hymenoptera: Platygastridae) in soybean and maize crops. Knowledge on mobility and dispersal capacity of parasitoids is crucial for the implementation of successful biological control strategies using this biological control agent. Experiments were conducted at the experimental farm of Embrapa Soja located in Londrina, PR (−51°11′0.54″ Long.; −23°11′58.94″ Lat.) in the crop seasons of 2012, 2012/13 and 2013 at different plant phenological stages. Experimental plots consisted of six concentric circles with radii of 5, 10, 15, 20, 25, and 30 m, with 8, 24, 40, 56, 72 and 88 parasitoid traps per circle, respectively. Host eggs were placed on each plant as parasitoid traps. Approximately 150,000 newly emerged (up to 24 h old) adults of T. remus reared on eggs of Corcyra cephalonica Stainton (Lepidoptera: Pyralidae) or Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) were released at the central point of each circle. Parasitism by T. remus decreased with increasing distance to the release points regardless of host, phenological stage, crop or season. Our findings allow the conclusion that T. remus should be released at a minimum density of 35 points/hectare in soybean crops and 34 points/hectare in maize crops to ensure T. remus dispersal over 100% of the area in the worst case scenario. Since wind direction influences the dispersal pattern of T. remus, the release methodology should be determined according to wind conditions, possibly with preference for a perimetric distribution of the released insects.

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We evaluated the effects of adult mating and temperature on the biological potential and parasitism of Telenomus podisi (Ashmead) (Hymenoptera: Platygastridae) on Euschistus heros (Fabricius) (Hemiptera: Pentatomidae). Females were isolated and the characteristics of the F1 generation were compared with those of females previously copulated. The parasitism capacity of T. podisi on E. heros eggs at 20, 25, 30, 35, and 40 °C was evaluated. The longevity of parental females (days), egg-adult period (days) of the F1 generation, parasitism of parental females (%), and parasitoid emergence (%) were not influenced by the lack or not of the copulation. The offspring of non-copulated females were males, and arrhenotokous parthenogenesis occurred. The temperatures most favorable to the parasitoid were 25 and 30 °C. Even previously copulated females generated mostly males after a few days of oviposition. Therefore, the biological characteristics and reproduction of T. podisi were impacted by adult mating prior to parasitism and by different temperatures. Although parasitism of T. podisi was not affected by mating parasitoid permanence in the field, it may be affected when unmated females are released.

Release of egg parasitoids for biological control of pests is a promising technique in integrated pest management (IPM). However, there is a lack of information on the performance of parasitoid females of different ages, and specifically on the behavior of the parasitoid Telenomus remus towards pest eggs at different stages of embryonic development. Thus, the relationships between host age, parasitoid age, and parasitism by T. remus on Spodoptera frugiperda eggs were evaluated. Three separate bioassays were performed, each in a completely randomized design. In the first bioassay, T. remus females grouped by age in days (ranging from 1 to 10 days old) were offered 100 ± 20 eggs of S. frugiperda for 24 hours. In the second bioassay, 100 ± 20 eggs of S. frugiperda (24, 48 or 72 hours old) were offered to females of T. remus for 24 hours. In the third bioassay, 24, 48- and 72-hour-old host eggs of S. frugiperda were offered to T. remus females in a choice test. The variables evaluated were: number of parasitized eggs, parasitoid emergence (%), and sex ratio of progeny in bioassays 1 and 2, and the number of eggs parasitized in bioassay 3. The age of T. remus females did not affect the number of S. frugiperda eggs parasitized or emergence of the progeny. However, the sex ratio was more male-biased in the progeny of 1- and 2-day-old females compared to older wasps. In bioassay 2, the highest parasitism was observed in 24- and 48-hour-old eggs. Percentage emergence and sex ratios were not influenced by the ages of the eggs tested. Telenomus remus preferred to parasitize 24-hour-old eggs in bioassays 3. Overall, the age of T. remus females tested did not affect the parasitism of S. frugiperda eggs, but the number of eggs parasitized decreased with increasing host age.

RESUMO: 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.

This study evaluated the occurrence of lepidopteran pests on millet cultivated in off-season in the state of Mato Grosso, Brazil. Larvae were collected from May to July 2013 in an area of 145 hectares located in Tangará da Serra, MT. After being collected, caterpillars were kept in the laboratory and fed an artificial diet until the pupal stage. After emergence, adults were dry mounted, identified, and deposited in the entomological collection of Embrapa Cerrados, Planaltina, Distrito Federal, Brazil. Adults obtained from 117 caterpillars were identified as Mocis latipes (Guenée), Spodoptera frugiperda (J.E. Smith), Helicoverpa armigera (Hübner), H. zea (Boddie), Mythimna (Pseudaletia) sequax Franclemont, Urbanus proteus (Linnaeus), and Leucania latiuscula Herrich-Schäffer. This study describes the first record of lepidopteran pests on millet plants in the state of Mato Grosso, and the incidence of lepidopterans in the system that uses millet as cover crop represents a risk of the occurrence of insect pests on subsequent crops on the straw of this grass.

Records in the literature with regard to the influence of freezing of pentatomid eggs on parasitism by microhymenopterans are scarce. In this research, we compared the storage of Euschistus heros (Fabricius) (Hemiptera: Pentatomidae) eggs in liquid nitrogen for different periods with the objective of optimizing the multiplication of Telenomus podisi Ashmead (Hymenoptera: Platygastridae) in the laboratory. Fresh eggs of E. heros were exposed (S3, S6) or not (NS3, NS6) to UV light for 30 min and stored in 1.5-mL plastic vials in liquid nitrogen either for 3 (S3, NS3) or 6 months (S6, NS6), and egg suitability to parasitoid development was compared to control eggs exposed (SC) or not (NSC) to UV treatment. Global data analysis showed that E. heros eggs stored in liquid nitrogen with or without UV treatment, for 3 or 6 months, were suitable for T. podisi parasitization.

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