Defesas induzidas por herbivoria e interações específicas no sistema tritrófico soja-percevejos-parasitoides de ovos

Abstract

Resumo -O objetivo deste trabalho foi avaliar a influência de voláteis de soja, induzidos pela herbivoria dos percevejos Euschistus heros e Nezara viridula, no comportamento de busca de hospedeiros dos parasitoides Telenomus podisi e Trissolcus basalis. Plantas injuriadas pela alimentação dos percevejos foram utilizadas como estímulos em bioensaios com fêmeas dos parasitoides, em olfatômetro de dupla escolha tipo Y. Telenomus podisi respondeu somente a voláteis liberados pela soja após a herbivoria de E. heros, seu hospedeiro preferencial. Trissolcus basalis não foi influenciado pelas plantas injuriadas pelos percevejos. Os resultados obtidos indicam existência de interações espécie-específicas no sistema tritrófico soja-percevejos-parasitoides de ovos.Termos para indexação: comportamento de busca, controle biológico, hospedeiro preferencial, interações tritróficas, olfatômetro de dupla escolha, voláteis de plantas. Defenses induced by herbivory and specific interactions on the tri-trophic system soybean-stink bug-egg parasitoidsAbstract -The objective of this work was to evaluate the influence of soybean volatiles, induced by the herbivory of the stink bugs Euschistus heros and Nezara viridula, on the host searching behavior of the parasitoids Telenomus podisi and Trissolcus basalis. Plants injured by the feeding activity of the stink bugs were used as stimuli in bioassays with parasitoid females in a two-choice Y type olfactometer. Telenomus podisi responded only to volatiles released by soybean after herbivory injury of E. heros, their preferential host. Trissolcus basalis did not respond to plants injured by the stink bugs. The obtained results indicate the existence of species-specific interactions in the tri-trophic system soybean-stink bug-egg parasitoids.

No impact of Bt soybean that express Cry1Ac protein on biological traits of Euschistus heros (Hemiptera, Pentatomidae) and its egg parasitoid Telenomus podisi (Hymenoptera, Platygastridae)

“…In addition, the tritrophic relation of plant/pest/parasitoid must be considered. Other studies have shown that the egg parasitoid T. podisi prefers plants damaged by E. heros to healthy plants (Lopes et al 2012) which emphasizes the need for further experiments with Bt-plants under field conditions in order to clarify this relationship. However, since no adverse impact of Bt soybean above T. podisi sex ratio was observed in our study, these results suggest that E. heros egg is nutritionally and chemically similar to the eggs originated from stink bugs which fed on both Bt and non-Bt soybean pods.…”

Selective responses of Trissolcus basalis and Telenomus podisi to chemical footprints of preferred hosts

“…podisi to discriminate between footprints of different stink bug species. Selective responses of these parasitoids are also reported for stimuli used in the early stages of a host search, such as plant volatiles (Lopes et al ., ) and host semiochemicals (Laumann et al ., ; Tognon et al ., ). Similarly, selective responses are reported for stimuli used after habitat location, such as host vibratory signals (Laumann et al ., , ) colour of the substrate (Aquino et al ., ) and egg volatiles (Michereff et al ., ; Tognon et al ., , ).…”

Selectivity of pesticides registered for soybean crop on Telenomus podisi and Trissolcus basalis

“…Despite their specificities, regarding the preferred host, both are found parasitizing eggs of the main soybean stink bug pests (Lopes et al 2012). Parasitism rates reach 80 % for T. podisi (Pacheco & Corrêa-Ferreira 2000) and 60 % for T. basalis (Corrêa-Ferreira & Moscardi 1995).…”