Soybean plant architecture influences the capacity of Telenomus podisi to parasitize Euschistus heros eggs: implications for field releases

BACKGROUND Plant architectural complexity can strongly influence the foraging behavior and abundance of arthropods. Increased structural complexity has been shown to reduce the ability of natural enemies to locate and attack their prey or hosts on plants with more intricate architectures. In this context, the present study investigated how soybean plant architecture affects the ability of Telenomus podisi to parasitize Euschistus heros eggs, and explored the implications of these effects for inundative biological control releases. RESULTS As soybean plant architecture became more complex, the parasitism efficiency of T. podisi decreased markedly. Compared with plants of simple architecture, parasitism of E. heros eggs was reduced by approximately half on plants with complex structures. Moreover, linear regressions revealed that plant height, number of leaves, total surface area, and architectural complexity index were all significant predictors of parasitism by T. podisi . Population growth projections for E. heros further indicated that, given the same number of released T. podisi females, this pest action threshold was reached more quickly on soybean plants with more complex architecture. CONCLUSION The morphological complexity of soybean plants is a key factor limiting the ability of T. podisi to parasitize E. heros eggs. Consequently, adjusting parasitoid release rates to match crop phenology (i.e., plant complexity) can significantly improve the optimization and calibration of augmentative releases in soybean fields.