PLoS ONE (2022) 17 (12 - e0271084)

Pablo Daniel Carpane, Matías Llebaria, Ana Flavia Nascimento and Lucía Vivan (2022)
Feeding injury of major lepidopteran soybean pests in South America
PLoS ONE 17 (12 - e0271084)
Abstract: Lepidopteran pests are major factors limiting soybean productivity in South America. In some cases, effective management of these species requires the use of foliar insecticides. For sustainable use of these insecticides, they should only be applied when insect population size exceeds an economic threshold. Since this estimation requires to determine the consumption of different species, this work aimed to integrate all these factors, studying the consumption of small (less than 1 cm long) and medium (1 to 1.5 cm long) size larvae of major lepidopteran pests to vegetative and reproductive tissues on Bt (M7739IPRO variety, containing the event MON87701 which expresses the Cry1Ac protein from Bacillus thuringiensis) and non-Bt (BMX Desafio RR variety) soybeans. The feeding injury to vegetative tissues was tested in detached-leaf assays in grow chambers, and for reproductive structures the study was conducted in greenhouse with infestations at early (flowering) and mid reproductive (mid grain filling) stages. Based on the feeding behavior of the species tested, they were cast in four groups: a) Anticarsia gemmatalis and Chrysodeixis includens, defoliating only the RR variety with the lowest consumption of foliar area; b) Spodoptera eridania, defoliating both RR and IPRO varieties, consuming twice than the species mentioned above; c) Helicoverpa armigera, defoliating and being the most damaging species to pods in the RR variety; and d) S. cosmioides and S. frugiperda, defoliating and damaging pods in both varieties. The species differed in their ability to feed on IPRO varieties, so a different economic threshold should be considered. Consequently, in cases where more than one species are found simultaneously, the species composition should be considered in estimating the economic threshold. Additionally, our findings may contribute to a better decision-making to control insect feeding injury in IPRO varieties, because a slower larval growth provides more time to ensure the need of control with insecticides. In summary, this clasification contributes to an improved recommendation of sustainable insecticide use, taking into account the behavior of each species that are major soybeans pests in South America.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Full text of article

Research topic(s) for pests/diseases/weeds:
damage/losses/economics

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Helicoverpa armigera	Soybean (Glycine max)
	Anticarsia gemmatalis	Soybean (Glycine max)
	Chrysodeixis includens	Soybean (Glycine max)
	Spodoptera frugiperda	Soybean (Glycine max)
	Spodoptera eridania	Soybean (Glycine max)
	Spodoptera cosmioides	Soybean (Glycine max)