Abstract
Spodoptera cosmioides Walk (Lepidoptera: Noctuidae) is a polyphagous species, considered a secondary pest in soybean crop. The Intacta soybean (Bt soybean) event was released in Paraguay with Bt proteins which are supposed to be toxic for caterpillars. However, the effects of these proteins in the Spodoptera cosmioides biology still uncertainty. This study evaluated the biological activity of Bt soybean in S. cosmioides that were fed on Bt and non-Bt soybean leaves under laboratory conditions. The experiment was carried out at the Laboratory of Entomology; temperature 26±2 ºC; relative humidity: 60±10%; photoperiod: 14:00 h where 150 neonate larvae were used per treatment. The period and viability of each stage, the mortality of larval, number of eggs and neonate per couple, and the period of larvae to adult were the assessed variables. Higher mortality was observed in larvae fed with intact soybeans, but without statistical differences with non-Bt soybeans. For larval survival, period, number and total period, no statistical differences were verified. Higher percentage of fertility was observed in soybeans non-Bt but no statistical differences.
Highlights
In Paraguay, as well as the neighboring countries Brazil and Argentina, a widely spread soybean production system is the high-intensity no-till agriculture
3.1 Mortality of S. cosmioides in Soybean Bacillus thuringiensis (Bt)
The sum of larvae mortality observed in Spodoptera cosmioides larvae fed Bt Cry1Ac soybean does not present statistical differences (p = 0.2451); compared to RR non-Bt. soybeans (Table 1)
Summary
In Paraguay, as well as the neighboring countries Brazil and Argentina, a widely spread soybean production system is the high-intensity no-till agriculture. 2017 in a study on the abundance and species richness of owlet moths reported that considering all species together, individuals of Spodoptera species represented 4.2% of all larvae found on non-Bt soybeans, while their representation on Bt soybeans was 16.3% Among these 16% larvae abundance, the Bt soybean technology protects against the following so-called secondary pests that affect soybean cultivation: Rachiplusia nu, Chrysodeixis (Pseudoplusia) includens, A. gemmatalis and Crocidosema aporema and others of secondary importance such as Helicoverpa gelotopoeon, Achyra bifidalis, Heliothis virescens (Bortolotto et al, 2014), Spilosoma virginica and Colias lesbia. Carrying out investigations to verify the technology control levels over these pests at regional levels is the priority to optimize integrated pest management In this context, studies were carried out in Paraguay to evaluate the Bt soybean event (Cry 1Ac) toxicity on the S. cosmioides biology. The Bt toxin is expected to have some effect on the biology of this species
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
