Abstract
BACKGROUNDCrop pest management requires an understanding of the complex interactions among species that potentially impact crop yield. In soybean, the velvetbean caterpillar, Anticarsia gemmatalis (Hübner), and the soybean looper, Chrysodeixis includens (Walker), are described as key pests, sharing the same feeding guild. We assessed the intraguild interactions of these species under laboratory conditions. Fitness cost study was conducted to examine the influence of competition on insect development. A video tracking system was used to evaluate behavioral parameters during larval interactions in scenarios with and without food availability.RESULTSIn the fitness cost assay, pupal weight was not significantly affected, regardless of sex. However, larval and pupal survival were influenced by the competition, especially in third versus fifth instar scenarios. We detected 40.00% cannibalism and 46.67% predation when A. gemmatalis and C. includens third instars competed with A. gemmatalis fifth instar, respectively. Distance moved, distance between larvae, body contact (food available) and frequency in food of C. includens larvae were negatively affected by interactions. Anticarsia gemmatalis larvae showed highly active behavior, moving twice or more the distance compared to C. includens larvae, and A. gemmatalis spent more time in body contact with food.CONCLUSIONOur results suggest that A. gemmatalis has a competitive advantage over C. includens. This study provides important information regarding lepidopteran behavior in soybean. We recommended that additional studies are necessary to understand the effects of interactions, especially in field conditions.© 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Highlights
The velvetbean caterpillar, Anticarsia gemmatalis (Lepidoptera: Erebidae), and the soybean looper, Chrysodeixis includens (Lepidoptera: Noctuidae), are among the major soybean pests, which have been causing economic damage from South to North America.[6,7,8]. The management of both lepidopteran species can be achieved using different control strategies as part of integrated pest management (IPM) programs, but recently in Brazil, genetically modified soybean expressing a Bacillus thuringiensis (Bt) insecticidal protein has assumed a prominent position for large scale management of lepidopteran insect pests.[9,10]
This biotechnology is an important tool for the integrated management of A. gemmatalis and C. includens, the use of Bt transgenic crops has been modifying Lepidoptera entomofauna in soybean.[9,11,12]
Mean pupal weight of A. gemmatalis females from third instar larvae isolated (202.64 mg) was significantly greater than the pupal weight of small larvae surviving in competition (F = 2.91; df = 4, 20; P = 0.0476)
Summary
Soybean [(Glycine max (L.) Merrill)] is one of the most important agricultural products and has been increasingly planted worldwide.[1,2] Despite the diverse climate conditions, important soybean producing areas in USA and South American countries are threatened by lepidopteran caterpillars.[3,4,5] The velvetbean caterpillar, Anticarsia gemmatalis (Lepidoptera: Erebidae), and the soybean looper, Chrysodeixis includens (Lepidoptera: Noctuidae), are among the major soybean pests, which have been causing economic damage from South to North America.[6,7,8]The management of both lepidopteran species can be achieved using different control strategies as part of integrated pest management (IPM) programs, but recently in Brazil, genetically modified soybean expressing a Bacillus thuringiensis (Bt) insecticidal protein has assumed a prominent position for large scale management of lepidopteran insect pests.[9,10] this biotechnology is an important tool for the integrated management of A. gemmatalis and C. includens, the use of Bt transgenic crops has been modifying Lepidoptera entomofauna in soybean.[9,11,12] In the US there is no Bt transgenic soybean; taking it as an example, the large scale adoption of Bt corn and cotton in the US has resulted in an intense selection pressure for the development of resistance and challenges the long-term sustainability of the technology.[13]. Soybean [(Glycine max (L.) Merrill)] is one of the most important agricultural products and has been increasingly planted worldwide.[1,2] Despite the diverse climate conditions, important soybean producing areas in USA and South American countries are threatened by lepidopteran caterpillars.[3,4,5] The velvetbean caterpillar, Anticarsia gemmatalis (Lepidoptera: Erebidae), and the soybean looper, Chrysodeixis includens (Lepidoptera: Noctuidae), are among the major soybean pests, which have been causing economic damage from South to North America.[6,7,8]. A video tracking system was used to evaluate behavioral parameters during larval interactions in scenarios with and without food availability
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