RESUMO
Anastrepha fraterculus (Diptera: Tephritidae) is considered an important pest in Neotropical countries. The laboratory rearing of this species should reproduce conditions in nature; thus, special attention is required to the nutritional quality of diets for larval development. Protein components (wheat germ) are costly and account for most production costs in lab insect rearing. In this sense, this work aimed to identify ingredients to replace wheat germ, without compromising diet quality for the lab rearing of A. fraterculus. We tested diets composed of whole rice flour, corn flour, and a mixture of whole wheat flour + soybean flour as substitutes for wheat germ as well as a raw wheat germ diet, considered the control. The protein sources used in the larval diet influenced the biological performance of both the larval and adult stages of A. fraterculus during six generations. The diet containing corn flour and wheat germ showed similar results in the different developmental parameters. The diet with rice flour also provided adequate biological development for A. fraterculus throughout its life cycle and was nutritionally similar to the control. As it is local product, rice flour can replace wheat germ (costly imported product) in artificial diets for A. fraterculus, reducing production costs by roughly 30% without compromising the biological and nutritional parameters of the insects. Faced with this, the rice flour can be considered suitable for the mass rearing of A. fraterculus in the laboratory.
RESUMO
BACKGROUND: Crop 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. RESULTS: In 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. CONCLUSION: Our 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.