Toxic Bait as an Alternative Tool in the Management of Spodoptera frugiperda in Second Corn Crops

Abstract

Managing the fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith, 1797), has been increasingly difficult owing to the increase in individual resistance to insecticides and genetically modified Bacillus thuringiensis (Bt) plants. This study used the attracting and killing method to control FAW adults in the field by spraying Noctovi® with methomyl insecticide. The experiments were conducted in commercial cornfields, non-Bt and Bt crops, over two agricultural years (2018 and 2019) at eight sites distributed in three cities located in the south of Mato Grosso do Sul State, Brazil. The following six insecticide treatments were used: spraying in continuous bands spaced every 100, 50, and 25 m; intermittent spraying every 25 m; control (without insecticide application); and spraying the entire area with insecticide (positive control). Food bait associated with the insecticide molecule was applied to the crop at vegetative stages V1 and V3, and the adult population size and level of leaf damage caused by the caterpillars (assessed via the Davis scale) were evaluated. The application of toxic bait in bands with spacing less than or equal to 50 m significantly reduced the percentage of damage to the plants, with the effect stronger in Bt crops. We suggest that the control of FAW adult populations would be more efficient if the attracting and killing technique was incorporated in integrated pest management programs for second corn crops.

Large‐area field application confirms the effectiveness of toxicant‐infused bait for managing Helicoverpa armigera (Hübner) in maize fields

“…Therefore, controlling adults is a prevention‐based control strategy which acts on the source of insects, and achieves a regional control goal of H. armigera populations 12,46 . Our research results show that toxicant‐infused bait can strongly attract and kill H. armigera adults, similar to the results found in studies of fall armyworms, sugar beet moths and other pest moths 29,47,48 . The number of male and female H. armigera adults attracted and killed by strip application of toxicant‐infused bait ranged from 1 to 37 and 4 to 36 per strip, respectively, of which female moths accounted for 53%, consistent with the results in cotton, maize, soybean and peanut fields by He et al 36 …”

“…Difference on the adjusted decline rate of the population of H. armigera eggs, the adjusted decline rate of damaged plants, yield increase of maize, and increased economic income were analyzed using the one‐way ANOVA, followed by Duncan's MRT. The proportional data was first arcsine square‐root‐transformed to meet the assumptions of normality and heteroscedasticity 29 . Multiple nonlinear models were used to fit major axis length, male age, index of ovarian development and mating frequency of female at different investigation stage (curve estimation).…”

“…In nature, the female lepidopteran follows volatiles of host plants to locate nectar or a suitable place to lay eggs, and males usually rely on sex pheromones released by females to find mates 19,43 . As an important measure in integrated pest management (IPM), the use of host plant volatiles to change and manipulate pest behavior can help reduce the amount of insecticides in agricultural production systems and improve the efficacy 29,35 . Cotton bollworms exhibit a remarkable reproductive capacity, coupled with seasonal host‐transfer habits and long‐distance migration tendencies.…”

“…With easily sourced raw materials, bio‐baits are a type of broad‐spectrum and environmentally friendly biological attractant that can be widely used in IPM 19,20,25,28,29 . However, in practice, several aspects need to be optimized and improved.…”

“…As an important bio‐control technology, bio‐baits play a vital role in monitoring and controlling many important agricultural and forestry pests, including H. armigera , Spodoptera frugiperda J.E. Smith, Cydia pomonella L., Frankliniella occidentalis Pergande and Bactrocera dorsalis Hendel, among others 19,21–31 . The bio‐bait Magnet® is widely used in crops such as cotton and maize in Australia and the United States.…”