SPATIAL DISTRIBUTION OF Chrysodeixis includens EGGS (WALKER, 1858) (LEPIDOPTERA: NOCTUIDAE) IN SOYBEAN CROP

Abstract

Among pest insects that attack soybean crops, Chrysodeixis includens (Walker, 1858) (Lepidoptera: Noctuidae) looper caterpillar deserves attention due to its key pest status in soybean crops. The spatial distribution of C. includens eggs should be investigated in order to understand the behavior of this species in the area. The aim of this study was to investigate the spatial distribution of C. includens eggs in soybean crops. The experiment was conducted with SYN 9070 RR soybean variety in an experimental area of the Teaching, Research and Extension Farm (FEPE) of FCAV/ UNESP, Jaboticabal, SP, Brazil. The area of 0.6 ha was divided into 60 equidistant plots of 100 m² each. For the study of the spatial distribution of P. includens eggs in the area, the following dispersion indexes were used: variance / mean ratio (I), Morisita index (Id), Green coefficient (Cx), k exponent of the negative binomial distribution for each sampling. Regarding the probabilistic models that describe the spatial distribution of a given variable, the data adjustment to the Poisson and negative binomial distributions was tested. According to values obtained for dispersion indexes, egg distribution occurred in an aggregate way, and the negative binomial distribution was the most appropriate probabilistic model to represent the distribution of C. includens eggs in the study area.

Selection and molecular characterization of Bacillus thuringiensis strains efficient against soybean looper (Chrysodeixis includens) and Spodoptera species

“…The soybean looper, Chrysodeixis includens [Walker, 1858] (Lepidoptera: Noctuidae), is a polyphagous pest present in several countries of the American continent, with occurrence from the north of the USA to the south of South America. C. includens causes economic losses in diverse crops (Moscardi et al, 2012;Souza et al, 2019) and, it is considered one of the most important pests in soybean crop in Brazil. The Spodoptera genus are composed of important species of defoliator caterpillars, such as S. cosmioides, S. eridania and the fall armyworm, S. frugiperda (JE Smith), responsible for significant losses in maize production in Brazil, African continent, India, and China (Goergen et al, 2016;Guo et al, 2018;Sharanabasappa et al, 2018).…”