Susceptibility of Alabama argillacea and Chrysodeixis includens (Lepidoptera: Noctuidae) larvae to Beauveria bassiana associated with kaolin.

C A D Silva,J S Galdino,J C Zanuncio,M A Castellani

doi:10.1590/1519-6984.233340

Abstract

The mortality of the Alabama argillacea and Chrysodeixis includens (Lepidoptera: Noctuidae) larvae caused by the kaolin inert powder and the entomopathogenic fungus Beauveria bassiana were determined under laboratory conditions. Using the caterpillar submersion method, the CG 138 B. bassiana isolate was more pathogenic to A. argillacea than the CG 70, GC 82, ESALQ 634, and ESALQ 645. All five tested isolates caused similar mortality of C. includens. The mortality of first-instar larvae of A. argillacea and C. includens by feeding on leaf-disc impregnated with B. bassiana (CG 138) and kaolin was also determined. Higher A. argillacea mortalities were observed in the B. bassiana (CG 138) treatments, regardless of the presence of kaolin. However, the activity of kaolin + B. bassiana (CG 138) against C. includens was higher than each ingredient alone, indicating an additive action against C. includes larvae. The mortality of A. argillacea and C. includens larvae treated with kaolin + B. bassiana (CG 138) was similar, and the A. argillacea mortality was higher than that of C. includens with kaolin and B. bassiana (GC 138) separated. The treatment kaolin + B. bassiana (CG 138) is promising for the simultaneous management of these two defoliator pests, mainly A. includes. In addition, the monophagous A. argillacea is more susceptible to both kaolin and B. bassiana (GC 138) than the polyphagous C. includens, suggesting that the nutritional ecology plays an important role in the susceptibility of these defoliator species to alternative insecticides.

Highlights

The cotton leafworm, Alabama argillacea (Hübner, 1818) and the soybean looper, Chrysodeixis includens (Walker, 1857) (Lepidoptera: Noctuidae) are cotton defoliator pests (Viana et al, 2014)
The use of kaolin particle film technology can improve the efficiency of insecticides to controlling cotton pests (Silva and Ramalho, 2013), including aphids, boll weevils, cotton leafworms, pink larvae and white flies, as well as the cotton bollworm complex and those of the genus Spodoptera (Neves et al, 2014; Gonçalves et al, 2015)
The objective of this research was to determine the susceptibility of the cotton leafworm, A. argillacea, and C. includes larvae to the entomopathogenic fungus B. bassiana combined with kaolin

Summary

Introduction

The cotton leafworm, Alabama argillacea (Hübner, 1818) and the soybean looper, Chrysodeixis includens (Walker, 1857) (Lepidoptera: Noctuidae) are cotton defoliator pests (Viana et al, 2014). These Lepidoptera pests have different specialization levels (monophagy and polyphagy) on cotton plants, and are controlled with synthetic chemical insecticides (Oliveira et al, 2010). The use of kaolin particle film technology can improve the efficiency of insecticides to controlling cotton pests (Silva and Ramalho, 2013), including aphids, boll weevils, cotton leafworms, pink larvae and white flies, as well as the cotton bollworm complex and those of the genus Spodoptera (Neves et al, 2014; Gonçalves et al, 2015). Kaolin may affect the insect cuticle permeability to water, a limiting factor for these organisms (Cook et al, 2008)

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