Entomopathogenic nematodes and their interaction with chemical insecticide aiming at the control of banana weevil borer, Cosmopolites Sordidus Germar (Coleoptera: Curculionidae)

Abstract

The banana weevil borer (Cosmopolites sordidus) is the main pest of banana crops, causing significant losses in productivity, being recommended control by chemical insecticides which cause several environmental impacts. On the other hand, entomopathogenic nematodes can be an alternative to the pest control, mainly because of their habits. Thus, this study aimed at evaluating isolated entomopathogenic nematodes under laboratory conditions and also their interaction with a chemical insecticide (carbofuran), aiming at their use for the weevil borer control. Sixteen Sterinernematidae and Heterorhabditidae isolates were evaluated, applied over the banana tree pseudo stem (100 JIs/cm²) and they were compared to one another concerning mortality caused in adults individual of C. sordidus. The most infective isolates were subjected to in vivo multiplication at the host Galleria mellonella and interaction with the insecticide carbofuran, including in this case, viability and infectivity analysis of the entomopathogenic nematodes exposed to the product, as well as the effect of the insecticide on the symbiotic bacteria of the entomopathogenic nematodes. The experiments at this stage were conducted in completely randomized design and the data were subjected to ANOVA, with application of the Tukey test (p < 0.05). The most virulent isolates were IBCBn24 and IBCBn40 (respectively 33.3% and 36.7% of confirmed mortality), which also showed high multiplication in corpses. The insecticide did not affect the viability of the isolate, but it really harmed its infectivity, although it did not affect the development of the symbiotic bacterium.