Chapter 13 - Microbial Control of Soybean Pest Insects and Mites

Abstract

The current and potential uses of microbial control agents against soybean pests are updated and discussed. Anticarsia gemmatalis, applied against the velvetbean caterpillar, and Heliothis zea, applied against the old world bollworm, are the main microbial control agents, considering their success and the extension of the area treated with entomopathogenic nucleopolyhedroviruses. So far, entomopathogenic fungi have not been applied to soybean systems to induce artificial epizootics. However, their preservation is of paramount importance since Entomophtoralean species such as Pandora gammae, Zoophtora radicans, and Entomophthora aulicae, or Metarhizium rileyi (Hypocreales: Clavicipitaceae), play very important roles in regulating lepidopteran populations, as do Neozygites floridana and Pandora neoaphidis in controlling spider mites (Tetranychus urticae and Mononychellus planki) and Aphis glycines populations, respectively. All these species are very sensitive to triazole and strobilurin fungicides, and applications against soybean rust usually interfere with their positive action, favoring pest resurgence. Despite the efficiency of bacterial applications and the lack of adverse effects on natural enemies, they are not recommended in countries planting Bacillus thuringiensis soybean in order to lower selection pressure with Cry toxins. Although the correct use of microbial control agents requires a more trained extension service, their application is highly desirable due to their selectivity and low environmental impact.