Bioactivity of neem (Azadirachta indica A. Juss, 1797) and Bacillus thuringiensis subsp. aizawai formulations in larvae of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

Abstract

The use of botanical and biological insecticides constitutes a promising alternative to control Spodoptera frugiperda on corn crop. Thus, the present work evaluated the effect of commercial formulations of neem (Natuneem® and Neemseto®) and Bacillus thuringiensis subsp. aizawai - Bta (Xentari®) on this pest under laboratory conditions. Newly hatched and 10 days old fall armyworm larvae were fed with corn leaves treated with the insecticides at concentration of 2.5, 5.0, 7.5, and 10 mL or g/mL and control (water). An increased effect of the insecticides was found as function of increasing concentration, causing higher larval mortality, longer larval period and lower larval weight. In some cases, reduction of pupa weight, pupa viability and longevity of adults were also verified. Newly hatched larvae (ca. 0-24 h old) were more susceptible to 5 and 10 mL or g/L of Neemseto® and Xentari® as compared with 10 days old larvae. With the increase of insecticide concentration, the effects on the pupa weight and pupa viability were also greater on larvae of 0-24h old.