Influence of Bacillus thuringiensis and Plant Extracts on Different Instars of Trilocha varians (Lepidoptera: Bombycidae) under Laboratory Conditions

The influence of plant extracts and bacteria (Bacillus thuringiensis) (Bt) strains on different larval stages of Trilocha varians (Walker) were studied under laboratory conditions. Results indicated that larval mortality increased with exposure time. Early instar (2nd instar larvae) were more susceptible to Bt and plant extracts than older instars (3rd instar larvae). At day seven, Turex (Bt subspecies kurstaki and aizawai) and Dipel (Bt subspecies kurstaki), showed 76.43 and 70.09% mortalities in 2nd instar larvae, respectively. Mortality rates of 3rd instar larvae were 71.17% and 65.40% for Turex and Dipel, respectively. Azadirachta indica and Eucalyptus globulus extracts caused 63.12 and 51.09% mortalities of 2nd instar larvae respectively at the highest dose rate (25 ppm/mL). These results are consistent with previous research and suggest that optimizing both dose and application duration can significantly improve pest control effectiveness. The study highlights the potential of herbal products as effective, safer and environmentally friendly organic insecticides. These products can be integrated into integrated pest management (IPM) programs and provide a sustainable alternative to traditional chemical insecticides.