Native <i>Bacillus thuringiensis</i> isolates against the old-world bollworm, <i>Helicoverpa armigera</i> (Hübner) (Lepidoptera: Noctuidae) in Ethiopia

Abstract

Chickpea (Cicer arietinum L.) production in Ethiopia has been seriously constrained by the insect pest, Helicoverpa armigera. Insecticides have been used for decades to control this noxious pest. However, the restriction on chemical insecticides necessitates biological pest control alternatives. Therefore, the present study investigated the effectiveness of native Bacillus thuringiensis (Bt) isolates against Helicoverpa armigera 3rd instar larvae. The treatments consisted of Bt concentrations at the LD90 values, whereas the control plots were sprayed with distilled water and a commercial Bt. var. thuringiensis product. The results revealed statistically (p < 0.05) significant differences between the native Bt isolates and the control plots. Post 1st, pre 2nd and post 2nd Bt sprayed larval populations counted per plant ranged from 0.8 ± 0.3–3.1 ± 0.1, 0.6 ± 0.1–3.6 ± 0.0 and 0.5 ± 0.1–3.6 ± 0.4, respectively. Pod damage (%) and grain yield (t/ha) ranged between 9.7 ± 3.1 and 47.5 ± 9.5, 1.0 ± 0.0 and 2.6 ± 0.5, respectively compared to 47.5 ± 9.5% pod damage and 1.0 ± 0.0 (t/ha) grain yield from the control plots. These results indicate the potential of these bio-insecticides in the management of chickpea pod borer. Future research in Ethiopia should focus on additional collection, screening, characterisation, and testing in field trials.