Effect of Bacillus thuringiensis (Kurs.) Exposed to Gamma-Ray on Certain Biological Assays of Pectinophora gossypiella (Saund.) (Gelechiidae: Lepidoptera)
The current study was conducted to evaluate the toxicity and certain biological assays of the pink bollworm, Pectinophora gossypiella (Saund.) treated with a bio-insecticide compound, Bacillus thuringiensis (Kurs.) alone and its exposure to gamma-ray doses (5, 10, 20, 40 & 80 Gy) under laboratory conditions. Gamma-ray can potentiate B. thuringiensis toxicity gradually from B. thuringiensis + 5 Gy until B. thuringiensis + 80 Gy to become more toxic than the same compound without exposing to gamma doses against P. gossypiella newly hatched larvae. Certain biological assays of P. gossypiella treated as newly hatched larvae were affected by B. thuringiensis exposed to gamma-ray treatments (5 up to 80 Gy). B. thuringiensis + 80 Gy were considered the best treatment compared with other treatment or the same compound without exposing to gamma-ray. Treatments caused an increase in the most biological assays during larval, pupal and adult stages (larval, pupal & adult period and mortalities; also, sterility was increased) in compared to the untreated one. Meanwhile, other biological assays of P. gossypiella were decreased (egg-laying rate, hatchability, control of hatchability & fecundity) as affected by B. thuringiensis exposed to gamma rays compared with untreated. So, gamma doses used can potentiate B. thuringiensis to become its efficacy higher than it’s used alone against P. gossypiella treated as newly hatched larvae.