Toxicity and biological effects of certain pesticides and natural oils on the peach fruit fly, Bactrocera zonata (Saunders, 1841) (Diptera: Tephritidae)

Abstract

Toxicity and biology studies were conducted on certain insecticides that belong to different chemical groups, namely malathion (organophosphate group), lambda-cyhalothrin (pyrethroid group), and spinosad (Benzophenyl urea group), and on lemon-grass and sesame oils as natural oils against adult male and female Bactrocera zonata (Saunders, 1841). They were carried out under laboratory conditions, and results were taken after 24h post treatment. Lambda-cyhalothrin was the most toxic on males and females of B. zonata at LC25 of 0.017 and 0.04, followed by spinosad with LC25 of 1.15 and 1.29, respectively. However, malathion was the least toxic to males and females, showing LC25 of 18.53 and 12.24, respectively. The same results were obtained at LC50, as lambda-cyhalothrin was the superior toxicant with LC50 of 0.65 and 1.008, followed by spinosad of 2.56 and 3.53, respectively. Furthermore, the natural sesame oil, Sesamum indicum (Linnaeus, 1753), was more toxic than lemon-grass oil to the males of B. zonata with LC25 of 0.06 and 0.08, respectively. Lemon-grass oil, Cymbopogon citratus (Stapf, 1906), was more toxic to females than sesame oil with LC25 of 0.05 and 0.07, respectively. At LC50, lemon-grass was more toxic than sesame on both males and females. In addition to the biological effects, results showed a significant reduction in the oviposition and post-oviposition periods of adults treated with different tested compounds, compared to the control group. Moreover, all tested compounds significantly decreased fecundity, hatchability, longevity, pupation, and the emergence of B. zonata adults, when compared to the untreated groups.