Inherited influence of low dose gamma radiation on the reproductive potential and spermiogenesis of the cowpea weevil, Callosobruchus maculatus (F) (Coleoptera: Chrysomelidae)

Abstract

The southern cowpea weevil, Callosobruchus maculatus (F) is a severe agriculture pest worldwide. In the current work, newly emerged adult males of C. maculatus have been irradiated with a low dose of 20Gy gamma radiation. The inherited deleterious effects on the fecundity, hatchability, adult emergence, and the sterility percent were recorded for the progenies F1 and F2 of the irradiated parental males. The fecundity, hatched larvae, the number of males and females were reduced in both F1 and F2. The sterility percent was high in F1 (70.8%) and increased in the F2 (88.3%) generation. Histopathological effects were also documented in the testes of F1 and F2 progenies. The spermatids and sperms have exhibited a variety of abnormalities. In the early spermatids, the nebenkern outer cell membrane was ruptured. The spermatid nucleus loses its homogeneous texture and has multiple foci of dense chromatin, as well as, profiles range has little dense material. In some groups, the nucleus had a peculiar ring of chromatin. The sperms had shown a variety of aberrations. The sperms irregularity distributed in lysed cysts by unusual manner. Also, some sperms had remarkably enlarged axoneme and small rounded nucleus. Many of the sperm cells were observed with two axonemes, abnormal mitochondria derivatives, and more than two accessory bodies. These results indicate that the low dose of 20 Gy induces semi-sterility in C. maculatus through generations. The same technique would help to improve using of sterile insect technique for other agriculture pests.

Keywords

• Cowpea weevil (Callosobruchus maculatus)
• 20 Gy gamma radiation
• Spermiogenesis
• Semi-sterile dose
• Sterile male technique