Effect of Mutagens and Antibiotics on Some Traits of The Ladybird Beetle Epilachna vigintioctopunctata (Coleoptera: Coccinellidae)

Abstract

Effects of methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS) and actinomycin-D (ACM-D) on the quantitative traits such as, dominant lethal mutation (DLM), number of eggs, number of larvae, number of pupae, sex-ratio, and incubation period, larval and pupal period and longevity of adult males and female were studied in Epilachna vigintioctopuntata. Four different doses of MMS, EMS viz. 1.0ml, 2.0ml, 3.0ml and 4.0ml were used, five types of crosses were designed and the experiments were carried out for three generations. In crosses of Epilachna vigintioctopuntata it was found that all the doses of MMS and EMS induced dominant lethal mutations. However, this effect was not significant in all the crosses. There was a linear relationship between the doses of mutagen and dominant lethal frequency. The mutagenic effect of actinomycin-D on the dominant lethal mutations revealed that it induced dominant lethal mutations (significant or not) but it produced weak effect in the induction. The effects of actinomycin-D on the frequency of MMS, EMS-induced dominant lethal mutations showed that actinomycin-D did not play any role to modify the effects of alkylating agent on the induction of dominant lethal mutations. Effects of MMS, EMS and actinomycin-D on the number of eggs, larvae and pupae were studied. It was observed that the number of eggs, larvae, and pupae were decreased in the treated crosses in comparison to the controls of the parental, F1 and F2 generations. It was also noted that the combined action of MMS or EMS and actinomycin-D significantly decreased the number of eggs, larvae and pupae in the parental generation. Mutagenic effects of MMS, EMS and actinomycin-D on the number of male and female were also studied. In the F1 and F2 generation numbers of male and female were decreased significantly in some treated crosses than in the controls. The incubation period was decreased in the treated crosses compared to the controls but the value was increased in only one treated cross in the parental generation. In the F1 and F2 generations, the incubation period was found to increase in some crosses than the controls. For the larval period, pupal period, longevity of male and female it was observed that in the parental, F1 and F2 generations, the larval period was increased for the treated

crosses in comparison to the control cross. But larval period did not change in the cross ACM-D♂ x control♀. For the effects of MMS and EMS on the pupal period was found to gradually increase with doses. The longevity of adult males and females were also gradually increased by the increased mutagenic doses and antibiotic in three generations. It was recorded that the longevities of males were longer than the females, but the longevity of adult males and females did not change in the cross ACM-D♂ x control♀.