Divergence in climate adaptations of seasonally variable wing spot dimorphism in Drosophila suzukii indicus, a Himalayan species

Abstract

Drosophila suzukii indicus, exhibits sexual dimorphism for wing melanisation but its ecological significance is not clear. We explored the effect of temperature and humidity on the mating behavior and success of D. suzukii indicus. The numbers of D. suzukii indicus, eclosing in winter and autumn differ significantly in accordance to wing melanisation. Our results of field and laboratory studies showed that the frequency of spotted and spotless males is different in different seasons i.e. cold and dry season. D. suzukii indicus is better in their mating success and fitness than those of wet and dry season because there are differences in mated pairs with spotted and spotless males which correlate significantly with winter and autumn climatic conditions. The degree of seasonal variation in wing melanisation in wild caught D. suzukii indicus was quantified to determine if it shows patterns of plasticity and male showed the characteristic seasonal adaptive plasticity for wing melanisation. Sexual dimorphism of wing melanisation may results from, and / or affects, sexual dimorphism of behavior and physiology of D. suzukii indicus. Mating with a high-quality male (spotted wing) results in offspring with high performance. To the best of our knowledge, this is the first report on the ecological of seasonally varying wing color dimorphism in D. suzukii indicus.