Mating disruption alters the rate of development in an aphidophagous ladybird Propylea dissecta (Mulsant)

Ladybird beetles like many other organisms show developmental rate polymorphism in response to various abiotic and biotic factors. Since mating disruption acts as a stressor, we decided to study its impact on the occurrence of developmental rate polymorphs in ladybird beetle, Propylea dissecta Mulsant, 1850 (Coleoptera: Coccinellidae). Ten-day-old females were subjected to mating disruptions at 120, 180 minutes and complete mating (211 + 8.1 minutes) and then provided with optimum diet of Aphis craccivora Koch. Larvae in each treatment were reared individually and newly emerged adults were assessed on the basis of their developmental durations. They were separated into two lines: Slow and Fast developers. Extended mating duration was found to be correlated to increased immature survival and reduced offspring development times. Also, in complete mating treatment percentage of fast developers were more in numbers, thus mating duration increased the availability of sperm for females and seminal fluid may have boosted maternal protein reserves which can then be used to produce offspring of better quality. Mating disruption might be a factor reducing the chances of fertilization success and offspring development in P. dissecta.