Heterospecific physical interference modulates the reproductive attributes of a ladybird beetle

Propylea dissecta and Cheilomenes sexmaculata (Coleoptera: Coccinellidae), are similar sized, co-ocurring aphidophagous insects that share common resources. We conducted the current study to observe the phenomenon of reproductive interference and effect of presence of heterospecific adults (C. sexmaculata) on the reproductive output of P. dissecta. For this, we used two reciprocal mating combinations of heterospecifics. The first heterospecific combination used P. dissecta males with C. sexmaculata females and the second heterospecific mating combination used P. dissecta females with C. sexmaculata males. To further examine the effect of C. sexmaculata male on P. dissecta female, we used mixed mating treatments (C. sexmaculata male with conspecific pair of P. dissecta). Our results suggested that (1) in the first heterospecific mating combination, mating did not commence between P. dissecta male C. sexmaculata female, while in the second heterospecific mating combination, mating was recorded between P. dissecta female and C. sexmaculata male, (2) C. sexmaculata male interferes the conspecific mating in P. dissecta through multiple mating attempts which resulted in reduced fitness and reproductive success of P. dissecta. Overall, we illustrated the negative effects of reproductive interference caused by C. sexmaculata on the reproductive output (fecundity and egg viability) of P. dissecta.