Heterospecific mating interference in ladybird beetles: age dependent patterns and consequences

The ladybird beetles Cheilomenes sexmaculata and Propylea dissecta serve as effective bio-control agents, preying upon aphid populations and thereby mitigating plant damage. These beetles coexist together and show different reproductive strategies. Previous studies have found prevalent heterospecific mating between C. sexmaculata male and P. dissecta female, documenting the effects of heterospecific male C. sexmaculata on the reproductive output of P. dissecta female. In light of these observations, we conducted an experiment examining the influence of heterospecific male age on the reproductive output of P. dissecta. This study involved three age groups of male: (a) young (10–20 days), (b) middle (30–40 days), and (c) old (50–60 days). These males were introduced into Petri dishes with conspecific mates of P. dissecta. Across all experimental treatments, we examined the impact of three different age cohorts of C. sexmaculata males on the mating and reproductive attributes of P. dissecta. Our findings unveiled that older heterospecific males, which displayed reduced choosiness and heightened activity, engaged in reproductive interference to a greater degree than younger C. sexmaculata males during conspecific P. dissecta mating. Further, post-mating encounters with young heterospecific males led to a reduction in the reproductive output of female P. dissecta. The insights gained from this study hold significant implications for comprehending the feasibility of releasing multiple species of ladybird beetles within the same agricultural field. Such understanding of interspecies interactions and their consequences is vital for optimizing integrated pest management strategies.