Comparison of the predatory impacts of indigenous and adventive ladybeetle species (Coleoptera: Coccinellidae) using a functional response approach

Abstract

Biological control has long been recognized for its economic and ecological bene ts as a pest management approach, but the use of non-native natural enemies has raised concerns about potential risks and unintended consequences. Indigenous predatory ladybeetles, such as Oenopia conglobata, play a crucial role in controlling many sap-sucking pests, including Agonoscena pistaciae, which is the most destructive pest of pistachio trees in Iran and other pistachio-growing regions worldwide. However, the abundance of Oenopia conglobata has recently decreased due to the presence of an adventive predatory ladybeetle, Menochilus sexmaculatus. To better understand the potential risks associated with this adventive species, we investigated the functional responses of female adults of M. sexmaculatus and O. conglobata against the third and fourth instar nymphs of A. pistaciae and Aphis gossypii. Our ndings revealed that both predators exhibited a type II functional response, with O. conglobata demonstrating a signi cantly higher attack rate against A. pistaciae nymphs than A. gossypii nymphs. In contrast, prey species did not have a signi cant effect on the attack rate of M. sexmaculatus. Notably, M. sexmaculatus displayed the highest predation rate and voracity against both prey species. These results provide valuable insights into the potential risks of M. sexmaculatus for indigenous predatory species like O. conglobata. The fact that M. sexmaculatus exhibits higher voracity for both prey species than O. conglobata does suggest that it may pose a threat to the native ladybeetle population, highlighting the need for further research and careful consideration when introducing non-native natural enemies for pest management. IntroductionsPistachio is one of the most economically important crops in Iran, covering ~ 420,000 ha of land (Mehrnejad, 2010). The common pistachio psyllid -Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Psyllidae)poses a signi cant threat to cultivated pistachio trees in the Russian Federation, Middle East and Mediterranean areas (Mehrnejad et al. 2010;. This insect has also evolved resistance to diverse pesticides, making chemical control strategies less effective (Mehrnejad, 2010). Biological control agents offer a promising