Multitrophic interactions between coccinellids and their parasitoids in natural and managed plant systems: host plant and aphid prey species matter

Multi-trophic and multispecies interactions among family of arthropods assemblages are ubiquitous and include all type of interactions from mutualistic to antagonistic. To better inform the biological control of aphids, the multitrophic interactions between aphids, coccinellids and their parasitoids in natural and managed plant systems were examined over a span of 4 years. Coccinellid larvae naturally found feeding on aphids on two non-crop plants growing in agricultural landscapes in Pakistan were studied; Aphis nerii Boyer de Fonscolombe (Hemiptera: Aphididae) feeding on Calotropis procera Aiton, and Nerium oleander L, and four crop host; Lipaphis erysimi Kalt (Hemiptera: Aphididae) feeding on Eurica sativa Mill. and Brassica campestris L., Uroleucon compositae Theobold (Hemiptera: Aphididae) feeding on Carthamus tinctorius L., and Diuraphis noxia Mordvilko (Hemiptera: Aphididae) feeding on Hordeum vulgare L.; were collected throughout the aphid season and reared on their respective aphid-plant combinations in the laboratory conditions to identify coccinellid species, their parasitoids and asses their performance in items of survival and pupal weight. The coccinellid pupal weight on different host plant-aphid combinations varied from 3.4 to 11.2 mg, as did the mortality of coccinellid larvae due to diseases and unknown causes (5 to 31%). Parasitism of coccinellid larvae by Homalotylus flaminus (Dalman) (Hymenoptera: Encyrtidae) ranged from approximately 10 to 30 in B. campestris and E. sativa, respectively. The parasitism of coccinellid pupae by Oomyzus scaposus (Thomson) (Hymenoptera: Eulophidae) ranged between 17 (C. procera) to 41% (B. compestris). One Dinocampus coccinellae Schrank (Hymenoptera: Braconidae) was reared. Coccinellids displayed selectivity towards host plants and aphids. Some coccinellids were never or rarely recorded on a particular aphid-plant combination, suggesting that their prey selection is more specific than often assumed. Management decision and conservation biological control cannot be based on superficial categories such as aphids and coccinellids but need to be plant and species specific.

Automated summary

This study examines the multitrophic interactions between aphids, coccinellids, and their parasitoids. It finds that coccinellids exhibit selectivity towards host plants and aphids, suggesting that prey selection is more specific than previously assumed.