Host size selection in the ectoparasitoid asilid Mallophora ruficauda.

CRESPO, J.E.; MARTÍNEZ, G.A.; ZERMOGLIO, P.F.; CASTELO, M.K.

Ciudad Autónoma de Buenos Aires

Conferencia; 7th International Entomophagous Insects Conference (7IEIC); 2023

FCEN-UBA, FAUBA, INTA, CEPAVE

Discrimination of the quality of nutritional resources would appear adaptive for consumers. For koinobionts, the quality of their resource units can vary over time. Potential advantages exist of choosing a host of better initial nutritional quality. We studied the effect of host nutritional quality on host selection. We used Mallophora ruficauda (Diptera: Asilidae), a solitary, koinobiont ectoparasitoid that attacks Cyclocephala signaticollis (Coleoptera, Scarabaeidae) larvae. In the field, lighter hosts were parasitized more often than heavier hosts. Male hosts were lighter than females, but sex did not explain parasitism patterns. Laboratory experiments confirmed thatparasitoids did not differentially orient to nor attacked male hosts. Laboratory experiments showed that parasitoid larvae did not differentially attack heavier or lighter hosts in either two- or four-choice selection experiments, but do show differential selection based on the size of the host.Experiments simulating a host patch showed that parasitoid larvae choose hosts of larger sizes, but at a finer scale, as the size of the hosts increased, larvae chose the smaller host in a dyad. These results suggest that M. ruficauda larvae may select hosts of better nutritional quality (i.e. larger) but that there is an upper limit where a trade-off between nutrients acquisitionand survival (related to life expectancy or host defenses) may drive the larvae decisions.