Host selection behavior is a key aspect of parasitoid foraging. Elucidating the host selection behaviors of a hymenopteran parasitoid on different hosts can clarify the interactions between the parasitoid and its hosts and further promote the development of biological control strategies utilizing this parasitoid. In the current study, we investigated the host-selection behavior of a predominant host-feeding parasitoid, Necremnus tutae Ribes & Bernardo (Hymenoptera: Eulophidae), on different instars of Tuta absoluta (Meyrick) larvae. We identified and described four host-selection behaviors of N. tutae: host feeding, oviposition, host killing and rejection. Ovipositor insertion was divided into three behavioral elements: ovipositor stabbing, ovipositor stirring and egg laying. This behavioral pattern facilitated the quick distinction of host-selection behaviors in a host-feeding parasitoid. Furthermore, we found that N. tutae directly fed on hosts of all instars but preferred 1st–2nd-instar hosts for feeding and 3rd-instar hosts for laying eggs. The duration of both host feeding and oviposition increased with larval host age. Further analysis revealed that the duration and frequency of two main behavioral elements of host-feeding behavior (ovipositor stirring and feeding on the host) also increased with larval host age. Understanding these basic behavioral traits is fundamental for developing parasite-rearing schedules and glasshouse introduction methods.
