Oviposition behavior and progeny production of Trichogramma evanescens (Hymenoptera: Trichogrammatidae) in patches of single and clustered host eggs

The ovi­position behavior of T. evanescens in each patch type (1mm²) with 12 single spaced or clustered eggs of Anagasta kuehniella Zeller  was observed continuously, recorded and calculated the patterns of patch use, time budgets, and the sequence of sex allocation for up to 1 hr. or until the female left the patch. The only significant behavioral event is the total walking in cluster patch because the female takes significantly more time walking out of patch. The parasitoid spends much time resting on eggs of cluster patch than in single patch. No significant differences occurred between single and cluster patches in their influence on the residence time spent in a patch. The handling time in a patch showed significant differences between single and cluster patch. There is no giving up time in single patch but it happened in cluster patch. Clustered patches led to a reduction in percent drumming and grooming time, but an increase in percent resting and total walking time. There were no significant differences between single and cluster patches in the number of eggs encountered. The progeny sex ratio from the parasitized eggs showed very little variation and was insignificant between patch types. The per­cent male progeny was 16.1 and 21.2 % in single and cluster patches, respectively. There were no significant differences for oviposition time for both male or female eggs in single and cluster patches. The female tended to produce male eggs at the second oviposition event in single patch which represented 16.67 % of the total male eggs deposited, while it deposited male eggs (8.7 %) at the first oviposition event. This study has important implications for Trichogramma inundation programs and selecting Trichogramma species and strains, it should be taken into consideration to match the behavioral and reproductive characteristics of Trichogramma species to the ovipositional strategies (single eggs versus egg masses) of target pests.