Controlling Riptortus pedestris (Hemiptera: Alydidae) using Ooencyrtus utetheisae (Hymenoptera: Encyrtidae)

Riptortus pedestris (Hemiptera: Alydidae) is an important pest that affects soybean cultivation in East Asia. In the present study, the ability of Ooencyrtus utetheisae (Hymenoptera: Encyrtidae) to provide biological control of R. pedestris was evaluated in laboratory and field-cage experiments. The developmental time, longevity, reproductive rate, and functional response of O. utetheisae attacking R. pedestris eggs were measured. The influence of parasitism by O. utetheisae females of different ages was assessed for R. pedestris eggs of different ages. In addition, rate of parasitism of R. pedestris eggs by O. utetheisae was evaluated in field-caged experiments. The developmental time of immature parasitoids (from egg to adult emergence) and adult female parasitoid longevity were longer than that of males. The average lifetime fecundity per female of O. utetheisae was 56.9 eggs, and the progeny sex ratio was 86.8% female. On average, 2.6 wasps emerged from each R. pedestris egg. The functional response of the parasitoid followed Holling’s Type III model, with a theoretical maximum daily parasitism rate of 14.9 eggs at an optimal host density per day. Parasitism was greater than 90% for 1–8 − day old O. utetheisae females attacking 1–3 − day old R. pedestris eggs. In field − cage trials, parasitism was 47% at 15 (parasitoid): 1 (pest) release ratio. In addition, O. utetheisae females killed 22% R. pedestris eggs by piercing host eggs with their ovipositors. These results indicated that O. utetheisae has significant potential as a biological control agent for augmentative release against R. pedestris.