The potential of Catolaccus hunteri (Hymenoptera: Pteromalidae) as a biocontrol agent of the hibiscus bud weevil, Anthonomus testaceosquamosus (Coleoptera: Curculionidae)

The hibiscus bud weevil (HBW) Anthonomus testaceosquamosus is an invasive pest of concern for tropical hibiscus production. Although Catolaccus hunteri is known to parasitize some Anthonomus species, HBW's suitability as a host is unknown. Our objective was to evaluate C. hunteri as a biocontrol agent of HBW and determine the preferred HBW stage for parasitoid feeding and development, and the optimal release rate. Two laboratory experiments were conducted in which all developmental stages were offered to parasitoids by either being exposed or concealed within flower buds. Parasitism was not observed, however, significant mortality in second-instar larvae was noted when hosts were exposed. Higher mortality was observed in first-instar larvae when hosts were concealed within flower buds. A subsequent laboratory experiment to evaluate three release rates was performed using cages with 15 infested flower buds and releasing 0, 1, 2, or 3 female parasitoids. One female did not differ from other rates but showed higher mortality than the control. In a greenhouse experiment female and male parasitoids were used to evaluate these rates under more natural conditions. HBW-infested hibiscus plants received 0, 1, 2, or 3 parasitoid couples. The parasitoid release rate did not affect mortality rates or differ from the control. However, when one couple was released, mortality tended higher compared to other treatments, suggesting males’ interference with reproductive activity. Although C. hunteri has potential as an HBW biocontrol agent, more research is needed to estimate release rates and determine whether this parasitoid can reduce HBW populations.