A Prophylactic Application of Systemic Insecticides Contributes to the Management of the Hibiscus Bud Weevil Anthonomus testaceosquamosus Linell (Coleoptera: Curculionidae)

The hibiscus bud weevil is an invasive pest that attacks tropical hibiscus. Its management has been challenging due to its cryptic adult and concealed immature stages. We evaluated the efficiency of four systemic insecticides (spirotetramat, chlorantraniliprole, flupyradifurone, and cyantraniliprole) against the pest using two approaches: one applied 4 weeks before infestation (prophylactic) and the other 1 week after (curative). The number of eggs, larvae, and feeding holes per sampled bud were recorded 7, 14, 21, and 28 days after the infestation (prophylactic), and after the application (curative), respectively. In general, a greater number of treatment effects were detected in the prophylactic approach in comparison with those in the curative. With the prophylactic approach, the mean number of larvae and feeding holes per actively growing bud was significantly greater for the control (water) than for all insecticides. Among fallen buds, chlorantraniliprole, cyantraniliprole, and spirotetramat had significantly fewer feeding holes than those in the control. With the curative approach, the mean number of feeding holes was greater in the control with no differences among insecticides. The prophylactic application can effectively suppress initial HBW infestation, in contrast to the curative application targeting already high populations. This provides the opportunity for reducing the impact of this regulated pest in areas of expansion.

Automated summary

The study evaluated the effectiveness of four systemic insecticides against the hibiscus bud weevil. The prophylactic approach was found to be more effective in suppressing the initial infestation of the pest. Some insecticides significantly reduced the number of feeding holes compared to the control group.