A prophylactic application of systemic insecticides contributes to the management of the hibiscus bud weevil anthonomus testaceosquamosus Linell (Coleoptera: Curculionidae)

Authors: VARGAS, GERMAN - University Of Florida; GREENE, A. DANIEL - University Of Florida; VELAZQUEZ-HERNANDEZ, YISELL - University Of Florida; Yang, Xiangbing; Kendra, Paul; REVYNTHI, ALEXANDRA - University Of Florida

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2023
Publication Date: 9/26/2023
Citation: Vargas, G., Greene, A., Velazquez-Hernandez, Y., Yang, X., Kendra, P.E., Revynthi, A.M. 2023. A prophylactic application of systemic insecticides contributes to the management of the hibiscus bud weevil anthonomus testaceosquamosus Linell (Coleoptera: Curculionidae). Agriculture. 13(10):1879. https://doi.org/10.3390/agriculture13101879.
DOI: https://doi.org/10.3390/agriculture13101879

Interpretive Summary: The hibiscus bud weevil (HBW), native to Mexico and southern Texas, was first detected in south Florida in 2017 where it has become a serious pest of ornamental hibiscus plants. HBW damages the hibiscus by feeding and ovipositing on developing flower buds, causing them to decay and drop, making this flowering plant unsuitable for market. To develop a management program for HBW, scientists from the University of Florida (Homestead, Florida) and USDA-ARS (Miami, Florida) investigated the efficacy of four registered systemic insecticides, including spirotetramat, chlorantraniliprole, flupyradifurone, and cyantraniliprole under greenhouse conditions. Two different approaches, consisting of prophylactic and curative soil drench applications, were evaluated to determine the effect of these insecticides on number of eggs, larvae, and feeding holes on either growing or fallen flower buds. The results showed that all insecticides demonstrated efficacy against HBW as compared to the control, with significantly fewer larvae and feeding holes per bud on insecticide treated plants with both approaches. Results suggested that drench applications of any of these insecticides are effective for control of HBW in early spring when populations of HBW start to increase.

Technical Abstract: BACKGROUND: The hibiscus bud weevil (HBW) is an invasive pest that attacks the flower buds of hibiscus in south Florida. As applications of foliar insecticides have shown low efficacy against HBW, four registered systemic insecticides (spirotetramat, chlorantraniliprole, flupyradifurone, and cyantraniliprole) were evaluated under greenhouse conditions. Two approaches, applications prior to weevil infestation (prophylactic) and after infestation (curative), were compared. With the prophylactic approach, six individual plants per treatment were drenched 4 weeks prior to weevil release, whereas with the curative approach, plants were drenched 1 week post weevil release. After insecticides were applied, observations were made 7, 14, 21, and 28 days after weevil release for both approaches. At each time point, five actively growing buds were collected from each plant, and all fallen buds were collected. The number of eggs, larvae, and feeding holes per bud were scored. RESULTS: With the prophylactic approach, the mean number of larvae and feeding holes per actively growing bud were 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. CONCLUSION: Our results suggested that drench applications of any of these insecticides can effectively suppress initial infestations in early spring (from middle of February to beginning of March) when HBW populations are increasing.