Lethal and Sublethal Effects of Contact Insecticides and Horticultural Oils on the Hibiscus Bud Weevil, Anthonomus testaceosquamosus Linell (Coleoptera: Curculionidae)

Abstract

In 2017, the hibiscus bud weevil (HBW), Anthonomus testaceosquamosus Linell (Coleoptera: Curculionidae), was found outside of its native range of Mexico and Texas, infesting hibiscus plants in Florida. Therefore, we selected 21 different insecticide and horticultural oil products to evaluate their effects on the reproductive rate, feeding, and oviposition behavior of the HBW. In laboratory experiments, significant mortality was observed in adult weevils exposed to diflubenzuron-treated hibiscus leaves and buds, and hibiscus buds treated with diflubenzuron contained the fewest number of eggs and feeding/oviposition holes. Among horticultural oil products, significant mortality was only observed in experiments in which adult weevils were directly sprayed (direct experiments). Pyrethrins and spinetoram plus sulfoxaflor reduced the oviposition rate and caused significant mortality in direct experiments. Diflubenzuron, pyrethrins, spinetoram plus sulfoxaflor, and spirotetramat were further tested via contact toxicity experiments and greenhouse experiments. Contact toxicity experiments demonstrated that the tested insecticides (except diflubenzuron) were highly toxic to HBW adults. In greenhouse experiments, only those hibiscus plants treated with pyrethrins had significantly fewer feeding/oviposition holes and larvae within their flower buds when compared to control (water-treated) plants. These results constitute an important first step in the identification of effective chemical control options for the HBW.

Efficacy of Conventional and Biorational Insecticides against the Invasive Pest Thrips parvispinus (Thysanoptera: Thripidae) under Containment Conditions

“…It is relatively volatile, and due to its rapid degradation rate, it greatly reduces the risk to beneficials [55]. Recently, it was demonstrated that the sulfoxaflor-spinetoram combination is highly effective against the hibiscus bud weevil, Anthonomus testaceosquamosus [56]. Likewise, this product proved to be highly effective against T. parvispinus.…”

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

“…If prophylactic applications targeting initial pest population growth are exercised starting in February, a single application employed during the growing season may be sufficient to delay the population increase, which typically occurs between March and June. Additionally, during the spring season, the combination of foliar applications of contact chemical insecticides [34] and other management options, such as entomopathogenic nematodes and/or entomopathogenic fungi, can synergistically suppress the population to low levels. This approach could also be used for non-conventional options for ornamentals, such as the use of insect repellents like Kaolin clay [35].…”