Performance of Entomopathogenic Fungal-Based Insecticides against the Citrus Mealybug (Hemiptera: Pseudococcidae) on Coleus (Lamiales: Lamiaceae) Plants under Greenhouse Conditions1

Abstract

Abstract The citrus mealybug, Planococcus citri (Risso) (Hemiptera: Pseudococcidae), is an important insect pest of greenhouse-grown horticultural crops. Citrus mealybug causes direct plant damage when feeding on plant leaves, stems, flowers, and fruits, and this damage can result in substantial economic losses. Insecticides are used to manage citrus mealybug populations in greenhouse production systems. Although entomopathogenic fungal-based insecticides are labeled for use against citrus mealybug, there is no quantitative information on their efficacy against this insect pest under greenhouse conditions. Consequently, four experiments were conducted in a research greenhouse at Kansas State University (Manhattan) from 2020 to 2022 to determine the efficacy of three commercially available entomopathogenic fungal-based insecticides on citrus mealybug feeding on coleus, Solenostemon scutellarioides (L.) Codd (Lamiales: Lamiaceae), plants: Beauveria bassiana strain GHA (BotaniGard®, Laverlam International Corp., Butte, MT), B. bassiana strain PPRI 5339 (Velifer™, BASF, Research Triangle, NC), and Isaria fumosorosea Apopka strain 97 (Ancora®, OHP, Inc., Bluffton, SC). The surfactant polyether and polyether-polymethylsiloxane-copolymer (CapSil®, Aquatrols, Paulsboro, NJ) was added to spray solutions to determine whether the surfactant would enhance efficacy. The entomopathogenic fungal-based insecticides, with or without the surfactant, were not effective in managing citrus mealybug populations, with <50% mortality in all four experiments. Our study indicates that entomopathogenic fungal-based insecticides are not effective in managing citrus mealybug populations in greenhouses.