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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Insects and Horticulture Research » Research » Publications at this Location » Publication #275704
Title: Toxicity of insecticidal soaps to the Asian citrus psyllid (Diaphorina citri) and two of its natural enemies

Author
item Hall, David
item Richardson, Matthew

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/2012
Publication Date: 5/10/2013
Citation: Hall, D.G., Richardson, M.L. 2013. Toxicity of insecticidal soaps to the Asian citrus psyllid (Diaphorina citri) and two of its natural enemies. Journal of Applied Entomology. 137:347-354.

Interpretive Summary: Insecticidal soaps are labeled for use by homeowners and also can be used in citrus grown for the organic market. Soaps control some insect pests and therefore might be an alternative to conventional pesticides for control of the Asian citrus psyllid. Our objective was to test whether multiple concentrations of two insecticidal soaps, M-Pede and Safer Insecticidal Soap Concentrate, caused mortality of adults, nymphs and eggs of the psyllid. In addition, we tested whether these soaps were toxic to two natural enemies of the psyllid, a lady beetle and a parasitoid. Direct sprays of these insecticidal soaps were acutely toxic to psyllid adults and nymphs when applied in solutions of 0.8 percent to 2 percent, killing most psyllids relatively quickly. The only significant control of eggs was provided by the highest concentration of soap (2 percent), but approximately 37 percent of the eggs survived, so insecticidal soap was less effective against eggs than adults and nymphs. Fresh dry residues of soaps were relatively nontoxic to adult psyllids, indicating little residual control. A 2 percent concentration of soaps applied as a direct spray was nontoxic to adult lady beetles but relatively toxic to adult parasitoids. Soaps may be effective as an alternative to conventional pesticides to manage psyllid adults and nymphs and in areas where conventional pesticides cannot be used, such as organic groves and urban landscapes.

Technical Abstract: Insecticidal soaps (hereafter “soaps”) are labeled for use by homeowners and also can be used in citrus grown for the organic market. Soaps control some insect pests and therefore might be an alternative to conventional pesticides for control of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), but the efficacy of soaps against the psyllid was unknown. Our objective was to test whether multiple concentrations of two insecticidal soaps, M-Pede and Safer Insecticidal Soap Concentrate, caused mortality of adults, nymphs and eggs. In addition, we tested whether these soaps were toxic to two natural enemies of the psyllid, the lady beetle Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae) and the parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae). Direct sprays of M-Pede and Safer insecticidal soap were acutely toxic to psyllid adults and nymphs when applied in solutions of 0.8% to 2%, killing most psyllids relatively quickly. The only significant control of eggs was provided by the highest concentration of soap (2%), but ~37% of the eggs survived, so control of this stage with insecticidal soap was less effective than adults and nymphs. Fresh dry residues of soaps were relatively nontoxic to adult psyllids, indicating little residual control. A 2% concentration of soaps applied as a direct spray was nontoxic to adult C. sanguinea but relatively toxic to adult T. radiata. Soaps may be effective as an alternative to conventional pesticides to manage psyllid adults and nymphs and in areas where conventional pesticides cannot be used, such as organic groves and urban landscapes.