Toxicity of insecticidal soaps to the Asian citrus psyllid and two of its natural enemies
Article first published online: 23 JUL 2012
Published 2012. This article is a U.S. Government work and is in the public domain in the USA.
Journal of Applied Entomology
Volume 137, Issue 5, pages 347–354, June 2013
How to Cite
Hall, D. G. and Richardson, M. L. (2013), Toxicity of insecticidal soaps to the Asian citrus psyllid and two of its natural enemies. Journal of Applied Entomology, 137: 347–354. doi: 10.1111/j.1439-0418.2012.01749.x
- Issue published online: 9 MAY 2013
- Article first published online: 23 JUL 2012
- Manuscript Accepted: 24 JUN 2012
- Manuscript Received: 17 JAN 2012
- Cycloneda sanguinea ;
- Diaphorina citri ;
- Safer Insecticidal Soap;
- Tamarixia radiata
The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is an important pest of citrus because it transmits plant pathogens responsible for a serious disease of citrus known as huanglongbing. Conventional insecticides are frequently used to manage ACP. Insecticidal soaps (hereafter ‘soaps’) are an insect control option labelled for commercial use as well as for use by homeowners and organic growers. Soaps have been shown to be toxic to some insect pests and therefore might be an alternative to conventional pesticides for control of ACP, but the efficacy of soaps against ACP was largely unknown. Our objective was to test whether different concentrations of two insecticidal soaps, M-Pede and Safer Insecticidal Soap Concentrate, caused mortality of ACP adults, nymphs and eggs. In addition, we tested whether these soaps were toxic to two natural enemies of ACP, adults of the lady beetle Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae) and the parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae). Direct sprays of M-Pede or Safer Insecticidal Soap were acutely toxic to ACP adults (regardless of gender) and nymphs when applied in solutions of 0.8–2% in water. Insecticidal soaps were non-toxic to eggs at rates of up to 2%. Residues of soap were less toxic to adult ACP than direct sprays, even when applied at concentrations of up to 4%. M-Pede or Safer soap at high concentrations (for example, 2% v/v in water) may be an effective alternative to conventional pesticides to manage adult and nymphal ACP, although multiple applications may be needed if a target population includes eggs. A 2% concentration of either soap applied as a direct spray was non-toxic to adult C. sanguinea but acutely toxic to adult T. radiata. Soaps therefore may be compatible with biological control of ACP by adult coccinellids but not the parasitoid T. radiata.