Submitted to: Biocontrol
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2010
Publication Date: 9/15/2010
Citation: Hall, D.G., Nguyen, R. 2010. Toxicity of pesticides to Tamarixia radiata, a parasitoid of the Asian citrus psyllid. Biocontrol. 55:601-611. Interpretive Summary: Asian citrus psyllid is an important citrus pest because it transmits the bacterium responsible for citrus greening disease, sometimes referred to as huanglongbing. This is the most devastating disease of citrus worldwide and is currently jeopardizing citrus production in North America. Growers fighting citrus greening disease have established psyllid insecticide programs, and sometimes these programs are intensive. In terms of food safety and crop sustainability, it would be desirable to find alternatives to insecticides for psyllid control. Further, the use of pesticides can be disruptive to biological control. We conducted research to assess the toxicity of 16 pesticides used in citrus to an insect parasitoid of the Asian citrus psyllid, Tamarixia radiata. This tiny parasite is capable of exerting good levels of natural control of the psyllid. We identified a number of pesticides that were so toxic to the parasitoid that they were basically incompatible in an IPM program for the psyllid. The information will be valuable to growers wanting to maximize natural control of the psyllid by avoiding insecticide treatments that would disrupt biological control.
Technical Abstract: Sixteen pesticides including two fungicides were evaluated for toxicity to adult Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae), a parasitoid of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). Percentage mortality data were evaluated to generally assess IPM-compatibility of the pesticides with adult parasitoids. The following were found to be least compatible with (most toxic to) adult T. radiata based on the toxicity of direct sprays and potential long residual life on leaves: carbaryl, chlorpyrifos, fenpropathrin, and phosmet. Although highly toxic to the parasitoid as direct sprays or freshly dried residues, each of the following was more compatible with T. radiata because the toxicity of residues of these pesticides was either low at 24 hours after application or sharply decreased within a few days after application: abamectin, chenopodium oil, diflubenzuron, fenpyroximate, spirotetramat, sulfur, and 435 spray oil; depending on environmental conditions, imidacloprid (foliar-applied) and pyridaben might also be somewhat more compatible for the same reasons. The pesticides that consistently appeared to be most compatible with T. radiata were aluminum tris, copper hydroxide, diflubenzuron, fenpyroximate, and kaolin clay.