|Michaud, J.P. - UNIVERSITY OF FLORIDA|
Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 25, 2003
Publication Date: January 2, 2004
Citation: Michaud, J.P., McKenzie, C.L. 2004. Safety of a novel insecticide, sucrose octanoate, to beneficial insects. Florida Entomologist. 87(1):6-9. Interpretive Summary: Previous work has demonstrated that these synthetic sucrose esters have good insecticidal activity against the Asian citrus psyllid, Diaphorina citri Kuwayama, (McKenzie and Puterka 2000) and the brown citrus aphid, Toxoptera citricida (Kirkaldy) (McKenzie, unpublished data), two important disease vectors in citrus. Although the safety of sucrose esters for beneficial insects in citrus has not yet been examined, Stansly and Liu (1997) found that they were selective for the whitefly parasitoid Encarsia pergandiella Howard. In order to ascertain the safety of sucrose octanoate for natural enemies in citrus, we selected candidate species for testing that represented four different orders of beneficial insects known to be important in biological control of homopteran pests, the primary targets of this material. Aphytis melinus De Bach (Hymenoptera: Aphelinidae) is a primary parasitoid of the California red scale. The green lacewing Chrysoperla rufilabris Burmeister (Neuroptera: Chrysopidae), and the insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae), are both generalist predators of many small insects in citrus, including mites, aphids, psyllids and thrips. We also tested four species of ladybeetles, Curinus coeruleus Mulsant, Cycloneda sanguinea L., Harmonia axyridis Pallas, and Olla v-nigrum Mulsant (Coleoptera: Coccinellidae) that are all important predators of homopteran citrus pests (Michaud 1999, 2002; Michaud et al., 2002).
Technical Abstract: Laboratory trials were used to estimate the toxicity of sucrose octanoate to beneficial insects representing four insect orders of importance in biological control in citrus. First instar larvae of the ladybeetles Cycloneda sanguinea L., Curinus coeruleus Mulsant, Harmonia axyridis Pallas and Olla v-nigrum Mulsant (Coleoptera: Coccinellidae) and the lacewing Chrysoperla rufilabris Burmeister (Neuroptera: Chrysopidae) all survived topical sprays of sucrose octanoate at 8000 ppm without significant mortality, a concentration corresponding to twice the field rate required to kill aphids and other homopteran pests. Similarly, adults of the red scale parasitoid Aphytis melinus De Bach (Hymenoptera: Aphelinidae) and 2nd instar nymphs of the predatory bug Orius insidiosus (Say) (Hemiptera: Anthocoridae) both survived 24 h exposures to residues of 8000 ppm sucrose octanoate on leaf discs without significant mortality. The efficacy of sucrose octanoate as a contact insecticide against various homopteran pests of citrus, combined with its low toxicity to key beneficial insects in the citrus ecosystem, suggest it may be a valuable material for incorporation into IPM programs for Florida citrus.