Abstract
Twelve pesticides commonly used in citrus in Spain were tested on adults of Aphytis melinus DeBach to determine their effects on parasitoid survival and fecundity, and the duration of the residue of each pesticide. Six of these pesticides were found to be harmless to moderately harmful to this parasitoid in a laboratory assay in closed Petri dishes: spinosad (bait formulation), azadirachtin, fenbutatin, fosetyl-Al, copper oxichloride, and mancozeb, with their scores on the reduction of beneficial capacity (RBC) index being between 21.4 and 94.6% after one week. The other six pesticides classified as harmful were tested on citrus plants to study their persistence over time under greenhouse conditions: Pirimicarb, pyriproxifen, paraffinic oil, abamectin, chlorpyrifos, and lambda-cyhalothrin. Most of these products reduced their negative effect on adults of A. melinus between one and six weeks after treatment, although lambda-cyhalothrin was still harmful to parasitoids 11 weeks after application. This information can help growers and consultants to make decisions about pesticide selection and application timing in citrus in order to support IPM implementation when A. melinus is present.
Highlights
Integrated pest management (IPM) philosophy stresses the use as little pesticide as possible and only those compounds that are reasonably compatible with the natural enemies that are important in a particular crop
Determining the compatibility of pesticides with key biological control agents in a crop should be an ongoing activity, in orchard crops such as citrus, where some key pests are under economically significant biological control (Kennett et al, 1999; Jacas & Urbaneja, 2010; Sorribas & García-Marí, 2010)
Some products tested produced a level of mortality no different from the control; these were azadirachtin and mancozeb in Experiment 1 (Fig. 1a), spinosad and copper oxichloride in Experiment 2 (Fig. 1b), and fosetyl-Al in Experiment 3a (Fig. 1c)
Summary
Integrated pest management (IPM) philosophy stresses the use as little pesticide as possible and only those compounds that are reasonably compatible with the natural enemies that are important in a particular crop. One of the key pests of citrus in Spain is the California red scale, Aonidiella aurantii Maskell (Hemiptera Diaspididae) (Franco et al, 2006; Jacas et al., 2010), and one of the most widespread and important natural enemies of this scale is Aphytis melinus DeBach (Hymenoptera Aphelinidae) (Kennett et al, 1999). This parasitoid, native to Pakistan and India, was introduced into California (USA) in the 1950s and since in many citrus producing regions of the word (Kennet et al, 1999). In Spain it is present since the 1980s (Jacas et al, 2006) and it is well established in most citrus areas (Pina & Verdú, 2007; Sorribas et al, 2008)
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