Side effects of different pesticides used in citrus on the adult stage of the parasitoid Aphytis melinus DeBach (Hymenoptera Aphelinidae) and its progeny

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.

Life stage-dependent susceptibility of Aphytis melinus DeBach (Hymenoptera: Aphelinidae) to two pesticides commonly used in citrus orchards

“…lemons and squashes, as showed in the case of spinosad susceptibility of egg-parasitoid pupae into the eggs of various insect species (Biondi et al, 2012b) and (ii) or to the intraspecific variation in insecticide resistance that has been previously reported in A. melinus Hoy, 1986, 1988). The intraspecific variation in pyriproxyfen susceptibility of this parasitoid species may also explain the discrepancy between our results and those of Gonzalez-Zamora et al (2013) that obtained 100% of mortality when exposing for 24 h adults to pyriproxyfen residues on inert substrate. However, in Vanaclocha et al (2013b) the mortality of A. melinus adults was not significant when parasitoids were exposed to dry residues on leaves in the laboratory.…”

Uniformity of petroleum-derived spray oils: lethal and sublethal effects on a herbivore pest and its parasitoid

“…The contrasting results among the various studies are likely a result of Gonzalez‐Zamora et al . () and Biondi et al . () exposing the parasitoids to treated glasses (without untreated surface availability; i.e.…”

“…However, this variability may be a result of the different methodologies used under laboratory conditions. Thus, for example, fresh residues of two PDSOs were shown to be highly toxic for A. melinus in two laboratory assays in which they were applied to the tops and bottoms of glass dishes (Gonzalez‐Zamora et al ., ; Biondi et al ., ). On the other hand, based on the toxicity of fresh residues sprayed on unattached citrus leaves in laboratory tests, Vanaclocha et al .…”

“…The main reason for the use of petroleum‐derived oils is their low toxicity to natural enemies (Grafton‐Cardwell & Reagan, ; Villanueva‐Jiménez & Hoy, ; Ulmer et al ., ; Cocco & Hoy, ; Urbaneja et al ., ). However, recent laboratory studies examining the lethal effect of petroleum‐derived oils on parasitoids presented contradictory results and three of these studies have classified them as toxic (Gonzalez‐Zamora et al ., ; Vanaclocha et al ., ; Biondi et al ., ). Regarding their efficacy, this divergence was attributed to the different commercial petroleum‐derived oils that are available (Vanaclocha et al ., ).…”

“…Moreover, Moreno and Luck () demonstrated the efficacy of augmentative releases of A. melinus in California. In the Mediterranean basin, A. melinus is also the main natural enemy of A. aurantii (DeBach & Argyriou, ; Orphanides, ; Pekas et al ., ; Zappalà et al ., ), although it does not control A. aurantii populations effectively under the current IPM program (Pekas et al ., ; Zappalà et al ., ; Tena et al ., , ) and is very sensitive to most of the insecticides employed, except spirotetramat (Rill et al ., ; Garcerá et al ., ; Gonzalez‐Zamora et al ., ; Vanaclocha et al ., ; Biondi et al ., ).…”