Effect of Insecticides on <i>Trichogramma</i> Parasitoids Used in Biological Control against <i>Prays oleae</i> Insect Pest

Abstract

This study investigated the direct effect of the insecticides deltamethrin and spinosad on three egg parasitoids species: Trichogramma oleae, T. cacoeciae and T. bourarachae. The parasitoid pupae were exposed to pesticide residues on fresh olive tree leaves at recommended concentrations (RC) at different time intervals: 3, 10, 17, 24 and 31 days after pesticide applications. Parasitism viability (% emergence from parasitized eggs) and adult emergence time (developmental time from pupa to adult emergence) were evaluated. Regarding to the International Organization of Biological Control (IOBC) guidelines, results of toxicity effects of insecticides show that: Deltamethrin was moderately harmful to all Trichogramma species at RC (Decis ® 100 milliliters•ha −1), however, spinosad was harmless to moderately harmful at RC (Tracer ® 20 milliliters•ha −1). Trichogramma species revealed differences with regard to adult emergence time and exhibited significant changes in parasitism viability with increasing time after pesticide treatment. While deltamethrin residues affected parasitism viability 31 days after the product application, spinosad displayed similar viability for almost species 24 days after the application. The usefulness of Trichogramma parasitoids used as biological control agents, in olive tree ecosystem, was discussed in integrated pest management programs for Prays oleae control when parasitoid species were exposed during pupal stage to the insecticide residue.

Lethal and sublethal effects of ten insecticides, used in date palm production in Saudi Arabia, on the parasitoid Trichogramma cacoeciae

“…68 thrin, malathion, methomyl, azadirachtin, and carbosulfan, causing 96, 98, 93, 91 and 93% adult mortality, respectively, as compared with the control, are classifi ed as moderately harmful (IOBC class 3) to T. cacoeciae. Our results corroborate those reported by Youssef et al (2004) for T. exgium on olive leaves, and Blibech et al (2015) who found that deltamethrin residues on olive leaves aff ected parasitism in T. oleae, T. cacoeciae, and T. bourarachae, 31 days post-treatment. Nevertheless, Suh et al (2000) showed that deltamethrin has short-term persistence on cotton leaves, and this diff erence in persistence may be attributed to variation among Trichogramma spp.…”

“…The dried fruit moth Ephestia calidella (Guenée) (Pyralidae) is a pest of economic importance on date palm in Saudi Arabia, attacking dates during harvest, storage and packinghouse processing (El-Shafi e et al, 2017). Development of the pest and its dam-2012; Blibech et al, 2015).…”

“…vary. Synthetic pyrethyroid insecticides appear to be the most harmful class (Youssef et al, 2004;Abdulhay and Rathi, 2014;Sohrabi and Amini, 2015;Thubru et al, 2016); Furthermore, the eff ect of deltamethrin on pupae of Trichogramma oleae (Voegele and Poitale), T. cacoeciae, and T. bourarachae Pintureau and Babault persisted for 30 days following exposure (Blibech et al, 2015).…”

Commercially formulated glyphosate can kill non‐target pollinator bees under laboratory conditions

“…Each potted plant was placed in a 30 9 30 9 30 cm BugDorm cage (n = 9). Using a handheld 450-ml sprayer bottle (Taizhou Youfeng Plastics, Taizhou, Zhejiang, China), the plants were sprayed manually with the recommended concentration of the glyphosate-based herbicide until run-off following Blibech et al (2015). Ten worker A. mellifera were placed inside each cage and allowed to interact with the freshly sprayed plants for 24 h following Cowles et al (2015).…”

“…Several studies have shown that insects (both pests and beneficial) are killed when in direct contact with insecticides or in contact with insecticide residues days after application (Blibech et al, 2015;Ihara et al, 2017;Ullah & Shad, 2017). Although insecticides are formulated to kill obnoxious insects, improper use could result in detrimental effects on non-target organisms (Fishel, 2005).…”