Assessing risks of pesticides targeting lepidopteran pests in cruciferous ecosystems to eggs parasitoid, Trichogramma brassicae (Bezdenko)

Abstract

Lethal and sub lethal effects of fresh and old residues of azadirachtin, spinosad, var. ( var. ), and deltamethrin, were evaluated at their recommended field doses against adult and immature stages of under conditions. The experiments were carried out at the Entomology section of Division of Crop Protection, ICAR Research Complex for NEH region, Umiam, Meghalaya, in 2012-2013. The effects of different pesticides were determined by bioassays using the residual film method, the diet contamination method, the pupal dip method and the topical application technique. The four pesticides were found harmful to adult after ingestion, however surface contact bioassays revealed that var. was the least toxic pesticide. Except var., other three pesticides were found harmful also to the immature stages of and significantly affected parasitism potential, adult emergence, longevity of adults, and sex ratio of the progeny. Deltamethrin and azadirachtin were the most harmful, even after 15 days of application. Spinosad was found to be relatively safe to after 15 days of application. As appeared to be the least toxic pesticide for, it could be used for the management of severe infestations of lepidopteran pests in cruciferous ecosystems. If essential, spinosad may be used 15 days after parasitoid release, thus minimizing the chances of parasitoid exposure.

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

“…Azadirachtin, although a botanical insecticide, was found to be moderately harmful to T. cacoeciae regarding mortality and slightly harmful regarding parasitism ratio. Our results are in confl ict with those reported by Thubru et al (2016), who found that surface contact toxicity of azadirachtin was Table 3. Parasitism ratio of Trichogramma cacoeciae on eggs of Ephestia cautella and longevity of adult females of the parasitoid, which survived 24 h exposure to dry residues of insecticides on glass plates treated at the recommended application rates.…”

“…Similar moderate to high toxicities of organophosphorus and synthetic pyrethroid compounds to adults of T. cacoeciae and other Trichogramma spp. have also been reported in other studies (Brunner et al, 2001, Youssef et al, 2004Jiu-Sheng et al, 2010, Zhu et al, 2009Abaar et al, 2011;Sohrabi and Amini, 2015;Thubru et al, 2016).…”

“…The plant extract azadirachtin (Amen 1.0%) was moderately toxic, supporting data from Thubru et al (2016) on another egg parasitoid, Trichogramma brassicae (Bezdenko).…”

“…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).…”

Biological attributes and feeding potential of three dominant predators of Lipaphis erysimi (Kaltenbach)

“…The brassicaceous ecosystems of Meghalaya harbour several natural enemies, many of them have a potential to reduce the pest damage (Firake et al, 2012a;Lytan and Firake, 2012;Firake et al, 2012b;Thubru et al, 2016). Among predators, the ladybird beetle, Coccinella septumpunctata Linnaeus (Coleoptera: coccinellidae) and syrphid flies, Episyrphus viridaureus (Wiedemann) and Betasyrphus isaaci (Bhatia) (Diptera: Syrphidae) are the major predators of mustard aphid in mid altitude hills of Meghalaya.…”