<b>Lethal and sublethal effects of neem on <i>Aphis gossypii</i> and <i>Cycloneda sanguinea</i> in watermelon

Abstract

ABSTRACT. The objective of this study was to evaluate the impact of oil extract of neem, Azadirachta indica, on the watermelon aphid Aphis gossypii and its natural enemy Cycloneda sanguinea. Toxicity bioassays were conducted with the commercial product DalNeem (1,475 g L -1 azadirachtin) at 0.0037 μg a.i. mL -1 , 0.0074 μg a.i. mL -1 and 0.0148 μg a.i. mL -1 , Malathion at 1 μg a.i. mL -1 and distilled water as a control treatment. The products were sprayed to watermelon leaf discs, and the insects were exposed to the product residues. The instantaneous population growth rate of A. gossypii and the survival of C. sanguinea larvae exposed to the different treatments were calculated. A decrease in the instantaneous population growth rate of A. gossypii with increasing concentrations of neem was observed, and the aphids did not reproduce on the leaf discs treated with malathion during the first 24 hours of exposure due to its rapid lethal effect on adult insects. The larvae of the predator C. sanguinea exposed to malathion survived only for 24 hours. The survival of the predator exposed to different concentrations of neem was also significantly reduced compared to the predators exposed only to water. However, laboratory experiments may overestimate the effect of neem on predators because the individuals cannot employ escape behavior caused by neem repellency.Keywords: Citrullus lanatus, Azadirachta indica, Coccinellidae, Aphididae.Efeito letal e subletal do nim em Aphis gossypii e Cycloneda sanguinea na cultura da melancia RESUMO. O objetivo deste estudo foi avaliar o impacto de extrato oleoso de nim, Azadirachta indica, no afídeo Aphis gossipii e em seu inimigo natural Cycloneda sanguinea, na melancia. Ensaios de toxicidade foram conduzidos com o produto comercial (DalNeem®) (1.475 g L -1 de azadirachtina) 0,0037 μg i.a. mL -1 , 0,0074 μg i.a. mL -1 and 0,0148 μg i.a. mL -1 , Malathion 1 μg i.a. mL -1 , e água destilada como tratamento controle. Os produtos foram aplicados em discos de folhas de melancia e os insetos foram expostos ao resíduo dos produtos. Foram calculados padrão de crescimento instantâneo da população de A. gossypii e sobrevivência das larvas de C. sanguinea expostos aos diferentes tratamentos. Houve uma diminuição no padrão de crescimento instantâneo da população de A. gossypii com aumento da concentração de nim. Afídeos não se reproduziram nos discos de folhas tratadas com malathion, devido ao rápido efeito letal em adultos, menor que 24 horas após a exposição. Larvas de C. sanguinea expostas ao malathion sobreviveram por 24 horas. Sobrevivência do predador exposto a diferentes concentrações de nim também foi significativamente reduzida quando comparada a exposição à água. Entretanto, experimentos de laboratório podem ter superestimado o efeito do nim em predadores porque eles não mostraram comportamento de escape causado pela repelência do nim.

Insecticidal and oviposition deterrent effects of essential oils and their constituents against the invasive pest Drosophila suzukii (Matsumura) (Diptera: Drosophilidae)

“…Macadamia nut originated in a similar climate as kukui and avocado nut, and as it is a growing industry (Axel and Fairman 1992; Elevitch and Manner 2006; Rietow 2012); oils were tested for potential efficacy, though no previous reports exist examining its insecticidal activity. The activity of neem oil has been widely demonstrated and it was therefore included in these assays (Gahukar, 2014; Shafie and Basedow, 2003;Souza et al, 2015;Thacker et al, 2003).…”

Effects of toxic baits and food-based attractants for fruit flies on the parasitoidFopius arisanus(Sonan) (Hymenoptera: Braconidae)

“…Several studies have classified malathion-based insecticides as harmful to different species of natural enemies (Castilhos et al, 2013;Beloti et al, 2015;Souza et al, 2015;Bhargavi, 2016). After ingestion and contact toxicity tests, Purcell et al (1994) inferred that bait formulations with malathion and hydrolysed protein are harmful to the fruit fly parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae).…”

“…Furthermore, parasitoids are widely used to reduce fruit fly populations, acting as biological control agents at diverse pest developmental stages (Nicácio et al, 2011;Poncio et al, 2016). In Brazil, the main tephritid parasitoid species belong to the families Braconidae, Figitidae, Eulophidae, Pteromalidae, and Diapriidae, among which the first is the most effective (Bittencourt et al, 2012;Souza et al, 2012).…”

Ecotoxicological potential of bordeaux mixture and Neem oil on non-target soil organisms

“…It also verified the toxicity of this oil for adults and nymphs of Aphis gossypii (target) and the larva of its natural predator Cycloneda sanguine (non-target). Therefore it is necessary to prove the real need of application in the agricultural crop (Souza et al, 2015) Regarding the Bordeaux mixture, the survival of adults from both organism tests was also significantly affected from the 4.15 mg g -1 dose. According to the literature, soil organisms such as springtail, mites, ants and earthworms also had negative effects on the application of Bordeaux mixture in the soil (Pozzebon et al, 2010;Hammad & Gurkan, 2012), since copper is a metal and high doses becomes toxic to soil invertebrates (Ardestani et al, 2013).…”

“…This is the main component responsible for anti-food and toxic effects on insects. It also causes deformities in the pupae, increasing in the instar period (which causes aging of the larvae) and reproductive effects (Souza et al, 2015, Zanuncio et al, 2016, Archana et al, 2017. Neem applications ranging from 0.5 to 7% in the control of Bemisia argentifolli, Keratoma tingomarianus, Liriomyza sativae, Sitophilus zeamais and Zabrotes subfasciatus; Gyropsylla spegazziniana are recommended (Fernandes et al, 2006, Silva et al, 2015, Formentini et al, 2016.…”