Toxicological and biochemical studies of Methylamine Avermactin, a new type of bioinsecticide against the cotton leafworm, Spodoptera littoralis (Biosd).

Abstract

Larvicidal efficacy of a new semi-synthetic avermectin derivative Methylamine avermectin (Radical 0.5% EC) was determined against larval instars of the Egyptian cotton leafworm, Spodoptera littoralis (Biosd.) in the laboratory, field and semi field experiments. 2 nd and 4 th instar larvae showed greatest susceptibility to the Radical in the laboratory experiment. The LC 50s values of the 2 nd and 4 th larval instar after 48 hours were 0.005 and 0.008 ppm, respectively. Radical was tested with recommended dosage (200 ml / 100 liter water) in field; it caused 84.6% reduction of pest population up to day 8 post-treatment. On the other hand, the semi field application of the same recommended dose on the 2 nd instar larvae showed general mean 73.6% mortality, 7 days after post-treatment. Also, some biochemical changed in the 4 th instar larvae after 48 hours of treatment with tested bioinsecticide were measured. It's clear from the results that activities of trehalase, invertase and acetylcholine esterase were increased in all treatments. Tested bioinsecticide reduced the activity of alkaline phosphatase at all doses compared to untreated larvae. No significant changes in acid-phosphatase activities were observed at all treatment doses. On studying the effect of esterases isozymes patterns, there were no differences in number and position of esterases isozymes between untreated and treated larvae in the whole larval body tissues although each band different in its concentration. The toxicity of the formulation to some beneficial predators was also evaluated in the field. There was no detectable effect of these bioinsecticide on naturally occurring beneficial species.

Field evaluation and biochemical studies of novel insecticide on the cotton leafworm, Spodoptera littoralis (Boisd).

“…These results showed that there were significant differences between the effect of the three tested insecticides and control. The present results agreed with that recorded by Abdel-Aal, 2006 andDahi et al, 2009 who recorded inhibition effect of chlorfluzuron and methylamine avermactinon total carbohydrate of S. littoralis. Also, El-Sheikh, 2012 state that the total carbohydrates content in 6 th larval instar treated with spinosad significantly decreased.…”

Toxicological, biological and biochemical impacts of Indoxacarb and Methoxyfenozoid on the larvae of the Cotton leafworm, Spodoptera littoralis (Boisd.). (Lepidoptera: Noctuidae)

“…The disturbance in carbohydrate was expressed by impairments in the activity of carbohydrate enzymes in treated larvae. Similar observation in S. littoralis has also been reported by several investigators (Radwan et al 1984;Eid, 2002;El-Barky et al, 2008;Dahi et al, 2009 andRashwan, 2013). In insects, as in other animals, the transaminases (GOT and GPT) are key enzymes in the formation of nonessential amino acids, in metabolism of most nitrogenous products and in glucogenesis (Tanani et al, 2009).…”

Immunity Changes in Locusta migratoria Linnaeus (Orthoptera: Acrididae) Infected by Entomopathogenic Nematode Steinernema carpocapsae (Rhabditida: Steinernematidae)

“…GST fluctuations could be the outcome of abnormalities in the functioning of the insect detoxificative system as consequences of the biopesticide treating. These fluctuations and the abnormal functions of GST can increase the sensitivity of the treated insects as noted by (Dubovskiy et al, 2008 andDahi et al, 2009) mentioned that the application of biopesticides guides to decline in the Acetylecholinsterase activity because of the sensitivity of insects to biopesticides, or guides to its rise because of the novel mode of action of recently biopesticides. Reduction in GST activity during the infection at 24-48h of nematodes may be associated with effective inhibition of the host defense systems by entomopathogenic nematodes.…”