Radiant SC12% (Spinetoram) is a new generation of spinosyn group. Effect of this bio-insecticide against larvae of Spodoptera littoralis (Boisd) was studied to evaluate the susceptibility of 2 nd and 4 th larval instars in laboratory. The LC 50 of radiant was 0.05 and 0.03 ppm. After 24 and 48 hours, respectively for the 2 nd larval instars. Where the LC 50 were 6.67 and 2.86 ppm after 24 and 48 hours, respectively for the 4 th larval instars. In the semi-field experiment, recommended doses of radiant exhibited high mortality 100 & 95.7 % after 0 and 1 days, respectively then decreased gradually to reach 58.1 % after 7 days. Also the field experiment showed high mortality 91.4% after 2 days then reduced gradually to reach 83.1% after 8 days. The effect of different concentrations in laboratory and recommended doses in field showed 100% mortality of entire hatched egg masses. Effect of recommended doses of radiant against predators inhabiting cotton field demonstrated that radiant was safe to natural enemies. The effect of LC 50 of radiant on the major biochemical component of 4 nd larval instars after 24 hours showed that, the amount of total carbohydrates, total proteins, carbohydrate hydrolyzing enzymes (invertase, trehalase and amylase), and acid & alkaline phosphates were significantly decreased. Where the acetylcholinstrase activity was significantly increased.
The present study is the first attempt in Egypt which focused on determining the development rate of Spodoptera frugiperda at different constant temperatures, the number of degree-days (DD's) required for each stage to complete development, as well as the degree-days required for overall egg-to-adult development. The study was conducted under three constant temperatures (20, 25
This study was conducted to investigate the biochemical defensive mechanisms in larvae of S. littoralis (Biosd.) (Lepidoptera: Noctuidae) collected from cotton fields in two Egyptian Governorates (Kalyobia and Behira), sprayed with spinetoram as well as its impact effect upon carbohydrate metabolism. The role played of spinetoram on different major defensive enzymes like glutathione S-transferases (GSTs) , non specific esterases and acetylcholinesterase(AChE) was discussed. It seems that these enzymes are not greatly involved in the detoxifying process of spinetoram except a marked over production of AChE reached up to 18.7% as well as the concentration of its substrate, ACh with an increase reached up to 42.8%. Spinetoram had also a prominent effect upon carbohydrate metabolism as in glycogen content which was decreased by 34.9%, LDH also was inhibited to 55.7% while trehalase had an elevated activity by 22.8%.In general, Behira Governorate was more affected and more sensitive to spinetoram rather than Kalyobia Governorate. The present work is an introductory study to understand the outline of the mechanism of this bioinsecticide as well as the resistance mechanisms may arise in the future.
The current work was carried out to evaluate the biochemical effects of LC 50 of four compounds; emamectin and spinetoram as bioinsecticides, hexaflumuron and teflubenzuron as Insect growth regulators (IGR's) against
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.
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