No abstract

Botanical biopesticides are alternative to hazardous synthetic insecticides. In the present study neem oil based nanoemulsion was synthesized using neem oil and tween 80. The particle size was estimated as 159.2 nm. The emulsion was characterized using particle size analyzer and TEM to confirm the formation of nano emulsion of neem oil. Trichogramma chilonis (Ishii) is an effective egg parasitoid of lepidopterous pests. It controls pests in eggs stage prior to its damaging to crops. The parasitoid is vulnerable to insecticides or oil sprays applied to the crops. The present study revealed the effects of neem nanoemulsion with T. chilonis under the controlled laboratory conditions.

Use of synthetic insecticides for the management of fall armyworm (FAW) Spodoptera frugiperda (J. E. Smith) for a longer period will led to development of insecticide resistance. Identification of an eco-friendly synergistic agent to enhance the toxicity potential and reduced pesticide use as well become mandatory in due process. Hence the present study was formulated to find the single and combined toxicity of chlorantraniliprole and Bacillus thuringiensis (Bt) against the 2nd and 3rd larval instars of S. frugiperda. Single toxicity of chlorantraniliprole against 2nd and 3rd larval instars were 0.87 and 1.52 ppm (LC25); 4.08 and 6.50 ppm (LC50), respectively. With respect to Bt, single toxicity against 2nd and 3rd larval instars were 474.39 and 693.48 ppm (LC25); 1008.62 and 1228.62 ppm (LC50), respectively. Combination effect of chlorantraniliprole with Bt revealed that 2nd instar of FAW showed supplemental synergism at LC50 of chlorantraniliprole + LC25 of Bt. In the case of LC50 of chlorantraniliprole + LC50 of Bt, LC25 of chlorantraniliprole + LC50 of Bt and LC25 of chlorantraniliprole + LC50 of Bt combinations, they showed sub additive synergism. In 3rd instar larvae, the combined toxicity results were similar for all the combinations of chlorantraniliprole + Bt except LC25 of chlorantraniliprole + LC50 of Bt where it showed an antagonistic synergism. Activity of Carboxyl Esterase (CarE), Mixed Function Oxidase (MFO) and Glutathione-S-Transferase (GST) were found to be lesser in chlorantraniliprole LC50 + Bt LC25 combinations than single toxicity treatments. Therefore, combined use of chlorantraniliprole with Bt at LC50 of chlorantraniliprole + LC25 of Bt had supplemental synergism on fall armyworm under laboratory condition.

Considering the importance of safe food, avoiding of excess pesticide application and pesticide pollution the present study was conducted. In this experiment totally four pesticides were tested against cowpea aphid Aphis craccivora under pot culture experiment at College of Agricultural Technology, Theni. Among the four acetamprid 20 SP (0.125g/ml) proved highly effective against Aphis craccivora compared to the rest of the pesticides with mortality of 98.75 per cent. In case of dosage wise acetamprid 20 SL (0.125g/ml) and imidacloprid17.8 SL(0.25ml/l)proved to be highly effective with mortality percentage of 98.33 and 86.66, respectively. Thus, it is concluded that all the studied pesticides, Acetamprid proved effective to control the cowpea aphids.How to view point the article : Gowtham, V., Dilipsundar, N., Balaji, K. and Karthikeyan, S. (2016). Study on the effectiveness of pesticides against cowpea aphid (Aphis craccivora) Koch. Internat. J. Plant Protec., 9(1) : 146-149.