P. Parthiban

Impact of intercropping system to minimise the sucking pests incidence in groundnut (Arachis hypogaea Linnaeus)

Field experiment was carried out during 2014 – 2015 at DARS, Chettinad, Sivagangai district of Tamil Nadu to find out cost-effective groundnut based inter-cropping system for the management of key insect pests. Groundnut (Arachis hypogaea Linnaeus; Variety: VRI II) when intercropped with bajra (Pennisetum glaucum L.; Variety: Co 7), maize (Zea mays L.; Variety; Co 6) and sorghum (Sorghum bicolor L.; Variety: Co 30) 4:1 ratio harboured significantly less mean population of sucking pests viz. leafhopper, Empoasca kerri Pruthi, Aphids, Aphis craccivora Koch and Thrips, Scirtothrips dorsalis Hood recording 23.05, 24.81 and 25.47 nos./10 plants, 21.27, 23.52 and 22.44 nos./2.5 cm shoot and 11.15, 12.62 and 12.19 nos./5 leaflet respectively, whereas intercropping with redgram (Cajanus cajan L.; Variety: VBN (Rg) 3), marigold (Tagetes erecta L.; Variety: MDU 1), sesame (Sesamum indicum L.; Variety: Co 1) and onion (Allium cepa L.; Variety: Co 1) recorded high mean population as compared to other cropping systems while groundnut as pure crop recorded the highest mean population of 33.14 nos./10 plants, 33.22 nos./2.5 cm shoot and 19.00 nos./5 leaflet respectively.

Enhancing In Vivo foraging activity of Trichogramma Chilonis Ishii and Chrysoperla zastrowi sillemi (Esben-Peterson) on eggs of Spodoptera Litura (F.) through kairomonic activity of saturated hydrocarbons

Twelve long chain saturated hydrocarbons ranging from C14 to C34 were screened under laboratory condition to find out their efficiency in enhancing the foraging activity of Trichogramma chilonis Ishii and Chrysoperla zastrowi sillemi (Esben-Peterson). Egg card of Spodoptera litura (F.) treated with various saturated hydrocarbons at two concentrations of 200 and 500 ppm were exposed to T. chilonis and C. zastrowi sillemi under laboratory conditions. The hexane extract of tetratriacontane (200- 500 ppm) was observed favourable with highest mean parasitization and emergence on T. chilonis (54.83 and 69.88%) followed by tricosane and pentacosane (50.70 and 64.61, 57.81 and 50.38%, respectively) as compared to hexane treated eggs (17.51 and 22.99%). Tetratriacontane, nonadecane, tetradecane and dotriacontane treated eggs of S. litura at 200- 500 ppm were favorable to C. zastrowi sillemi with a mean predatory activity of 79.19, 67.45, 63.09 and 60.60%, respectively, 24 h after introduction while it was 26.20% with hexane treated eggs.

Evaluation of Toxicity of Emamectin Benzoate 5 Wg to Honey Bees

SUMMARY Laboratory studies were carried out to assess the contact toxicity of emamectin benzoate 5 WG to workers of Indian bee, Apis cerana indica and Italian bee, Apis mellifera. Emamectin benzoate 5 WG to Indian bees showed that there was no mortality in emamectin benzoate 5 WG @ 100 and 125 g/ha, while emamectin benzoate 5 WG @ 150 g/ha caused 10.00 per cent at 6 (Hours after Treatment) HAT, and it increased to 6.67, 16.67 and 23.33 per cent, respectively after 24 HAT. However, standard insecticides lufenuron 5 EC @ 600 ml/ha, chlorantroniliprole 18.5 SC @ 150 ml/ha and spinosad 45 SC @ 125 ml/ha caused increased mortality of 30.00, 50.00 and 70.00 per cent, respectively. The mortality increased as the time of exposure increased from 6 to 24 HAT. Similar trend was also observed in Italian bees. Hence, emamectin benzoate 5 WG considered could be highly safe to both the species of honey bees than standard insecticides.