Vyas, H. N.Patel, Dilip P.2018-06-292018-06-291998http://krishikosh.egranth.ac.in/handle/1/5810055918Studies on bionomics and predatory potential of Menochilus sexmaculatus Fabricius and Chrysoperla carnea Stephens, reared on maize aphid (Rhopalosiphum maidis Fitch.) alongwith their comparative susceptibility to some neem based pesticides were carried out at Entomology laboratory, B.T.R.S., Gujarat Agricultural University, Anand during 1997-98. The length and breadth of eggs of M. sexmaculatus were on an average 1.035 and 0.396 ram, respectively. The average incubation period of egg was 1.57 day when reared on R. maidis F. The average length and breadth of eggs of C. carnea were 0.815 and 0.375 mm, respectively, with an average foot stalk length of 3.937 mm. The incubation period of egg was on an average 3.97 days when reared on R. maidis. The larva of M. sexmaculatus passed through four distinct instars and each instar lasted for 1.64, 1.35, 1.52 and 2.39 days, respectively. The total larval duration of M. sexmaculatus was on an average 6.91 days, when reared on R. maidis. Whereas, the larva of C. carnea passed through three distinct instars and each instar lasted for 5.10, 3.24 and 3.84 days, respectively. The total larval duration of C. carnea was on an average 12.28 days when reared on R. maidis. The average pre-pupal and pupal periods of M. sexmaculatus were observed as 15.78 hrs. and 3.30 days, respectively when reared on R. maidis. Whereas, the average pre-pupal and pupal periods of C. carnea were observed as 6.87 hrs. and 7.92 days, respectively when reared on R. maidis. Average pre-oviposition, oviposit ion and post-oviposit ion periods of M. sexmaculatus were 2.85, 14.92 and 2.46 days, respectively. INhereas, average pre-oviposition, oviposition and post-oviposition periods of C. carnea were 5.08, 12.38 and 10.08 days, respectively when fed on same aphid species. Longevity of male and female beetles of M. sexmaculatus with food was 16.00 and 20.38 days, respectively whereas without food, it was 2.80 and 3.60 days, respectively. The average entire life span of male and female of M. sexmaculatus was 2770 and 32.8 days, respectively with ratio of 1:1.30 when fed on R. maidis under laboratory conditions. Similarly, longevity of male and female adults of C. carnea was 17.00 and 27.54 days, respectively, while without food it was 2.40 and 2.80 days, respectively. The average entire life span of male and femle of C. camea was 42.66 and 53.00 days, respectively with the ratio of 1:1.14 when fed on same aphid species under laboratory conditions. The predatory potential of first, second, third and fourth instar larvae of M. sexmaculatus on maize aphid (R. maidis) wets on an average of 8.26, 15.10, 20.77 and 23.50 aphids per day, respectively, while average number of maize aphid consumed by M. sexmaculatus during entire larval and adult period was 122.60 and 412.39 aphids, respectively. Whereas, the predatory potential of first, second and third instar larvae of C. carnea to the maize aphid was on an average 5.07, 16.31 and 41.27 aphids per day, respectively with an average 236.43 aphids during total larval instars. Studies on toxicity of some neem based pesticides in comparison with simthetic insecticides to immature stages of M. sexmaculatus and C. carnea revealed that all tested neem based pesticides were less toxic than Monocrotophos (0.036 per cent) and Endosulfan (0.07 per cent) to eggs and larvae of M. sexmaculatus and C. carnea. Among the neem based pesticides Parasmani (0.4 per cent) and Gronim (1500 ppm) were found to be highly toxic than other neem based pesticides to eggs and larvae of M. sexmaculatus and C. carnea. Whereas, NSKS (5 per cent), Neembicidine (0.4 per cent) and Amrutguard (0.5 per cent) were observed less toxic to eggs and larvae of M. sexmaculatus and C. carnea.enAGRICULTURAL ENTOMOLOGY, AGRICULTUREA STUDYThesis