Exploitation micromus igorotus Banks and micromus timidus Hagen Hemerobliidae Neuroptera in the management of aphids in cotton and tobacco

Abstract

Micromus timidus accepted nine aphid species and a psyllid as host. Leaves, open newlinebolls and cotton thread served as oviposition substrates. Full grown larva pupated in double newlinelayered cocoon in counseled places. Aphis gossypii and Melanaphis sacchari found to be newlinemost suitable hosts as growth, development reproductive traits and feeding potential were in newlinefavour. Egg to adult and egg to egg duration was shortest on A. craccivora followed by M. newlinesacchari. Both larva and adult of M. timidus consumed higher number of A. gossypii and M. newlinesacchari as most palatable food sources. Morphometry of mouth and body parts were also newlinerecorded. Rearing of Micromus igorotus on A. gossypii and C. lanigera for five generations did newlinelower fecundity slightly but not other traits. Reduction in survivability of egg, larva and adult newlinewas evident. newlineMicromus igorotus at 1,000 adults/ha outperformed in reducing cotton aphid newlinepopulation. Five pairs of M. timidus adults/plant reduced the cotton aphid population. Five newlinepairs of M. timidus adults/plant reduced the cotton aphid population effectively with higher newlinepredatory recovery. On tobacco, 20,000 to 25,000 M. igorotus adults/ha reduced aphid newlinepopulation and increased yield by 46.6 and 56.8 per cent. Release of five pairs of M. timidus newlineadults/plant was also effective. newlineEmamectin benzoate was highly toxic to all stages of M. igorotus and M. timidus and newlinethiodicarb was least toxic to eggs and larva. Profenophos at recommended field concentration newlinepersisted at greater level to inflect above 90 per cent mortality to grubs up to 7 days and newlineretained toxicity for 30 days. The order of persistent toxicity was profenophosgtthiomethoxam newlinegtmethomylgtimidaclopridgtnovalurongtthiodicarbgtemamectin benzoategtspinosad gt indoxacarb. newlineMicromus igorotus eggs were devoured by C. carnea grubs, C. sexmaculata grubs and adults newlineand syrphid maggots under free choice in the presence of aphid. While, M. igorotus did not newlinefeed on any stage of these predators.