DIVERSITY OF MITE PESTS ON SOME SUMMER VEGETABLE CROPS WITH SPECIAL REFERENCE TO MANAGEMENT OF OKRA MITE (TETRANYCHUS URTICAE KOCH.)

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Date
2016
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Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu
Abstract
Experimentation for management of okra mite (Tetranychus urticae Koch.) on okra was conducted at Chatha farm, SKUAST- Jammu from February 2015 till the harvest of crop (July, 2015). In the present investigation, 10 different vegetable crops were surveyed for the diversity of mite pests and recorded five different types of phytophagous mite species such as two-spotted spider mite, Tetranychus urticae Koch; Tetranychus neoealidonicus Andre; Polyphagotarsonemus latus Banks; Red-legged spider mite, Tetranychus ludeni Zacher; and Spider mite, Tetranychus macfarlanei Baker & Pritchard. Apart from phytophagous mites, one predatory mite viz., Amblyseius tetranychivorus (Gupta) was also recorded feeding on okra mite. Further, seven other predatory fauna on Tetranychus urticae mite on okra such as Coccinellids beetles (Coccinella septempunctata and C. sexmaculata); Small black beetle (Stethorus sp.); Rove beetle (Paederus spp.); Green lace wing, Chrysoperla carnea; Spiders (Oxyopes spp. and others); and minute pirate bug (Orius spp.) were also observed in the okra field. The seasonal incidence of okra mite observed at experimental sites indicated that okra mite, T. urticae was found damaging and remain active on the okra crop and attained two peaks i.e., in 18th standard week (44.13 mean number of mites per 2.5 cm2) and in in 25th SW (55.53 mean number of mites population/2.5 cm2), respectively. The increase in temperature coupled with decrease in relative humidity from March 2015 to June 2015 favoured the increase of T. urticae Koch. The correlation studies showed that the highly significant and positively correlated with maximum temperature had existed with okra mite whereas, negatively correlated with relative humidity (highly significant with morning R.H and significant with evening R. H) and negatively correlated and significant with rainfall. Predatory mite population build-up observed on okra crop had two peaks viz., in 19th SW (5.00 mite/leaf) and again in 27th SW (8.67 mite/leaf). Predatory mite population was positively correlated and highly significant with minimum temperature and significant with maximum temperature, respectively. Predation study revealed that A. tetranychivorus (Gupta) prefer the egg stage of prey than larvae, nymph and adult. Mean consumption rate of A. tetranychivorus (Gupta) on T. urticae egg was found to be 4.16 ± 0.33 per day per gravid female. Bio-efficacy of certain acaricides/ botanicals / allelochemicals / insecticide against okra mite in laboratory condition Bio-efficacy of certain acaricides/ botanicals / allelochemicals / insecticide against okra mite was recorded after two spray (1st and 2nd spray). After 14th days of 1st spray, Abamectin was found to be the best treatment in reducing the mites population (74.64 per cent) on okra followed by Diafenthiuron (68.02 per cent) and Fenazaquin (60.43. per cent). Among the biopesticides, pongamia oil gave 46.32 per cent reduction followed by neem oil application resulted in only 42.68 per cent reduction in mites population at 7 days after second spray. The present investigation shall be useful in monitoring the mite pest population by encouraging the predatory mites and devising the sustainable Integrated Pest Management strategies against emerging mite pests of summer vegetable crops.
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