Bio-intensive pest management strategies for mango shoot gall psylla, Apsylla cistellata Buckton
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Date
2018-07
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Studies carried out on different biological attributes of mango shoot gall psylla, Apsylla cistellata showed that pre-oviposition, oviposition and post-oviposition period of shoot gall psylla female varied from 10-22, 1-5 and 0-3 hours, respectively. A single female laid 45-182 eggs and incubation period of eggs varied from 138-177 days. It was also found that females outnumbered males and sex ratio was computed to be 1: 1.64 -1.79 (male: female). Data also indicated that number of galls/twig became proportionately higher as the number of eggs bearing leaves increased on a twig (40 cm). It was observed that, if all the leaves of twig carry 200 eggs, the number of galls formed were maximum (40 and 41 galls/ twig), by converting all buds to galls. Correlation analysis indicated that number of eggs were positively significantly correlated with gall formation (r=0.923, 0.916) and adult emergence (r=0.956, 0.945). Whereas, significantly negatively correlated with panicle initiation (r= -0.885,-0.881). Seasonal incidence of mango shoot gall psylla indicated that nymphal emergence initiated from 33 SW and continued to 39 SW, whereas gall formation started in the 38 SW and appeared constantly in every week till 15 SW. It was also recorded that nymphs 1st appeared inside galls in 41 SW and further observed in every week till 6 SW. Later, nymphs transformed into adults and adult population started appearing inside galls from 8 SW which continued upto 17 SW. However, oviposition of psylla was recorded only during the 12 to 18 SW in the month of March and April. Correlation coefficient stated that nymphal emergence had positive significant association with maximum temperature (r= 0.434), minimum temperature (r= 0.830) and rainfall (r= 0.652). However, gall formation and nymphal population inside galls was found negatively correlated with maximum temperature (r= -0.791, -0.579) and minimum temperature (r= -0.728, -0.575). Whereas, egg laying of shoot gall psylla was significantly positively correlated to maximum temperature (r= 0.419) and negatively correlated to morning (r= -0.658) and evening R.H (r= -0.348), respectively. Studies on evaluation of yellow and blue coloured sticky traps for visual preference during adult emergence period in the month of March-April indicated that adults were attracted more towards yellow sticky traps (6.96-7.82 adults/trap/week) as compared to blue sticky traps (1.91-2.40 adults/trap/week). Traps installed at upper height were found significantly better with maximum number of adults as compared to traps installed at lower height. Different plant extracts were also evaluated against oviposition of shoot gall psylla, which indicated neem leaves extract and hemp leaves extract were found highly effective with minimum number of eggs and highest oviposition deterrence (30.26-74.61%) in all the concentrations. Data on the efficacy of different insecticides showed that thiomethoxam @ 1g/l & 3 g/l and imidacloprid @ 0.5 ml/l and 1 ml/l proved most effective with highest nymphal mortality (54.33-73.04%), minimum gall formation (0.07-2.94 galls/twig), maximum panicle initiation (1.75-4.50 panicles/twig) and minimum nymphs inside galls (0.00-1.80 nymphs/gall/twig). Impact of different plant growth regulators on shoot galls showed that NAA and 2,4-D were found superior over other plant growth regulators with their ability to open the galls, at 100, 250 and 500 ppm. Galls were opened abnormally in both the treatments, having an elongated axis with completely lose and open scales. Nymphs further were not able to survive in those opened galls. However, 2,4-D at higher doses (500 ppm) caused phytotoxicity symptoms on leaves and galls. Although, such kind of phytotoxicity was not found due to the spray of NAA even at higher doses (500 ppm).
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