Population dynamics and management of shoot webber and hoppers infesting mango using safer molecules

Abstract

The work entitled “Population dynamics and management of shoot webber and hoppers infesting mango using safer molecules” was conducted at the College of Agriculture, Vellayani and College of Agriculture, Padanakkad during 2014-2016 with the objectives to study the population dynamics of mango shoot webber and hoppers in relation to climatic factors and standardize the use of newer and safer molecules for their management. A survey was conducted in 20 homesteads in Kalliyoor panchayath (one plant homestead-1) and in the Instructional Farm, Vellayani (20 plants) to study the population dynamics in relation to climatic factors. Mango shoot webber was identified as Orthaga exvinacea Hampson, and hoppers as Amritodus sp., Idioscopus nagpurensis Pruthi, Idioscopus clypealis Letheirry and Idioscopus nitidulus Walker. Shoot webber occurrence was observed throughout the year, peak incidence was in January (25.6 webs tree-1, 8.2 larvae web-1 and 103.6 damaged leaves composite web-1) at homesteads of Kalliyoor, but in the Instructional Farm, Vellayani the peak infestation was in the month of March (22.25 webs tree-1, 5.7 larvae web-1 and 62 damaged leaves composite web-1). Studies on correlation with weather parameters revealed that maximum temperature and morning relative humidity had positive significant correlation with the population of mango shoot webber. The occurrence of mango hoppers (Amritodus sp., Idioscopus clypealis, I. nitidulus, I. nagapurensis) was the highest in the month of April (12.97 hoppers panicle-1, 17.07 sweep net-1and 4.74 shoot-1) in Kalliyoor panchayath, where as in the Instructional Farm, Vellayani the occurrence of the pests was low throughout the period of observation. Studies on correlation with weather parameters and population of mango hoppers showed that maximum temperature had positive significant correlation. Occurrence of other mango pests were identified as Clovia nebulosa (Fab.), Ptyelinellus praefractus (Dist.) (Aphrophoridae) and Otinotus sp.,(Membracidae). Scales and mealybugs were identified as Ceroplastes sp., Formicococcus robustus (Ezzat & Mcconnell), Eucalymnatus tessellates (Signoret), Rastrococcus iceryoides (Green), Rastrococcus invadens (Williams) and Icerya sp. Ants viz. Camponotus compressus (Fabricius) and Oecophylla smaragdina (Smith) were the natural enemies. Field experiments were carried out in completely randomised design to evaluate the efficacy of safer molecules against mango shoot webber and hoppers respectively. The treatments evaluated for shoot webber were emamectin benzoate 0.002%, spinosad 0.015%, lambdacyhalothrin 0.005%, flubendiamide 0.01%, chlorantraniliprole 0.03%, indoxacarb 0.02%, malathion 0.1%, azadirachtin-1%, B. bassiana (ITCC 6063) WP 2%, water spray and untreated. All the treatments showed significant difference compared to control. Chlorantraniliprole 0.03% showed the highest efficacy with 95.18 per cent reduction over control, followed by flubendiamide 0.01% (85.58 per cent). Azadirachtin 1% and B. bassiana (ITCC 6063) WP 2% were also significantly superior to the control. For the management of hoppers the treatments were lambda cyhalothrin 0.005%, thiamethoxam 0.005%, deltamethrin 0.05%, imidacloprid 0.005%, dimethoate 0.05%, malathion 0.1%, azadirachtin 1%, B.bassiana (ITCC 6063) WP 2%, water spray and untreated. Imidacloprid 0.005% showed the highest efficacy with 97.92 per cent reduction followed by thiamethoxam 0.005% (89.9 per cent), compared to control. Azadirachtin 1% was also found effective in managing the pest. It is concluded that the peak incidence of mango shoot webber and hoppers is in the month January and March, respectively. Correlation studies revealed that the webber population had significant positive correlation with maximum temperature and morning relative humidity whereas, hopper population showed significant positive correlation with maximum temperature only. Chlorantraniliprole 0.03%, flubendiamide 0.01% and biopesticide B.bassiana (ITCC 6063) WP 2% are found effective against mango shoot webber. Imidacloprid 0.005%, thiamethoxam 0.005% and botanical azadirachtin 1% are found effective against mango hoppers.