Management of Insect Pests of Cotton Through Eco-Friendly Measures

Abstract

Five experiments were conducted consecutively for two years (2006 and 2007) for management of cotton insect pests through eco-friendly measures. In experiment-1, cotton agro-ecosystem analysis was carried out mainly based on measurement of the basic components i.e. recording the pest population, damage and natural enemies interactions with pest populations. In experiment-2, eight cotton varieties (CIM-499, TH-57/76, FH-901, CIM-473, CRIS-134, Chandi, Shahbaz and NIAB-78) were screened and monitored for their resistance against sucking insect complexes and bollworms. In experiment-3, sunflower, maize, okra and Sorghum were used as trap crops (sown in cotton) and sucking complex on cotton was compared; the effect of natural enemies on the insect pest population was examined. The population monitoring of spotted bollworm through pheromone traps was carriedout.Similarly, in experiment-4, biopesticiedes (Neem extract, Neem oil, Asafoetida (Hing) and Tobacco) were evaluated against sucking complex, with the compoent-5, model of eco-friendly measures package and IPM techniques was suggested.

The results of experiment-1; showed that thrips population appeared on cotton at the age of 24-31 days after planting (DAP) and continued up to harvest. Its peak activity period varied from 1st week of June to last week of July during two years of the study period. This showed that after reaching the age of about two months the cotton crop observed maximum mean thrips population (8.71) per leaf during June-July. The whitefly attacked its vegetative growth at the age of 20-24 (DAP). The peak activity of the pest was recorded from 2nd week of June to 3rd week of July. Maximum peak population (3.20) per leaf was recorded during 2nd week of July. The jassid appeared at the age of 24-31 (DAP) in third week of May and continued upto crop harvest. Maximum activity on cotton remained during June and July with maximum mean of (2.13) per leaf during 2nd week of July. Similarly, the spotted bollworm species appeared on cotton in 3rd week of June on fruiting bodies and continued up to crop harvest. Its peak activity (0.93-2.60) per plant was recorded from 2nd week of August to 3rd week of September and decreased upto crop harvet. The larvae 265 collected from cotton were kept under labartory conditions in which 224 of Earias vitella and 41 of E.insulana emerged. The study confirmed that E. vitella existed in large nembers than E. insulana at the ratio of 57.33: 7.33.

The findings of experiment-2; revealed that none of the variety was found immune to the attack of insect pests CIM-499 variety of cotton received the lowest mean whitefly population (0.51), jassid (0.61) and thrips (3.10) per leaf. Whereas, the overall lowest mean population of spotted bollworms (1.41) per plant was recorded in Shahbaz. The findings of experiment-3, indicated that cotton plant alone suffered maximum attack of pests in comparison to cotton planted with different trap crops.Theoverall maximum mean population of thrips was recorded in cotton alone (3.11) followed by (2.99), (2.93), (2.41) and(0.89) per leaf in cotton with Sorghum, cotton with sunflower, cotton with okra and cotton with maize.Similarly, the maximum jassids number (2.61) per leaf was obseved in cotton alone followed by (1.25), (1.24), (1.14) and (0.87) per leaf in cotton with sunflower, cotton with Sorghum, cotton with maize and cotton with okra.The maximum number of whitefly (1.54) per leaf was recorded in cotton alone followed by (1.07) (1.04), (0.89) and (0.82) per leaf in cotton with Sorghum, cotton with maize, cotton with sunflower and cotton with okra. Comparatively higher mean number of spotted bollworms (1.72) per plant was observed in cotton alone followed by (0.79), (0.64), (0.55) and (0.50) in cotton with maize, cotton with sunflower, cotton with Sorghum and cotton with okra, respectively. This showed that the trap crops contributed in pest reductions on cotton crops by attracting the pests as well as natural enemies which ultimatly reduced pest pressure on cotton (main crop). The okra and sunflower attracted sucking pests.The use of sex pheromone traps is advised for supressing of spotted bollworm in cotton. Two species of spiny bollworms were attracted to the sex pheromones traps. Average number of E. vitella (7.22-9.01) was attracted whereas, E. insulana ranged between (1.08-1.33) under field condition.

The experiment regarding evaluation botanical pesticides showed that among all pesticides reduction of thrip (67.65%) was recorded in neem extract followed by Neem oil (60.00%), Tobacco (63.59%) and Hing (Asafoetida) (52.68%) after 96 h. of application of pesticides. Overall maximum mean reduction (64.69%) was recorded in neem extract followed by neem oil (57.74%), tobacco (52.91%) and Asafoetida (46.52%).The heighest reduction of jassid (71.97%) was recorded followed by neem oil (70.06%), Hing (Asafoetida) (68.15%) and tobacco (23.56%) after 96 h., of application of pesticides. With regards to reduction percent of whitefly revealed that maximum reduction (60.18%) was recorded in Hing (Asafoetida) followed by neem oil (59.78%), neem extract (59.38%) and tobacco (40.61%) after 96 h., of spray application. The botanical pesticides started reducing their toxicity after 96 h. However, the effective reduction of pests was recorded up to one week. Therefore, the bio-pesticides reduced their effectiveness. Development model of IPM package control measures recommendation were based on two year study on different IPM techniques for benefit of farming community through seminars, trainings and pamphlates. Using the safe botanical pesticides remained effective against sucking pests and is recommended against cotton pests, which showed less effective to natural enemies and environment friendly