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Keywords: Applied Sciences
Agriculture & related technologies
Plants injuries, diseases& pests
Insect culture
Agricultural entomology
Issue Date: 2012
Abstract: Canola (Brassica napus L.) is the second most important source of vegetable oil after soybean. Its oil is widely used in cooking and for making salads and margarines, while the meal is commonly used in animal feeds all around the world. Pakistan, being an agricultural country, is still essentially deficient in edible oil production. It is estimated that more than three fourths of the country’s vegeTable oil requirements are met through imports. Canola is one potential crop which can fulfill the country’s requirement for edible oil. Insect pests are a major yield limiting factor of this crop. Among the insect pests, aphids are considered the major pest. Three aphid species are known to infest the canola crop, the cabbage aphid, Brevicoryne brassicae (L.), the turnip aphid, Lipaphis erysimi Kalt, and the green peach aphid, Myzus persicae (Sulzer) (all are Hemiptera: Aphididae). Heavy aphids attack on canola seedlings can cause wilting of the cotyledons and yellowing of the leaves. Heavy infestations of aphids on pods and flowers lead to yield reductions. Normally aphids cause about 30-35% yield losses on brassica plants but under uncontrolled situations the yield losses may exceed 70%. Control of the pest relies exclusively on pesticides. The indiscriminate use of pesticides has resulted in the development of resistance and resurgence by pests together with associated environmental and health hazards. This situation urgently demands alternate bio-intensive control measures as the main components of an IPM program. The present study was conducted on sustainable management of aphids on canola grown under organic and conventional farming systems in Punjab, Pakistan. The main objective of this study was to develop the most economical and effective management models by determining population distribution of aphids and their natural enemies, screening relatively tolerant crop genotypes, to identify sources of resistance, studying the biology of aphids and determining the efficacy of mechanical, biological and chemical practices for pest suppression. The results of these findings revealed that the cabbage aphids and mustard aphid were found in all four locations studied (Faisalabad, Bahawalpur, Khanpur and D.G. Khan) while the green peach aphid was recorded at two locations (Faisalabad and Khanpur).The genotypes ‘Cyclone’ , ‘Shiralee’ and Oscar were found to be susceptible with maximum population of aphids. The genotypes ‘Hyola-401’ and ‘Rainbow’ were observed to be relatively resistant with lower populations of aphids. The results regarding the biochemical basis of resistance revealed that the availability of nitrogen increases susceptibility, and crop genotypes and farming systems with more nitrogen inputs suffered higher aphid populations. The different evaluated farming systems significantly affected the total life span of aphids, and maximum numbers of nymphs were produced on canola grown under fertilizer applications. All tested insecticides (Carbosulfan, Acetamaprid, Imidacloprid, Nitenpyram and Profenofos) were found to be effective against aphids and reduced population densities. Results revealed that treatments consisting of chrysoperla + coccinellid + blank water spray were highly effective against aphids on canola under both systems of farming. Predators performed well one week after release and their efficacy increased over time. A higher and noticeable yield was obtained under inorganic farming system where Chrysoperla carnea, coccinellids and blank water spray were integrated or blank water spray was applied. However, a higher CBR (10.36:1) was attained under organic (farm yard manure application) where blank water spray was applied on the canola crop. Integration of C. carnea, coccinellids and blank water spray under organic farming system also produced a rationally higher CBR (4.02:1). In conclusion, organic farming system (FYM application) with blank water spray or integration of C. carnea, coccinellids and blank water spray is better option and recommendation for aphid management in canola.
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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