A practical decision making pattern for pest managment of cucumber leafminer Liriomyza sativae (Diptera: Agromizidae) in greenhouse
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
Economic injury level (EIL) is main concept in pest management context. In this study, a decision making algorithm was designed based on economic measurements for vegetable leafminer Lirimyza sativae (Diptera: Agromyziade) in greenhouse cucumber (Cultivar simensis). The algorithm proposed by Richelderfer was followed. All calculations were done based on 1000m2 area. First gross benefit was calculated as kg fruit per plant × unit fee × number of plants/1000m2. Costs including irrigation, cooling, heating, worker, fertilizer, seed etc. were included regarding seasonal changes. The total net benefit was calculated by subtracting costs from gross benefit. Finally the trend of decreasing in net benefit by damage was used to calculate injury in Iranian Rials (IRR). Relationship between damage and yield was included based on previous work. The yield was 7.2 kg/plant in control which decreased 148g per 10000 mm2.d damage. The net benefit of summer and winter production was 89000000 and 226000000 IRR (≈2374 and 6027 US$) considering 15000 IRR and 25000 IRR unit fee respectively. Every insecticide application costs 200000 IRR which corresponds to 337.8 and 585.9 damage unit of winter and summer production respectively. The plant may tolerate damages as large as 10500 mm2.d, so damages lower than 11000 unit do not necessitate action. This correponds to 0.5, 1, and 2 mines per plant appeared at the days of 30, 90 and 120 of the crop growing respectively. Assuming a random distribution of mines among plants, the poisson probabilities of observing x=0, 1, 2, ..., mines per plant was estimated and then frequency of the observations for 2000 plants of a 1000m2 greenhouse was calculated. Then random samples of 10 plants in 1000 trials were taken repeatedly from a hypothetical greenhouse using spreadsheet Microsoft Excel. Number of mines then was summed over 10 plants and arranged by size. The smallest 25 data as well as largest 25 were excluded and 950 median data was considered as 95% more frequently observed sums. The lower confidence level then was adopted as action threshold. Hence decision pattern will be observing 1, 4 and 12 mines per 10 plants randomly or systematically sampled respectively prior to 30th, 90th and 120th day of production.
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