Abstract
Efficient chemical is achieved when insecticides are active against insect pests and safe to natural enemies (parasitoids). In this study the toxicity of four toxicants, Pyriproxifen (10% EC), Imidacloprid (20% SG), Methoxyphenozide (24% SC) and CAPL-2 (96% EC) are used to explore the role of washing insecticides after 1, 12 and 24 hours of application against immature stages of Bemisia tabaci (Genn.) and associated parasitoids (Encarsia lutea Masi. and Eretmocerus mundus Mercet). The washing may be due to natural events (rainfall, mist or dewy) or mechanical reason (any irrigation system causes washing). Statistical analysis was showed that, the tested insecticides have significant differences on two cases of application (unwashed and washed insecticides) against eggs, nymphs of B. tabaci and associated parasitoids in all tested compounds after 1 and 12 hours of washing insecticides, while after 24hr. of insecticidal washing causes non significant difference between two cases except for Pyriproxifen (10% EC) gave significant difference after three times of washing against eggs. This may be due to that compound act as Insect Growth Regulator (IGR). Insecticides washing cause decrease in efficiency of insecticides against the target (pest), but causes passive effect against the parasitoids. The differences value between previous cases of application, in case of eggs range between (11.68-55.57), (17.32-43.48) and (9.77-28.0) after 1, 12 and 24 hr., respectively. But, nymph ranged between (14.49&19.98), (8.41&16.5) and (0.93 & 2.52) after 1, 12 and 24 hr., respectively, while in parasitoid recorded (3.8 & 7.02), (2.68 & 2.97) and (0.1 & 2.3) after 1, 12, 24 hr, respectively. To avoid the insecticidal washing must be taken in consideration: 1- Check the metrologistic report and schedule irrigation time of pivot or any irrigation system causes washing the insecticides from plants. 2- Do not apply the insecticides at expected rainfall, mist or dewy.
Highlights
Bean plant, (Phaseolus vulgaris L.) is one of the important crops that fit for foreign and local markets
Each of the first three parts were divided into two parts (A and B).The A part of each first, second and third part represent the wash insecticides after 1,12 and 24 hr., respectively, insecticides application
The same trend occurs in case of nymph where reduction percent of the previous insecticides recorded (70.82, 65.5, 66.69 and 55.69%) incase of unwashed insecticides comparing with (53.28, 49.01, 48.71 and 36.54% ) for insecticide wash after 1 hr., respectively., ( 71.27, 65.62, 67.92 and 56.65%) in case in unwashed comparing with ( 62.86, 56.77, 51.4 and 43.87%) for washing after 12 hr., respectively. (68.62, 65.25, 65.3and 53.28%) in case of unwashed comparing with (66.1, 66.41, 63.5 and52.35%) for insecticide wash after 24hr., respectively
Summary
Bean plant, (Phaseolus vulgaris L.) is one of the important crops that fit for foreign and local markets. It is considered as a high yielding seeds legume, and one of the productive protein-rich fodder plants. Various pests’ attack this plant, among which is whitefly, Bemisia tabaci (Genn.). Infestation by B. tabaci modifies the vegetative and reproductive development of the injured plant (Toscano et al, 2004). This insect can cause direct damage by sucking the plant sap and injecting toxins in the plant. The later cause physiological changes including leaf silvering in cucurbits (Costa et al, 1993), irregular ripening of tomatoes (Schuste et al, 1990) and foliar disorders in ornamentals (Tsai et al, 1997)
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Schedule a callMore From: Egyptian Academic Journal of Biological Sciences, F. Toxicology & Pest Control
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