Survey and population fluctuations of parasitoids of the green peach aphid, Myzus persicae (sulzer) attacking squash plantations and adverse effects of insecticide applications on it [electronic resource].

Includes references.

The current study was carried out at both laboratory and experimental farm of Sakha Agric. Res. Station, Kafr El-Sheikh Governorate during two successive seasons 2003/2004 and 2004/2005 (summer, nili and winter Plantations), to survey and investigate population fluctuations of parasitoids of the green peach aphid, Myzus persicae (SUlzer) attacking squash (Cucurbita pepo L.) plantation. Also, adverse effects of insecticidal applications on parasitoid populations were considered. Three solitary hymenopterous parasitoids were detected, i.e. Diaretiella rapae McIntosh, Aphidius matricariae Haliday and Aphidius colemani Viereck. Percentage of parasitism by D. rapae was higher than those of A. matricaria and A. colemani. In the summer squash plantation, the parasitism by the first parasitoid ranged 8.80-6.57%, the second parasitoid 1.06¬ 1.35% and the third one ranged 0.73-0.72%, respectively. Corresponding values of nili plantation were 7.29-7.31, 0.82-0.65% and 0.42-0.44%. In winter plantation, parasitism by D. rapae greatly exceeded those of A. matricariae and A. coleman;' 12.18-3.30%, 3.21-1.65% and 1.28-1.65%, respectively. population fluctuation of total parasitism in untreated plots of summer plantation ranged 4.39-18.80 and 2.65-17.00 in 2003 and 2004 seasons, respectively. The corresponding values in treated plots were 1.13-13.42 and 3.23-26.67%. In nili plantation, total parasitism was the lowest on September and the highest during November and December. In winter plantation, parasitism in 2004, was relatively low during the last week of January and second week of March but high during the second week of February. In 2005, the lowest values were obtained on early January and by mid- February, while the parasitoids were totally absent at last week of February and second week of March. It was found that spraying squash plantation by Marshal (200 g/100 L of water) negatively affected the parasitoid population. They were reduced by 34.66, 37.75 and 47.81% in summer, nili and winter plantations, respectively in 2003/2004 season. The corresponding reduction values in 2004/2005 were 13.79, 16.67 and 31.68%. Accordingly, insecticides should be avoided, or wisely applied.

Summary in Arabic.

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