The population density of the cowpea aphid, Aphis craccivora Koch. and its associated predators on faba bean and cowpea fields were studied at El-Khattara district, Sharkia Governorate, Egypt in 2010-2011 and 2011-2012 seasons. A. craccivora had three peaks on faba bean for each season the first peak was during the fourth week of December , the second one was in the second week of February, where the last peak was in the first week of March (2010-2011 season), The three peaks of 2011-2012 were recorded in the first week of January, the fourth week of February and the second week of March 2012. There was one peak only on cowpea in the third and fourth week of July in 2011 and 2012, respectively. The common predators observed in faba bean and cowpea fields were: Coccinella undecimpunctata L., Chrysoperla carnea Steph., Paederus alfierii (Koch.), Orius sp., Syrphus sp. Scymnus sp. and Cydonia vicina isis (Muls.) Regarding predators on faba bean, two peaks were found in the first weeks of February and second week of March (37 and 79 predators/ 100 plants) during the first season 2010-2011, also, two peaks were found in the third week of February and second week of March (61 and 58 predators / 100 plants), respectively in 2011-12 season.On cowpea, however, also two peaks were found in the fourth week of July and second week of August (89 and 69 predators/ 50 plants), respectively in 2011 season, while, one peak was found in the third week of July (78 predators/ 50 plants) in 2012.Statistical analysis showed that temperature and relative humidity had different effects (significant or insignificant) on insects under investigation.

Seasonal abundance of the oleander aphid, Aphis nerii Boyer de Fonscolombe and its associated parasitoids on duranta plants were studie in Zagazig and Mansoura during the three seasons 2004/05, 2005/06 and 2006/07. Obtained data revealed that: A. nerii infestation of duranta started by late September and early October, respectively. It continued to late March in the three season. The aphid numbers ranged between 10.88-48.04, 9.40-38.16 and 8.44-39.52 individuals/leaf, respectively in Zagazig during the three seasons. While, in Mansoura the infestation started earlier in the first half of September. It continued to early March. The aphid numbers ranged between 16.08-52.16, 15.72-37.56 and 14.00-41.00 individuals/leaf, respectively during the three seasons. In Zagazig, the aphid abundance showed three peaks in the three seasons of study. The mean numbers of aphids/leaf was 25.64, 25.04 and 22.75, respectively during the three seasons, meanwhile in Mansoura the aphid abundance showed three peaks in first season, four peaks in second season and two peaks in third seasons. The mean numbers of aphids/leaf were 26.63, 24.91 and 24.83, respectively during the three seasons. Five hymenopterous parasitoids, Diaeretiella rapae (M`Intosh), Aphidius sp. (Aphidiidae), (primary parasitoids) Pachyneuron sp. (Pteromalidae), Alloxysta sp. (Cynipidae) and Aphidencyrtus sp. (Encyrtidae) (Hyper parasitoids) were recorded..

Rate of parasitism by the aphid parasitoid, Diaeretiella rapae (M´ Intosh) on the cauliflower aphid, Brevicoryne brassicae L. as well the hyperparasitism on D. rapae were recorded, at Kafer Sakr district Sharkia Governorate during the two successive seasons 2010-11 and 2011-12. Total means of parasitism rates of D. rapae were 23.58 and 28.06 % during the two successive seasons, respectively. The parasitoid, D. rapae was parasitized by two hyperparasitism species Pachyneuron sp. and Alloxysta sp .The seasonal means of hyperparasitism percentage were 28.42 and 29.67% during period of study, respectively. The parasitoid density, in relation to that of host density, had influenced on percentage of parasitism. The highest percentage reached was 87.75% at 15 D. rapae female parasitoids per cage and the minimum was 46.1% at three female adult per cage. On the other hand, the average parasitism ratios in green houses were 73.

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The present study was conducted to survey and population density of aphid Aphis gossypii Glover (Homoptera: Aphididae) infesting cucumber plants and its parasitoids were investigated at Diarb Nigem district during two season 2015 and 2016. Three primary parasitoids Lysiphlebus fabarum (Marshall), Diaeretiella rapae (M Intosh) and Binodoxys angelica (Haliday) and a hyperparasitoid, Pachyneuron sp. ((Hymenoptera: Aphidiidae)), were recorded. Primary parasitoid Lysiphlebus fabarum was the highly dominant species by relative density 53.76 and 52.24%, followed by D. rapae 22.58 and 27.73%, Binodoxys angelica 15.06 and 12.14%, while the hyperparasitoid , Pachyneuron sp., occurred by 8.60 and 7.89%, during 2015 and 2016 seasons respectively. The percentage of parasitism ranged from 3.14 % to 21.0 % in 2015, while it is starting by 2.66 % to reach its maximum 42.66% in 2016. Total developmental period of the parasitoid Lysiphlebus fabarum was 14.67 ± 1.16 days at 18.30°C ±1°C and 64 ±2RH%. Investigation the behaviour of the same parasitoid Lysiphlebus fabarum at varying host densities showed increase number of sting and number of mummies increased with increase of host density but decrease leaf arrival times and host arrival times with increasing. The obtained results showed that the longevity of the parasitoid Lysiphlebus fabarum was affected by temperature and food supply.

The journal of Toxicology and pest control is one of the series issued twice by the Egyptian Academic Journal of Biological Sciences, and is devoted to publication of original papers related to the interaction between insects and their environment. The goal of the journal is to advance the scientific understanding of mechanisms of toxicity. Emphasis will be placed on toxic effects observed at relevant exposures, which have direct impact on safety evaluation and risk assessment. The journal therefore welcomes papers on biology ranging from molecular and cell biology, biochemistry and physiology to ecology and environment, also systematics, microbiology, toxicology, hydrobiology, radiobiology and biotechnology. www.eajbs.eg.net Provided for non-commercial research and education use. Not for reproduction, distribution or commercial use.

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