Suitability of Two Sampling Methods for Determining the Population Trends of Certain Sap-Sucking Species Inhabiting Tomato and Cucumber Plantations

Faunistic composition and seasonal abundance of certain sap-sucking species inhabiting tomato and cucumber plantations were determined by using sweep net and direct count methods, during summer seasons of 2015 and 2016 in Assiut Governorate, Northern Upper Egypt.  Twelve species belonging to 8 families and 3 orders in addition to the acarid mite were recorded. Heteropteran species were found to be constituted 69.24% of the gathered species. However, Homopteran species were found to be constituted 15.38%. Thysanoptera and Tetranichidae were presented by 7.69% for each. Concerning to the sampling method, 76.92% of the collected species were captured by the sweep net method, while 23.08% were gathered by the direct count method. The recovered species were classified as predominantly predaceous, predominantly phytophagous, predaceous in part and phytophagous in part species. Seasonal abundance of the recorded species was determined. The distinct predators, Coranus aegyptius (Fabricius, 1775) and Orius spp. showed relatively low abundance percentages. The predatory-phytophagous mirid species [Campylomma unicolor Poppius, 1914; Nesidiocoris tenuis (Reuter, 1895); Creontiades pallidus (Rambur, 1839). and Deraeocoris serenus (Douglas & Scott, 1868)], showed different abundance percentages. Amongst these taxa, N. tenuis revealed the highest abundance percentage on tomato plantations with an average of 63.00 and 75.00% during 2015 and 2016 seasons, respectively. The distinct phytophagous species, Thrips tabaci Lindeman, 1889; Bemisia tabaci (Gennadius, 1889) and Tetranychus urticae Koch, 1836 presented the greatest abundance percentages on cucumber when estimated by the direct count method.So, this work can be reflect the importance of sweep net as a suitable sampling method for determine the faunistic composition of the flight predatory insects inhabiting tomato and cucumber. However, direct count can be consider the most suitable method for determine the population trends of mobile or non-mobile arthropods inhabiting the same crops. Also, use of more than one sampling method could be successful to clarify the relation between useful and harmful arthropod species.