ROLE OF CERTAIN ECONOMIC SPIDERS AS PREDATORS OF HARMFUL PESTS IN GREENHOUSES

Abstract

The present work aimed to through light on the spiders occurrence on some plants in greenhouses in Giza governorate to conduct families and species in this ecosystem to maximize its role to reduce the population of some pests. Random samples were collected twice a month from the vegetables Tomato, Eggplant and Green bean and the fruit trees Mango and Citrus in the commercial greenhouses structure, gutter connected. There were (46) species belonging to (18) families; Dictynidae, Dysderidae, Gnaphosidae, Linyphiidae, Lycosidae, Oecobiidae Oonopidae, Pholcidae, Philodromidae, Salticidae, Scytodidae, Sicariidae, Synaphridae, Theridiidae, Thomisidae and Titanoecidae on vegetable plants. In addition to these families except the family Pholcidae the two families Eutichuridae and Uloboridae were found on fruit trees. The most abundant spider family on vegetable plants was Linyphiidae, while that on fruit trees was Eutichuridae. There was evident relationship between Cheiracanthium isiacum and its prey Phyllocnistis citrella. In the mango orchard there were13 spider families on the ground of which the family Salticidae had the highest number and six families on the foliage with Eutichuridae had the highest number. There were 27 species recorded new locality in Giza governorate and one species as a new record in Egypt. Some biological aspects of the two spider species and its food range were studied on Nigma conducens of the family Dictynidae and Theridion hannoniae of the family Theridiidae as a first rearing. N. conducens fed and developed on two types of prey, Drosophila melanogaster and Pealius mori. Social behavior was observed on this spider species. Type of prey had a statistical significant effect on the duration of the developmental stages and also on the female fecundity. Female life cycle averaged 75.91 and 107.19 days on D. melanogaster and P. mori respectively. The second species T. hannoniae fed and developed on Tetranychus urticae. Female and male life cycle averaged 94.1 and 103.06 days respectively.