الفهرس 
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Abstract
The present work was carried out to study the ecology and predation by some malacophagous insects. A survey of aquatic and terrestrial malacophagous insects associated with snails was carried out during 2016-2018 in Sharquia Governorate. Four terrestrial snails and three aquatic snails were collected.
Terrestrial snails were more abundant on clover, wheat, lettuce and faba beans. Aquatic snails were abundant in rice fields.
Three aquatic and three terrestrial malacophagous insect species were found associated with the above-mentioned snails. The population fluctuations of Monacha obstructa (Ferussac) snails and their associated insects, Pterostichus barbarus (Dejean) and Megaselia scalaris (Loew) was carried out for two growing seasons at two villages in Sharquia Governorate. In general, Monacha obstructa snails were more abundant on clover than on wheat. Insect population increased by increase of M. obstructa snails. Adult of Pterostichus barbarus showed more predatory activity on M. obstructa snails and its eggs. The predator became more voracious in case of group than in single predation as well as on snail eggs. Predation of P. barbarus on M. obstructa snails increased with increasing temperatures. Results suggested the possible role of P. barbarus as biological control agent against harmful snails.
Only larvae of Megaselia scalaris (Loew) showed strong gregarious predation on immature stages than mature stages of M. obstructa and Eobania vermiculata snails. The predation activity of Sphaerodema urinator on aquatic snails Physa acuta Draparnaud revealed that female insects were more predaceous than males. The gregarious of nymphs of Hemianax ephippiger and Crocothemis erythraea was greater in group than individual predation than individual predation. The results of this study highlights the possible role of malacophagous insects as biological control agents against terrestrial and aquatic snails.