A Two-Year Study on the Population Trends of Certain Insect Groups Attracted to Rothamsted Light Traps in Tripoli (Libya)

Abstract

The population trends of 25 insect groups caught in Rothamsted light traps, located in the college farm at two sites, were reported during the 2 years of study. Brief discussion for the seasonal distribution of rate groups was offered. Both traps were supplied with normal light.

Larger catches were obtained by one of the traps located in an area of dense vegetation. The size of the catches for both traps was proportionally affected by factors such as: temperature; rain; relative humidity; existence or abundance of preferred host plants; presence or absence of host insects or natural enemies. These factors also affected the incidence of occurrence, i.e. the abundance and peaks for the seasonal distribution of many insect groups separately caught by the two light traps.

The present study showed that some groups were more abundant than others with very large catches reaching a maximum of 7,000, 8.000 and 3.500 insects per month from family Cicadellidae, moths from Microlepidoptera. and flies from Brachycera respectively, were caught by the 2 light traps in spring, summer and autumn. Smaller catches with a miximum of 280. 240. 450, 400. 800. 300, 500, 240. 240. 500, 340. and 400 insects per month were trapped in case of the hemipteran bugs Creontiades pallidas Rambur and Acrosternum millierei M. & R.; the green lacewings; the moths, Mythimna unipuncta Haw.. Spodoptera exigua (Hb.). Spodoptera littoralis (Boisd.). Rho-i dometra sacraria L.. Ancylolomia innornata stdgr., Palpita unionalis Hb.; the olive-fruit fly Dacus oleae Gmel; the scarabaeid Aphodius lividus (Ol.); and the braconid Zele chlorophthalma Nees, respectively.