Diel response of EPT families to light traps in broad-leaved and planted coniferous forest basins, Japan

Many aquatic insects tend to be attracted to light, but the diel periodicity of this activity has not been well documented. To define this diel selectivity, insects of the orders Ephemeroptera, Plecoptera and Trichoptera (EPT) were collected hourly using light traps, and daily changes in abundance were monitored. Twenty-nine families were collected over six sampling dates. The number of trichopteran individuals, but not the numbers of ephemeropteran and plecopteran individuals, differed between the natural and conifer forests. Among the Trichoptera, this difference was significant for Stenopsyche and Glossosomatidae. Activity appeared to be correlated with time after sunset in Ephemeroptera and Plecoptera, and activity level differed between the natural and conifer forests. However, activity level was not correlated with time after sunset in Trichoptera and did not differ between forest types. At the individual family level, activities were correlated with time after sunset more clearly in the conifer forest than in the natural forest even in trichopteran families.