The Effect of the Blue and Black Light Trap on the Diversity of the Trichoptera (Caddisfly Adult) and Other Insects in Lotic and Lentic Area of Mae Tam Reservoir, Thailand

Abstract

This study was conducted using two types of light traps to collect the insects at Mae Tam Reservoir from January to April 2018. The sampling area was divided into 4 points. Two points were located at the reservoir’s bank, and the others were located at the reservoir’s outlet. The study aimed to compare the efficiency of the fluorescent tube's blue and purple light, which had a different wavelength on insect’s attraction. To compare the diversity of Trichoptera in the different stream habitats, Sørensen similarity index, Shannon-Wiener index, and Evenness index were used. The result showed that purple light could attract insects better than blue light. Hymenoptera was attracted by purple light. Coleoptera and Hemiptera were attracted by blue light. The study on the diversity of Trichoptera showed that there were 2,534 individuals of 9 families 48 species were collected. Ecnomus puro was the most abundant species (1,120 individuals). The highest Shannon-Wiener diversity index was sampling points 4 (2.10). The highest Evenness index was sampling points 4 (0.62). Sørensen similarity index showed that sampling points 3 and 4 had the highest value (67.92 %) because they were adapted from a natural creek to concrete where boulder, gravel, cobble, sand, and woody material were deposited at the stream bottom. These provided various microhabitats for insect larva to live and develop. The riparian had affected the distribution and colonization of mature insects.