An aquatic light trap designed for live capture of predatory Tropisternus sp (Coleoptera: Hydrophilidae) larvae in Arkansas rice fields.
Construction of an aquatic light trap developed for the live capture of 3rd-stage larvae of predatory Tropisternus sp. for use in laboratory bioassays against larvae of Anopheles quadrimaculatus and Psorophora columbiae is described. On 10 occasions, an average of 5.2 traps was used per evening, resulting in 52 trap-nights that accumulated 106.7 h of trapping time, or an average of 10.6 h per trap. Use of 2 heavy-duty alkaline D-sized batteries and appropriate in-circuit resistance effectively increased bulb life and trap operating time, ranging from 22 to 36 h. During both seasons, approximately 3 wk after permanent flooding of large rice fields was the most productive period in which to capture larvae of Tropisternus sp. Live trapping worked well and provided numerous larvae of Tropisternus sp. for use in laboratory predation bioassays with An. quadrimaculatus and Ps. columbiae larvae. Six hundred fifteen 3rd-stage larvae of Tropisternus sp. and 740 adult Tropisternus lateralis were captured in aquatic light traps in 1999 and 2000. Of traps containing larval Tropisternus sp. and adult T. lateralis, average numbers of 15.3 and 19.4 were captured per trap, respectively. Among all traps, the largest nightly captures of larval Tropisternus sp. and adult T. lateralis consisted of 263 and 404 specimens, respectively. The largest single trap captures for larval Tropisternus sp. and adult T. lateralis were 94 and 184, respectively. Additionally, 478 rice water weevils (Lissorhoptrus oryzophilus) also were captured. Rice water weevils averaged 36.7 per trap, with the largest single trap capture of 102 weevils on an evening where 287 weevils were captured among all traps. Other predatory insect species were captured infrequently, consisting primarily of 3rd-stage larvae of Hydrophilus triangularis and adult belostomatids, dytiscids, and notonectids. Predatory larvae of H. triangularis may have been attracted to the traps by the presence of larval Tropisternus sp. Larval Tropisternus sp. may have been attracted by the light source and prey items that entered the trap, such as chironomid larvae.
Dennett
J A
JA
Department of Entomology, University of Arkansas, Fayetteville 72701, USA.
Meisch
M V
MV
D000383:Agriculture; D000818:Animals; D000852:Anopheles; D001131:Arkansas; D001517:Coleoptera; D009033:Culicidae; D007814:Larva; D008027:Light; D012275:Oryza; D010572:Pest Control, Biological