Phoretic associations between Nanocladius asiaticus (Diptera, Chironomidae) and its hosts Gestroiella (Heteroptera, Naucoridae) and Euphaea masoni (Odonata, Euphaeidae) in streams in Western Thailand

Department of Zoology, Faculty of Science, Kasetsart University, Animal Systematics and Ecology Speciality Research Unit (ASESRU), Bangkok 10900, Thailand

Corresponding author: fscibtb@ku.ac.th

Received: 29 June 2015
Accepted: 21 August 2015

Abstract

Phoretic associations between larvae of Nanocladius (Plecopteracoluthus) asiaticus (Diptera, Chironomidae) and two species in the genus Gestroiella (Heteroptera, Naucoridae) were studied in Kanchanaburi and Ratchaburi Provinces (Western Thailand). Gestroiella siamensis was used by chironomid larvae as a host more frequently than was Gestroiella limnocoroides. Moreover, N. asiaticus larvae were associated symphoretically with nymphs of the damselfly Euphaea masoni (Odonata, Euphaeidae). This is the first report of a symphoretic association involving E. masoni. Approximately 44% of the population of naucorids harboured symphoretic chironomids, whereas only 13% of damselfly nymphs were hosts of the chironomid larvae. Most of the brachypterous male (59%) naucorids hosted chironomid larvae. The attachment site of the chironomids was frequently along the mesofemur and mesosternum of the naucorid hosts. The chironomids were attached to the ventral sides of abdominal segments of E. masoni nymphs. There was a positive correlation in body length between chironomids and naucorids (r=0.389, P<0.01). There are many benefits of symphoresis in the Chironomidae, such as improved feeding opportunities, increased mobility, suitable pupation sites and decreased predation risks.