Activity of Culicoides furens larvae (Diptera: Ceratopogonidae) as related to light and nutritional state
Aussel, J.P.; Linley, J.R.
Journal of medical entomology 30(5): 878-882
1993
ISSN/ISBN: 0022-2585 PMID: 8254634 Document Number: 421857
The diel activity of fourth-instar Culicoides furens (Poey) was studied in the laboratory by means of video recordings. Larvae in 0.5% agar under a photoperiod of 12:12 (L:D) h were observed under three nutritional states: starved 24 h before and during observation; fed (with nematodes) 24 h before, but starved during, observation; and fed both before and during observation. Starved larvae displayed considerably reduced activity compared with those that were better fed, both in terms of speed and type of movement (the proportion of time spent in continuous rather than intermittent motion). Under all nutritional states, larvae were more active during dark than light hours; 3-hourly observations of speed plotted for four periods of 24 h strongly indicated a diel cycle of activity, which may, in the field, be accompanied by vertical migration in the soil. Overall, our observations indicated that during development, C. furens larvae rove constantly through the substrate, at speeds of approximately 2 m/h (and up to 4 m/h), and that this movement is maintained even in the presence of abundant food.