Host selection by larvae of a marine insect Halocladius variabilis : nutritional dependency or escape from predation?

• Published in: Journal of the Marine Biological Association of the United Kingdom
• Main Authors: Brown, Norah E., Mitchell, Sean C., Garbary, David J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2012
• Subjects: Aquatic Science; North Atlantic
• Online Access: http://dx.doi.org/10.1017/s0025315412001634; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0025315412001634

Larvae of the Holarctic marine chironomid, Halocladius variabilis (Staeger), have strong fidelity to the tuft-forming brown alga, Elachista fucicola (Velley) Areschoug, an abundant epiphyte on intertidal fucoids of the North Atlantic. We show that larvae are sufficiently motile to select an algal host in a Petri dish within 3–4 cm, and that larvae show differential behaviour with respect to host selection in the presence or absence of a predator. In the absence of predators 53% of larvae found an algal host within 1 hour; however, after 24 hours, there was no significant difference in host selection. When an isopod predator ( Idotea sp.) was present, more larvae found a host within 1 hour (81%) and Elachista was chosen over three of the four other hosts. Furthermore, when larvae were present in Elachista , predator ( Carcinus maenus ) success was significantly reduced relative to two other algal hosts. The adaptive significance of Elachista as a refuge from predation was confirmed by experiments demonstrating that larval growth with other algal hosts was greater than with Elachista . These experiments suggest that microhabitat selection by larvae of H. variabilis reveals important tradeoffs for growth and predator avoidance.