Effect of nutritional condition on larval food requisition behavior in a subterranean termite Reticulitermes speratus (Isoptera: Rhinotermitidae)
Although optimal investment theory would be similarly applicable to eusocial insects to maximize colony reproductive outputs, directly distinguishing an amount of investment in each larva should be a difficult task for workers because of the characteristics of group living. Thus, it is expected that workers adjust brood care by using a cue or signal conveying information of larval status. In termites, which are typical group of eusocial insects, there are nevertheless few direct observations on worker brood care and little is known about cues inducing worker feeding. I show here that a Japanese subterranean termite Reticulitermes speratus uses an overt food solicitation by larva, “pecking”, as a cue for worker feeding. Direct observations demonstrated that workers feed larvae in response to larval pecking. Furthermore, nutritional experiments showed that larvae exhibited pecking more frequently when their nutrient status is lower; hence, pecking may be an honest reflection of larval hunger status. These results indicate that workers can feed more starved larvae than less starved ones because pecking honestly reflects larval hunger state. That is, feeding in response to pecking should standardize the total amount of food intake of each larva and help a termite colony make worker investment efficient.
KeywordsEusocial insects Optimal investment Worker brood care Observation experiment Honest signal
I thank Dr. Kenji Fujisaki for help with the study. I also thank Prof. Kenji Matsuura for reading and helpful comments on the manuscript. This study was partly supported by the 21st century COE Program for Innovative Food and Environmental Studies Pioneered by Entomomimetic Sciences, from the Ministry of Education, Culture, Sports, Science, and Technology of Japan, and a Research Fellowship for Young Scientists from the Japan Society for the Promotion of Science (JSPS).
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- Brian MV (1977) Ants. Collins, GlasgowGoogle Scholar
- Clutton-Brock TH (1991) The evolution of parental care. Princeton University Press, PrincetonGoogle Scholar
- LaFage JP, Nutting WL (1978) Nutrient dynamics of termites. In: Brian MV (ed) Production ecology of ants and termites. Cambridge University Press, Cambridge, pp 165–232Google Scholar
- Le Conte Y, Sreng L, Poitout SH (1995) Brood pheromone can modulate the feeding behavior of Apis mellifera Workers (Hymenoptera: Apidae). J Econ Entomol 88:798–804Google Scholar
- McMahan EA (1969) Feeding relationships and radioactive techniques. In: Krishna K, Weesner FM (eds) Biology of termites, vol 1. Academic, New York, pp 387–406Google Scholar
- O’Neal J, Markin GP (1973) Brood nutrition and parental relationships of the imported red fire ant Solenopsis invicta. J Georgia Entomol Soc 8:294–303Google Scholar
- Takematsu Y (1992) Biometrical study on the development of the castes in Reticulitermes speratus (Isoptera, Rhinotermitidae). Jpn J Entomol 60:67–76Google Scholar
- Trivers RL (1974) Parent–offspring conflict. Am Zool 14:249–264Google Scholar
- Wilson EO (1971) The insect societies. Harvard University Press, CambridgeGoogle Scholar
- Yanagawa A, Shimizu S (2005) Defense strategy of the termite, Coptotermes formosanus Shiraki to entomophatogenic fungi. Jpn J Env Entomol Z 16:17–22Google Scholar