Développement larvaire et bilan d'utilisation d'énergie en fonction de l'hygrométrie chez Tinea pellionella L. (Lepidoptera : Tineidae)

Abstract

We studied the ability of the case-bearing clothes moth (Tinea pellionella L.) larva to develop in a dry environment and we examined the strategy developed by this species to survive under dry conditions. In a dry environment the larval development was characterized by a high level of mortality and a reduced growth rate. The weight of the fully grown larva was twice as low at 5% relative humidity (RH) as at 95% RH. The consumption index was higher at 5% RH than at 95% RH but the oxygen consumption per day was unchanged. For the same quantity of food ingested, oxygen consumption was higher at 5% RH than at 95% RH. The digestibility of ingested food was low under dry conditions and the efficiency with which digested food was converted to body substance was much reduced at 5% RH. A large proportion of digested food was utilized by the larva for water production. In spite of a high energy extraction efficiency, the larval production was greatly reduced in a dry medium because of the low efficiency of storage of metabolizable energy. In a dry environment the amount of energy required for water production is so large (24% of ingested energy) that it does not allow optimal development; only survival is possible under these conditions.