Poziom konsumpcji i produktywność larwalna Eriocampa ovata (L.) (Hymenoptera Tenthredinidae)

Abstract

Celem pracy było zbadanie poziomu konsumpcji oraz obliczenie bilansu energetycznego u rośliniarki Eriocampa ovata w trakcie życia larwalnego. E. ovata w stadiach larwalnych żeruje przez perforację na liściach olszy (Alnus Mill.), zarówno na olszy czarnej (А. glutinosa (L.) Gaertn.) jak i szarej (А. incana (L.) Mnch.). Należy do pospolitych ale umiarkowanie licznych rośliniarek; spotykana od czerwca do października. Dominującą formę rozrodu E. ovata jest partenogeneza telitokiczna. Samicze larwy przechodzą na ogół w swoim rozwoju przez 5 stadiów, rzadziej rozwój jest sześciostadialny (Pieronek 1976, 1980).

Feeding levels, productivity and bioenergetics of the larvae of E. ovata are presented. The investigations were carried out in the laboratory. The measured medium values were expressed in mg of dry eweight. The larvae were fed on grey alder (Alnus incana (L.) Mnch.). The feeding levels for E. ovata rose from 0,9% in the first instar to 74,4% in the last one. One individual consumed about 130 mg of food, excreted about 76 mg of frass and reached the body weight of about 20 mg during its life-span (ca. 13 days). (table 1. ). To produce 1 mg biomass one larva used up 6,6 mg of food during its development. The utilization of the food taken (Е[с]) was 0, 40 for the whole larval period of E. ovata. The energy budget points to the fact that one individual consumed with food 687 cal (С) during its life-span. From this amount the larva assimilated 43% cal (А) and excreted with frass 57% cal. Out of the calories consumed 17,7% cal was used for biomass production (Р) and 25,3% cal for respiration (R). (table 3., fig. 1). The intensity of metabolism was the highest in the last instar (са. 4,4 days). During this period one larva took with food 511 cal i.e. 74,4% of the whole amount. From this quota it assimilated 216 cal and excreted with frass 295 cal. For production of 1 cal contained in the dry biomass of the body one larva used 5,65 cal during its whole life period. The results obtained for larva of E. ovata within the field of productivity and the index of assimilation efficiency (А/С) are similar to those for other species of sawflies. Moreover, the index А/С is contained in the range 0,2-0,6 for Arthropoda.