Food preference, diet dependent fecundity and larval development in Harpalus rufipes (Coleoptera: Carabidae)

The carabid beetle Harpalus rufipes has been examined with respect to food preference and food quality. Three different experiments were performed to clarify the role of weedy seeds and insects as food for H. rufipes: 1) adult's food preference, 2) fecundity dependent on diet, and 3) larval development dependent on diet.
No direct relation between food preference and food value was found. The seeds of Taraxacum spl were the most preferred among all the food types tested.
Among the insects the cereal aphid Metopolophium dirhodum and Drosophila were highly preferred. The value of insects as a food source was much lower than the value of seeds, for the larvae as well as for the adults. Survival was identical, however, on a mixed insect diet and a mixed seed diet, but the developmental time for first and second larval instar was about twice as long on the mixed insect diet. The single species diets also differed in value. Seeds of Poa annua were of high value whereas the aphid Rhopalosiphum padi was of extremely low value.