Influence of food on the growth, development and hibernation of Large White Butterfly (Pieris brassicae)
1Institute of Plant Protection, Estonian Agricultural University, Kreutzwaldi 64, 51014 Tartu, Estonia; e-mail: email@example.com
2Department of Field Crop Husbandry, Estonian Agricultural University, Kreutzwaldi 64, 51014 Tartu, Estonia
The abundance of Large White Butterfly (LWB), Pieris brassicae fluctuates from year to year, and a peak in the population is reached in every five to seven years, after which there occurs an abrupt decrease in the abundance. The natural checks of the population are primarily weather, parasitoids and pathogens, but the quality of food is also an important factor. The criteria for estimating the influence of food were the duration of caterpillar stage, the mortality rate of caterpillars and prepupae, the weight of pupae and the winter mortality of diapausing pupae. Foodplants: Brassica oleracea var. capitata f. alba, B. oleracea var. capitata f. rubra, B. oleracea var. gemmifera, B. oleracea var. botrytis, B. oleracea var. acephala, B. napus var. napobrassica, Tropaeolum majus, Armoracia rusticana.
In our experiments, the most unsuitable foodplants for larvae were Tropaeolum majus and Armoracia rusticana. There appeared a high mortality rate among caterpillars feeding on both of them as well as among their hibernating pupae. It can be concluded that one of the reasons for the remarkable decrease in the pest population following the massive reproduction of LWB is the high mortality rate of caterpillars growing on less valuable foodplants. The pupae are underweight and, in most cases, they perish during winter.