Conservation and enhancement of Chrysoperla carnea (Stephens) (Neuroptera, Chrysopidae) in the field by providing hibernation shelters
1992
Sengonca, C. (Bonn Univ. (Germany). Inst. fuer Pflanzenkrankheiten) | Henze, M.
In the present paper the attractiveness of the "Green Lacewing Chamber" for Chrysoperla carnea (Stephens) at three locations, a fallow field, freshly sown winter barley, and sugarbeets ready for harvest was investigated in fall 1989 as well as the population development of the C. carnea and cereal aphids following the release of hibernated Chrysoperla adults in wheat fields in spring 1990. In the fallow and winter barley fields the first C. carnea entered the hibernation boxes in the 4th week of September which was two weeks earlier than in sugarbeet. In all fields the peak number, which was highest in sugarbeet (64 individuals) entered the boxes in the 5th of October. In the end of winter the number of lacewings in the boxes was counted. The boxes placed in sugarbeet had the highest number, a mean of 224 lacewings per box as compared to 209 in fallow and only 117 in winter barley. The mortality during hibernation in the boxes was low, ranging between 0.7 and 1.8%. In addition to C. carnea, spiders and Diptera were found in the hibernation boxes, but only in low numbers. In the release plot adult lacewings were recorded two weeks earlier and in higher numbers than in the non-release check plot. Likewise C. carnea eggs were observed four weeks earlier in the release plot. The development of the aphid populations was similar in both in the release and non-release plot, the highest number of 15.3 aphids per stalk, however, was recorded in the non-release plot.
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