29Maiszunslers, Ostriniu nubikzlis Hbn., mit der Verwirrungstechnik. Mitt. Schweiz. Ent. Ges. DAUMAL, J.; VOEGELE, J.; BRUNETTI, P., 1975: Les trichograrnmes. 11. Unite de production massive et quotidienne d'un hBte de substitution Ephestia kuehniellu Zell. Ann. Zoo1.-Ecol. Amin., 7, 45-59. MEIER, W.; ANDRESXA, S.; KOLAR, O., 1972: Neuere Beobachtungen zurn Auftreten des Maiszunslers. Mitt. Schweiz. Landw. 20, 151-163. MEISSELI~RE, C. de la, 1982: Methodes d'ivaluation des risques. Agromais, 8, 27-29. MURBACH, R.; HACHLER, M.; GOY, G., 1973: La pyrale de rnds (Ostriniu nubilalis Hbn.) en SUTER, H.; RAMSER, E., 1978: Auftreten und biologische Bekampfung des Maiszunslers (Ostriniu J4, 87-98. Suisse romande. Rev. suisse Agric., 5, 108-111. nubilalis Hbn.) in der deutschsprachigen Schweiz. Mitt. Schweiz. Landw. 26, 57-65. AbstractInundative releases of Trichogrurnmu minuturn Riley for biological control of the spruce budworm, Choristoneuru furniferunu (Clemens), were investigated in Canada's boreal forest during 1982 and 1983. The most significant factors affectin the level of egg mass parasitism were the time of release, the density of the parasitoids, and the focal weather conditions. Food supply to the female parasitoids, vertical location of the host egg mass in the stand, intensity of solar radiation, and density of the host insect were less im ortant. Parasitism was not affected by the tree species on which budworm e g masses were laid: Parasitoids reared at different temperatures and on different host eggs differed in biological characteristics and could influence the success of field releases. Geographical strains of T. minuturn were not considered as important in subsequent releases as the rearing conditions because of the high degree of individual variation within each strain.

Balsam woolly aphids were reared on young grand fir trees maintained in controlled environment or outdoors. Solutions of various nitrogen fertilizers were applied repeatedly to the trees and the effects on aphids and bark amino acids were studied. On trees fertilized with ammonium nitrate or a sequence of compounds, aphid population growth was less than on trees fertilized with urea or potassium ammonium nitrate. On urea-fertilized trees, populations multiplied 16.5 times in five generations, compared with a 5.7-fold increase on unfertilized trees and a 1.4-fold increase on ammonium nitrate-fertilized trees. These differences resulted from effects of these nutrients on aphid life history. Urea promoted aphid establishment and reproduction, whereas ammonium nitrate affected these processes, as well as survival, adversely. The highest establishment and survival rates resulted from potassium ammonium nitrate.These differences may be related to fertilizer-induced changes in the amino acid diet of the aphid. Thin layer electrophoresis and chromatography revealed that urea, ammonium nitrate, and calcium nitrate each increased arginine concentrations in the bark, the highest levels resulting from ammonium nitrate. Traces of phenylalanine and asparagine, found in other treatments, were absent from trees fertilized with ammonium nitrate during June.

Can. Ent. 100: 47&485 (1968) The relationship between nutrition of the host tree, Abies amabilis (Doug].) Forbes, as influenced by nitrogen fertilizers, and the growth of populations of the balsam woolly aphid, Adelges piceae (Ratz.), was investigated. Sixty trees, growing in a greenhouse in two soil types, a nutrient-deficient mineral soil and an enriched humic soil, were infested with woolly aphid larvae. Subsequently, groups of 10 trees received foliar treatments of various concentrations of ammonium nitrate and urea. The following year, 32 young trees in Seymour Valley, B.C., were studied to determine the effect of fertilization of uninfested trees on establishment of aphid larvae.In the greenhouse, foliar sprays of 1% ammonium nitrate solution resulted in a 23% decrease in population in 10 weeks, as contrasted with a 31% increase in the control population. In the field, larval establishment was 31% to 37% lower on the ammonium nitrate-treated trees than on the control trees. Inasmuch as there was no evidence of increased mortality of aphids in situ, we infer that the fertilizer acts primarily by inhibiting initial settling of larvae on the host trees.