<論文>ヒラタキクイムシの個体生態学的研究I : ヒラタキクイムシのマス・カルチャー

Abstract

わが国で最も重要な乾材害虫であるヒラタキクイムシLyclus brunneus (STEPHENS)の防除の基礎として,そのマス・カルチャーを試み,その過程で飼育法,およびそれと関連する生態等につき,種々の新知見を得た。飼育室の機械化による恒温恒湿化,東京長大式人工飼料の水分添加量の改善,飼育室内の恒久的照明による羽化脱出成虫の活動の抑制,落下幼虫の取扱い,等のテクニックを記載し,飼育方法への寄与とした。個休符の性比(雄/雌)は,およそ1であったが,飼育初期には,雌が雄の数を上回った。昆虫に対する人工飼料量が少ないと次世代産出量が誠少し,密度効果が見られた。

An attempt to rear powder-post beetles, Lyctus brunneus (STEPHENS), in a mass culture scale was carried out successfully, and some improvements of technique and knowledges were obtained. The automatic control of the temperature and humidity in the rearing chamber is essential for the mass culture. The critical condition (25～26℃, 75% R.H.) seems to afford the occurrence of mold on artificial diets, and an advisable condition to prevent, mold occurrence is 24.5℃, 70% R.H. The prescription of the artificial diet of Tokyo Univ. of Agriculture was used for the mass culture (lauan sawdust 56%, soluble starch 10%, cellulose powder 9%, brewer's yeast powder 25%). For the better solidity of this diet, it is recommended to add more water than is prescribed, viz. 100～120% of water by weight to powder material. Every caution should be paid against the invasion of natural enemies, above all the mites. And it is also necessary to be careful in handling the miticide β-naphthol (ca. 2.5% alcohol solution) which is toxic to human bodies. In order to make "the culture renewal" smoother, the activity of new adult beetles on the diet pieces can be controlled by illuminating the rearing chamber all through the day. However, this method requires the regular works to take out beetles from pupal chambers once a week. The larvae which dropped out from diets can be saved with little labor; sandwiching the frass and diet fragments with live larvae between solid diets, a part of them can bore into diets, and pupate. The sex ratio seems to be near 1:1. However, in the beginning of rearing, females outnumbered males. The progeny yield is reduced if the quantity of diet per one ovipositing female beetle is too small; what is called the density effect is observed.