Fertility schedules ofunaspis yanonensis (Hemiptera: Diaspididae) in relation to daily temperature

Fertility schedules of Unaspis yanonensis on citrus leaves were investigated from 1962 to 1971 for the first generation and from 1964 to 1971 for the second generation, at the Okitsu Branch of the Fruit Tree Research Station in Shizuoka Prefecture. The fertility curves were commonly characterized by a first major peak and a few subsequent minor peaks, although their shapes differed from year to year. Models estimating these fertility curves of each generation were constructed in relation to the fluctuations in average daily temperature, on the assumption that the curve was composed of two peaks, i.e., bimodal. Estimated curves were well fitted to observed ones.     

Economy of food utilization in a gregarious sawfly,Arge nigrinodosa Motschulsky (Hymenoptera: Argidae): Relative abundance of food in the natural habitat and behavioral pattern of larval feeding

Summary Relative abundance of natural food resource, leaves of wild rose, ofArge migrinodosa was evaluated by comparing the food quantity which the larvae composing a colony utilized throughout the larval stage with that which is available in the habitat. In this connection, behavioral pattern of larval feeding was also observed under natural conditions, and its ecological significance was discussed. It was quantitatively clarified that the larvae faced the severe shortage of food and had to disperse to other shoots with the expense of probably high risk. Under pressures of such insufficient supply of food, the larvae follow the most efficient pattern of feeding behavior that they move to the tip of shoot at first and feed regularly downward thereafter. Though individual larvae behaved completely independently of each other, the aggregation appeared to be formed and maintained because all the larvae from the same egg mass follow this fixed feeding pattern.     

Effects of a Plant Growth Regulator, Prohexadione Calcium (BX-112), on the Elongation of Rice Shoots Caused by Exogenously Applied Gibberellins and Helminthosporol, Part II

Prohexadione calcium (BX-112) is a novel plant growth regulatorthat inhibits the late stages of the biosynthesis of gibberellinsin plants. Fourteen kinds of gjbberellin, helminthosporol and'helminthosporic acid were applied simultaneously with BX-112to rice seedlings (Oryza sativa L. ), and their growth-promotingactivities in terms of shoot elongation were examined. The growth-promotingactivities of GA₁, GA₄, GA₁₈, GA₂₂, GA₂₃, GA₃₈, helminthosporoland helminthosporic acid were not inhibited by BX-112, but thoseof GA₅, GA₉, GA₁₅, GA₁₉, GA₂₀, GA₃₁, GA₄₄ and GA₅₃ were inhibited.These results suggest that 3ß-hydroxylation is animportant and necessary step in the biosynthesis of gibberellinsthat promote shoot elongation in rice seedlings. The weak promotionof shoot elongation by GA₂₂ in the presence of BX-112 suggeststhat the effect of a hydroxyl group at C-18 of GA₂₂ might beable to mimic the effect of the 3ß-hydroxyl groupof GA₁. Helminthosporol and helminthosporic acid may promotethe shoot elongation of rice by mimicking physiologically activegibberellins and not by stimulating their biosynthesis. ¹Part I is the previous paper by Nakayama et al. (1990a) ³Present address: Frontier Research Program RIKEN, Wako-shi,Saitama, 351-01 Japan. (Received June 26, 1991; Accepted September 4, 1991)