Insect herbivores were collected from Castanopsis acuminatissima (Fagaceae) at Wau, Papua New Guinea, by beating the foliage of 15 trees during four one-month sampling periods, each representing different leaf-flush events. The association of leaf-chewing beetles with C. acuminatissima was verified with feeding trials. Of 59 species of leaf-chewing beetles that were collected, 36 species could be used in feeding trials. Only 9 of these species fed on C. acuminatissima. A further 27 beetle species were tested in feeding trials but did not feed. Of these, 7 were specialists feeding on other tree species within the surrounding vegetation. Most beetle species collected from C. acuminatissima foliage were probably transient species, dispersing from other tree species. Path analyses showed that herbivore abundance during a particular sampling period was significantly influenced by rainfall, leaf flush of other conspecific trees and air temperature, but not so by the species richness of surrounding vegetation, number of surrounding conspecific trees and size (DBH) of trees sampled. The species richness of leaf-chewing beetles collected on particular study trees depended on that of the surrounding vegetation, thus supporting the hypothesis that most beetle species collected were transient. The abundance of insect herbivores on particular C. acuminatissima trees probably depends on a balance between the leaf flush of conspecific trees and that of the particular tree sampled. The results also emphasize the need to remove transient species in analyses of insect faunas of tropical trees, at the risk of analyzing species richness patterns derived from loosely defined "assemblages" of species., Yves Basset, and Lit
The influence of host intrapatch spatial distribution on parasitoid host acceptance behavior was investigated with Trichogramma principium parasitizing eggs of grain moth, Sitotroga cerealella. Single females were placed in Petri dishes, each containing 60 host eggs arranged either as a compact patch or partitioned into 60 or 12 clusters each consisting of 1 or 5 eggs, respectively. Partitioned patches provoked parasitization more often than compact patches. The percentage of ovipositing females (i.e., females parasitizing at least one of 60 host eggs) increased with the number of clusters, while it was independent of the intercluster distance over intervals of 2.5-15 mm. The mean number of eggs parasitized by ovipositing females during 48 h was almost independent of the host egg spatial pattern. As a result, the rate of parasitization was higher when the hosts were sparsely distributed within a patch than when they were aggregated., Nataliya D. Voinovich, Taisiya Ya. Umarova, Sergey Ya. Reznik, and Lit
To assess the relationship between chlorophyll (Chl) fluorescence (CF) and photosynthetic pigments, soybean was grown under varying phosphorus (P) nutrition at ambient and elevated CO2 (EC). The EC stimulated, but P deficiency decreased plant height, node numbers, and leaf area concomitantly with the rates of stem elongation, node addition, and leaf area expansion. Under P deficiency, CF parameters and pigments declined except that carotenoids (Car) were relatively stable indicating its role in photoprotection. The CF parameters were strongly related with Chl concentration but not with Chl a/b or Car. However, total Chl/Car showed the strongest association with CF parameters such as quantum efficiency and yield of photosystem II. This relationship was not affected by CO2 treatment. The high correlation between CF and total Chl/Car underscores the significance of the quantification of both, Chl and Car concentrations, to understand the photochemistry and underlying processes of photoprotection and mechanisms of excess energy dissipation in a given environment., S. K. Singh, V. R. Reddy, D. H. Fleisher, D. J. Timlin., and Obsahuje bibliografii