1_Chestnut (Castanea sativa Mill.) is one of the economically more important trees in the north of Portugal. Spiders, as generalist predators, are potential controlling agents of pests, yet the composition of the community of spiders associated with this crop is only poorly known. The objective of this study was to determine the spider communities in the canopies of chestnut trees subject to three different soil management practices in northeastern Portugal. Three chestnut groves each subject to a different agricultural practice (grazed, tilled or untilled) were studied in 2008 and 2009. The Araneae communities were sampled by beating the branches and the individuals collected were identified to family and species when possible. To investigate the structure of the spider community in each grove the abundance and family richness of spiders were calculated and compared between managements. In total, 4172 spiders were collected and, in both years, the three most abundant families were Araneidae, Philodromidae and Linyphiidae. In 2008, there was a greater abundance of spiders in the grazed, followed by the tilled and untilled groves, but no significant differences among groves. However, in 2009 there was a greater abundance of spiders in the tilled grove, followed by grazed and untilled groves and the differences between the untilled and the other two groves were significant. Araniella, Oxyopes and Anyphaena were the most abundant genera in the three groves. This study showed that soil management may influence the diversity of spiders, but the effects were weak and not consistent between years., 2_The reduction or absence of a suitable habitat for spiders under the trees in the tilled treatment might have resulted in the spiders migrating up into the canopy. However, based on the weak effects on spider abundance recorded and its potentially adverse effects on soils, tillage is not recommended for managing the incidence of pests in chestnut groves., Jacinto Benhadi-Marin ... [et al.]., and Obsahuje seznam literatury
Eumerus purpurariae, described from the Canary Islands (Atlantic), has been reared from the stems (platyclades) of the cactus Opuntia maxima (the first known host) on Nueva Tabarca, a Mediterranean island close to the Iberian coast. The egg, larva and puparium of E. purpurariae, as well as its life cycle on the above host-plant are described. The feeding behaviour of the larva in relation to the cephalopharyngeal skeleton morphology is analysed. Based on the present data, comparative table containing the main morphological characteristics of the injurious Eumerus species of the Palaearctic region is presented.
Insect pests cause billions of dollars in crop losses and there is the ever-present threat of insecticide resistance, pesticide pollution of food and environmental damage. New ways of controlling insect pests are urgently needed. Arginine kinase (AK) is a phosphotransferase, which plays a critical role in cellular energy metabolism in invertebrates. It only presents in invertebrates and may be a suitable chemotherapeutic target in the control of pests. In this study, we cloned and characterized the full-length AK gene from Phyllotreta striolata, one of the most destructive beetle pests worldwide. Furthermore, we constructed a dsRNA targeting AK and used RNAi to control the beetle. The feeding bioassays indicated that minute quantities of dsRNA greatly impaired the beetle's development. Ingestion of dsRNA not only significantly retarded the development and increased the mortality of adults, it also greatly reduced fecundity and fertility, suggesting that RNAi targeting AK is a potential and attractive tool for controlling insect pests.
Social wasps are often considered as nuisance pests in urban environments and are often controlled by using traps. The majority of commercially produced traps for catching wasps have yellow as the dominant colour around the trap entrance. However, the observations on the function of yellow as an attractant for wasps are controversial. The efficiency of yellow, compared with green striped (N = 15) and yellow and green striped beer traps (N = 15) was evaluated. According to the results, yellow does not have a specific role as an attractant for wasps of the genera Vespula Linnaeus and Dolichovespula (Rohwer). For wasps, it may be the bait that is the major lure and it might be sufficient on its own for both control and monitoring purposes.