Bacteria abundance and diversity of different life stages of Plutella xylostella (Lepidoptera: Plutellidae), revealed by bacteria culture‐dependent and PCR‐DGGE methods

Microbial abundance and diversity of different life stages (fourth instar larvae, pupae and adults) of the diamondback moth, Plutella xylostella L., collected from field and reared in laboratory, were investigated using bacteria culture‐dependent method and PCR‐DGGE analysis based on the sequence of bacteria 16S rRNA V3 region gene. A large quantity of bacteria was found in all life stages of P. xylostella. Field population had higher quantity of bacteria than laboratory population, and larval gut had higher quantity than pupae and adults. Culturable bacteria differed in different life stages of P. xylostella. Twenty‐five different bacterial strains were identified in total, among them 20 strains were presented in larval gut, only 8 strains in pupae and 14 strains in adults were detected. Firmicutes bacteria, Bacillus sp., were the most dominant species in every life stage. 15 distinct bands were obtained from DGGE electrophoresis gel. The sequences blasted in GenBank database showed these bacteria belonged to six different genera. Phylogenetic analysis showed the sequences of the bacteria belonged to the Actinobacteri, Proteobacteria and Firmicutes. Serratia sp. in Proteobacteria was the most abundant species in larval gut. In pupae, unculturable bacteria were the most dominant species, and unculturable bacteria and Serratia sp. were the most dominant species in adults. Our study suggested that a combination of molecular and traditional culturing methods can be effectively used to analyze and to determine the diversity of gut microflora. These known bacteria may play important roles in development of P. xylostella.     

Insect pests of Norway spruce cones: incidences and altitude preferences with emphasis on Cydia strobilella (L.)

Pest species infesting spruce cones were identified from 109 locations approved for the collection of seed material in the Czech Republic. Four (occasionally five) cones were studied from each location, and 448 cones were examined in total. Each cone was assessed for external damage and was then cut open along the spine. The predominant pest species, Cydia strobilella, was detected in 65% of the cones, while the next most common species, Dioryctria abietella, was detected in 13% of the cones. Ernobius abietis, Eupithecia sp., and Thekopsora areolata were less numerous. Kaltenbachiola strobi and Megastigmus sp. were recorded sporadically. Most cones (68%) were infested with only one species. The maximum number of C. strobilella larvae detected in one cone was 13. Cone damage resulting from C. strobilella declined markedly with increasing elevation. Thus, cone infestation by C. strobilella was greater in those forest vegetation zones located in lowlands and uplands rather than in highlands and at lower mountain elevations. The number of cones without damage tended to increase with elevation, but infestation by D. abietella was unrelated to elevation. In some cases, C. strobilella damage to cones was severe. External markings on the cone (resin and deformation) cannot by themselves serve as reliable criteria for predicting C. strobilella infestation, although cones with such signs should be preferentially assessed when seed material is inspected.     

Efficacy of entomopathogenic nematodes (Rhabditida: Heterorhabditidae and Steinernematidae) against codling moth,Cydia pomonella (Lepidoptera: Tortricidae) in temperate regions

The biocontrol potential of South African isolates of Heterorhabditis zealandica, Steinernema citrae, S. khoisanae, S. yirgalemense, and Steinernema sp., was evaluated against codling moth, Cydia pomonella. Codling moth was susceptible to all six nematode isolates at a concentration of 50 infective juveniles/insect (78–100% mortality). Low temperatures (10 h at 17°C; 14 h at 12°C) negatively affected larvicidal activity (≤3%) for all isolates. All tested isolates were most effective at higher levels of water activity (a _w=1). The average a _w50-values for all isolates tested was 0.94 (0.93–0.95), except S. khoisanae 0.97 (0.97–0.98). Regarding host-seeking ability, no positive attraction to host cues could be detected amongst isolates, except for H. zealandica. Three of the isolates, H. zealandica, S. khoisanae, and the undescribed Steinernema sp., were selected for field-testing and proven to be effective (mortality >50%). Insect containment methods used during field experimentation was shown to influence larvacidal activity, as different levels of mortality were obtained using various containment methods (wooden planks vs. pear tree logs vs. mesh cages). Pear tree logs were impractical. Predictive equations were subsequently developed, enabling future trials to be conducted using either planks or cages, enabling the prediction of the expected level of control on tree logs. All tested isolates therefore showed a certain degree of biological control potential, however, none of the experiments showed clear efficacy-differences amongst isolates. The study highlighted the importance of environmental factors to ensure the successful application of these nematodes for the control of diapausing codling moth larvae in temperate regions.     

不同性诱剂诱芯对小菜蛾引诱效果研究

小菜蛾Plutella xylostella(L.)是我国为害最严重的蔬菜害虫之一,为提高检测和诱捕效率,2009年在广东广州、云南通海和浙江上虞3个试验点测试了5种性诱剂诱芯对小菜蛾的引诱效果,实验结果表明,广东省昆虫研究所研发的性诱剂诱芯在广东试点对小菜蛾诱捕效果最好,持效期在1个月以上,日平均诱蛾量21.3头/盆,是荷兰Koppert公司诱芯的5.3倍,适合应用于广东菜区小菜蛾田间种群的预测预报和综合控制;北京中捷四方商贸有限公司提供的性诱剂诱芯比较适合云南试点的应用,日平均诱蛾量13.6头/盆;中国科学院动物研究所研发的小菜蛾性诱剂诱芯对浙江试点小菜蛾日平均诱捕量13.6头/盆,效果最佳,适合浙江地区小菜蛾田间种群动态的预测预报及综合防控。     

Climate change effects on walnut pests in California

Increasing temperatures are likely to impact ectothermic pests of fruits and nuts. This paper aims to assess changes to pest pressure in California's US$0.7 billion walnut industry due to recent historic and projected future temperature changes. For two past (1950 and 2000) and 18 future climate scenarios (2041–2060 and 2080–2099; each for three General Circulation Models and three greenhouse gas emissions scenarios), 100 years of hourly temperature were generated for 205 locations. Degree‐day models were used to project mean generation numbers for codling moth (Cydia pomonella L.), navel orangeworm (Amyelois transitella Walker), two‐spotted spider mite (Tetranychus urticae Koch), and European red mite (Panonychus ulmi Koch). In the Central Valley, the number of codling moth generations predicted for degree days accumulated between April 1 and October 1 rose from 2–4 in 1950 to 3–5 among all future scenarios. Generation numbers increased from 10–18 to 14–24 for two‐spotted spider mite, from 9–14 to 14–20 for European red mite, and from 2–4 to up to 5 for navel orangeworm. Overall pest pressure can thus be expected to increase substantially. Our study did not include the possibility of higher winter survival rates, leading to higher initial pest counts in spring, or of extended pest development times in the summer, factors that are likely to exacerbate future pest pressure. On the other hand, initiation of diapause may prevent an extension of the season length for arthropods, and higher incidence of heat death in summer may constrain pest population sizes. More information on the impact of climate change on complex agroecological food webs and on the response of pests to high temperatures is needed for improving the reliability of projections.     

Does landscape composition alter the spatiotemporal distribution of the pine processionary moth in a pine plantation forest?

Landscape composition and physiognomy affect community structure and species distribution across space and time. The pine processionary moth (PPM) (Thaumetopoea pityocampa Den. & Schiff., Lepidoptera, Notodontidae) is a common pine defoliator throughout southern Europe and Mediterranean countries. We surveyed the spatiotemporal distribution of the PPM in a pine plantation forest in southwestern France and used the density of the winter nests as a proxy for population density. The study spanned 4 years (2005–2008) and showed a high temporal variability in nest density. We found a strong edge effect with nest densities at stand edges more than twice as large as within-stand densities. At the landscape scale, the spatial distribution of the moth exhibited a significant spatial autocorrelation in 3 out of 4 years of our study. The spatial scales of the autocorrelation ranged from ca. 2 km to more than 22 km. We found a positive correlation between spatial distributions corresponding to certain sampling years, but the relationship was not systematic. Landscape configuration appeared to be an important driver of the PPM spatial pattern. Bivariate Moran’s I correlograms showed that patch richness density as well as the percentage of local landscape covered by various land uses were correlated with population density. The study showed that accounting for landscape characteristics may be important in order to understand forest insect pest distribution, even in cases where the host species is abundant and homogeneously distributed throughout the study area, e.g., pure plantation forests.     

Gas chromatography column as an ambient‐temperature volatile trap

Open‐tube volatile traps have largely been shunned in favor of solid adsorbent containing traps for the collection of volatile pheromones and attractants. Solid adsorbents require large solvent rinses and glass capillaries can be difficult to maneuver for the collection of volatiles from small or hard‐to‐reach odor sources. A gas chromatograph (GC) column (DB‐1), an open‐tube glass capillary, and a SuperQ^®‐containing capillary were compared for their collection efficiencies from rubber septa and live calling insects. All three traps captured similar ratios of test compounds from septa at airflows >10 ml per min. Eluting analytes from a packed adsorbent, SuperQ, required at least 30× more solvent than was required to collect all the pheromone from the open‐tube glass capillaries, and the GC column enjoyed an additional three‐fold reduced solvent volume compared to the glass capillary. Thus, analytes could be eluted from the GC‐column trap and directly analyzed on GC without solvent evaporation. We placed glass wool ‘plugs’ in both GC columns and glass capillaries and found no volatiles in these plugs, indicating that breakthrough did not occur during 1‐h collections at 25 ml per min. We demonstrate here that at ambient laboratory temperatures, a DB‐1 GC column effectively collects Oriental fruit moth sex pheromone volatiles from a rubber septum and live pheromone‐releasing moths. Release ratios of pheromone from rubber septa are consistent with earlier reports from static air systems, whereas the release ratio of the (Z)‐8‐dodecenyl alcohol (Z8‐12:OH) from female Grapholita molesta Busck (Lepidoptera: Tortricidae) differed from published results and is likely due to different collection methods or moth‐strain origin.     

More than meets the eye: a morphological and phylogenetic comparison of long‐spurred,white‐flowered Satyrium species (Orchidaceae) in South Africa

Superficial similarities among unrelated species are often a result of convergent evolution and can cause considerable taxonomic confusion. A case in point is Satyrium eurycalcaratum , described here as a new species, which has been confused with several other Satyrium spp. with similar long‐spurred, white flowers. A phylogenetic analysis, based on molecular data, indicated that S. eurycalcaratum is not closely related to any of the species with which it has been previously confused. A comparative analysis of morphological characters in the seven South African Satyrium spp. with long‐spurred, white flowers showed that each of these, including S. eurycalcaratum , is characterized by a unique combination of traits. Despite the similarity in pollination syndrome characters, such as spur length and flower colour, variation in rostellum structure was particularly pronounced and four distinctive forms were present. There was no phylogenetic signal in patterns of interspecific rostellum variation, as some closely related species had different rostella, whereas some distantly related species shared similar rostellum structures. We therefore conclude that the use of rostellum traits in conjunction with phylogenetic evidence can resolve species delimitations among orchid species that share the same pollination syndrome. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 166 , 417–430.     

The infectivity and host range of Orgyia anartoides nucleopolyhedrovirus

The painted apple moth (PAM), Teia anartoides (Walker) (Lepidoptera: Lymantriidae) made a recent incursion into New Zealand. A nucleopolyhedrovirus (NPV), Orgyia anartoides NPV (OranNPV), originally isolated from PAM in Australia, was tested for its pathogenicity to PAM and a range of non‐target insect species found in New Zealand, to evaluate its suitability as a microbial control for this insect invader. Dosage‐mortality tests showed that OranNPV was highly pathogenic to PAM larvae; mean LT₅₀ values for third instars ranged from 17.9 to 8.1 days for doses from 10² to 10⁵ polyhedral inclusion bodies/larva, respectively. The cause of death in infected insects was confirmed as OranNPV. Molecular analysis established that OranNPV can be identified by PCR and restriction digestion, and this process complemented microscopic examination of infected larvae. No lymantriid species occur in New Zealand; however, the virus had no significant effects on species from five other lepidopteran families (Noctuidae, Tortricidae, Geometridae, Nymphalidae and Plutellidae) or on adult honeybees. Thus, all indications from this initial investigation are that OranNPV would be an important tool in the control of PAM in a future incursion of this species into New Zealand.     

Performance of Orius insidiosus on alternative foods

Orius insidiosus is economically important for biological control of pests of vegetable and ornamental crops. To improve pest control with this predator, its densities in the crops can be enhanced by the provision of alternative foods, especially when prey are scarce. We therefore compared the performance of O. insidiosus on three alternative foods (Ricinus sp. pollen, bee pollen and the mixed stages of the astigmatid prey Tyrophagus putrescentiae) that are cheaper than frozen eggs of Ephestia kuehniella. Juvenile development was significantly shorter on E. kuehniella and T. putrescentiae than on Ricinus sp. pollen and on bee pollen and lowest without food. Female bugs had a higher oviposition rate when fed either E. kuehniella or T. putrescentiae, but produced fewer eggs when feeding on bee pollen and Ricinus sp. pollen. This shows that T. putrescentiae can possibly be used as cheap alternative food to boost predator populations in periods of low prey densities.