Maize plants sprayed with either jasmonic acid or its precursor,methyl linolenate,attract armyworm parasitoids,but the composition of attractants differs

Treatment of both uninfested and armyworm‐infested maize plants with jasmonic acid (JA) is known to attract the parasitic wasp, Cotesia kariyai Watanabe (Hymenoptera: Braconidae). Here, we show that treatment with a methyl ester of a JA precursor, methyl linolenate (MeLin), also causes maize plants to attract this wasp, yet does not cause elevated levels of endogenous JA. The volatile chemicals emitted from either infested or uninfested maize plants treated with MeLin were qualitatively and quantitatively different from those emitted from JA‐treated plants. Among compounds emitted from MeLin‐treated plants, α‐pinene and menthol attracted wasps in pure form in a two‐choice test using a choice chamber. A mixture of methyl salicylate, α‐copaene, and β‐myrcene also attracted wasps. In contrast, (Z)‐3‐hexenyl acetate was among the main attractants for C. kariyai in JA‐treated plants. These data show that in addition to JA, MeLin also has the potential to increase the host‐finding ability of C. kariyai, but that the composition of attractants they induce differs.     

Nucleopolyhedroviruses of forest and western tent caterpillars: cross-infectivity and evidence for activation of latent virus in high-density field populations

Abstract. 1. Cyclic population dynamics of forest caterpillars are often associated with epizootics of nucleopolyhedrovirus, but it is not known how these viruses persist between generations or through the fluctuations in host population density. 2. To explore the question of virus persistence at different phases of the population cycle, the nucleopolyhedroviruses of two species of tent caterpillar that co‐occur in British Columbia, Canada, Malacosoma californicum pluviale (western tent caterpillar) and Malacosoma disstria (forest tent caterpillar), were characterised. The cross‐infectivity of the viruses in these two host species was investigated to determine whether there might be a route for virus persistence via the alternative host species. Any virus produced in the cross‐infections was characterised to confirm true cross‐infection or to ascertain whether cross‐inoculation triggered latent virus persisting within the population. 3. The virus associated with forest tent caterpillars (MadiNPV) did not infect western tent caterpillars from low‐density populations, nor did it trigger a latent virus infection; however, inoculation of forest tent caterpillars from high‐density populations with virus from western tent caterpillars (McplNPV) resulted in viral infection, but without a dose–response relationship. 4. Analysis of DNA profiles of virus resulting from cross‐infection of the forest tent caterpillar with McplNPV, revealed that 88% of these infections were caused by MadiNPV rather than McplNPV; however the virus from all 44 infected individuals was identical and differed in DNA profile from the stock MadiNPV used for cross‐infection. This suggests strongly that forest tent caterpillars from high‐density field populations harbour a latent, persistent, or sublethal form of MadiNPV that was triggered by exposure to nucleopolyhedrovirus from the western tent caterpillar. 5. Virus was not activated in western tent caterpillars collected over 2 years of late population decline and the first year of population increase.     

褐边绿刺蛾幼虫刺毛结构及蛰伤机制初探

刺蛾科幼虫是我国常见的农林业害虫之一,其体表长有防御性的有毒刺毛,会伤害接触者,使其产生瘙痒、刺痛、丘疹、红肿、皮炎等症状.本研究利用体视显微镜、扫描电镜对褐边绿刺蛾Parasa consocia末龄幼虫的刺毛形态结构进行了观察,将不同刺毛提取物进行小鼠足底皮下注射,测试刺激活性,并使用SDS-PAGE电泳对提取物成分...     

蛹虫草超氧化物歧化酶分离纯化及稳定性的研究

以蛹虫草为材料,经过硫酸铵盐析、Sephedex G-75柱层析和DEAE-52柱层析,得到纯化的超氧化物歧化酶（SOD）,经聚丙烯酰胺凝胶电泳显示单一区带,此酶比活力为17855．73u／mg,纯化倍数为53．7,回收率为21．8％。同时鉴于SOD在溶液中容易失活,无法长期保存,该文研究了不同浓度的糖类及不同浓度的有机酸类对SOD活力的影响,发现糖类对SOD活力影响不明显,有机酸均使SOD活力下降,但随着酸浓度的增加,SOD活力下降的程度也减轻。     

A review of the sentinel prey method as a way of quantifying invertebrate predation under field conditions

Sentinel prey can provide a direct, quantitative measure of predation under field conditions. Live sentinel prey provides more realistic data but rarely allows the partitioning of the total predation pressure; artificial prey is less natural but traces left by different predators are identifiable, making it suitable for comparative studies. We reviewed the available evidence of the use of both types of invertebrate sentinel prey. Fifty‐seven papers used real prey, usually measuring predation on a focal (often pest) species, with studies overwhelmingly from North America. The median predation was 25.8% d^?1. Artificial sentinel prey (45 papers) were used in both temperate and tropical areas, placed more above ground than at ground level. The most commonly used artificial prey imitated a caterpillar. Up to 14 predator groups were identified, registering a median of 8.8% d^?1 predation; half the studies reported only bird predation. Predation on real prey was higher than on artificial ones, but invertebrate predation was not higher than vertebrate predation. Invertertebrate but not vertebrate predation was negatively related to prey size. Predation near the Equator was not higher than at higher latitudes, nor in cultivated than noncultivated habitats. The use of sentinel prey is not yet standardised in terms of prey size, arrangement, exposure period or data reporting. Due to the simplicity and ease of use of the method, such standardisation may increase the usefulness of comparative studies, contributing to the understanding of the importance and level of predation in various habitats worldwide.     

Tobacco-expressed Brassica juncea chitinase BjCHI1 shows antifungal activity in vitro

We have previously isolated a Brassica juncea cDNA encoding BjCHI1, a novel chitinase with two chitin-binding domains, and have shown that its mRNA is induced by wounding and methyl jasmonate treatment (K.-J. Zhao and M.-L. Chye, Plant Mol. Biol. 40 (1999) 1009–1018). By the presence of two chitin-binding domains, BjCHI1 resembles the precursor of UDA (Urtica dioica agglutinin) but, unlike UDA, BjCHI1 retains its chitinase catalytic domain after post-translational processing. Here, we indicate the role of BjCHI1 in plant defense by demonstrating its mRNA induction upon Aspergillus niger infection or caterpillar Pieris rapae (L.) feeding. To further investigate the biological properties of BjCHI1, we transformed tobacco with a construct expressing the BjCHI1 cDNA from the CaMV 35S promoter. Subsequently, we purified BjCHI1 from the resultant transgenic R₀ plants using a regenerated chitin column followed by fast protein liquid chromatography (FPLC). Also, the significance of the second chitin-binding domain in BjCHI1 was investigated by raising transgenic tobacco plants expressing BjCHI2, a deletion derivative of BjCHI1 lacking one chitin-binding domain. Colorimetric chitinase assays at 25 °C, pH 5, showed no significant differences between the activities of BjCHI1 and BjCHI2, suggesting that chitinase activity, due to the catalytic domain, is not enhanced by the presence of a second chitin-binding domain. Both BjCHI1 and BjCHI2 show in vitro anti-fungal activity toward Trichoderma viride, causing reductions in hyphal diameter, hyphal branching and conidia size.     

Integrative taxonomy of New World Euplectrus Westwood (Hymenoptera,Eulophidae), with focus on 55 new species from Area de Conservación Guanacaste,northwestern Costa Rica

90 species of Euplectrus are treated: 55 newly described, all from Area de Conservación Guanacaste (ACG), and 35 previously described species, of which 20 occur in ACG. Three of the previously described species (Euplectrus brasiliensis Ashmead, Euplectrus hircinus (Say), Euplectrus ronnai (Brèthes)) have unknown status, owing to missing or severely damaged type material. The new species, all authored by C. Hansson, are: Euplectrus alejandrovalerioi, Euplectrus alexsmithi, Euplectrus alvarowillei, Euplectrus andybennetti, Euplectrus andydeansi, Euplectrus annettewalkerae, Euplectrus billbrowni, Euplectrus bobwhartoni, Euplectrus carlosarmientoi, Euplectrus carlrettenmeyeri, Euplectrus charlesmicheneri, Euplectrus charlesporteri, Euplectrus chrisdarlingi, Euplectrus chrisgrinteri, Euplectrus corriemoreauae, Euplectrus daveroubiki, Euplectrus davesmithi, Euplectrus davidwahli, Euplectrus dianariasae, Euplectrus donquickei, Euplectrus eowilsoni, Euplectrus garygibsoni, Euplectrus gavinbroadi, Euplectrus gerarddelvarei, Euplectrus henrytownesi, Euplectrus howelldalyi, Euplectrus hugokonsi, Euplectrus iangauldi, Euplectrus jacklonginoi, Euplectrus jesusugaldei, Euplectrus jimwhitfieldi, Euplectrus jjrodriguezae, Euplectrus johnheratyi, Euplectrus johnlasallei, Euplectrus johnnoyesi, Euplectrus josefernandezi, Euplectrus lubomirmasneri, Euplectrus markshawi, Euplectrus mikegatesi, Euplectrus mikeschauffi, Euplectrus mikesharkeyi, Euplectrus ninazitaniae, Euplectrus pammitchellae, Euplectrus paulhansoni, Euplectrus paulheberti, Euplectrus paulhurdi, Euplectrus philwardi, Euplectrus robbinthorpi, Euplectrus ronaldzunigai, Euplectrus roysnellingi, Euplectrus scottshawi, Euplectrus sondrawardae, Euplectrus sydneycameronae, Euplectrus victoriapookae, Euplectrus wonyoungchoi. The species are described or redescribed, and thoroughly and uniformly illustrated, and included in two identification keys, one for females and one for males. Lectotypes are designated for eight species: Euplectrus catocalae Howard (♂), Euplectrus junctus Gahan (♀), Euplectrus leucotrophis Howard (♂), Euplectrus marginatus Ashmead (♀), Euplectrus pachyscaphus Girault (♀), Euplectrus platyhypenae Howard (♂), Euplectrus semimarginatus Girault (♀), Heteroscapus ronnai Brèthes (♂). One synonym is established: Euplectrus walteri Schauff is a junior synonym of Euplectrus testaceipes (Cameron). Brief image notes and host records are provided on the natural history of the wasps as well as the details of their morphology. Hosts are known for 74 Euplectrus species.     

Experimental climate warming alters aspen and birch phytochemistry and performance traits for an outbreak insect herbivore

Climate change and insect outbreaks are key factors contributing to regional and global patterns of increased tree mortality. While links between these environmental stressors have been established, our understanding of the mechanisms by which elevated temperature may affect tree–insect interactions is limited. Using a forest warming mesocosm, we investigated the influence of elevated temperature on phytochemistry, tree resistance traits, and insect performance. Specifically, we examined warming effects on forest tent caterpillar (Malacosoma disstria) and host trees aspen (Populus tremuloides) and birch (Betula papyrifera). Trees were grown under one of three temperature treatments (ambient, +1.7 °C, +3.4 °C) in a multiyear open‐air warming experiment. In the third and fourth years of warming (2011, 2012), we assessed foliar nutrients and defense chemistry. Elevated temperatures altered foliar nitrogen, carbohydrates, lignin, and condensed tannins, with differences in responses between species and years. In 2012, we performed bioassays using a common environment approach to evaluate plant‐mediated indirect warming effects on larval performance. Warming resulted in decreased food conversion efficiency and increased consumption, ultimately with minimal effect on larval development and biomass. These changes suggest that insects exhibited compensatory feeding due to reduced host quality. Within the context of observed phytochemical variation, primary metabolites were stronger predictors of insect performance than secondary metabolites. Between‐year differences in phytochemical shifts corresponded with substantially different weather conditions during these two years. By sampling across years within an ecologically realistic and environmentally open setting, our study demonstrates that plant and insect responses to warming can be temporally variable and context dependent. Results indicate that elevated temperatures can alter phytochemistry, tree resistance traits, and herbivore feeding, but that annual weather variability may modulate warming effects leading to uncertain consequences for plant–insect interactions with projected climate change.     

Host–plant quality alters herbivore responses to temperature: a case study using the generalist Hyphantria cunea

The nutritional quality of host plants is an important determinant of fitness in insect herbivores. However, it remains an open question whether the ingestion of a particular plant will have the same effects on an herbivore under differing thermal conditions. We measured the performance of the generalist‐feeding caterpillars of Hyphantria cunea Drury (Lepidoptera: Arctiidae) raised on one of five natural host plants to determine their nutritional quality: Platanus occidentalis L. (Platanaceae), Sophora japonica (L.) Schott (Fabaceae), Prunus × yedoensis Matsum. (Rosaceae), Cornus kousa Hance (Cornaceae), or Betula platyphylla Sukaczev (Betulaceae). Caterpillars performed well on P. occidentalis, S. japonica, and P. × yedoensis, but poorly on C. kousa and B. platyphylla. The nutritional phenotype of caterpillars varied among host–plant groups, with the proportion of lipid‐free body mass to lipid content being higher for caterpillars raised on P. occidentalis and S. japonica (3.8–4.2:1) than for caterpillars raised on P. × yedoensis (1.6–2.1:1). A multi‐factorial experimental design was employed to investigate the interactive effects of host–plant quality and temperature on the performance of H. cunea caterpillars raised on either P. occidentalis or P. × yedoensis at three rearing temperatures (20, 25, or 30 °C). Caterpillars raised on P. occidentalis displayed a monotonic decrease in development time with increasing temperature, but the development time of those on P. × yedoensis decreased rapidly as temperature rose from 20 to 25 °C and then stayed unchanged despite further increase in temperature. The rate at which body size increased with decreasing temperature was much steeper for caterpillars raised on P. occidentalis than for those on P. × yedoensis. Collectively, these results indicate that host plant can alter the thermal reaction norms for the key life‐history traits of herbivores. This study has implications for understanding the impacts of climate change on herbivore–plant interactions.     

松毛虫DpKettin基因片段的克隆与初步定位研究

对于ZW型鳞翅目昆虫, 雄性为ZZ, 雌性为ZW; 细胞内Z染色体数与常染色体组数之比在雌雄间存在差异, 雄性为2Z∶2A=1.0, 雌性为Z∶2A=0.5, 如果某物种一个基因(假如K基因)位于Z染色体上, 另一个基因(假如N基因)位于常染色体上, 则雄体中2K∶2N=1.0, 雌体中K∶2N=0.5。研究利用家蚕、棉铃虫等昆虫Kettin基因序列, 克隆了松毛虫的同源基因(DpKettin)片段, 并采用荧光定量PCR技术, 以松毛虫的ANT基因为参照基因, 检测松毛虫雌雄不同个体间DpKettin基因与腺苷酸转移酶基因(ANT)的拷贝数之比, 结果表明: 雄体DpKettin∶ANT=1.0, 雌体DpKettin∶ANT=0.5, 说明DpKettin基因位于松毛虫Z染色体上。