First report of the repellency of 2-tridecanone against ticks

2‐Tridecanone and 2‐undecanone are both found naturally in the trichomes of wild tomato plants and are important in plant resistance to herbivory. 2‐Undecanone is the U.S. Environmental Protection Agency (EPA)‐registered active ingredient in the commercially available arthropod repellent, BioUD^®. The goal of this study was to examine the tick repellency of 2‐tridecanone. Two‐choice bioassays were conducted using 8% 2‐tridecanone vs. the repellent carrier (absolute ethanol) and compared with two‐choice studies using 8% 2‐undecanone vs. absolute ethanol. Unfed, host‐seeking adult (mixed sex) Amblyomma americanum (L.) (Acari: Ixodidae) and Dermacentor variabilis Say (Acari: Ixodidae) were used to evaluate repellency and time to repellent failure at room temperature. The present study shows in filter paper assays (0.63 mg test compound/cm²) that 2‐tridecanone was 87% repellent to A. americanum at 12 h after application, but had no statistically significant repellency at 15 h and 24 h, and was 72% repellent to D. variabilis at 15 h, but had no statistically significant repellency at 24 h. By contrast, 2‐undecanone was 74% and 75% repellent to A. americanum and D. variabilis, respectively, at 2 h after application, but no statistically significant repellency was noted at 2.5 h and 3 h. In two‐choice assays on cheesecloth, 2‐tridecanone at 0.25 mg/cm² was 85% repellent to A. americanum 6 h after application, demonstrating its potential use as an arthropod repellent that can be used on clothing without the need for formulation. No statistically significant repellency was found at 9 h or 12 h. The potential use of 2‐tridecanone as a tick repellent is discussed.     

Large‐scale longitudinal gradients of genetic diversity: a meta‐analysis across six phyla in the Mediterranean basin

Biodiversity is the diversity of life at all scales, from genes to ecosystems. Predicting its patterns of variation across the globe is a fundamental issue in ecology and evolution. Diversity within species, that is, genetic diversity, is of prime importance for understanding past and present evolutionary patterns, and highlighting areas where conservation might be a priority. Using published data on the genetic diversity of species whose populations occur in the Mediterranean basin, we calculated a coefficient of correlation between within‐population genetic diversity indices and longitude. Using a meta‐analysis framework, we estimated the role of biological, ecological, biogeographic, and marker type factors on the strength and magnitude of this correlation in six phylla. Overall, genetic diversity increases from west to east in the Mediterranean basin. This correlation is significant for both animals and plants, but is not uniformly expressed for all groups. It is stronger in the southern than in the northern Mediterranean, in true Mediterranean plants than in plants found at higher elevations, in trees than in other plants, and in bi‐parentally and paternally than in maternally inherited DNA makers. Overall, this correlation between genetic diversity and longitude, and its patterns across biological and ecological traits, suggests the role of two non‐mutually exclusive major processes that shaped the genetic diversity in the Mediterranean during and after the cold periods of the Pleistocene: east‐west recolonization during the Holocene and population size contraction under local Last Glacial Maximum climate in resident western and low elevation Mediterranean populations.     

New Afrotropical species belonging to genera never recorded before for the Afrotropical fauna (Diptera: Tachinidae)

Five remarkable new Afrotropical species belonging to four Old World genera never recorded before for the Afrotropical region (Neophryxe, Calliethilla, Metadrinomyia, Pseudalsomyia) are described and compared with congeners. Existing keys to tropical African tachinid genera are implemented. A brief discussion on the apomorphic support to each genus is provided.     

Effects of ungulates on epigeal arthropods in Sierra Nevada National Park (southeast Spain)

This paper examines the effect of ungulates on epigeal arthropod communities in two common plant communities of the high mountains of the Sierra Nevada (southeast Spain). We have compared the abundance, biomass, diversity and specific composition of arthropod communities in grazed and ungrazed plots experimentally excluded from ungulates. In general, we found that arthropods were more abundant and diverse in grazed than in ungrazed plots. However, the effect of ungulates depended on the variable considered (diversity versus abundance versus biomass). Moreover, ungulates also affected species composition. This means that without affecting diversity, ungulates can still have a strong effect on arthropod communities by changing species composition. Also, the relationship between ungulates and arthropods differed depending on the year of study and the sampling period. In conclusion, our study indicates that to extrapolate the results obtained for a group of insects, a habitat or a sampling period is not appropriate for the conservation of arthropod communities.     

抗虫转基因水稻和化学杀虫剂对稻田节肢动物群落的影响

从功能团优势度、功能团内科组成及其优势度、功能团个体数量、群落主要参数及群落结构相异性等方面,就含crylAb／crylAc融合基因的Bt水稻和化学杀虫剂对稻田节肢动物群落影响进行比较研究．结果表明,与对照田相比,Bt稻田的节肢动物功能团组成及其优势度、各功能团内科组成及其优势度分布、功能团内个体数量的时间动态、群落参数(物种丰富度、Shannon-Wiener多样性指数、均匀性指数、优势集中性指数)及时间动态在大多情况下均无显著差异,两者间群落结构相似性较高．Bt水稻对稻田节肢动物群落基本无明显的负效应、而化防田的功能团优势度等群落特征指标与对照田相比,有时具有明显甚至显著的差异;群落结构相似性也较低．综合分析表明,Bt水稻对稻田节肢动物群落的影响明显弱于化学杀虫剂。     

The role of natural habitats in agricultural systems for bird conservation: the case of the threatened Lesser Grey Shrike

Birds of agricultural systems are one of the most threatened groups of birds in Europe mainly due to their sharp population decline in recent decades. Habitat intensification resulting from more productive agricultural practices has been proposed as a major cause for these declines. However, especially in some regions such as Eastern European and Mediterranean countries, little is known about the ultimate factors linked to habitat intensification that drive population declines for different species. The Lesser Grey Shrike is a good study species for a better understanding of such processes since it is closely related to agricultural habitats in Europe and has suffered a strong decline in range and population size across the western half of the continent. In this study, we explored variations in breeding parameters of this shrike related to habitat composition and food supply at the territory level. We found that fledgling success of early breeders was related to the presence of natural (shrub lands) and semi-natural (fallows) habitats in the predominantly agricultural matrix that dominated breeding territories. Their influence on fledgling success appeared to be mediated by a higher arthropod availability on these habitats. Indeed, Lesser Grey Shrike showed a strong preference for these habitats as hunting locations. Our results highlight the importance of natural habitats in intensified agricultural land mosaics for the conservation of bird species. We suggest that management plans should pay special attention to the availability of habitats which serve as high quality food reservoirs and can potentially contribute to enhance the species population viability in an area. Finally, we discuss the possible link between agricultural intensification and Lesser Grey Shrike population declines in Western Europe.     

Evidence for Wg-independent tergite boundary formation in the millipede Glomeris marginata

The correlation between dorsal and ventral segmental units in diplopod myriapods is complex and disputed. Recent results with engrailed (en), hedgehog (hh), wingless (wg), and cubitus-interruptus (ci) have shown that the dorsal segments are patterned differently from the ventral segments. Ventrally, gene expression is compatible with the classical autoregulatory loop known from Drosophila to specify the parasegment boundary. In the dorsal segments, however, this Wg/Hh autoregulatory loop cannot be present because the observed gene expression patterns argue against the involvement of Wg signalling. In this paper, we present further evidence against an involvement of Wg signalling in dorsal segmentation and propose a hypothesis about how dorsal segmental boundaries may be controlled in a wg-independent way. We find that (1) the Notum gene, a modulator of the Wg gradient in Drosophila, is not expressed in the dorsal segments. (2) The H15/midline gene, a repressor of Wg action in Drosophila, is not expressed in the dorsal segments, except for future heart tissue. (3) The patched (ptc) gene, which encodes a Hh receptor, is strongly expressed in the dorsal segments, which is incompatible with Wg-Hh autoregulation. The available data suggest that anterior-posterior (AP) boundary formation in dorsal segments could instead rely on Dpp signalling rather than Wg signalling. We present a hypothesis that relies on Hh-mediated activation of Dpp signalling and optomotor-blind (omb) expression to establish the dorsal AP boundary (the future tergite boundary). The proposed mechanism is similar to the mechanism used to establish the AP boundary in Drosophila wings and ventral pleura.     

节肢动物α-淀粉酶系统进化树构建及分析

目的:构建节肢动物α-淀粉酶的系统进化树,探讨其进化关系,找出进化树中聚类在一起的α-淀粉酶的特异性序列。方法:在美国国立生物技术信息中心(National Center for Biotechnology Information,NCBI)数据库中选取了56个节肢动物的α-淀粉酶氨基酸序列,利用CLUSTALX2.0进行序列比对、MEGA6.0建立进化树,通过BOXSHADE找到聚类的α-淀粉酶特异性序列。结果:56个α-淀粉酶聚类成A、B、C、D四大簇,A簇特异性序列为"VD NHD NQ",B簇特异性序列为"ID NHD NX",C簇特异性序列为"ID NHD NQ",D簇特异性序列为"XGN NHD X"。A、B、C、D四簇都含有保守的NHD(天冬酰胺-组氨酸-天冬氨酸)序列,但序列两端氨基酸种类不同。结论:56个节肢动物α-淀粉酶分为4簇,每簇都有其特异性序列,但都含有保守序列NHD。     

Drosophila Chitinase 2 is expressed in chitin producing organs for cuticle formation

The architecture of the outer body wall cuticle is fundamental to protect arthropods against invading pathogens and numerous other harmful stresses. Such robust cuticles are formed by parallel running chitin microfibrils. Molting and also local wounding leads to dynamic assembly and disassembly of the chitin-matrix throughout development. However, the underlying molecular mechanisms that organize proper chitin-matrix formation are poorly known. Recently we identified a key region for cuticle thickening at the apical cell surface, the cuticle assembly zone, where Obstructor-A (Obst-A) coordinates the formation of the chitin-matrix. Obst-A binds chitin and the deacetylase Serpentine (Serp) in a core complex, which is required for chitin-matrix maturation and preservation. Here we present evidence that Chitinase 2 (Cht2) could be essential for this molecular machinery. We show that Cht2 is expressed in the chitin-matrix of epidermis, trachea, and the digestive system. There, Cht2 is enriched at the apical cell surface and the dense chitin-matrix. We further show that in Cht2 knockdown larvae the assembly zone is rudimentary, preventing normal cuticle formation and pore canal organization. As sequence similarities of Cht2 and the core complex proteins indicate evolutionarily conserved molecular mechanisms, our findings suggest that Cht2 is involved in chitin formation also in other insects.     

苜蓿人工草地节肢动物群落的时间格局

调查了甘肃省庄浪县苜蓿人工草地节肢动物群落的组成及多样性变化,应用主分量分析和最优分割法对节肢动物群落的时间格局进行了研究。结果表明,苜蓿人工草地节肢动物群落的物种丰富度,多样性和均匀度指标在时间过程中的变化有明显的差异和规律性,6月下旬害虫和天敌的物种丰富度均达到最大值,但天敌的个体数量高峰明显落后于害虫,在时间变化过程中,影响节肢动物群落的主导因素和时间格局分化明显,根据研究结果,将苜蓿人工草地节肢动物群落在时间动态中的变化划分为5月上旬以前,5月中旬-6月上旬,6月中旬-7月中旬,7月中旬以后4个阶段,并结合气候,物候变化,分析了各阶段内主要害虫和天敌的发生特点,提出了害虫的治理对策。