Prey selection by Dicyphus hesperus of infected or parasitized greenhouse whitefly

The development of effective biological control programs in which predators are integrated with other natural enemies such as parasitoids and entomopathogens requires an understanding of their interactions. In this study we examined the extent to which the omnivorous mirid bug Dicyphus hesperus, an effective biological control agent of greenhouse whiteflies, accepts prey that are either parasitized by the specialist whitefly parasitoid, Encarsia formosa or infected by the generalist fungal entomopathogen, Beauveria bassiana. In non-choice laboratory experiments, we measured how parasitism and infection of greenhouse whitefly, Trialeurodes vaporariorum, as related to parasitoid age and course of fungal infection, might alter the probability of feeding by second instar or adult female predators. Predation by D. hesperus was similar for parasitized and unparasitized whiteflies, regardless of parasitoid age. However, predators generally avoided feeding on infected whiteflies, particularly when infection was manifested through the presence of oosporein or hyphae on the surface of prey.     

Are you more than the sum of your parents’ genes? Phenotypic plasticity in a clonal vertebrate and F1 hybrids of its parental species

All known vertebrate clones have originated from hybridization events and some have produced distinct evolutionary lineages via hybrid speciation. Amazon mollies (Poecilia formosa) present an excellent study system to investigate how clonal species have adapted to heterogeneous environments because they are the product of a single hybridization event between male sailfin mollies (Poecilia latipinna) and female Atlantic mollies (Poecilia mexicana). Here, we ask whether the hybrid species differs from the combination of its parental species’ genes in its plastic response to different environments. Using a three-way factorial design, we exposed neonates produced by Amazon mollies and reciprocal F1 hybrid crosses to different thermal (24°C and 29°C) and salinity (0/2, 12, and 20 ppt) regimes. We measured various ontogenetic and life history characteristics across the life span of females. Our major results were as follows: (1) Reaction norms of growth and maturation to temperature and salinity are quite similar between the two hybrid crosses; (2) Amazon molly reaction norms were qualitatively different than the P. latipinna male and P. mexicana female (L×M) hybrids for the ontogenetic variables; (3) Amazon molly reaction norms in reproductive traits were also quite different from L×M hybrids; and (4) The reaction norms of net fertility were very different between Amazon mollies and L×M hybrids. We conclude that best locale for Amazon mollies is not the best locale for hybrids, which suggests that Amazon mollies are not just an unmodified mix of parental genes but instead have adapted to the variable environments in which they are found. Hybridization resulting in asexuality may represent an underappreciated mechanism of speciation because the unlikely events required to produce such hybrids rarely occur and is dependent upon the genetic distance between parental species.     

Dietary niche overlap in sympatric asexual and sexual livebearing fishes Poecilia spp

The present study investigated the spatiotemporal patterns in trophic resource use in a system of a gynogenetic poeciliid fish, the Amazon molly Poecilia formosa, and its sexual congeners the sailfin molly Poecilia latipinna and the Atlantic molly Poecilia mexicana using gut contents analysis. No statistically significant differences in trophic resource use were found between sexual and gynogenetic species, but gut contents varied significantly across sites and over time. In addition, variation in trophic morphology (i.e. gut length) was significant across sites but not species, and laboratory experiments indicated that gut length is phenotypically plastic. Overall, trophic differentiation between coexisting asexual and sexual Poecilia appears to be minimal, and it is unlikely that niche differentiation contributes to a stable coexistence of the two reproductive forms.     

基于SCAR标记技术的丽蚜小蜂快速识别

丽蚜小蜂Encarsia formosa Gahan作为温室粉虱Trialeurodes vaporariorum Westwood和烟粉虱Bemisia tabaci (Gennadius)等粉虱类害虫的优势寄生蜂而备受关注。针对丽蚜小蜂体型微小, 难以与其他同域近缘种寄生蜂快速、 准确区别的问题, 本研究采用SCAR (sequence characterized amplified region, 特异性扩增区域)标记技术, 筛选出一对丽蚜小蜂特征片段扩增引物(EFZZF/EFZZR), 其扩增片段的大小为287 bp。种特异性检验结果表明, 该对引物只对丽蚜小蜂的基因组DNA具有扩增能力, 对其近缘种属寄生蜂如浅黄恩蚜小蜂Encarsia sophia (Girault & Dodd)、 海氏桨角蚜小蜂Eretmocerus hayati Zolnerowich & Rose、 本地未知种桨角蚜小蜂Eretmocerus sp.、 蒙氏桨角蚜小蜂Eretmocerus mundus Mercet、 刺粉虱黑蜂Amitus hesperidum Silvertri不具有扩增效果, 对丽蚜小蜂的寄主包括不同生物型 (B型、 Q型、 ZHJ 1型和ZHJ 2型)的烟粉虱、 温室粉虱以及我国最常见的黑刺粉虱Aleurocanthus spiniferus (Quaintanca)等亦不具有扩增能力。同时, 该检测技术灵敏度高, 对成虫的最低检出阈值为7.812 ng/μL (相当于1/1 600头成虫)。研究结果对丽蚜小蜂的种类识别、 寄主谱的确定及其有效利用具有重要意义。     

美丽青背姬小蜂生物学特性研究

美丽青背姬小蜂Chrysonotomyiaformosa（Westwood）是美洲斑潜蝇的优势天敌,在美洲 斑潜蝇的自然控制中发挥着非常重要的作用。本文对其生物学进行了研究,结果表明：在实验 温度范围内,随着温度的升高,寄生蜂羽化趋早,羽化时间更集中,羽化高峰也更明显;随着 温度的升高,成蜂的寿命逐渐缩短。在提供清水时,寄主可以显著地延长雌蜂的寿命;在有寄 主时,提供10%蜂蜜水,雌蜂的寿命显著延长。美丽青背姬小蜂对3龄寄主幼虫有偏好,对3龄寄 主幼虫的致死率和寄生率都高于对1～2龄寄主幼虫的,且产下后代的雌雄性比为5.11∶1。在 实验温度范围内,发育历期随温度的升高而缩短。     

雪莲果为替代寄主植物繁育的丽蚜小蜂对MED烟粉虱生防潜能

雪莲果Smallanthus sanchifalius被视为替代烟草高效繁育丽蚜小蜂Encarsia formosa Gahan的理想寄主植物,且中间寄主植物雪莲果繁育的丽蚜小蜂对温室白粉虱Trialeurodes vaporariorum（Westwood）具有更高的生防潜能。但中间寄主植物雪莲果繁育的丽蚜小蜂对烟粉虱Bemisia tabaci（Gennadius）的生防效果尚未明确,本研究测定了雪莲果繁育的丽蚜小蜂对MED烟粉虱1~4龄若虫的寄生率、取食数量、杀死数量,及其子代发育时间和羽化率。研究结果表明,雪莲果繁育的丽蚜小蜂对MED烟粉虱各龄幼虫的寄生率、取食数量均显著高于烟草繁育的丽蚜小蜂,其中,对3龄若虫的防控效果最好,杀死数量为10.5头,寄生率为17.2%,取食数量为1.9头。雪莲果为寄主植物繁育的丽蚜小蜂寄生MED烟粉虱1~4龄若虫的发育时间分别为21.2 d、16.0 d、13.9 d和13.4 d,均显著短于烟草繁育丽蚜小蜂子代发育时间。综合来看,中间寄主植物雪莲果繁育的丽蚜小蜂对MED烟粉虱生防潜能显著高于中间寄主植物烟草繁育的丽蚜小蜂。研究结果为进一步应用中间寄主植物雪莲果繁育的丽蚜小蜂防治烟粉虱提供了理论依据。     

美丽马醉木叶化学成分的研究

从美丽马醉木(Pieris formosa D.Don)叶中分离得到马醉木亭(Ⅰ)、β-谷甾醇(Ⅱ)、β-香树脂醇(Ⅲ),蒲公英醇(Ⅳ)4个已知化合物。     

Limia vittata as host species for the Amazon molly: no evidence for sexual reproduction

DNA fingerprinting demonstrated no sexual reproduction of the gynogenetic Amazon molly Poecilia formosa with Limia vittata as host species, in contrast with a single report that claims to have found sexual reproduction with such matings.     

Two synonymy cases within the genus Neoseiulella (Acari: Phytoseiidae): is the molecular evidence so evident?

Synonymy is considered as a great problem for diversity characterization and further applications, especially for biological control success with regard to the accurate identification of natural enemies. The present study focuses on two synonymy cases of natural enemies, belonging to the family Phytoseiidae, the genus Neoseiulella, specifically five species of this genus: Neoseiulella tiliarum, Neoseiulella formosa, Neoseiulella aceri, Neoseiulella squamiger, and Neoseiulella aceris. Morphological and molecular analyses [12S rRNA, cytochrome b (Cytb) mitochondrial (mt)DNA, internal transcribed spacer DNA] were applied. First, the results obtained support the synonymy of N. tiliarum and N. formosa. Second, because morphological differences (solenostomes occurrence) were observed for the first time between the type material of N. aceris and N. squamiger, the present study does not provide sufficient evidence to synomymize these two species and further analyses are required. Lastly, we assume that N. squamiger and N. aceri are synonyms. However, three groups of specimens, including N. aceri and N. squamiger, were identified by two mitochondrial DNA genes (12S rRNA and Cytb mtDNA). Therefore, the present study highlights the problems encountered when using only mitochondrial genes to diagnose species. The great mtDNA variations observed appear to reflect population differentiation (linked to plant support). This is the first time that such high intraspecific differentiation is be observed within the family Phytoseiidae. Further experiments, such as cross‐breeding and microsatellite DNA marker analyses, are planned to characterize gene flow and reproductive isolation levels within this species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 323–344.