Improvement bread characteristics of high level sunn pest (Eurygaster integriceps) damaged wheat by using transglutaminase and some additives

The purpose of this study was to improve the baking quality of high level sunn pest damaged wheat (HLSPDW; 20.6%) sample by using at varying levels transglutaminase, and fixed additive combination (diacetyl tartaric acid esters of mono and diglycerides + citric acid + L-ascorbic acid) with or without transglutaminase. It was observed that transglutaminase plays an important role in baking quality of HLSPDW. The increase in transglutaminase caused very clear increase on bread characteristics of wheat. Bread yield, height, pore structure, and crumb softness values increased sharply; weight loss and wideness of bread samples decreased accurately depending on increasing transglutaminase level. This increase did not affect obviously on bread quality at a certain proportion (0.3%). However, when the transglutaminase was more than 0.3% and depend on increase of percentage, bread characteristics showed significant increase. It was determined that, in the absence of transglutaminase; other additives could not improve the bread qualities examined. The unique application of using transglutaminase was found to be considerably to improve the bread quality of the HLSPDW. Overall results indicate that the properties of the bread from HLSPDW can be restored by the addition of transglutaminase. The highly disrupted protein structure present in the HLSPDW gluten requires higher transglutaminase concentrations.     

茶角胸叶甲高毒力球孢白僵菌菌株的筛选

茶角胸叶甲(Basilepta melanopus Lefevre)是一种茶树上常见的食叶性害虫,其发生为害严重影响茶叶的产量和品质。近年来,该虫在局部茶园,尤其是有机茶园中常爆发成灾。如何有效防治该害虫,已成为亟待解决的问题。本研究选择原寄主为茶园鞘翅目害虫的9个球孢白僵菌(Beauveria bassiana)菌株,依据菌落形态、菌株生长速率、产孢量、孢子萌发率、耐热力和抗紫外能力等生物学性状初步筛选出Bb338、Bb346和Bb2-1等3个生物学性状优良的菌株;在此基础上,利用浸虫法研究了3个菌株对茶角胸叶甲成虫的杀虫毒力。生测结果表明,用每毫升1×10~7个孢子的孢悬液处理后,球孢白僵菌Bb2-1对茶角胸叶甲成虫的累计校正死亡率达100%,僵虫率达86.11%;LT_(50)仅为3.32 d。综合上述各生物学特性和杀虫毒力表明,筛选到的Bb2-1菌株具有生长速率快、产孢量大、耐热力和抗紫外能力强,以及对茶角胸叶甲杀虫毒力最强和杀虫速率最快等优点,在今后茶角胸叶甲的生物防治中将发挥重要的作用。     

Influence of Different Types of Phyllostachys pubescens (Poales: Poaceae) Leaves on Population Parameters of Pantana phyllostachysae (Lepidoptera: Lymantriidae) and Parasitic Effects of Beauveria bassiana (Moniliales: Moniliaceae)

We found that Pantana phyllostachysae, a dangerous pest of moso bamboo (Phyllostachys pubescens), showed differences in growth and development after feeding on diverse types of moso bamboo leaves. The mortality rate of Pa. phyllostachysae due to Beauveria bassiana, an entomopathogenic fungus, was also affected by the varied larval diet. Larval and pupal developmental duration of Pa. phyllostachysae was longer when feeding on “off-year” bamboo leaves. Pupal weight and adult fertility were higher when feeding on “on-year” bamboo leaves. Mortality due to B. bassiana was significantly lower in larvae fed on on-year bamboo leaves than in larvae fed on off-year bamboo leaves. Larvae fed on new bamboo leaves had a shorter development period and higher survival rate than those fed on off-year bamboo leaves. However, mixed feed (mixture of new, on-year, and off-year bamboo leaves) decreased the egg production of Pa. phyllostachysae. After infection by the second generation of B. bassiana, the survival time of Pa. phyllostachysae fed on mixed feed increased significantly compared with the first generation. We also fed Pa. phyllostachysae different proportion of new bamboo leaves in mixed feed to simulate natural conditions. We found that increasing the proportion of new bamboo leaves in the food promoted pupal development and increased egg production; it also increased the resistance of larvae to the first generation of B. bassiana. The pathogenicity of the second generation of B. bassiana declined in all mixed feed treatments.     

Potential of two entomopathogenic fungi,Beauveria bassiana and Metarhizium anisopliae (Coleoptera: Scarabaeidae), as biological control agents against the June beetle

The aim of this study was to evaluate the effectiveness of the entomopathogenic fungi (EPF), Beauveria bassiana (Bals.) Vuill. (Deuteromycotina: Hyphomycetes) strain PPRI 5339 [BroadBand, an emulsifiable spore concentrate (EC) formulation] and Metarhizium anisopliae (Metsch.) Sorokin (Hypocreales: Clavicipitaceae) strain F52 [Met52, both EC and granular (GR) formulations] against the larvae of Polyphylla fullo (L.) (Coleoptera: Scarabaeidae). Larvicidal bioassays were performed in foam boxes (100 by 75 by 50 cm; length by width by height), containing moist soil medium with some humus and potato tubers as food. Although the B. bassiana product (min. 4 × 10⁹ conidia/ml) was applied at 100, 150, and 200 ml/100 l water; M. anisopliae strain F52 was applied at 500, 1,000, and 1,500 g/m³ of moist soil medium for GR (9 × 10⁸ cfu/g) and 75, 100, and 125 ml/100 l water for EC (5.5 × 10⁹ conidia/ml) formulation. Both fungi were pathogenic to larvae of the pest; however, young larvae (1st and 2nd instars) were more susceptible to infection than older ones (3rd instar). Mortality rates of young and older larvae varied with conidial concentration of both fungi and elapsed time after application. The B. bassiana product was more effective than both of the formulations of the M. anisopliae product, causing mortalities up to 79.8 and 71.6% in young and older larvae, respectively. The highest mortality rates of young and older larvae caused by the M. anisopliae product were 74.1 and 67.6% for the GR formulation, 70.2 and 61.8% for the EC formulation, respectively. These results may suggest that both fungi have potential to be used for management of P. fullo.     

Impacts of transgenic Bt cotton on a non-target pest, Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae), in northern China

Transgenic Bt (Bacillus thuringiensis) cotton has been effectively used to control the cotton bollworm, Helicoverpa armigera (Hübner) in China. However, in recent years, following the wide commercialization of Bt cotton in northern China there have been frequent outbreaks of the non-target pest Apolygus lucorum (Meyer-Dür). To clarify how transgenic cotton contributes to these outbreaks, a four-year field investigation of population dynamics and laboratory life table studies were carried out from 2007 to 2010 to evaluate the impact of two transgenic cotton cultivars (SGK321 expressing Cry1Ac + CpTI and GK12 expressing Cry1Ac) and their corresponding parental non-transgenic lines (Shiyuan321 and Simian3) on A. lucorum. There were no significant differences in the population densities of A. lucorum found in Bt cotton and non-Bt cotton plots, whether one compared those that had received insecticide treatments or those that had not. However, population densities of A. lucorum were significantly lower in pesticide treated plots than in controls. Furthermore, there were no significant differences in the net reproductive rates, generation times or intrinsic rates of increase of A. lucorum when reared on either Bt or non-Bt cotton cultivars. These results suggest that Bt cotton has no direct positive or negative effects on the biology of A. lucorum, so the most logical explanation for the observed outbreaks is the decrease in pesticide applications following the commercial release of Bt cotton.     

Relative Abundance of Carsonella ruddii (Gamma Proteobacterium) in Females and Males of Cacopsylla pyricola (Hemiptera: Psyllidae) and Bactericera cockerelli (Hemiptera: Triozidae)

Carsonella ruddii (Gamma Proteobacterium) is an obligate bacterial endosymbiont of psyllids that produces essential amino acids that are lacking in the insect’s diet. Accurate estimations of Carsonella populations are important to studies of Carsonella-psyllid interactions and to developing ways to target Carsonella for control of psyllid pests including pear psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae) and potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae). We used two methods, namely fluorescence in situ hybridization and quantitative polymerase chain reaction (qPCR), to estimate relative abundance of Carsonella in bacteriocytes and whole bodies of psyllids, respectively. Using these two methods, we compared Carsonella populations between female and male insects. Estimations using fluorescence in situ hybridization indicated that Carsonella was more abundant in bacteriocytes of female C. pyricola than in those of males, but Carsonella abundance in bacteriocytes did not differ between sexes of B. cockerelli. Analyses by qPCR using whole-body specimens indicated Carsonella was more abundant in females than in males of both psyllids. Neither fluorescence in situ hybridization nor qPCR indicated that Carsonella populations differed in abundance among adults of different ages (0–3 wk after adult eclosion). Using fluorescence in situ hybridization, Carsonella was observed in ovarioles of newly emerged females and formed an aggregation in the posterior end of mature oocytes. Results of our study indicate that female psyllids harbor greater populations of Carsonella than do males and that sex should be controlled for in studies which require estimations of Carsonella populations.     

Field efficacy of wintertime insecticide applications against greenbugs, Schizaphis graminum (Rondani) (Hemiptera: Aphididae) on winter wheat (Triticumaestivum L.)

Winter wheat producers in Oklahoma often combine an insecticide with a top-dress application of nitrogen during late fall and winter to control existing greenbug populations. We evaluated the efficacy of three classes of insecticides applied in cold weather field conditions ranging from −13.3 to 28.9 °C from 2002 to 2004 for greenbug control in winter wheat in replicated small plots. Insecticides provided control ranging from 0% to 98%, but generally responded similarly to temperature. Percent control of greenbugs resulting from applications of dimethoate, chlorpyrifos and λ-cyhalothrin was correlated with maximum, minimum and average daily temperatures that occurred two days post-treatment. While percent control was unique for each insecticide, a combined regression of percent control against average daily temperature predicted that a 95% level of control would be achieved when post-treatment temperatures exceeded 13.6 °C. Rainfall that occurred post-treatment affected the efficacy of dimethoate but did not affect the other insecticides. Insecticide persistence was extended under cooler temperatures, allowing acceptable control 14 days post-treatment if temperatures warmed. The decision to apply insecticides should be made based on existing treatment thresholds for greenbug, but if treatment with an insecticide is warranted, winter wheat producers can expect reasonable control of greenbugs from insecticides applied during the winter, as long as post-treatment temperatures exceed 13 °C within the following 14 days.     

Development,Survival, and Reproduction of Orius insidiosus (Hemiptera: Anthocoridae) Reared on Frankliniella invasor (Thysanoptera: Thripidae)

The minute pirate bug Orius insidiosus (Say) is an important predator in mango agroecosystems. It attacks several species of thrips, particularly Frankliniella invasor Sakimura, which is considered a species of economic importance in mango. We investigated the effect of six diets on the development, survival, and reproduction of O. insidiosus: 1) first instars of F. invasor, 2) second instars, 3) adults, 4) pollen, 5) pollen plus thrips larvae, and 6) water. Individuals fed on thrips larvae, with or without pollen, completed their immature development significantly faster. Nymphs of O. insidiosus were able to complete their development feeding on pollen only, while individuals that received water as a diet were unable to reach the adult stage. The highest intrinsic growth rate was obtained when O. insidiosus were fed on pollen plus thrips larvae, and the lowest when individuals were fed on thrips adults. Our studies show that a diet of pollen plus F. invasor larvae is optimal for O. insidiosus development and population growth.     

A preliminary study on the effects of a transgenic corn event on the non-target pest Dalbulus maidis (Hemiptera: Cicadellidae)

The inclusion of the cry gene in corn may produce direct effects on non-target pests. Our research was focused on the relationship between Bt corn germplasm, expressing the cry1F protein to control the fall armyworm [Spodoptera frugiperda (Noctuidae)], and a non-target pest, the corn leafhopper [Dalbulus maidis (Cicadellidae)]. The aim of this contribution was to elucidate if Bt corn plants have influence on the oviposition preference of the leafhopper and to evaluate the effect of the transgenic plant on the hatching rate of egg. Female corn leafhoppers were released in cages each containing two potted plants in the V2 stage: a Bt germplasm and the corresponding isogenic hybrid. Laid eggs were counted and the number of hatched nymphs recorded. D. maidis females oviposited and laid more eggs in Bt plants. The egg hatching rate was negatively affected by the Bt germplasm. In addition, a field study was conducted in order to determine the abundance of D. maidis adults in Bt corn and the corresponding non-Bt isoline. Two corn plots sown with the same germplasms as used in the laboratory bioassays were sampled weekly. In the field, the population of the corn leafhopper was higher in the Bt corn plot than in the non-Bt isoline. Possible hypotheses for the differences in abundance of the vector in the field are: a) that pleiotropic effects of Bt corn could attract adults; b) the existence of a possible direct competition between the corn leafhopper and the target pest in order to utilize the whorls of corn plants as refuge and feeding sites, so the high populations of the vector could be due to the large supply of healthy whorls in the transgenic plot; and/or c) a differential attack of natural enemies occurring in non-Bt plots.     

Balancing pest management and forest biodiversity: Vole populations and habitat in clearcut vs. variable retention harvested sites

Voles of the genus Microtus are long-standing pests in temperate and boreal forests of North America, Europe, and Asia where they feed on newly planted trees on cutover forest land. Clearcutting (CC) dominates forest harvesting and produces homogeneous habitats for voles. Variable retention (VR) harvests involve various partial cutting practices that produce heterogeneous habitat patterns compared with CC. This study tested the hypotheses (H) that compared to CC, VR harvesting will (H₁) limit population size of Microtus and feeding damage to tree seedlings; (H₂) provide some mature forest habitat for red-backed voles (Myodes gapperi); and (H₃) enhance abundance and species diversity of the terrestrial small mammal community. Microtus, red-backed voles, and other forest-floor small mammals were live-trapped for three years (2007-2009) on “young” and “older” CC and VR sites near Golden, British Columbia, Canada. Mean basal area (BA) and density of overstory coniferous trees were significantly (P ≤ 0.03) higher in the young VR than CC sites. Abundance of herbaceous vegetation and grasses was similar in both harvesting systems at 3- and 5-years post-harvest. Although not statistically significant, the relatively higher numbers (2.3-2.9 times) of Microtus on CC than VR sites at 3-4 years post-harvest is suggestive that VR may reduce Microtus population size. However, the mean abundance of 35 Microtus/ha in VR sites at 3 years post-harvest was at the border-line of moderate to high risk of feeding damage. Based on equivocal levels of vole damage to plantation trees on CC and VR sites, the damage part of H₁ was refuted. With respect to H₂, VR harvesting did provide some forest habitat for red-backed voles, at least initially in the third year, and then again at 10-20 years, after VR cutting. Total abundance and species diversity of the terrestrial small mammal community were similar in CC and VR sites, and hence H₃ was rejected. The mean BA (14.7 m²/ha) and density (73-127 trees/ha) of overstory (>10-20 m height) trees of our VR sites were insufficient to alter development of understory herbaceous vegetation and abundance of Microtus. Higher levels of VR should be investigated as a means of reducing this pest problem in young plantations.     

中国海南海岛小花蝽(Orius maxidentex Ghauri)的发现及生物学记述

花蝽是一类捕食性半翅目昆虫。花蝽科目前约包含70个属,其中小花蝽属（Orius Wolff, 1811）是最大的属,全世界包含约80种,中国目前有15种。小花蝽属的种类在蓟马的生物防治方面具有极大的应用前景,是生物防治领域研究和利用的热门天敌类群。目前在我国针对蓟马的有害生物综合治理及绿色防控项目中,能够应用的仅东亚小花蝽（O. sauteri）及南方小花蝽（O. strigicollis）。最近在海南发现的海岛小花蝽（Orius maxidentex Ghauri）为中国新记录种,国外分布于泰国、印度、巴基斯坦、伊朗、阿拉伯联合酋长国、苏丹、塞内加尔。本研究对海岛小花蝽的形态学特征和生物学特征进行了描述,拍摄了海岛小花蝽各虫态及生殖器特征图,并对其发育历期、捕食、交配、产卵、孵化、蜕皮、羽化及同类相食的现象进行了简单描述和研究。此外,本研究获得了海岛小花蝽线粒体细胞色素氧化酶亚基I（COI）基因序列,并提交到美国国家生物技术信息中心（GenBank登录号：OL798096）进行序列比对,分子鉴定结果表明与塞内加尔的海岛小花蝽序列高度一致。海岛小花蝽常见于青葙（Celosia argentea）、小蓬草（Conyza canadensis）等杂草,及芒果（Mangifera indica）、豇豆（Vigna unguiculata）和茄子（Solanum melongena）等作物的花及幼叶上。卵产于植物组织中,若虫阶段有5个龄期,成虫和若虫均以蓟马为食,可捕食花蓟马（Frankliniella intonsa）、黄胸蓟马（Thrips hawaiiensis）、棕榈蓟马（T. palmi）、豆大蓟马（Megalurothrips usitatus）、茶黄蓟马（Scirtothrips dorsalis）及美洲棘蓟马（Echinothrips americanus）等。海岛小花蝽在海南岛全年可见,且具有明显的种群优势,是海南蓟马害虫的重要天敌。本研究在实验室条件下,利用美洲棘蓟马（E. americanus）和大豆幼苗进行室内饲养和观察,发现海岛小花蝽在温度(25±2)℃及相对湿度75%±5%条件下,可以取食美洲棘蓟马完成世代发育,卵期(3.66±0.67)d,1龄若虫(1.72±0.65)d,2龄若虫(2.21±0.82)d,3龄若虫(2.62±0.62)d,4龄若虫(2.45±0.74)d,5龄若虫(3.21± 0.82)d。本研究凭证标本保存于中国热带农业科学院环境与植物保护研究所和中国农业大学植物保护学院昆虫标本馆。     

Variation in Bactericera cockerelli (Hemiptera: Triozidae) Oviposition,Survival, and Development on Solanum bulbocastanum Germplasm

The potato psyllid, Bactericera cockerelli, is a key pest of potato and important vector of the pathogen that causes zebra chip disease. Control of zebra chip relies entirely on the use of insecticides to reduce populations of this vector. The development of potato varieties resistant to B. cockerelli would contribute to cost-effective control of this insect. Wild potato germplasm are key sources for desirable traits including pest resistance to develop new potato cultivars. Our objective was to screen Solanum bulbocastanum germplasm for resistance to B. cockerelli. The combined use of choice and no-choice assays demonstrated considerable variability among S. bulbocastanum populations in their susceptibility to psyllids. At least six S. bulbocastanum populations exhibited resistance to B. cockerelli: PI 243512, PI 243513, PI 255518, PI 275194, PI 275197, and PI 283096. The documentation of the variability among S. bulbocastanum germplasm populations in their susceptibility to B. cockerelli can aid the development of potato cultivars that are naturally resistant to the potato psyllid.     

Interactions between Metopolophium festucae cerealium (Hemiptera: Aphididae) and Barley yellow dwarf virus (BYDV-PAV)

Interactions between an invasive aphid, Metopolophium festucae (Theobald) subsp. cerealium, and Barley yellow dwarf virus (BYDV-PAV) were studied under laboratory conditions. M. festucae cerealium is an economic pest of wheat and barley that has recently been found in high population densities in wheat in the Pacific Northwest of the United States. BYDV-PAV is the most prevalent and injurious species of BYDV worldwide and in the Pacific Northwest. Although M. festucae sensu stricto (Theobald 1917) has been reported previously as a vector of some BYDV isolates, there is no confirmed transmission of BYDV by M. festucae cerealium. Two experiments examined the ability of M. festucae cerealium to transmit BYDV-PAV. The first used single aphids caged to indicator plants of a BYDV-susceptible winter wheat cultivar and the second used multiple aphids on each test plant. M. festucae cerealium did not transmit BYDV-PAV in either experiment, whereas transmission by a known BYDV vector, Rhopalosiphum padi L., was consistently high (≥93%). A third experiment compared the intrinsic growth rate, days until first reproduction and daily reproduction by M. festucae cerealium on sham-inoculated and BYDV-PAV-infected wheat, but detected no differences. The findings are reviewed in light published data on M. festucae species, BYDV transmission, and the potential pest status of this new invading aphid.     

Thermal Biology of Liorhyssus hyalinus (Hemiptera: Rhopalidae) and Nysius simulans (Hemiptera: Lygaeidae), Fed on the Milky Stage of Maize Grains

When quinoa, Chenopodium quinoa Willd., is cultivated in South America outside of its Andean origin, the heteropterans Liorhyssus hyalinus (Fabricius) and Nysius simulans Stål may emerge as important pests. Here we studied the development and reproduction of both species at different constant temperatures in the laboratory. Egg and nymphal development were investigated at 18, 22, 26, 30, 34, and 36°C. For both species, egg incubation time significantly decreased as the temperature increased. Nymphs did not successfully develop at 18°C and the total nymphal time significantly decreased as the temperature increased from 22 to 36°C. Based on a linear day-degree (DD) model, the lower developmental threshold (LDT) temperatures for eggs and nymphs were estimated to be 16.0 and 17.9°C for L. hyalinus, and 16.1 and 19.7°C for N. simulans, respectively. Thermal requirements for egg and nymphal development were 68.6 and 114.8 DD for L. hyalinus, and 77.7 and 190.3 DD for N. simulans, respectively. Reproduction and adult longevity were studied at 22, 26, 30, and 34°C. For both species preoviposition time decreased as temperature increased, and the oviposition period was longest at 26°C. The highest fecundity and egg viability were observed at 30°C, whereas longevities were higher at 22–26°C than at 30–34°C. As the lowest tested temperatures were not suitable to both heteropterans and 30°C was found to be the optimal temperature for development and reproduction, peak densities are expected in warm areas and seasons.     

Spatiotemporal Distribution of Two Euschistus spp. Stink Bugs (Hemiptera: Pentatomidae) in Southeastern Farmscapes

Stink bugs (Hemiptera: Pentatomidae) are ubiquitous, cryptic, phytophagous pests that are found in many crops. In agroecosystems, individuals disperse from adjacent noncrop hosts and tend to aggregate or cluster within fields. In this study, we characterized the distribution of Euschistus servus (Say) and Euschistus tristigmus (Say) (Hemiptera: Pentatomidae) over 2 yr at three southeastern United States farmscapes. Stink bugs were captured in pheromone-baited traps, and Spatial Analysis by Distance Indices (SADIE) used to identify the location of significant aggregations by habitat type and season. Euschistus servus adults were more likely to be captured in pecan orchards, cotton, other crops, or unmanaged habitats than in woodland habitats. Significant aggregations of E. servus were detected in a variety of habitats including pecan, corn, cotton, peanut, and tobacco, as well as fallow and hay fields, pastures, and hedgerows. Fewer adult E. tristigmus were captured than E. servus adults, and E. tristigmus adults were typically trapped and aggregated in woodland habitats. The resulting data provide an important understanding regarding the seasonal movement and relative abundance levels of stink bug populations, which are critical to the development of integrated pest management strategies.     

Effect of photoperiod on development and reproduction of Megacopta cribraria(Hemiptera:Plataspidae)

Megacopta cribraria (Hemiptera: Plataspidae) continually outbreaks due to suitable photoperiod in recent years. Effect of photoperiod on growth, development and reproduction of M. cribraria were assessed in this study. Results indicated that developmental duration, nutrient accumulation efficiency, and adult fecundity of M. cribraria were significantly different under 6 photoperiodical conditions. Developmental duration of nymph stage gradually tended to be shorter as day time increase. Body weights of 5th instar nymphs for 16 h and 4 h day time photoperiods were 5.2 mg and 4.6 mg, respectively. Moreover, longevity of adults tended to be longer as day time increase. However, for the short day photoperiod (4 L:20 D and 8 L:16 D), population showed no reproductive behaviors. Index of population trend increased with photoperiod extension and adults showed stronger reproductive capacity and longer longevity. This research identified the favorable photoperiodical conditions before outbreak. It may provided reference for ecological adaptability of M. cribraria, and contribute to the scientific basis for forecasting and controlling of M. cribraria.     

Ecology of Meimuna mongolica (Hemiptera: Cicadidae) Nymphs: Instars,Morphological Variation,Vertical Distribution and Population Density,Host-Plant Selection,and Emergence Phenology

The cicada Meimuna mongolica (Distant) (Hemiptera: Cicadidae) is one of the most important pests of economic forest in Guanzhong Plain of Shaanxi Province, China. Information about ecological characteristics and some sustainable control measures of this species is urgently required for its control. In this study, nymphal instars, morphological variation, vertical distribution, and population density in soil, and emergence phenology of nymphs of M. mongolica on three main host plants (Pinus tabuliformis Carr., Populus tomentosa Carr., and Pyrus xerophila Yü) were studied, based on combined morphological and molecular identification, investigation of the first-instar nymphs hatched from eggs and others excavated from soil, and investigation of exuviae in the adult emergence period. Five nymphal instars of M. mongolica were redetermined according to the distribution plots of the head capsule widths of the nymphs. Nymphs of third and fourth instars showed morphological variation, which is closely related to host-plant association. The mean densities of nymphs in soil under the three host plants were significantly different, indicating a distinct host preference. The nymphs could extend their distribution from the 0–10 cm soil layer to the 51–60 cm soil layer underground but not beyond 60 cm soil layer under all the three host plants. The 21–30 cm soil layer under all the three host plants has the highest nymphal population density. The sex ratio of the entire population was nearly 50:50, but males dominated in the early half of the duration of the emergence. These ecological characteristics of M. mongolica could provide important information for sustainable control measures.     

褐飞虱NlTgo基因的克隆及功能研究

转录因子Tango(Tgo)在昆虫神经元发生、血细胞生成、性别决定、肠道发育等过程中发挥重要作用。克隆了褐飞虱Tango基因(NlTgo),应用荧光定量PCR和RNAi探索了NlTgo在褐飞虱中的表达动态和生物学功能。结果表明,NlTgo的开放阅读框为2007bp,推测编码669个氨基酸残基。多序列比对表明NlTgo与已知的Tgo高度同源,其中与人体虱(Pediculus humanus corporis)Tgo的一致性达68%。系统进化分析表明,NlTgo与豌豆长管蚜(Acyrthosiphon pisum)、始红蝽(Pyrrhocoris apterus)和臭虫(Cimex lectularius)的Tgo在系统发育树中形成一个类群。时空表达谱表明NlTgo在褐飞虱1龄、2龄时期高表达,在卵期表达量较低;在卵巢中表达量最高,在体壁的表达量较低。RNAi结果表明,注射ds NlTgo后4d,NlTgo的表达量较空白对照组显著降低了77%,并导致若虫不能正常蜕皮而死亡。其中,处理5d后褐飞虱的存活率仅为23%,显著低于注射dsGFP的对照组(98%)。结果显示,NlTgo与褐飞虱的生长发育有关,可作为防治褐飞虱的潜在靶标。     

Density,Demography, and Influential Environmental Factors on Overwintering Populations of Sogatella furcifera (Hemiptera: Delphacidae) in Southern Yunnan,China

Sogatella furcifera (Horváth) (Hemiptera: Delphacidae) is the most serious pest on rice in southwestern China. Yunnan province is within this region and is a major overwintering area for S. furcifera in China. This field study was carried out over 4 yr (2010–2013) and focused on S. furcifera distribution, population density, and demography, as well as the relationship between various environmental factors and the distribution and density of overwintering S. furcifera in Yunnan. Our study demonstrated that overwintering populations of S. furcifera mainly occurred in valleys and lowlands below 25.02°N and 1,680 m above sea level (a.s.l.), where ratooning rice was present. The overwintering range of S. furcifera has expanded in Yunnan compared with 20 yr ago, and regional climate change is believed to be the main contributing cause for this expansion. Environmental factor analysis showed that the mean air temperature of the coldest quarter and precipitation of the coldest quarter were two key factors that were strongly linked to the overwintering distribution and density of S. furcifera in Yunnan. Wintertime temperature was the principal influencing factor to determine the distribution and density of S. furcifera, while the effect of precipitation was indirect in that it influenced the insect’s distribution via its host. This study documented the major overwintering areas of S. furcifera in Yunnan, which can be used to predict outbreak potential in the following spring. Hence, key climatic factors, overwintering distribution, and density of S. furcifera should be used when forecasting outbreaks in spring.     

Cross-resistance, inheritance and stability of resistance to acetamiprid in cotton whitefly, Bemisia tabaci Genn (Hemiptera: Aleyrodidae)

The cotton whitefly Bemisia tabaci, (Genn.) is an important pest of field crops, vegetables and ornamentals worldwide. Neonicotinoids are considered an important group of insecticides being used against B. tabaci for several years. B. tabaci has developed resistance to some of the compounds of the group. This study was designed to investigate if the selection of B. tabaci with acetamiprid would give a broad-spectrum of cross-resistance and to genetically classify the resistance. At G₁ a low level of resistance to acetamiprid, imidacloprid, thiamethoxam, thiacloprid and nitenpyram was observed with resistance ratios of 3-fold, 8-, 9-, 6- and 5-fold, respectively, compared with a laboratory susceptible population. After selection for eight generations with acetamiprid, resistance to acetamiprid increased to 118-fold compared with the laboratory susceptible population. Selection also increased resistance to imidacloprid, thiamethoxam, thiacloprid, nitenpyram, endosulfan and bifenthrin but no change in susceptibility to fipronil was observed. Furthermore resistance in a field population was stable in the absence of acetamiprid selection pressure. Genetic crosses between resistant and susceptible populations indicated autosomal and incompletely recessive resistance. Further genetic analysis suggested that resistance could be controlled by a single factor. The high level of cross-resistance and stability of incomplete resistance in the field population is of some concern. However, lack of cross-resistance between acetamiprid and fipronil or unstable resistance in the resistant population could provide options to use alternative products which could reduce acetamiprid selection pressure.