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。     

用气质联谱测定褐飞虱体内的保幼激素

用气质联谱法检测了稻褐飞虱1~5龄若虫及羽化后1 d的成虫的保幼激素滴度,结果表明在各龄若虫及成虫的各种翅型下都能检测到JH-1和JH-3。以JH-3滴度计算,就1龄、2龄、3龄、4龄、5龄以及成虫而言,其检测下限分别为25、15、15、10、1、1头。此方法测定的全过程回收率JH1和JH3分别为91.3%和95.7%。     

Development of a Method for Rearing Nezara viridula (Heteroptera: Pentatomidae) on a Semi-solid Artificial Diet

A method for rearing the southern green stinkbug, (Nezara viridula L.) (Heteroptera: Pentatomidae), using a modified lygus semi-solid artificial diet was developed. First to second-instar nymph were reared in a density of 631.5 ± 125.05 eggs per Petri-dish (4 cm deep × 15 cm diam). Second instar to adult were reared in a density of 535.0 ± 112.46 s instar nymphs per rearing cage (43 × 28 × 9 cm). Mating and oviposition occurred in popup rearing cages (30 × 30 cm), each holding 60–90 mixed sex adults of similar age. Adults emerged 35.88 ± 2.13 d after oviposition and survived for an average of 43.09 ± 9.53 d. On average, adults laid 223.95 ± 69.88 eggs in their lifetime, for a total production of 8,099 ± 1,277 fertile eggs/oviposition cage. Egg fertility was 77.93% ± 16.28. Egg masses held in petri-dishes had a total hatchability of 79.38% ± 20.03. Mortality of early nymphs in petri-dishes was 0.64% ± 0.12 for the first instar and 1.37% ± 0.45 for second instar. Late nymphal mortality in rearing cages was 1.41% ± 0.10, 3.47% ± 1.27, and 4.72% ± 1.29 for the third, fourth, and fifth instars, respectively. Survivorship from nymphs to adults was 88.48% ± 2.76. Using artificial diet for rearing N. viridula could reduce cost by avoiding time-consuming issues with daily feeding fresh natural hosts and insect manipulation. It could increase reliability and simplicity of bug production, which should facilitate mass rearing of its biological control agents.     

Analysis of Differential Proteins in Two Wing-Type Females of Sogatella furcifera (Hemiptera: Delphacidae)

Sogatella furcifera (Horvath) is an important rice pest with the wing dimorphism, including macropterous and brachypterous morphs. The protein expression profiles in two wing-type adults and two wing-type disc fifth-instar nymphs were analyzed using two-dimensional gel protein electrophoresis and mass spectrometry. In adults and fifth-instar nymphs, 127 and 162 protein spots were detected, respectively. Fifty-five differentially expressed protein spots were identified between the long-winged adults and the short-winged adults, and 62 differentially expressed protein spots were found between the long-winged disc fifth-instar nymphs and short-winged disc fifth-instar nymphs. In long-winged and short-winged adults, six and seven specific protein spots were identified, respectively, with five and seven protein spots having more than threefold increased level, respectively. In long-winged and short-winged disc morph nymphs, 8 and 12 specific protein spots were identified, respectively, with 11 and 17 spots containing more than threefold increased level, respectively. Among the 16 identified proteins, five proteins are associated with muscle function, suggesting that muscle is a main tissue where the genes were differentially expressed between the two wing types. In addition, the content of a peptidase with an insulinase domain was higher (by 3.02 ± 0.59 fold) in the short-winged fifth-instar nymphs than in the long-winged fifth-instar nymphs, which suggests that this peptidase may be involved in wing differentiation by regulating insulin receptors. The results of this study provide some genetic clues for the wing differential development in S. furcifera and provide more references for future studies.     

桑小头木虱Paurocephala sauteri Enderlein生物学特性研究

近年在海南各植桑区均发现桑小头木虱（Paurocephala sauteri Enderlein）严重为害,桑园被害株率达100%。在我国,该木虱仅记录于台湾省,为我国大陆新入侵害虫。本研究在实验室条件下[(27±1)℃、RH (70±5)%、12L∶12D],采用45日龄桑树扦插苗和离体叶片饲养,对桑小头木虱的发育与繁殖特性及各虫态的形态特征开展观察。结果表明,桑小头木虱生活史包括卵、1~5龄若虫和成虫期。各龄期主要形态特征为：卵呈水滴形,带短的卵柄,端部具细长的端丝,初产时乳白色,待孵化时可见淡红色眼点;1龄若虫头、胸部乳白色,复眼和腹部橘黄色,无翅芽;2~5龄若虫黄绿色,随着龄期增加,体长增加,翅芽随之变化。2龄翅芽出现,稍突起;3龄翅芽较小,呈三角形;4龄和5龄翅芽长椭圆形,其中5龄超过腹部第1节。各龄若虫和初羽化成虫均可分泌白色球形蜡质。雌雄成虫以两性生殖方式繁殖后代,羽化3 d后体色由黄绿色逐渐变为黄褐色并开始交配,交配时间为0.5~3 h,结束交配18~21 h后开始产卵,产卵量为20~42粒。卵单个散产于叶片背面叶脉处,偶尔可见产于新抽嫩叶正面边缘,5~7 d后孵化,孵化率为98.19%,雌性百分率为70.44%。若虫期12~18 d,完成一代的时间为18~24 d。本研究将为桑小头木虱的准确识别与监测,以及防控策略的制定提供前提条件和理论依据。     

Effect of temperature on the life history of Dysmicoccus neobrevipes (Hemiptera: Pseudoccocidae): An invasive species of gray pineapple mealybug in South China

The gray pineapple mealybug, Dysmicoccus neobrevipes Beardsley, is an invasive pest that during recent years has caused serious damage on Sisal (Agave sisalana Perrine) crops in South China. The biology of D. neobrevipes including its development, survivorship, longevity and reproduction was investigated at six constant temperatures (17, 20, 23, 26, 29 and 32 °C) under laboratory conditions. Results indicated that the developmental periods of D. neobrevipes females (from the first instar nymph to adult) shortened from 55.4 days at 17 °C to 16.9 days at 29 °C, while the males' decreased from 54.0 days at 17 °C to 15.8 days at 32 °C. The highest survivorship of D. neobrevipes from the first instar nymph to adult was recorded at 29 °C; 88.8% for females and 89.2% for males. The average longevity of females was 95.0 days at 17 °C, but decreased to 30.0 days at 26 °C. This was still significantly longer than those of males; 5.6 days at 17 °C and 2.3 days at 32 °C. The average number of nymphs laid per female increased with increasing temperature and reached a maximum of 409.4 nymphs at 23 °C. The intrinsic rates of increase (r_m) of D. neobrevipes at the range of temperatures between 17 and 32 °C were 0.0287, 0.0613, 0.0941, 0.1131, 0.1202 and 0.0485, respectively. The lower temperature thresholds for females and males of D. neobrevipes from the 1st instar nymph to adult estimated using the linear model were 8.7 and 10.3 °C, respectively. The thermal constants for females and males were 370.4 and 312.5DD, respectively. The results indicate that temperature has significant effects on the biology of D. neobrevipes and that the optimum temperature range for its population growth is 23–29 °C.     

中华稻蝗对植物挥发性化学物质的触角电生理和行为反应

采用触角电位仪(EAG)和Y型嗅觉仪测定了中华稻蝗6龄若虫和成虫对9种植物挥发性化学物质的嗅觉和行为反应.EAG反应结果表明,中华稻蝗成虫对9种植物挥发性化学物质的反应值均低于6龄若虫,其中对顺-3-己烯-1-醇的EAG反应值6龄若虫显著高于成虫,对香叶醇的EAG反应6龄雌性若虫显著高于成虫及雄性若虫.1-戊醇可引发中华稻蝗雌、雄6龄若虫间显著的EAG反应差异,雌、雄成虫对9种挥发性化合物的EAG反应表现一致.行为测定结果表明,除6龄雄虫外,中华稻蝗其他各虫态对反-2-己烯醛和乙酸顺-3-己烯酯2种化合物均表现出显著的行为趋性.中华稻蝗对香叶醇的EAG反应和行为反应相一致.对水稻、稗草和马唐3种寄主植物的行为反应测定结果表明,中华稻蝗雌性成虫和雌性6龄若虫对马唐存在显著的行为趋向性,而所有试虫对水稻和稗草却表现出随机选择效应.因此,香叶醇很有可能会在中华稻蝗对寄主植物的定向行为中发挥重要作用,而对寄主植物的选择性可能会影响中华稻蝗雌虫的生长发育及产卵行为.     

Population density and life-history parameters of the psyllid Bactericera nigricornis (Forster) on four commercial cultivars of potato

The psyllid Bactericera nigricornis (Forster) (Hemiptera: Triozidae) is one of the most important pests of potato, Solanum tuberosum L., in the Ardabil region, Iran. The use of host plant resistance is an essential component of the integrated management of B. nigricornis. In this study, we investigated the population density of B. nigricornis on four commercial cultivars of potato under field conditions and its life-history parameters under laboratory conditions. In field experiments, the lowest and highest densities of B. nigricornis were observed on cvs. Agria and Marfona, respectively. Population densities did not differ significantly between cvs. Kaiserkrone and Satina. In experiments on life-history parameters, the longest and shortest developmental times of nymphs were observed on cv. Agria (22.3 days) and cv. Marfona (18.2 days). The developmental time of nymphs on Kaiserkrone did not differ significantly from that on Satina. The lowest number of eggs laid per female (47.2) and the lowest survival rate (50%) were observed on Agria. The survival rate on Agria did not differ significantly from that on Kaiserkrone and Satina. The intrinsic rate of natural increase (r_m) and population growth rate (λ) were lowest on Agria and highest on Marfona. The generation time on Agria and Kaiserkrone was significantly longer than on Satina and Marfona. The doubling time (DT) was longest on Agria (15.9 days) and shortest on Marfona (11.8 days). Amongst the cultivars investigated, host plant resistance acted by decreasing the numbers of eggs laid per female, increasing the development time and reducing the survival rate of B. nigricornis, so decreasing population growth. Of the cultivars tested, Agria is the most resistant host and has potential for use in the integrated management of B. nigricornis on potato.     

Use of reciprocal grafts to elucidate mode of resistance to Colorado potato beetle (Leptinotarsa decemlineata (Say)) and potato aphid (Macrosiphum euphorbiae (Thomas)) in six wildSolanum species

Reciprocal grafts were done between potato (Solanum tuberosum) and six wildSolanum species known to be resistant to the Colorado potato beetle (Leptinotarsa decemlineata (Say)). Potato or wildSolanum foliage from each reciprocal graft was fed to first instar beetles or adult potato aphids (Macrosiphum euphorbiae (Thomas)). The proportion of second instar larvae after 48 h and survival and fecundity (number of nymphs per female) of the aphids were used to i estimate the resistance level of the foliage. Survival and fecundity of potato aphid were reduced on wildSolanum foliage (except withS. circaeifolium ssp.capsicibaccatum andS. okadae) used as scion or rootstock, but were not different from the control (potato-potato graft) on potato foliage. Development of Colorado potato beetle onSolanum foliage was reduced. In some cases, potato foliage grafted to wildSolanum became resistant to the beetle. Results suggest that a chemical factor or factors providing resistance to Colorado potato beetle are translocated from foliage of some wildSolanum species to potato foliage. They also indicate that mode of resistance to the two insects differs quantitatively or qualitatively.     

Impacts of Cucurbit Chlorotic Yellows Virus (CCYV) on Biological Characteristics of Its Vector Bemisia tabaci (Hemiptera: Aleyrodidae) MED Species

Plant viruses can change the phenotypes and defense pathways of the host plants and the performance of their vectors to facilitate their transmission. Cucurbit chlorotic yellows virus (CCYV) (Crinivirus), a newly reported virus occurring on cucurbit plants and many other plant species, is transmitted specifically by Bemisia tabaci MEAM1 (B biotype) and MED (Q biotype) cryptic species in a semipersistent manner. This study evaluated the impacts of CCYV on B. tabaci to better understand the plant-virus-vector interactions. By using CCYV-B. tabaci MED-cucumber as the model, we investigated whether or how a semipersistent plant virus impacts the biology of its whitefly vector. CCYV mRNAs were detectable in nymphs from first to fourth instars and adults of B. tabaci with different titers. Nymph instar durations and adult longevity of female whiteflies greatly extended on CCYV-infected plants, but nymph instar durations and adult longevity of male whiteflies were not significantly influenced. In addition, the body length and oviposition increased in adults feeding on CCYV-infected plants, but the hatching rates of eggs and survival rates of different stages were not affected. Most interestingly, the sex ratio (male:female) significantly reduced to 0.5:1 in whitefly populations on CCYV-infected plants, while the ratio remained about 1:1 on healthy plants. These results indicated that CCYV can significantly impact the biological characteristics of its vector B. tabaci. It is speculated that CCYV and B. tabaci have established a typical mutualist relationship mediated by host plants.     

Interference by Western Flower Thrips in rearing Asian citrus psyllid: Damage to host plants and facultative predation

An infestation of Western Flower Thrips (WFT), Frankliniella occidentalis (Pergande), recently developed on young citrus trees in a greenhouse devoted to rearing Asian citrus psyllid (ACP), Diaphorina citri Kuwayama. Large numbers of young flush leaves were killed which negatively impacted ACP, as ACP is dependent on flush for oviposition and nymph development. Further, WFT predated on immature ACP killing a large proportion of young nymphs. Two experiments were subsequently conducted to assess WFT damage to two ACP rearing host plants, orange jasmine [Murraya exotica (L.)] and sweet orange [Citrus sinensis (L.) Osbeck]. Direct comparisons of WFT damage to the two host plants were not made because the plants were not studied at the same time and the age of adults used in the experiments was not known. An infestation of ten adult WFT per flush shoot caused significant damage to orange jasmine: most (73%) flush shoots were killed, and shoots not killed were significantly growth retarded. Ten adult WFT per flush shoot caused little damage to sweet orange. A third experiment showed that five adult WFT per 90 ACP eggs predated on large numbers of eggs and 1st instar ACP − only 13% of the eggs hatched and developed beyond the 1st nymphal instar (WFT did not attack later instars). Predation on ACP immatures in this experiment included an evaluation of a minute pirate bug [Orius insidiosus (Say), regarded as effective against WFT] also at five adults per 90 ACP eggs. All ACP eggs were killed by this predator before eclosion. O. insidiosis might be useful for reducing infestations of WFT on citrus or other ACP host plants, but the predator would be incompatible with rearing ACP.     

Insecticide-induced increase in the protein content of male accessory glands and its effect on the fecundity of females in the brown planthopper Nilaparvata lugens Stål (Hemiptera: Delphacidae)

The brown planthopper Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) is a classical resurgent rice pest induced by insecticides. The past focus on resurgence mechanisms has been on the stimulation of the reproduction of adult females induced by insecticides. To date, the role that males play as a resurgence of N. lugens has not been investigated. The present study examined changes in protein levels in both male accessory glands and female ovaries induced by the insecticides triazophos and deltamethrin as well as the stimulating effect of treated males on the fecundity of adult females via mating following foliar sprays of the insecticides. For adults that had been exposed as nymphs to treated rice plants, the protein content in both the male accessory glands and in the female ovaries of N. lugens were significantly affected by male mating status, insecticide and insecticide concentration. There was a higher protein content in male accessory glands when males were exposed to triazophos as third instars compared to fifth instars, and there was a higher protein content before mating compared to after mating. In addition, the protein levels in male accessory glands after mating for individuals exposed to high doses of the two insecticides as 3rd and 5th instars were significantly lower than untreated control except for exposed to triazophos as 3rd instar, indicating that treated males transferred more male accessory gland protein to adult females via mating. The protein content was also affected by different combinations of treated mating pairs. Adult males (♂_t) developed from third instar nymphs treated with triazophos stimulated the fecundity of the female significantly via mating (♂_t × ♀_ck) with untreated females (♀_ck) (control females), increasing the reproductive rate by 43.5% as compared to the mating (♂_ck × ♀_ck) of untreated males and females. Also, the fecundity of the females after the mating (♂_t × ♀_t) of treated males and females was significantly higher than that after the mating (♂_ck × ♀_t) of untreated males with treated females. These findings indicated that the reproductive effects of insecticide on males can be transferred to females via mating. The present findings provide valuable information for understanding the potential role that males play in the pesticide-induced resurgence of N. lugens.     

Injury to apples and peaches at harvest from feeding by Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) nymphs early and late in the season

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive species that has become an important orchard pest in the Mid-Atlantic region of the US. Adults and nymphs feed on tree fruit. Feeding injury from adults has been characterized but the injury from nymphs has not been examined systematically. Since the four plant-feeding instars of H. halys (second through fifth) differ substantially in size, it is plausible that the effects of their feeding on fruit injury and injury expression may differ among them. We compared feeding injury at harvest from young nymphs (second plus third instars), older nymphs (fourth plus fifth instars), and adults that were caged on ‘Smoothee Golden’ apples and ‘Redhaven’ peaches in early June (peach and apple), late July (peach), and late August (apple). Individual apples and peaches were caged at fruit set and assigned to the following treatments (n = 28/treatment): 1) control (no H. halys), 2) young nymphs or 3) adults early in the season, and 4) young nymphs, 5) older nymphs or 6) adults later in the season. Fruit in each treatment were exposed to 3–4 young nymphs, two older nymphs or 1–2 adults placed in the cages for 96 h and evaluated for external and internal feeding injury within 36 h after harvest. No injury was recorded from unexposed peaches or apples. The percentage of injured fruit and number of injuries per fruit varied significantly among the exposed treatments. Early season feeding by young nymphs yielded the least injury to peaches and apples. In apples, the highest percentage of injured fruit and number of injuries per fruit were caused by late season feeding by adults. In peaches, early season adult feeding produced the highest percentage of injured fruit and injuries per fruit. More internal than external injury was recorded on peach and no such difference was observed on apple. The implications of these findings on H. halys management in fruit orchards are discussed.     

Effects of plant essential oils on immature and adult sweetpotato whitefly, Bemisia tabaci biotype B

Effects of essential oils derived from garden thyme, Thymus vulgaris L., patchouli, Pogostemon cablin (Blanco) Benth., and lemon-scent gum, Corymbia citriodora (Hook.) K. D. Hill & L. A. S. Johnson, on mortality of eggs, first-instar nymphs, and pupae, and on adult oviposition, of Bemisia tabaci (Gennadius) biotype B were determined under laboratory conditions. Three concentrations of essential oils, 0.125%, 0.25% and 0.5% (v/v), were applied in contact toxicity experiments. In separate experiments, 0.5% essential oil treatment was tested for repellency. Greater mortality was observed with increasing dose of essential oils. No phytotoxicity was observed on plants treated with these essential oils. First-instar nymphs were more sensitive to essential oil treatments, compared with eggs and pupae. The greatest effect was found with essential oil extracted from T. vulgaris, which reduced the survival rate of B. tabaci by 73.4%, 79.0% and 58.2% after treatment of eggs, nymphs and pupae, respectively, as compared with controls. In no-choice tests, the cumulative survival rates of B. tabaci females treated with T. vulgaris, P. cablin and C. citriodora were 46.4%, 38.8% and 26.8% lower, respectively, as compared with controls. In choice tests, the mean numbers of eggs laid on P. cablin, T. vulgaris and C. citriodora oil-treated plants were 74.5%, 59.0% and 48.0% fewer, respectively, than on control plants. Based on this study, essential oil derived from T. vulgaris possessed the greatest contact toxicity, while P. cablin oil exerted the strongest repellency to B. tabaci. Hence, these two oils could be used as effective and environmentally sustainable bio-insecticides for the control of B. tabaci.     

Seasonal Changes in the Caste Distribution of Foraging Populations of Formosan Subterranean Termite in New Orleans,Louisiana

This study examined the relationship between temperature, precipitation, soil composition, levels of feeding damage, and the caste distribution (workers, soldiers, nymphs) of the Formosan subterranean termite, Coptotermes formosanus Shiraki, collected in underground monitoring stations over a 12 mo period. Because nymphs are the caste that develops into alates, the seasonal abundance of nymphs was examined over a 5 yr period. Numbers of workers, soldiers, and soldier/worker ratio were significantly affected by month. Recruitment and retention of foraging termites in stations was significantly affected by the level of feeding damage. The number of nymphs collected in monitoring stations was highly variable. In the 12 mo test, there was a significant correlation between numbers of nymphs and level of feeding damage, temperature, precipitation, and soil composition. Over a 5 yr period, significantly more nymphs were collected in 2011 than in 2007 and 2008. Peak nymph collections varied from year to year. Overall, peak nymph collections were more likely to occur in Mar., Sept., and Oct. Increasing our knowledge of the environmental factors that influence recruitment and retention of foraging termites in monitoring stations could influence termite bait placement and improve baiting strategies for termite control. Identifying the key factors that cause aggregations of nymphs in underground stations could increase our ability to predict the intensity and location of alate swarms.     

温度对海岛小花蝽5龄若虫捕食茶黄蓟马功能反应的影响

海岛小花蝽（Orius maxidentex Ghauri）是蓟马的重要天敌昆虫,在热带地区,海岛小花蝽是优势天敌,对高温有较强的适应能力,较适合热带地区的害虫防治。目前海岛小花蝽对茶黄蓟马（Scirtothrips dorsalis Hood）的控害情况尚未明确,为了解海岛小花蝽对茶黄蓟马的控制作用,明确不同温度对海岛小花蝽捕食茶黄蓟马功能反应的影响。本研究以海岛小花蝽5龄若虫为例,在16、20、24、28、32℃温度条件下,测定海岛小花蝽5龄若虫对茶黄蓟马2龄若虫和成虫的捕食功能反应。在16~32℃,随着温度的升高,海岛小花蝽5龄若虫随猎物密度的增加,其捕食量有明显的逐级上升趋势;试验温度范围内海岛小花蝽5龄若虫对茶黄蓟马的捕食功能反应均符合Holling Ⅱ型方程。海岛小花蝽5龄若虫对茶黄蓟马2龄若虫的捕食能力与茶黄蓟马成虫的捕食能力并无明显差异,在28~32℃范围内,海岛小花蝽对茶黄蓟马的捕食量显著高于其他试验温度;海岛小花蝽5龄若虫在试验温度32℃,猎物密度为60头时捕食量最大,对茶黄蓟马2龄若虫与成虫的捕食量分别为34.6、34.0头。海岛小花蝽5龄若虫对茶黄蓟马2龄若虫与成虫在32℃时的处理时间最短,分别为0.0119、0.0115 d。海岛小花蝽5龄若虫对茶黄蓟马的捕食量与茶黄蓟马猎物密度呈正相关,但寻找效应与猎物密度呈负相关,在相同的猎物密度下,随着温度的升高,寻找效应逐渐下降,海岛小花蝽5龄若虫对茶黄蓟马表现出较高的寻找效应。当猎物密度大于最大捕食量时,海岛小花蝽5龄若虫取食具有选择性,仅取食茶黄蓟马腹部。海岛小花蝽5龄若虫在较高的温度条件下表现出对茶黄蓟马有良好的控害能力,是热带地区重要的天敌资源。