栗山天牛幼虫龄数和龄期的测定

栗山天牛Massicus raddei (Blessig)是危害我国东北柞树天然林的重要蛀干害虫, 长期营隐蔽性生活, 3年发生1代, 防治困难。幼虫的龄数和龄期测定是害虫预测预报以及制订其科学治理策略的重要依据。本研究于2008-2011年通过林间定期解剖受害树进行取样, 在辽宁省宽甸县采集不同发育阶段的栗山天牛幼虫, 分别测量幼虫上颚长、 主单眼间距、 前胸背板宽、 中胸气门长和体长等5项形态指标, 利用频次分析的统计方法, 测定了栗山天牛幼虫的龄数。结果表明: 栗山天牛幼虫有6龄, 雌雄性幼虫龄数相同。上颚长、 主单眼间距和前胸背板宽3项指标均可用于分龄, 中胸气门长和体长变异较大, 不宜用作幼虫龄数划分。利用种群众数龄期法计算1-6龄幼虫的平均龄期分别为9.25, 266.85, 48.09, 51.29, 260.33和385.71 d, 幼虫期共1 021.52 d。在我国东北地区, 自然条件下栗山天牛世代发生非常整齐而且高度同步, 完成1代发育需跨越4个年份, 幼虫经历3次越冬, 第1年以2-3龄幼虫越冬, 第2年主要以4-5龄幼虫越冬, 第3年全部以末龄幼虫越冬。研究结果进一步明确了栗山天牛幼虫期的生物学特性, 为生产上合理防治该害虫提供了参考依据。     

杨黑点叶蜂幼虫龄数和龄期

夏季,采用室内常温、常光照条件下饲养的方法和解剖镜测微技术,研究杨黑点叶蜂Pristophora conjugata Dahlbom幼虫龄数和龄期。结果表明,杨黑点叶蜂雄性幼虫共5龄,雌性幼虫共6龄;各龄幼虫头宽值分别为(mm):0.585~0.849;0.849~1.371;1.371~1.960;1.960~2.350;2.350~2.868;2.868。根据幼虫头宽值确定幼虫所处龄期,为准确掌握防治时期提供科学依据。     

白蜡外齿茎蜂幼虫龄数和龄期测定

为掌握白蜡外齿茎蜂Stenocephus fraxini幼虫的龄数和发育历期,本文测量了幼虫体长、头宽、体宽(胸部第3节)、尾铗长和尾铗基径宽等5项指标.经频次分布和回归分析,结果表明:白蜡外齿茎蜂幼虫可分5龄.头宽和尾铗基径宽均可作为分龄指标.各龄头宽值分别为:0.414±0.002、0.526±0.002、0.71...     

眉斑并脊天牛幼虫龄数及各龄特征

测定头壳宽度室内观察结果表明,眉斑并脊天牛Glenea cantor(Fabricius)幼虫有4龄。1~4龄幼虫的头壳宽度分别为(0.66±0.20),(1.45±0.20),(2.22±0.23),(3.26±0.29)mm。其龄数(Y)与幼虫头壳宽(X)度符合关系式Y=0.2975+1.1606X。在25℃条件下,1~4龄幼虫的平均龄期分别为(5.25±0.60),(4.94±0.58),(5.98±0.63)d和(22.92±1.28)d,整个幼虫期为(39.09±2.14)d。还对眉斑并脊天牛各龄幼虫的形态特征作了描述。     

梨小食心虫幼虫龄数和龄期的划分

【目的】为明确梨小食心虫Grapholitha molesta(Busck)幼虫的发育状况,以便进行预测预报及采取防治措施。【方法】试验对幼虫头壳宽、上颚宽、体长和体宽4项指标进行测量。【结果】头壳宽和上颚宽符合Dyar法则和Crosby法则并呈现明显的线性回归关系,可作为龄期划分的重要指标,确定其龄期为5龄。室内26℃温度下饲养幼虫历期约为15 d,1~4 d为1龄期、4~7 d为2龄期、6~10 d为3龄期、8~12 d为4龄期、11~15 d为5龄期。【结论】幼虫刚毛、体色、斑纹也可作为龄期划分辅助参考方法,体长和体宽变异性较大,不宜作为幼虫龄数划分的标准。     

栎黄枯叶蛾幼虫龄数的确定

【目的】为明确栎黄枯叶蛾Trabala vishnou gigantina Yang幼虫的发育状况,以便进行预测预报及采取防治措施。【方法】通过野外采样获取不同发育状态的栎黄枯叶蛾幼虫,对其头壳宽度,体长,体宽,额宽,上颚基部宽和单眼间距6项形态指标进行测量,利用Crosby生长法则和线性回归方法,推断栎黄枯叶蛾幼虫的龄数。【结果】栎黄枯叶蛾幼虫有7龄,头壳宽度为最佳分龄结构。单眼间距、额宽和上颚宽3项指标均可作为分龄的辅助手段,体长和体宽变异较大,不宜用作幼虫龄数划分。【结论】研究结果为生产上合理防治该害虫提供了参考依据。     

萧氏松茎象幼虫龄数的估测

室内和林间调查的结果表明 ,萧氏松茎象HylobitelusxiaoiZhang幼虫期为 5～ 7龄。该虫在林间以老熟幼虫的前 1龄幼虫 ,即以第 4～ 6龄幼虫越冬 ,其中以 5～ 6龄幼虫为主 ,4龄幼虫仅占少数     

蜂巢奇露尾甲幼虫龄期的划分

为了明确蜂巢奇露尾甲Aethina tumida Murray幼虫的龄期和最佳分龄指标,本研究分别对不同发育阶段幼虫的头壳宽进行测量,根据各指标的频次分布结果初步确定龄期,并运用Crosby生长法则和线性回归方法进行验证分析。结果表明：蜂巢奇露尾甲幼虫可分为4龄,1~4龄头壳宽度平均值分别为0.1842 mm、0.2942 mm、0.4613 mm、0.7280 mm;此外,本文还对蜂巢奇露尾甲幼虫的形态特征进行描述。本文为研究蜂巢奇露尾甲的发生规律、生物学特性及制定防治措施等提供参考。     

榆木蠹蛾幼虫龄数的确定

为弄清榆木蠹蛾Holcocerus vicarius Walker幼虫的发育情况及预测其发生时间, 通过测量榆木蠹蛾幼虫的头壳宽、 体长、 体宽、 前胸背板宽、 上颚长和上颚宽, 运用Crosby生长法则和线性回归方法分析来找出判定幼虫龄数的最佳形态指标, 推断其幼虫的龄数。结果表明： 各龄幼虫头壳宽平均值的变异系数和Crosby指数最小, 其他5项指标的变异系数和Crosby指数较大, 头壳宽为最佳分龄指标。根据头壳宽将榆木蠹蛾幼虫分为20龄, 不同龄幼虫头壳宽值符合Dyar定律提出的幼虫头壳宽增长规律, 头壳宽和龄数的回归方程为y=0.233+1.686x+0.127x²-0.005x³ （R²=0.996）。榆木蠹蛾幼虫龄数的确定为研究其发生规律、 生物学习性及进行综合防治提供依据。     

椰子织蛾幼虫龄数及取食量的雌雄差异

为了明确椰子织蛾幼虫的龄数、取食量及龄期。在室温25℃±3℃,寄主食料椰子叶饲养条件下,测量了雌、雄幼虫头壳宽、取食量并记录了各龄幼虫的发育历期。结果表明,椰子织蛾雌性幼虫有9-10个龄数,雄性幼虫有8-10个龄数。1-10龄雌虫的头壳宽约为0.2300,0.3250,0.4300,0.5267,0.7700,0.9633,1.3775,1.5850,1.8200,2.1929 mm。1-10龄雄虫的头壳宽约为0.2233,0.3214,0.4125,0.5300,0.6529,0.8675,1.1267,1.3375,1.4950,1.8925 mm。9-10龄雌虫的头壳宽显著大于雄虫的头壳宽。头壳宽与龄数具有很强的相关性。椰子织蛾幼虫的取食量随龄数的增大而增加。椰子织蛾1代雌性幼虫平均取食椰子叶的面积(3607.23±146.83 mm~2)显著高于1代雄性幼虫平均取食椰子叶的面积(1991.25±143.92 mm~2)。1-5龄幼虫的取食量最小,小于50 mm~2。8-10龄为暴食期。1-10龄幼虫的发育历期分别为4.55±0.16,5.69±0.24,5.73±0.37,5.22±0.15,5.11±0.46,4.61±0.46,5.12±0.68,6.00±0.43,6.86±0.40和8.75±1.55 d。对于雌、雄成虫个体差异较大的昆虫,对其幼虫头壳宽值和取食量的测定应雌、雄幼虫分别测定。椰子织蛾的防治适期应在未造成严重为害的1-5龄幼虫高蜂期进行。以幼虫头壳宽为主,同时结合取食面积判定幼虫所处龄数,可为准确掌握防治时期提供科学依据。     

Inter- and intra-specific differences in the number of larval instars in British populations of 24 species of stoneflies (Plecoptera)

1. Ontogenetic changes during the life cycle of aquatic insects are important not only in life‐history studies but also in evaluating food‐web structure. They require information on the growth and number of larval instars but such information is lacking for many species, including Plecoptera. Therefore, the chief objectives of the present study were to determine inter‐ and intra‐specific differences in the number of larval instars in British populations of 24 species of stoneflies, to test Dyar’s hypothesis that growth followed a geometric progression, and to synthesise this information with previously published values for four British species. 2. Larvae were reared at constant temperatures in the laboratory from eggs from 63 populations (one to six populations per species). First instars from each population were divided into three batches and each batch was reared at one of three constant temperatures. For each species, the rearing temperature and source population had no significant effect on the mean size of each larval instar. 3. The relationship between the geometric mean length of each instar and instar number was well described by an exponential equation (P < 0.001, r² > 0.9 for all species), thus supporting Dyar’s hypothesis. Only one species, Brachyptera risi, had the same number of instars for males and females (12–13). For the other 15 herbivorous species and the four smaller carnivorous ones, the number of instars was higher for females than males (range 11–16 for males, 12–17 for females). The larger size of the females was due to their additional instars, not a sex difference in growth rates. In contrast, there was a clear growth separation of the sexes after the 9th or 10th instar for the four largest carnivores. The number of larval instars was highest for these four species (range 16–19 for males, 18–23 for females), and females were much larger than males. 4. A multiple regression equation with data from the present and previous studies (n = 27) showed that variability in the mean length of the first instar and the maximum number of larval instars for each species accounted for 88% and 91% of the variability in the mean length of the final instar for males and females, respectively. 5. Values for Plecoptera in other countries were in general agreement with those in the present study, especially in the same families. Two old, but widely quoted, high values are doubtful. The present study and four previous ones provide a sound basis for ontogenetic studies on 28 species of Plecoptera and their role in aquatic ecosystems.     

星天牛幼虫龄期的划分

本文测量了人工饲养的星天牛Anoplophora chinensis(Forster)幼虫的9个形态结构数据,运用频次分布、均差分析和回归分析对测量数据进行统计分析,结果表明,星天牛幼虫可分5龄,其额宽是最佳的分龄结构,其次是上颚长和上颚宽。     

Identification of instars and species in some larval Polypedilum (Polypedilum) (Diptera: Chironomidae)

Instars II and III of Polypedilum aviceps Townes, Polypedilum convictum (Walker), and Polypedilum illinoense (Malloch) can be identified to species by associating them with instar IV because key taxonomic characters remain relatively unchanged from instar to instar. Instars I cannot be identified to species or genus unless they are associated with older, identifiable larvae reared from the same egg masses. No single character evaluated on slide material can be used to clearly separate instars in all three species. Larvae of P. aviceps can be separated into instars based on any four of seven characters; P. convictum by either of two characters; and, P. illinoense by a combination of two characters. Changes in structures of instars II, III, and IV are described for all three species. Growth ratios for some structures are compared and discussed with regard to Dyar's Rule.     

Seasonal dynamics and larval drift of Chironomus riparius (Diptera) in a metal contaminated lowland river

Chironomus riparius is one of the insect species which inhabit polluted rivers in large densities, indicating a high adaptive capacity. Previous studies showed that this capacity is expressed by the occurrence of adapted strains in metal polluted rivers. Differences in life history between metal-exposed and non-exposed midges have been demonstrated in laboratory experiments, and therefore a comparative field study of seasonal dynamics was carried out at two metal polluted sites and one reference site. Just downstream from a massive metal discharge, seasonal dynamics were almost identical to the upstream reference site. Circa four generations per year were produced. Further downstream, lower larval densities were recorded, especially during the second half of the sampling period. The influx of upstream C. riparius larvae into polluted sites was estimated by measuring larval drift just upstream from the point source of metal contamination and indicated a massive input to the standing stock downstream. It is concluded that drift of non-tolerant larvae is dominating the seasonal dynamics of midges downstream. Accordingly, genetic uniformity of chironomids inhabiting upstream and downstream sites is expected most of the time. However, research performed during the last decade, demonstrated that genetically adapted strains of C. riparius may develop at certain stages in the seasonal cycle. However, a stable metal-adapted C. riparius population at the first downstream site, is most likely present on rare occasions only.     

桔小实蝇和番石榴实蝇幼虫取食阶段的种内竞争

种内竞争是实蝇的重要生态学特性。本文研究比较了近缘种桔小实蝇Bactrocera dorsalis(Hendel)和番石榴实蝇B.correcta(Bezzi)在幼虫人工饲料中种内竞争的密度效应。研究结果显示,桔小实蝇和番石榴实蝇都有密度过低效应,均表现出发育历期较长、蛹较轻和成活率较低;结合蛹重和成活率两个重要参数指标,明确了桔小实蝇和番石榴实蝇的最宜密度均在5-20头虫/10 g饲料;不同生长参数之间的变化均有一定的正负相关性。当种群密度超过最宜密度,桔小实蝇和番石榴实蝇均有明显的种内竞争现象,随着种群密度的升高,种内竞争越激烈。其主要表现为化蛹率和羽化率不断下降、幼虫历期逐渐缩短、蛹历期不断延长和蛹逐渐变小;当100头虫/10 g饲料时,桔小实蝇和番石榴实蝇成活率从86.00%±4.2688%和86.00%±4.1096%分别下降到60.08%±2.5166%和76.33%±2.2333%。桔小实蝇和番石榴实蝇的种内竞争的密度效应极具相似性,推测这两种实蝇有类似的种群调节机制,但番石榴实蝇的幼虫比桔小实蝇的拥有更强的抗拥挤能力。     

基于外部形态特征量化分析判别菱角水螟幼虫龄期

【目的】本实验拟为田间准确快速判别菱角水螟Parapoynx crisonalis(Walker)幼虫龄期提供一种新方法,以便监测其发生规律、预测其发生时间。【方法】本研究通过对幼虫头壳宽、复眼距、体宽和体长4项外部形态指标的测量,运用Crosby生长法则和线性回归分析方法,结合各项指标的频次分布进行分析。【结果】各龄幼虫头壳宽平均值的变异系数和Crosby指数最小,为判别幼虫龄期的最佳分龄指标,幼虫期共分为5龄,1~5龄的头壳宽分别为(0.2493±0.0053)、(0.3454±0.0018)、(0.5079±0.0031)、(0.7419±0.0190)和(1.1287±0.0369)mm,其与龄期数呈线性关系。通过实验室饲养观察菱角水螟幼虫蜕皮次数验证该虫幼虫期分为5个龄期。【结论】头壳宽为判定菱角水螟幼虫龄期的最佳指标,复眼距次之。     

Knockdown of specific cuticular proteins analogous to peritrophin 3 genes disrupt larval and ovarian development in Bactrocera dorsalis (Diptera: Tephritidae)

Cuticular proteins (CPs) are critical components of the insect cuticle and play important roles in maintaining normal insect development and defense against various environmental stresses. The oriental fruit fly (Bactrocera dorsalis) is one of the most destructive pests worldwide, and its eight CPs analogous to peritrophin 3 (BdCPAP3) family genes have been identified in our previous study. In the present study, we further explored the possible roles of CPAP3 genes in B. dorsalis development. Each sequence of BdCPAP3 genes contained three conserved ChtBD2 (chitin-binding) domains. Spatial and temporal expression patterns revealed that the four BdCPAP3 genes (BdCPAP3-A1, B, E, and E2) might play important roles in larval pupariation of B. dorsalis. Moreover, treatment with a juvenile hormone analog (methoprene) significantly restricted expression of these four CPAP3 genes, whereas treatment with 20-hydroxy-ecdysone induced expression. The RNA interference (RNAi) results revealed that down-regulated CPAP3 genes led to significant delay of pupariation, and injection of dsBdCPAP3-E into 5-d-old B. dorsalis larvae caused approximately 40% mortality. Interestingly, we also confirmed that BdCPAP3-D2 was involved in B. dorsalis ovarian development. This study showed that some specific CPAP3 genes had crucial roles in B. dorsalis development, and these CP genes could be used as potential targets to control this pest via RNAi.     

圆柏大痣小蜂幼虫龄期测定

明确圆柏大痣小蜂Megastigmus sabinae Xu et He（1989）幼虫的最佳分龄指标、幼虫龄数与各虫龄龄期,为探明圆柏大痣小蜂幼虫期的生长规律奠定基础。本研究通过测量圆柏大痣小蜂幼虫上颚关节宽、头宽、体宽和体长4个形态指标,利用频次分布推测幼虫龄数,运用Crosby生长法则和线性回归的方法判断圆柏大痣小蜂幼虫的最佳分龄指标并验证幼虫的龄数。将最佳分龄指标作为龄期判断依据,根据测量结果对其幼虫龄期进行划分。圆柏大痣小蜂幼虫共划分为5个龄期,上颚关节宽为圆柏大痣小蜂幼虫龄期划分的最佳形态指标,各龄幼虫的历期约为30 d、200 d、30 d、30 d、15 d,共305 d,主要以2龄越冬。