豌豆彩潜蝇幼期各虫态的形态学研究

【目的】豌豆彩潜蝇Chromatomyia horticola (Goureau)是我国蔬菜上常见的一种重要害虫,目前尚未见该虫幼期卵到蛹各虫态形态特征的系统研究。【方法】本研究采用野外取样和室内饲养的方法收集豌豆彩潜蝇的卵、不同龄期的幼虫以及蛹,对该虫从卵期到羽化成成虫的全过程进行了详细的观察,并通过测量幼虫口钩和头咽骨的长度对幼虫龄期进行了划分。【结果】卵期观察到了豌豆彩潜蝇及其他潜蝇科昆虫中从未记述过的卵的呼吸角。利用口钩和头咽骨长度将幼虫划分为3个龄期,并对不同龄期幼虫的形态特征进行了比较和描述,确定了通过骨化结构对幼虫龄期准确鉴定和通过外部形态快速鉴定的方法。根据豌豆彩潜蝇蛹期发育的形态特征变化将蛹期划分为5个明显的发育阶段。【结论】本研究记述了豌豆彩潜蝇卵到蛹期的形态特征并对幼虫龄期进行了划分,为潜蝇幼虫和蛹的形态学及豌豆彩潜蝇生物学、生理学和防治研究提供基础。     

Morphological variations in the pre-imaginal development of the ponerine ant Diacamma ceylonense

In the present paper, the larval development of the queenless ponerine ant Diacamma ceylonense is studied. Four instars were identified on the basis of cuticular processes – tubercles and spinules – which show discontinuous variation during growth and provide precise and reliable external morphological criteria for instar discrimination. In the first three instars, the larva possesses a striking proboscis, which disappears between the third and fourth instars. Larval weight increased around 50‐fold in the 21 days of larval life between eclosion and pupation (mean weight for first instar = 0.37 mg; for fourth instar = 20 mg). In addition, the morphology of the gemmae, structures resembling vestigial wings in workers, is described in nymphae.     

The larva of Norfolius (Neuroptera: Nymphidae)

The three larval stages of the sole species of Norfolius Navás, N.howensis (Tillyard), are described and figured. Features of possible phylogenetic value are discussed in relation to other known nymphid larvae, and differences between instars are appraised for the first time in the family.     

Scanning electron microscopy of the four larval instars of the Dengue fever vector Aedes aegypti (Diptera: Culicidae)

Aedes aegypti is the main insect vector of Dengue fever and dengue hemorrhagic fever/dengue shock syndrome and represents the only vulnerable element in the control of this disease. Therefore, the identification and quantification of this mosquito is an important task; however, the majority of taxonomic keys are based on the 4th larval instar. For that reason, this study describes the four larval instars ofA. aegypti using scanning electron microscopy. Morphological changes during larval development were observed at the pecten, comb scales and the ventral brush of the abdominal segment X; however, the 3rd and 4th instars showed similar structures with only a slight variation. The structures described in this study will be helpful in the identification of the four instars of A. aegypti, a fundamental task for comprehending the natural history of dengue mainly in new territories affected.     

骆驼斯氏副柔线虫病传播媒介西方角蝇和截脉角蝇的幼虫龄期划分

【目的】本研究旨在找出区分西方角蝇Haematobia irritans和截脉角蝇H.titillans幼虫龄期划分标准,为准确鉴定两种角蝇各龄幼虫,研究斯氏副柔线虫在角蝇体内的发育过程,以及制定防控骆驼斯氏副柔线虫病的有效措施等奠定基础。【方法】采用实验室人工孵育两种角蝇幼虫的方法,分别测量不同发育阶段幼虫的虫体长、咽骨体长和咽骨体宽3项指标,利用SPSS Statistics 19.0统计软件对数据进行处理,结合Crosby生长法则和线性回归的方法进行分析,比较两种角蝇幼虫之间差异,以确定两种角蝇幼虫最佳龄期划分标准。【结果】结果表明,两种角蝇的幼虫均分为3龄,咽骨体是两种角蝇幼虫龄期划分的特征性结构,两种角蝇各龄幼虫相同指标的测量值随龄期的增长呈现出相同的增长规律。咽骨体长是划分两种角蝇幼虫龄期的最佳测量指标,咽骨体宽可作为分龄的辅助指标;两种角蝇相邻龄期幼虫的体长变化范围存在相互重叠,不能准确划分角蝇幼虫龄期。【结论】研究表明通过西方角蝇和截脉角蝇幼虫咽骨体的形态特征可简便、快速和准确地鉴定两种角蝇幼虫的龄期。     

Comparative susceptibility of larval instars and pupae of the western corn rootworm to infection by three entomopathogenic nematodes

As a first step towards the development of an ecologically rational control strategy against western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte, Coleoptera: Chrysomelidae) in Europe, we compared the susceptibility of the soil living larvae and pupae of this maize pest to infection by three entomopathogenic nematode (EPN) species. In laboratory assays using sand-filled trays, Heterorhabditis bacteriophora Poinar and H. megidis Poinar, Jackson & Klein (both Rhabditida: Heterorhabditidae) caused comparable mortality among all three larval instars and pupae of D. v. virgifera. In soil-filled trays, H. bacteriophora was slightly more effective against third larval instars and pupae, and H. megidis against third larval instars, compared to other developmental stages. In both sand and soil, Steinernema feltiae (Filipjev) (Rh.: Steinernematidae) was least effective against second instars. In conclusion, all larval instars of D. v. virgifera show susceptibility to infection by all three nematodes tested. It is predicted that early application against young larval instars would be most effective at preventing root feeding damage by D. v. virgifera. Applications of nematodes just before or during the time period when third instars are predominant in the field are likely to increase control efficacy. According to our laboratory assays, H. bacteriophora and H. megidis appear to be the most promising candidates for testing in the field. I. Hiltpold similarly contributed to this paper as the first author.     

Effects of carbon-dioxide anaesthesia on the number of instars,larval duration and adult body size of the German cockroach, Blattella germanica

Effects of repeated carbon-dioxide anaesthesia during larval development on the number of moults, larval duration, and the body size of resulting adults were investigated. Concentration of carbon dioxide administered was 70%, and each period of anaesthesia lasted for 3 min. Anaesthesia administered twice a week until the 3rd instar increased the number of instars required to reach maturity. However, repeated anaesthesia after the 4th instar scarcely influenced the number of instars. On the other hand, repeated anesthesia prolonged larval duration whenever administered during the early or late instars. It is thus suggested that anaesthesia by carbon dioxide during larval development has two distinct effects: increasing the number of moults and prolonging larval duration. The former is stage specific and effective only during early instars, whereas the latter is effective during any particular instars until the last instar. The body size of resulting adults remained almost the same as for controls even after the repeated carbon-dioxide anaesthesia as many as 14 times. Some further observations concerning correlations between the number of moults, larval duration and adult body size are shown, and differences between the sexes regarding the number of instars and larval duration are also presented.     

Ultrastructural changes of the posterior silk gland cells in the early larval instars of the silkworm, Bombyx mori

The posterior silk gland cells in the first three larval instars show characteristic changes during growth that are essentially similar to those undergone in the fourth larval instar. In the feeding stage, when the cells grow rapidly, vesico-tubular rough endoplasmic reticulum and a number of Golgi vacuoles occur in the cytoplasm and the glandular lumen is filled with fibrous materials, probably fibroin. In the moulting cycle when the cells stop growing, a series of degenerative changes occur such as the appearance of autophagosomes, autolysosomes, and large vacuoles. Fibrous materials disappear from the glandular lumen. These cyclic changes are discussed in relation to hormonal changes. Intercellular junctions and the tracheal system of the silk gland are described.     

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。     

A change of heart: cardiovascular development in the shrimp Metapenaeus ensis

The larval development of penaeid shrimp is among the most complicated in crustaceans. In Metapenaeus ensis, there are six naupliar, three protozoeal and three mysid larval instars, followed by postlarval development. Irregular heartbeat begins late in naupliar instar 6. Co-ordinated beating at 400-600 beats min(-1) commences in the first protozoeal instar and continues throughout larval life. Initially, the contractile region is located more posteriorly in the cephalothorax and has a single pair of ostia, and the arterial distribution is limited to a single anterior vessel. In later mysid instars, a second cardiac pumping site develops posterior to, but connected with, the original site. This extension is more muscular, contains additional ostia and develops additional distribution vessels supplying the cephalothorax and abdominal areas. The original site is gradually merged into the new extension and only small refinements in the circulation occur in postlarval and juvenile life. Changes in physiological responses of the heart also occur throughout development. Responses to intra-pericardial microinjection of 5-hydroxytryptamine change drastically during development, as do cardiac responses to ambient hypoxia. Similarly, heartbeat of later juvenile instars is inhibited by injection of tetrodotoxin, while heartbeat of larval and early juvenile instars is not, suggesting that neurogenic regulation via the cardiac ganglion arises later in development. Our present studies attempt to integrate the anatomical and physiological changes in the development of the crustacean heart.     

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.     

Larval development and growth ratios of Odonata of the Azores

To fully understand odonate life cycles, it is vital to analyse the patterns of larval growth, which are tightly associated with variations in environmental factors. However, the identification of larval instars is often difficult, especially for early development stages. We hypothesise that pond hydroperiod influences odonate larval growth, and test this idea with novel information about the environmental characteristics of 12 study ponds in Terceira Island (Azores). This study, which represents the first analysis of larval development of Odonata in the Azores, involved determining the instars of development and growth ratios. We measured the morphological characteristics of 898 Odonata larvae, and found that they significantly differed between temporary and permanent ponds. To estimate the larval instars, we used two methods: frequency distribution methods and correlation diagrams between body characteristics. The first method was the most effective, allowing the estimation of 17 instars for Anax imperator, 13 for Sympetrum fonscolombii and 10 for Ischnura hastata, as well as growth ratios between instars for head width, total length, abdomen length, wings and antenna length. Our results also suggest that a combination of the two methods is the most appropriate strategy for estimating the number of instars and growth ratios during larval development.     

Larval mortality and development of Pseudoplusia includens (Lepidoptera: Noctuidae) reared on a transgenic Bacillus thuringiensis-cotton cultivar expressing CryIAc insecticidal protein.

The effects of a transgenic Bacillus thuringiensis (Bt)-cotton cultivar (DPL 32) on three instars of the soybean looper, Pseudoplusia includens (Walker), were determined in laboratory studies. First, third, and fifth instars were fed field collected Bt-cotton leaves for 1, 2, four and 7 d or until pupation, and then transferred to artificial diet. Mortality during the larval stage increased linearly in response to an increase in the length of feeding time on Bt-cotton by first and third instars. The maximum mortality of about two out of three larvae occurred for first instars fed on Bt-cotton until pupation. For the fifth instar, there was no significant response to feeding time; however, most of these larvae reached pupation before 4 d of feeding on Bt-cotton. The length of the larval developmental period also increased linearly with an increase in feeding time on Bt-cotton in first and third instars; again, there was no significant response in the fifth instars. For both mortality and larval developmental time, the linear trend lines for the first and third instars were quite similar. Pupal weight declined linearly in the first and fifth instars in response to feeding time on Bt-cotton. Although pupal weight also declined for third instars, the response was not linear. The effect of Bt-cotton appears not to extend past pupation in that there were no significant responses in mortality and developmental time of pupae during the pupal stage. These data indicate that larvae surviving Bt-cotton are adversely affected in several ways, which should be considered in evaluating Bt-cotton suppression of soybean looper infestations.     

青蒿蛀虫——白钩小卷蛾初步研究

白钩小卷蛾Epiblema foenella L.是药用植物青蒿(Artemisia apiacea Hance)的蛀干害虫,通过田间定点定时系统调查,得出该虫在长沙地区田间1年发生3代,以高龄幼虫在寄主残株及根部蛀洞内越冬,世代发育起点温度为12.122℃,有效积温为726.52日·度。描述了白钩小卷蛾各虫态及各龄幼虫的形态特征及生活习性,提出了有关预测技术及防治措施的建议。     

广州地区达摩凤蝶生物学特性观察

详细描述了达摩凤蝶Papilio demoleus L．各虫态的形态特征、生活史及生活习性。在广州地区。该蝶1年发生5代以上,以蛹在寄主植物上越冬,成虫3月初始见,幼虫共5龄,以芸香科的金橘属、酒饼筋和柑橘类等植物叶片为食料。     

Mass production of polyhedral occlusion bodies of NPV of Helicoverpa armigera in relation to dose,age and larval weight

A significant difference was noticed in the yield of polyhedral occlusion bodies (POBs) in various larval instars of H. armigera when three different doses of the nuclear polyhedrosis virus (NPV) were administered. The yield of POBs from a single larva ranged from 0.35 x 10(6) to 25033.33 x 10(6) with a mean of 18422.33 x 10(6) for fourth instar inoculated. Positive correlation existed between larval weight and number of POBs recovered. The regression analysis indicated POBs recovered responded with predictable manner to the weight of different larval instars and the various concentration of virus administered. The medium lethal time increased in the instars of the larva advanced with a minimum of 3.5 and maximum of 8 days in the first and fifth instars respectively.     

Developmental polymorphism in a Newfoundland population of the hemlock looper, Lambdina fiscellaria (Lepidoptera: Geometridae)

The hemlock looper [Lambdina fiscellaria (Guenée)], a widespread and highly polyphagous Geometridae, is considered one of the most economically important defoliators of North American coniferous forests. Variations in the number of larval instars between geographic populations of this species have been previously reported in the literature. However, whether such developmental polymorphism occurs within a given population is unknown. In this study, we report the presence of both four and five larval instar individuals within a population of hemlock looper in Newfoundland when reared on balsam fir. For both sexes, the majority of individuals reared on balsam fir shoots went through four larval instars, but more than one third of the females (35.3%) went through five larval instars. Females with four larval instars developed faster and had smaller pupal weight than females with five larval instars. However, a growth-related index (weight gain per unit of time) was similar for the two ecotypes (four or five larval instars). No significant difference was observed between the two ecotypes in terms of reproductive capacity (fecundity and egg size). We also found significant differences in life history traits between males and females. Results indicate that developmental polymorphism, in this case, the variation in the number of larval instars, might provide some adaptive attributes that allowed exploitation of a broader ecological niche.     

Distribution Patterns and Habitat Characterization of Elmidae and Hydraenidae (Insecta: Coleoptera) in the Weidlingbach Near Vienna,Austria

A total of 870 adult and 831 larval Elmidae and Hydraenidae were caught from September 1995 to September 1996 at the Weidlingbach, a fourth order tributary of the Danube near Vienna, Austria, using a Heß sampler at 14 sampling stations from source to mouth. Elmis maugetii (Latreille ) and Riolus subviolaceus (Müller ) accounted for 66.3% of the total, whereas Hydraena gracilis (Germar ) was the most abundant Hydraenidae species. Based on head width, instars 1–6 were collected in E. maugetii, instars 2–6 in R. subviolaceus and instars 3–6 in Limnius volckmari (Panzer ) and Riolus cupreus (Müller ); from the remaining species, only instars 4–6 were sampled. E. maugetii was most abundant on coarse, moss-covered substrates (median = 22.2 mm) exposed to high water velocity (median = 69.4 cm/s; range = 6.0–117.6 cm/s); the latter was also true for R. subviolaceus although it favoured smaller sediment grain sizes (median = 10.7 mm). Sites exposed to only moderate flow and with abundant filiform algae were preferred by Esolus parallelepipedus (Müller ) and L. volckmari, whereas the Hydraenidae species, Esolus angustatus (Müller ), R. cupreus and Oulimnius tuberculatus (Müller ) were collected mostly at sites with moderate current speed and abundant moss-covered pebbles of various size. Species richness and population density increased from source to mouth. At the spring sampling site Elmidae and Hydraenidae were completely lacking.     

Relating larval distributions to patterns of oviposition: evidence from lotic hydrobiosid caddisflies

1. To assess the influence of oviposition patterns on distributions of hydrobiosid caddisfly larvae, abundances of three hydrobiosid caddisfly species were estimated in whole reaches with and without suitable oviposition substrata along an upland temperate Australian stream. In addition, within‐reach spatial patterns were examined in relation to known oviposition locations as well as flow characteristics that corresponded to oviposition preferences. 2. Larval abundances in all samples were low relative to previous estimates of egg inputs into reaches. The presence of suitable oviposition substrata at a reach did not influence the abundances of larvae. For one species, benthic samples taken proximate to oviposition substrata revealed a sharp decline in abundance between first and later instars. Larvae of two taxa exhibited flow‐specific habitat preferences mirroring those described as important as cues for oviposition site selection. Previous estimates of egg mass aggregation were also reflected in similarly high levels of larval clumping; however, larval aggregation did not differ between reaches with and without oviposition sites. 3. Collectively, our results suggest that a large difference in the supply of potential recruits does not translate into marked differences in larval abundances of hydrobiosids at the reach level but may account for some variation in larval distribution within a reach and between instars. This evidence is consistent with the notion that (i) posthatching dispersal between reaches is substantial and (ii) mortality of larvae, particularly early instars, is high and (iii) within reach habitat preferences change with larval growth. 4. If adults are unable to lay eggs at reaches without suitable oviposition substrata, then reaches with oviposition substrata may be crucial as a source of recruits elsewhere. Furthermore, high mortality and/or dispersal among first instars signal this as an important part of the life history. Further data on the mortality and dispersal rates of newly hatched larvae would greatly benefit our understanding of the importance of local births in structuring patterns of abundance in stream invertebrates.