The life histories, trophic relations and production of Stenoperla prasina (Plecoptera) and Deleatidium sp. (Ephemeroptera) in a New Zealand river

The life history, feeding relations and production of the stonefly Stenoperla prasina were studied for 16 months in the Selwyn River, South Island, New Zealand. Larval life is about 1 year with growth occurring in all months. Although emergence of adults was observed only from November to February, egg hatching probably occurred over an extended period as small larvae were present in most months. Larvae were mainly carnivorous except in early instars when most guts contained detritus. Larvae of a mayfly, Deleatidium sp. and a chironomid, Orthocladiinae sp. were the most important prey items. In April of two successive years the guts of most stoneflies examined were filled with diatoms (Gomphonema sp.) and filamentous algae which were abundant in the river only at these times. Algal feeding was not found in other months. Larvae of the main prey species, Deleatidium, were present in all months, being most abundant in summer and declining in numbers during winter. Maximum emergence occurred in March and April. The annual cycle of Deleatidium was diflicuit to interpret as larvae of all sizes were present in all months. Two generations probably occurred in a year, a fast-growing summer generation and a slower-growing and less synchronized winter generation. Mean annual standing biomass, annual production and turnover ratios (P/B) were calculated for both species. The latter were within the range of values given by Waters (1969) but may be subject to error from several sources. Shortcomings in the method used to estimate production are discussed.     

Within‐generation dynamics of leatherjackets (Tipula paludosa Meig.)

Larvae of Tipula paludosa (leatherjackets) are pests of grassland and cereals, and important prey items for a range of farmland birds. Their population dynamics from year to year have been the subject of study, but within‐generation dynamics have received much less attention. The duration and occurrence of instars and size of the population is important to both pest management and bird conservation. Leatherjackets were collected monthly from four grass fields over five generations (October to September). Count data were analysed for sources of variability and used to estimate the timing and duration of instars and population changes over a single generation. Instar durations were correlated with temperature. From the first to third instars, sample counts were strongly influenced by the location of the site and the generation. Fourth instar larvae showed a similar decline in numbers across all sites and generations. The duration and timing of first to third instars was more variable than that of the fourth instar, but there was limited evidence that this was influenced by temperature. Only the durations of the third and fourth instars were correlated. The population decline from April to September coincided with the onset of the fourth instar. Our results show that the factors influencing leatherjacket numbers change over the life cycle, but by the fourth instar, these are biotically driven. The predictability of its numerical decline indicates defined windows for crop damage and availability as prey. The stability of its timing suggests that day length may synchronize the annual cycle. Fixed timing of the fourth instar will have important consequences for the timing of crop damage and the conservation of farmland birds as climate changes.     

Variation in genetic structure among populations of the caddisfly Helicopsyche borealis from three streams in northern California, U.S.A.

1. Allozyme electrophoresis was used to describe the genetic structure of Helicopsyche borealis caddisflies collected from three sites in each of three streams in northern California, U.S.A.: the Rice Fork of the Eel River; Big Sulphur Creek; and Alameda Creek. Between 7 and 11km separated adjacent sites within these three streams. Helicopsyche borealis from three additional streams in eastern North America (Christiana Creek, Indiana; Byrd's Mill Creek, Oklahoma; Susquehanna River, Pennsylvania) were also analysed electrophoretically to address taxonomic questions that arose during the study. 2. Four genetically distinct groups of individuals were identified (i.e. Helicopsyche types A, B, C, and D). Lack of interbreeding between sympatric groups (as evidenced by fixed allelic differences) and large genetic differences (mean Nei's genetic distances = 0.396–0.693) indicate that these four groups of Helicopsyche were actually reproductively isolated species rather than genetic variants of a single species. 3. Occurrence of Helicopsyche type A at multiple sites permitted an analysis of spatial variation in genetic structure. Within a drainage basin, small differences in allele frequencies were observed among sites in the Rice Fork and Big Sulphur Creek, but not in Alameda Creek. Larger genetic differences were found among sites in separate drainage basins. Genetic distances (Nei's) between Helicopsyche type A from California and from eastern North America sites (mean = 0.236) were greater than interpopulation differences commonly observed for insects, which suggests that Helicopsyche type A from California may represent a different species than Helicopsyche type A from eastern North America. 4. Geographical and taxonomic differences observed in this study underscore the importance of understanding both population structure and genetic relationships among populations in the design and interpretation of stream faunal studies.     

河南信阳地区茶毛虫发生代数研究

通过连续4年的调查研究表明,茶毛虫Euproctis pseudoconspersa Strand在河南信阳茶区年发生3代,而不是过去认为的每年发生2代。第1、2、3代幼虫分别在4月中旬至5月下旬、6月下旬至7月下旬、8月中旬至9月下旬为害茶树。     

Life cycle of the lilac pyralid Palpita nigropunctalis (Bremer) (Lepidoptera: Crambidae) on five oleaceous tree species

The seasonal abundance of Palpita nigropunctalis larvae was studied on five oleaceous tree species in Ibaraki, central Japan, for two years. The larval population peaked on some tree species in both spring and autumn while it peaked on other tree species only in autumn. In bimodal populations, the spring peaks consisted of larvae infesting leaves, while the autumn peaks consisted of larvae infesting various tree parts (flowers, fruits and leaves). Larval development was longer and pupal weights were lower on Ligustrum lucidum fruits than on Ligustrum japonicum fruits. Thus, L. japonicum fruits were suitable for larval development in autumn. First-instar larvae appeared to occur three times per year (in late April to early May, mid to late September and early to mid October). Adults were observed from late March to early April, mid May to early June, and early September to mid November at the census sites, showing that P. nigropunctalis had three generations a year. The percentage of females having premature ovaries were 64.3 and 12.5% at 15 °C under 14-h and 15-h photophases, respectively, and 28.6 and 25% at 20 °C under the respective photophases. These temperatures and photoperiods are typical of those in May and June in the census sites. The ovaries of females collected in the field between late May and mid July were premature, in agreement with the laboratory experiments. The pupal duration was prolonged under the short photoperiod, especially at reduced temperatures. We discuss a possible life cycle of P. nigropunctalis in Ibaraki.     

Invertebrate Food Supplies and Diet of Blue Duck on Rivers in 2 Regions of the North Island, New Zealand

Benthic invertebrates and samples of blue duck faeces were collected in September 1988 from sites along Manganuiateao River, central North Island, and in November 1988 from seven rivers and streams on the East Cape. The occurrence of invertebrate taxa in the faeces varied within and between rivers, and within pairs of birds and family groups on the East Cape. In both regions, most blue duck had been consuming large proportions of cased caddisfly larvae. These are thought to have been mainly species of Helicopsyche and Pycnocentrodes at the East Cape sites and Beraeoptera roria at the Manganuiateao sites. Plecoptera larvae were also relatively abundant in blue duck faeces from most Manganuiateao sites in September. Overall, blue duck consumed proportionately more cased caddisfly larvae than occurred in the benthos (especially at the East Cape sites), but fewer Chironomidae, Coloburiscus humeralis and leptophlebiid mayfly (mainly Deleatidium spp.) larvae. Factors that affect the type of invertebrate foods available to blue duck at a particular site could include habitat heterogeneity, chance encounter, frequency and magnitude of floods, and geographic differences in the pool of invertebrate colonists. Apparent selectivity or avoidance of some benthic invertebrate groups by blue duck may partly reflect predator evasion by fast-moving invertebrate species, and differences in activity and distribution on upper stone surfaces where invertebrates should be more susceptible to predation by blue duck.     

First record of a walnut shield bearer Coptodisca (Lepidoptera: Heliozelidae) in Europe

A leafminer of the Nearctic genus Coptodisca Walsingham (Lepidoptera: Heliozelidae), a species of potential economic interest, is reported for the first time from Europe, infesting the black (Juglans nigra L.) and the common walnut (Juglans regia L.). Mines were collected since September of 2010 in several sites of two Italian regions (Campania and Lazio). The species is rather similar to Coptodisca juglandella (Chambers), the only Coptodisca known to attack walnuts, but at present, an unambiguous identification cannot be provided because of the unsatisfactory characterization of this leafminer and congeneric species. Three generations were recorded per year and leafminers overwinter as mature larvae. The first adults emerged in May–June while mature larvae of the last generation started the overwintering in September. During the last generation of the year, infestation levels of leaves were 100% in all sampled localities. Several species of parasitoids were reared from infested mines, with specimens belonging to the genus Chrysocharis (Hymenoptera: Eulophidae) being the most frequent parasitoids.     

小波分析二点委夜蛾发生规律

二点委夜蛾Proxenus lepigone(Moschler),属鳞翅目夜蛾科,主要分布于日本、朝鲜、俄罗斯和欧洲等地。我国于2005年7月在河北省夏玉米田首次发现。近年来,该虫发生范围不断扩大,为害程度日益加重。2011年二点委夜蛾在我国夏玉米产区严重暴发,虫情涉及6省47市302个区(县),面积近220万hm2。山东省2007年首次在德州市发现该虫为害玉米,2011年全省17个地市普遍为害严重。为更准确地确定该虫的发生代次、每代各虫态发生历期、发生盛期、发生高峰日等信息,适时准确监控发生时期,本文采用symlets小波函数变换滤除高频信息,对山东省多地点二点委夜蛾成虫诱虫数据进行分析,结果显示,二点委夜蛾在山东省一年发生4代,越冬代、1代、2代、3代,始见蛾日在3月底—4月上旬,越冬代成虫发生期在3月底至4月上中旬,1代发生期在4月上旬至6月中下旬,2代发生期在6月中旬至8月上中旬,3代发生期在8月上旬至9月中下旬,越冬代幼虫发生期在9月中旬至10月中下旬,10月下旬左右老熟幼虫做茧越冬。另外,通过调查和室内观察还发现高温环境不利于二点委夜蛾幼虫生长发育,7—8月份高温期,成虫致畸率较高。     

Comparison of macroinvertebrate assemblages inhabiting pristine streams in the Huron Mountains of Michigan, USA

Benthic macroinvertebrate assemblages were surveyed from similar erosional biotopes of four pristine streams in the remote Huron Mountain region of the upper peninsula of Michigan during the summers of 1992 and 1993. Semi-quantitative samples from five sites, each in a 1.5 km stretch of Mountain Stream, Pine River, Salmon-Trout River and Huron River, were the basis for structural and functional comparisons between streams. Ancillary water chemistry data reflect the relative pollution free nature of these streams. Both water chemistry and macroinvertebrate data served as the first baseline data for Huron Mountain streams. No new or rare species were found among the 194 species sampled. Temporal differences in taxonomic makeup within streams were due to differences among insect species life cycles. Taxonomic makeup between streams was generally similar, but certain differences are shown to be possibly related to factors such as lake sources, interspecific interactions, and stream size. Based on relative abundance of each functional feeding group, assemblages in all streams were functionally similar and collector-dominated. ANOVA results indicated significant differences in functional feeding group abundance and biomass between streams in every case. The functional variations reflected by specific differences in taxonomic composition between stream assemblages are discussed.     

Description and Bionomics of Mesomermis camdenensis n. sp. (Mermithidae), a Parasite of Black Flies (Simuliidae)

Mesomermis camdenensis n. sp. is described from larvae of Simulium tuberosum (lundstroem) collected in Camden Valley Creek, Washington County, New York. This species possesses a barrel-shaped vagina, vulval flap. two short separate spicules, terminal mouth, six longitudinal chords, six cephalic papillae, large sexually dimorpbic anaphids, an esophagns of uniform width which extends for less than one-third of the body length, and a cone-shaped tail directed ventrally without appendage. Juveniles also are described and illustrated.A detailed morphological comparison with the mermithid M. flumenalis Welch is presented. The most pronounced morphological differences between these species are in the shape of the vulva, juvenile tail, and infective stage. Cross-mating trials support the integrity of the new species.The life cycle of M. camdenensis is closely synchronized with that of its primary host, S. tuberosum larvae. Infected S. tuberosum larvae were first collected in May. Emergence of postparasites from late instars took place from mid-June through mid-October. Sampling data indicate a lower susceptibility to infection among S. venuslum Say larvae.     

The life cycle and growth ofIsoperla grammatica andI. difformis (Plecoptera) in southernmost Sweden: intra- and interspecific considerations

Studies on the life cycle and growth ofIsoperia grammatica andI. difformis from eight southern Swedish streams demonstrated that the former species shows greater between-stream differences than the latter species.I. grammatica larvae had typically two periods of rapid growth, autumn and spring, whileI. difformis larvae grew mainly in autumn-winter. In one of the streams, however,I grammatica grew rapidly throughout all winter. Maximum larval size differed between streams, and so did the timing of the first appearance of nymphs and nymphal maturation. Temperature was probably the most influential factor explaining all these differences. While sexual dimorphism inI. grammatica is slight but significant, it is very prominent inI. difformis. The sizes of larvae overlapped little between species as well as sexes suggesting that intra- and interspecific competition was, or had been, important. InI. grammatica this reduced overlap was expressed in several size-classes of males and females successively replacing each other, resulting in a meandering pattern of the size distribution charts. There were additional indications of possible interactions, such as a significant negative correlation between the densities of the two species.     

黑脉蛱蝶的生物学特性与生境调查

通过野外观察、室内饲养、野外调查等方法研究黑脉蛱蝶Hestina assimilis(L.)的生物学特性以及生境状况。该蝶幼虫以榆科朴属(Celtis spp.)植物为食,在南京地区1年发生3代,10月下旬以4龄或5龄幼虫在寄主植物的落叶中越冬,翌年4月初越冬幼虫眠起活动。越冬代成虫5月上旬始见、中旬为高峰期;第1代7月上旬始见、中旬为高峰期;第2代9月上旬始见、中旬为高峰期。幼虫共5龄,在室内饲养的条件下,卵期为4～5d,幼虫期为28～42d,蛹期为7～8d。     

矢尖蚧发生动态及其寄生性天敌

柑桔矢尖蚧在福建闽北地区一年发生3代。以雌成虫和部分若虫及少数雄蛹越冬．一龄幼蚧盛期,第一代为4月中,下旬。第二代7月上．中旬,第三代9月中旬前后。二龄幼蚧盛期．第一代为5月上、中旬,第二代7月下旬,和第三代9月下旬．后期世代重叠．福建已知寄生蜂6种．其中一种为重寄生蜂,以矢尖蚧黄蚜小蜂为优势种．寄生生蜂自然寄生率最高达49.1%。     

The biology and life cycles of Lipsothrix spp. (Diptera: Tipulidae) inhabiting wood in Western Oregon streams

SUMMARY. 1. The immature stages of the craneflies Lipsothrix nigrilinea and L. fenderi are spent in galleries within decayed red alder ( Atntts rtibra ), in low order streams of the Pacific Northwest. L. fenderi also occurs in some coniferous wood and wood in semi-terrestrial sites at stream margins. Larvae of both species feed on the wood and are important degraders of this material.
2. The immature stages are briefly described and behaviour of the two species is compared.
3. L. nigrilinea has a predominantly biennial life cycle. It emerges from April to August in response to receding water level. The absence of this cue results in an extension of the life span to 3 or more years. The non-deterministic life cycle results in high variability of juvenile and adult weights.
4. L. fenderi is basically a biennial species, with a more synchronized autumn emergence. A portion of the population may emerge after 1 year if oviposition occurs early enough to allow autumnal growth of larvae or if growth is relatively rapid.
5. The extended life cycle of Lipsothrix spp. and the broad emergence of L. nigrilinea are concluded to be adaptations to a habitat/resource which is relatively stable and allows long-term association.     

The Life Cycle of Lestes viridis (Odonata: Lestidae) in Two Seasonal Streams of the Sierra Morena Mountains (Southern Spain)

The life cycle of the zygopteran odonate Lestes viridis in two seasonal streams in the Sierra Morena Mountains is inferred from size-frequency analyses of handnet samples of larvae and records of presence and reproductive activity of adults during three consecutive years. The egg stage (duration 5–6 months) overwinters, larval development is brief (6–8 weeks) and adults undergo a protracted, prereproductive, summer diapause (up to 3 months) before mating and ovipositing in late September, about one week after the first appreciable fall of rain, but before surface water reappears in the streams after having been absent for about four months during the hot, dry summer. Comparison between this life cycle and those of more northerly populations reveals a latitude-correlated cline in phenology resembling that found in some other northern hemisphere odonates that, like L. viridis, maintain an obligatorily univoltine life cycle at different latitudes.     

OBSERVATIONS ON THE DISTRIBUTION,EMERGENCE AND BEHAVIOUR OF CENTRAL AFRICAN CHAOBORIDAE

SUMMARY

The distribution of four species of Chaoboras over selected parts of Zimbabwe is given. The effect of temperature on the duration of the larval life cycle is discussed in relation to the generation time and the lunar periodicity of the adult emergence period. There were apparently two generations of larvae present in the habitat at any one time, although these generations were not distinct due to the variations in the time taken by the larvae to complete development at any temperature. The emergence was synchronized to the lunar cycle, but the actual moon phase at which emergence occurred was variable, as the two populations under observation both changed from new moon emergences to full moon emergences during the study. Some observations on the behaviour of adult Chaoboras edulis are given.     

Optimal seasonal schedules and the relative dominance of heteromorphic and isomorphic life cycles in macroalgae

Marine macroalgae (seaweed) show diverse life cycles. Species with a heteromorphic life cycle have a large multicellular algal body in one generation but have a very small body in the second generation of the same year. In contrast, the diploid and haploid life forms of isomorphic species have similar morphology, and these species often have more than two generations in a year. Here, we first study the optimal life cycle schedule of marine macroalgae when daily mortality changes seasonally, and then we discuss the conditions for coexistence and relative dominance of different life cycles. According to the optimal life cycle schedule, heteromorphic species tend to have a generation with a large algal body when mortality is low, and a microscopic-sized generation when mortality is high. In contrast, isomorphic species tend to mature when body size reaches a threshold value that is the same for different generations. We then examine the coexistence of the two life cycles when growth rate decreases with biomass. The model predicts that (1) at high latitudes (i.e., in strongly seasonal environments), heteromorphic species are likely to dominate over isomorphic species, and (2) species with a heteromorphic life cycle should dominate in the supratidal and upper intertidal zones where macroalgae tend to suffer high mortality, and also in the subtidal zone, where mortality is low, whereas isomorphic species are likely to be more successful when mortality is intermediate. These predictions are consistent with the observed distribution patterns of the two life cycles in macroalgae.     

千屈菜一种新害虫——肾毒蛾

肾毒蛾Cifuna locuples Walker是2007年在武汉发现危害千屈菜(Lythrumsalicaria L.)的一种新害虫,幼虫能取食千屈菜叶片和花朵。室外观察和室内饲养结果表明,肾毒蛾在武汉市1年发生3代,以低龄幼虫越冬,次年3～4月开始为害。5月初越冬代成虫出现,6月下旬第1代成虫羽化,8月中旬第2代成虫羽化。成虫羽化1d后即可分多次产卵于叶背,卵粒数十几到两百多粒。幼虫有5龄,初孵幼虫群集为害,2龄以后分散取食,4～5龄取食量大。幼虫在叶背吐丝结稀疏的薄茧化蛹。     

Age structure and growth of Semotilus atromaculatus(Mitchill) in PCB‐contaminated streams

Creek chub Semotilus atromaculatus from two PCB contaminated streams (Clear Creek and Richland Creek) at three locations and a reference stream (Little Indian Creek), Indiana, U.S.A., were examined to determine if age class structure and growth variables were correlated with in‐situ PCB exposure. Approximately five to 15 fish were captured weekly during the spring spawning season and monthly thereafter for a 12 month period. Fish collected ranged from 25 to 267 mm total length (L_T). Throughout the course of this study, no spawning activity was observed at either location in Clear Creek, although some very small young‐of‐the‐year (YOY) creek chub fry were observed at the downstream location by late summer. Creek chub nests were observed in both Richland Creek and Little Indian Creek but YOY were common only in Little Indian Creek. Exposure to PCBs was shown to both enhance and decrease growth in varied laboratory tests; subtle but significant gender‐specific differences in the growth of creek chub populations between the sites were observed. Creek chub up to 24 months in age from Clear Creek and Richland Creek were significantly larger (both L_T and mass for males and L_T for females) than reference site creek chub. This trend was reversed for creek chub aged ≥24 months as the reference site fish were consistently larger with reference males weighing significantly more. Older age classes of creek chub were missing in areas of higher PCB contamination. Female population growth rates and individual instantaneous growth rates were consistently higher at the reference site in comparison to the PCB‐contaminated sites. Calculation of ‘functional b’(as a condition factor) did indicate that growth enhancement in young males did occur at the most contaminated site and reductions in growth (mass relative to L_T) occurred in females from all contaminated sites. Furthermore, long‐term survivorship for females was reduced in the PCB‐contaminated streams. All of these subtle alterations in growth would not have been observed if males and females had not been analysed separately.     

The life cycles of three species of Ephemeroptera in two streams in Poland

Nymphs of Rhithrogena iridina, Baetis alpinusand Baetis melanonyx were collected in theWoosatka and Terebowiec streams; Bieszczady NationalPark, southeastern Poland. The streams have differentenvironmental conditions. The life cycles of Rhithrogena iridina in the Woosatka and theTerebowiec streams were of the univoltine winter type.In the Woosatka (Station 1) this species had aunivoltine life cycle with one cohort. In theTerebowiec (Station 2), R. iridina had aunivoltine life cycle with two cohorts – winter andsummer. The development of Baetis alpinus tookvarious courses depending on environmental conditions.At the lower station (Woosatka), where watertemperature reached higher values and the stream bedis less shady, the species had a winter-summer cyclewith two generations a year. At the higher station,(Terebowiec) it likely had a winter cycle with one ortwo generations. Baetis melanonyx had summercycles with one generation at both stations.