Nocturnal migration of dragonflies over the Bohai Sea in northern China

Abstract.  1. A sudden increase and subsequent sharp decrease of catches of dragonflies in a searchlight trap, with Pantala flavescens Fabricius (Odonata: Libellulidae) predominating, observed at Beihuang Island in the centre of the Bohai Gulf, in 2003 and 2004, indicated a seasonal migration of these insects over the sea during the night in China. The movements were associated with the onset of fog.
2. Simultaneous radar observations indicated that the nocturnally migrating dragonflies generally flew at altitudes of up to 1000 m above sea level, with high density concentrations at about 200–300 or 500 m; these concentrations were coincident with the temperature inversion.
3. During early summer, the dragonflies oriented in a downwind direction, so that the displacement direction varied between different altitudes. In contrast, during late summer, the dragonflies were able to compensate for wind drift, even headwind drift, so as to orient south-westward no matter how the wind changed, and thus the displacement direction was towards the south-west.
4. The duration of flight, estimated from the variation of area density derived from radar data and hourly catches in the searchlight trap through the night, was about 9–10 h. The displacement speed detected using radar was ≈5–11 m s⁻¹. Therefore, the dragonflies might migrate 150–400 km in a single flight.
5. The dragonflies were thought to originate in Jiangsu province and they migrated into north-east China to exploit the temporary environment of paddy fields in early summer. Their offspring probably migrated back south during late summer and autumn.     

Mass aerial migration in the carabid beetle Notiophilus biguttatus

Abstract.  1. Catches in traps at 12 and 200 m above ground, and observations with entomological radar, were used to document the high-altitude windborne movements of carabid beetles over agricultural land in south-east U.K. during July 1999, 2000, 2002, and 2004.
2.  Notiophilus biguttatus (Fabricius) was found to be the most abundant species at altitude, with flights by reproductively immature adults resulting in millions of beetles passing through a 1 km² window during the brief migration period in July 2002.
3. This result was unexpected in view of the conclusions of an earlier, classic Dutch study by den Boer and colleagues that classified N. biguttatus as a poorly dispersing species that tended to become isolated in remnants of natural habitat.
4. Reasons for the discrepancy between the two studies are discussed. It is hypothesised that the high mobility seen in the N. biguttatus populations results from a recent adaptation of the beetle's migration syndrome allowing it to exploit the mosaic of temporary habitat patches making up the increasingly intensive agroecosystems of northern Europe.     

Evidence of autumn overseas migration in the rice planthoppers, Nilaparvata lugens and Sogatella furcifera: analysis of light trap catches and associated weather patterns

ABSTRACT. 1. Daily trap catches of the rice planthoppers, N.lugens Stal and S.furcifera Horvath, and associated synoptic weather patterns were analysed in Kyushu, south-west Japan, in the autumns of 1980–85.
2. Certain weather patterns which seemed to favour overseas immigration, were reflected in trap catches: of eighteen occasions in which back-tracks on 850 mbar wind fields reached central China, marked mass catches in a light trap occurred on six occasions, and peaks in catch curves were found on another seven occasions.
3. These results strongly imply overseas immigration of the planthoppers from China to Kyushu in autumn, identical to invasions by the same species in early summer. However, such autumn migration is apparently non-adaptive because migrants or their progeny are soon killed by cold weather.     

Doppler radar detection of exceptional mass-migration of aphids into Finland

Our objective was to detect mass migrations of insects of economic significance by insect traps and a Doppler weather radar. Migrants were sampled by suction traps, tow nets and light traps in the Helsinki region. We used radar to observe the migrating insects, and trajectories to backtrack mass migrations of aphids (Homoptera, Aphididae) in spring 1988. The aphid migrations were clearly observed in trap catches and by radar. The first migration, mainly involving Euceraphis betulae, occurred on 18 May and was tracked back to northern Poland. The second migration, mainly of Rhopalosiphum padi (a serious pest of small-grain cereals), occurred 3 days later and was tracked back to a large area covering Latvia and western Russia south of St Petersburg. The third migration included both E. betulae and R. padi, and took place on 30 May. It originated from Estonia. Neither trap nor radar data provide exact quantitative information on migrations. Trapping efficiency depends strongly on wind speed and insect size. Radar echo intensity is very strongly related to the sizes of insects in the large volume of air measured, and the sizes are not known accurately. Weather data, especially temperature, can be used in predicting the development of aphids, and air-parcel trajectories in estimating the source areas of migrants. These methods for forecasting aphid migrations, combined with radar observations, are useful for warning purposes and to intensify insect trapping. This would contribute to more efficient agricultural pest management. Received: 11 March 2000 / Revised: 24 April 2000 / Accepted: 26 April 2000     

滇西南稻区白背飞虱种群特征及其关键影响因子

为明确滇西南沧源县稻区白背飞虱Sogatella furcifera的种群发生特征及其影响因子,于2010-2019年通过灯诱监测和田间调查的方法,分析沧源县白背飞虱的越冬种群、灯诱种群及田间种群发生特征,并对白背飞虱种群数量的影响因素进行相关性分析.结果表明:(1)白背飞虱以成、若虫在再生稻、落粒稻上越冬,越冬虫量最...     

New methods for the detection of insecticide resistant Myzus persicae in the U.K. suction trap network

1  Myzus persicae is a highly polyphagous pest of U.K. agriculture. It presents particular control difficulties because it has developed resistance to several insecticide classes.
2 For almost 20 years, M. persicae collected in the U.K. suction trap network have been analysed for insecticide resistance and the data disseminated to growers via a resistance bulletin. These data are generated by the biochemical analysis of individuals for two major resistance phenotypes: (i) elevated carboxylesterase and (ii) modified acetylcholinesterase (MACE).
3 The development of new polymerase chain reaction (PCR)-based technologies using fluorescently labelled probes has allowed other resistance mechanisms, such as knockdown resistance to pyrethroids (kdr/super-kdr), to be detected and has greatly increased the speed and accuracy of resistance monitoring. Unfortunately, these newer PCR-based assays are incompatible with the older biochemical assays.
4 The present study describes the development and testing of new compatible methods for detecting elevated carboxylesterases and MACE for use on M. persicae caught in the field or suction traps.
5 These new tests have significant advantages over present methodologies by allowing individual aphids to be tested for three resistance mechanisms quickly and accurately on a single platform.     

草地螟2007年越冬代成虫迁飞行为研究与虫源分析

草地螟 Loxostege sticticalis L.是危害我国北方农牧业的一种重要迁飞性害虫,明确草地螟的虫源地及迁飞路线对其早期预警具有重要意义。本文利用垂直监测昆虫雷达的长期观测,迁飞高峰期雌虫卵巢解剖、大区环流分析、各地虫情信息收集和利用Hysplit_4模型进行轨迹分析,研究了2007年越冬代草地螟的空中迁飞行为和东北地区严重暴发的草地螟虫源。结果表明：6月7–9日,雷达观测点诱虫灯内草地螟具有典型迁飞昆虫生理特征;草地螟主要在夜间迁飞,飞行高度集中在300～500 m,400 m是主要飞行高度,迁飞高峰期夜间迁移可持续9 h。东北地区严重发生的草地螟虫源,一部分来自内蒙古乌盟地区,一部分来自蒙古共和国中东部及中俄边境地区。据此推测我国与国外草地螟存在虫源交流。     

Seasonal variation in the migration strategies of the green lacewing Chrysoperla carnea species complex

Abstract.  1. Insect migration strategies are generally poorly understood due to the propensity for high-altitude flight of many insect species, and the technical difficulties associated with observing these movements. While some progress has been made in the study of the migration of important insect pests, the migration strategies of insect natural enemies are often unknown.
2. Suction trapping, radar monitoring, and high-altitude aerial netting were used to characterise the seasonal migrations in the U.K. of an assemblage of aphid predators: three green lacewings in the Chrysoperla carnea species complex.
3. Chrysoperla carnea sens. str . was found to be very abundant at high altitudes during their summer migration, and some individuals were capable of migrating distances of ≈ 300 km during their pre-ovipositional period. In contrast, high-altitude flights were absent in the autumn migration period, probably due to a behavioural adaptation that increases the probability that migrants will encounter their over-wintering sites. The other two species in the complex, C. lucasina and C. pallida , were much rarer, making up ≈ 3% of the total airborne populations throughout the study period.
4. The summer migration of C. carnea sens. str . was not directly temporally associated with the summer migration of its cereal aphid prey, but lagged behind by about 4 weeks. There was also no evidence of spatial association between aphid and lacewing populations.
5. The results show that to understand the population ecology of highly mobile insect species, it is necessary to characterise fully all aspects of their migration behaviour, including the role of high-altitude flights.     

Fertilizer affects the behaviour and performance of Plutella xylostella on brassicas

1 Foliar nitrogen concentration, which can be manipulated in crop plants by fertilizer supply, has long been recognized as a major factor in phytophagous insect abundance and performance. More recently, the type of fertilizer supplied has been shown to influence the abundance of some herbivore species. The diamondback moth Plutella xylostella is a global pest of Brassica crops. Although it has been the subject of numerous studies on host-plant resistance and pest control, few studies have addressed the effect of abiotic factors, such as nutrient supply, on its performance and behaviour.
2 We assessed oviposition preference, larval feeding preference and larval performance of P. xylostella on two cultivars of Brassica oleracea . Plants were grown using two fertilizer types, John Innes fertilizer and an organic animal manure, at high and low concentrations.
3  Plutella xylostella laid more eggs on cultivar Derby Day than Drago. Derby Day was also the cultivar on which larval performance was maximized. However, differences in larval performance between cultivars were only found when plants were grown in compost with John Innes fertilizer, and not when fertilized with animal manure.
4 Foliar nitrogen concentration was greater in plants grown in high fertilizer treatments but did not differ between cultivars. The concentrations of three glucosinolate compounds (glucoiberin, sinigrin and glucobrassicin) were greater in the high fertilizer treatments. Glucosinolate concentrations were higher in the Drago than the Derby Day cultivar.
5 These results are discussed in relation to the preference-performance hypothesis, and the assessment of plant resistance differences between cultivars using different types of fertilizer.     

Nocturnal windborne migration of ground beetles,particularly Pseudoophonus griseus (Coleoptera: Carabidae), in China

1 A network of light‐traps, an aerial net carried by kytoon (balloon) and two entomological radars were used to investigate whether ground beetles migrate nocturnally through China. The network‐wide, simultaneous sudden increase in light trap catches, and after subsequent decrease, indicated a seasonal long‐distance night migration of ground beetles, with Pseudoophonus griseus (Panzer) predominant, in August. 2 Aerial net trapping indicated that carabids were able to ascend to altitudes of at least 200 m and become windborne. Radar observations indicated that the migratory beetles formed high‐density layer concentrations at approximately 200–300 m. 3 These concentrations were coincident with the top of the temperature inversion and a wind speed maximum, which suggested that the carabids tended to select warm, fast moving air for their long‐distance migration. 4 The ground beetles orientated and displaced towards the downwind direction in southerly winds. Their air speed decreased as the tailwind increased and, thus, migrating beetles appeared to be conserving energy. 5 The mean ± SD displacement speed (ground speed) and air speed were 6.85 ± 1.73 m/s (n= 172) and 4.45 ± 1.54 m/s (n= 172), respectively. The duration of flight, estimated from the variation in area density derived from radar data, was approximately 9–10 h, indicating that the beetles might migrate hundreds of kilometres in a single flight.     

Radar observations of moths migrating in a nocturnal low-level jet

Abstract. 1. Radar observations of insects migrating at night over central-western New South Wales have detected an instance of migration in a low-level wind jet.
2. From the characteristics of the radar echoes, and from the catches obtained in traps at ground level and at the altitude of migration, the migrants can be identified as noctuid and pyralid moths of a number of different species.
3. The migration, which was in a downwind direction, started at dusk and ended at about dawn. During the period immediately before first light, a large proportion of the migrants were concentrated into a 100m deep layer at an altitude of about 250m; this layer had not been present during the first half of the night.
4. The boundary layer wind profile at dawn exhibited a clear low-level jet structure, with a wind maximum between 100 and 300m, and strong shear in the wind direction below 300m. A strong surface temperature inversion, but not a wind-speed maximum, had been present the previous evening.
5. The formation of the layer concentration in the upper part of the jet may be accounted for in terms of previously described responses of nocturnally migrating insects to a surface temperature inversion. It is not therefore necessary to assume that the migrants were responding specifically to the presence of a wind-speed maximum.     

A preliminary study of insect abundance on West Island,Aldabra Atoll,Indian Ocean

• 1 Heath and Rothamsted light traps and a Johnson-Taylor suction trap were used to sample flying insects on Aldabra Atoll.
• 2 The present study extended over two wet seasons. The pattern of relative monthly insect activity resembled the rainfall pattern. Catches were greatest during the months when there was a sudden marked increase in precipitation.
• 3 Lepidoptera dominated light trap catches and Diptera suction trap catches, the total monthly insect numbers therefore reflecting the abundance of these two orders. Hemiptera, Coleoptera and Hymenoptera were also common.
• 4 Predominant families were represented by only a few or even only one dominant species. These species were present throughout the study period although their monthly totals varied considerably, different species dominating the catches during different months.
• 5 The composition and size of catches in the three light traps was affected by the type of light source and surrounding vegetation.
• 6 A comprehensive list of families and selected common species is given with their relative monthly abundance in the light traps.
• 7 Suction trap catches were segregated on an hourly basis to give a broad indication of insect flight periodicity.

     

Effects of specialist parasitoids on oviposition preference of phytophagous insects: encounter–dilution effects in a tritrophic interaction

Abstract.  1. Host plant preferences of the female diamondback moth Plutella xylostella were studied.
2. Female moths preferred conspecific-damaged cabbage plants over undamaged cabbage plants. The performance of P. xylostella larvae on conspecific-infested plants did not differ significantly from that of larvae on undamaged plants.
3.  Cotesia plutellae , the specialist parasitoid wasp of P. xylostella larvae, displayed equal preference for plants with differing levels of host-larvae damage, and the wasp attacked only one or two hosts on average before leaving an infested plant, irrespective of the number of hosts on the plant. It is hypothesised that the oviposition preferences of P. xylostella females for host plants already damaged by conspecific larvae demonstrate an encounter–dilution effect against C. plutellae .     

Bottom-up cascading effects in a tritrophic system: interactions between plant quality and host-parasitoid immune responses

Abstract.  1. Little is known about underlying mechanisms by which plants indirectly affect parasitism success in hymenopteran endoparasitoids. The hypothesis that host-plant effects can challenge the innate immune system of an insect host was experimentally tested in this study using a model tritrophic, crucifer – lepidopteran [ Plutella xylostella (L.)] – parasitoid [ Cotesia plutellae (Kurdjumov)], system.
2. The effects of host-plant suitability on herbivore performance and parasitism were examined. The bottom-up effect of plant suitability on host-parasitoid immune responses was then evaluated using measures of cellular and humoral effectors.
3. Host-plant quality showed a significant effect on the encapsulation response of P. xylostella to first instar but not to second instar parasitoid larvae. Encapsulation was never sufficient to prevent parasitoid emergence.
4. Poor host-plant suitability suppressed phenoloxidase activity in the absence of the parasitoid. The suppressive effect of C. plutellae on phenoloxidase activity was much greater and no plant effects were detectable after insects had been parasitized.
5. Despite strong plant effects on parasitism, those on immune effectors of the host were transitory or overwhelmed by the effect of the parasitoid.
6. These results demonstrated that plant-mediated variation in parasitism success by C. plutellae were not as a result of plant nutritional status or other attributes affecting the immune function of P. xylostella , nor to host-plant effects on superparasitism.
7. In these experiments, P. xylostella was a fully permissive host to C. plutellae and host-plant-mediated effects on the innate immune response appeared to play no part in parasitoid survival within hosts.     

Long-term changes of aphid vectors of Barley yellow dwarf viruses in north-eastern Italy (Friuli-Venezia Giulia)

Migrations of aphid vectors of Barley yellow dwarf viruses (BYDV) were monitored using a Rothamsted Insect Survey suction trap in Friuli-Venezia Giulia (north-eastern Italy). Catches from 1983 to 2002 were studied for trends, correlations of total catches of each year with those of previous years, correlations between the autumn and the spring + summer catches of the same year and between spring + summer catches of one year with catches of the previous autumn. Infectivity of autumn alates was studied using biological tests, and infectivity indexes were calculated for all vector species and for Rhopalosiphum padi alone. Colonisation of barley and proportion of infected plants were checked in a field close to the suction trap from 1992 to 2002 and related to trap catches. Catches were also correlated to acreage dedicated to cereal and fodder crops in the region. During the 20 years, 15 BYDV vector species were caught in the trap, but only five species were found consistently colonising barley plants during autumn. R. padi was the most numerous species in catches, while Sitobion avenae was the predominant colonising species in the barley field. Relatively to R. padi , S. avenae colonies were about six times more numerous than expected from catches. The yearly abundance of catches of most species did not change significantly during the 20 years, with a few exceptions, significantly correlated to changes in the acreage dedicated to cereal and fodder crops. There was a significant decrease of the autumn catches of both R. padi and the total of BYDV vectors.     

东北地区粘虫的季节性迁飞行为(英文)

粘虫Mythimna separata是我国农业生产上的重要害虫, 为了明确其季节性迁飞行为参数, 本研究采用垂直监测昆虫雷达（vertical-looking radar, VLR）及相关辅助设备的长期自动观测, 结合基于GIS的大区环流和轨迹模拟, 调查分析了2005年东北地区粘虫季节性迁飞行为。结果表明： 粘虫在不同季节和夜间不同时间空中飞行高度具有明显差异, 空中飞行行为受气象条件尤其是空中风场影响较大; 春季和秋季主要借助气流运载进行大规模长距离迁飞, 夜间持续飞行时间可达9 h, 多数个体能完成整夜飞行, 春季迁飞高度主要在300~600 m, 秋季飞行高度相对较低主要在300 m以下和400~500 m。夏季雷达回波有明显的成层现象, 最高可达1 000 m, 主要集中在500 m和700 m两个高度层。轨迹分析显示： 5月29日由山东潍坊、 临沂等虫源地起飞的黏虫, 顺西南气流越海迁飞, 6月1日在气旋天气影响下, 在吉林省白城等地降落; 7月中旬主要为当地黏虫受对流天气影响进行短距离迁飞扩散; 9月11日虫源来自内蒙古呼伦贝尔, 顺西北气流向吉林省东南方向迁飞。研究结果为东北地区粘虫的有效防控提供了技术支撑。     

Extracting bird migration information from C‐band Doppler weather radars

Although radar has been used in studies of bird migration for 60 years, there is still no network in Europe for comprehensive monitoring of bird migration. Europe has a dense network of military air surveillance radars but most systems are not directly suitable for reliable bird monitoring. Since the early 1990s, Doppler radars and wind profilers have been introduced in meteorology to measure wind. These wind measurements are known to be contaminated with insect and bird echoes. The aim of the present research is to assess how bird migration information can be deduced from meteorological Doppler radar output. We compare the observations on migrating birds using a dedicated X‐band bird radar with those using a C‐band Doppler weather radar. The observations were collected in the Netherlands, from 1 March to 22 May 2003. In this period, the bird radar showed that densities of more than one bird per km³ are present in 20% of all measurements. Among these measurements, the weather radar correctly recognized 86% of the cases when birds were present; in 38% of the cases with no birds detected by the bird radar, the weather radar claimed bird presence (false positive). The comparison showed that in this study reliable altitudinal density profiles of birds cannot be obtained from the weather radar. However, when integrated over altitude, weather radar reflectivity is correlated with bird radar density. Moreover, bird flight speeds from both radars show good agreement in 78% of cases, and flight direction in 73% of cases. The usefulness of the existing network of weather radars for deducing information on bird migration offers a great opportunity for a European‐wide monitoring network of bird migration.     

Conservation implications of genetic variation between spatially and temporally distinct colonies of the endangered damselfly Coenagrion mercuriale

Abstract.  1. Good conservation management is underpinned by a thorough understanding of species' historical and contemporary dispersal capabilities along with the possible adaptive or neutral processes behind any spatio-temporal genetic structuring. These issues are investigated with respect to the rare damselfly Coenagrion mercuriale (Charpentier) – the only odonate species currently listed in the U.K.'s Biodiversity Action Plan – in east Devon where its distribution has become fragmented.
2. The two east Devon C. mercuriale populations, only 3.5 km apart, have accumulated strong differences in frequencies of alleles at 14 microsatellite loci as a consequence of poor adult dispersal and drift. There is no contemporary migration between sites.
3. A genetic signature of population decline at both sites corresponds with known demographic reductions. Coenagrion mercuriale in east Devon are now significantly genetically less diverse than those from a population stronghold in the Itchen Valley.
4. Colonies would benefit from improved connectivity between areas and possibly by a transfer of individuals from other ecologically similar areas.
5. Because C. mercuriale has a semivoltine life cycle throughout the U.K., the possibility that alternate-year cohorts are reproductively isolated is explored. Genetic differentiation among cohorts is an order of magnitude less than between sites, suggesting that some larvae delay their development into adults for a year and recruit to a different cohort.
6. To our knowledge, this is the first study to document migration and gene flow between alternate-year cohorts in a species of odonate. From a conservation standpoint, the cohorts do not require separate management.     

Intraguild predation of the aphid pathogenic fungus Pandora neoaphidis by the invasive coccinellid Harmonia axyridis

Abstract.  1. The ladybird Harmonia axyridis is an invasive alien species in many countries and is predicted to have a negative impact on native biodiversity. However, little is known on the status of this aphidophage as an intraguild predator of natural enemies of aphids such as insect-pathogenic fungi.
2. The study assessed the predation of the aphid-specific pathogenic fungus Pandora neoaphidis by adult and larval H. axyridis collected from the U.K. (an invasive population) and Japan (a native population) relative to that of the ladybird Coccinella septempunctata (native to the U.K.) and the non-U.K. C. septempunctata subspecies brucki that were either starved or unstarved.
3. Overall, predation of uninfected aphids was greater than infected aphids and, when given a choice, a preference for aphids was shown. However, the extent of this preference was dependent on the species and origin of the coccinellid. Harmonia axyridis (U.K.) consumed the greatest quantity of fungal cadavers and showed little preference for uninfected aphids over infected aphids. In contrast, C. septempunctata rarely consumed infected aphids. Life stage had no direct effects on predation but starved coccinellids consumed more uninfected aphids than infected aphids.
4.  Harmonia axyridis (U.K.) is a stronger intraguild predator of P. neoaphidis cadavers than the native species C. septempunctata and, therefore, may have an impact on the occurrence and persistence of P. neoaphidis . The differences in intraguild predation by H. axyridis collected in the U.K. and those from Japan suggests that individuals that invaded the U.K. could have a different genetic profile to those in its native range.     

Radar observations of the spring migration into northeastern China of the oriental armyworm moth, Mythimna separata, and other insects

Abstract. 1. The spring migration of the oriental armyworm moth, Mythimna separata (Walker), and other insects into northeastern China was observed by radar at a site in central Jilin province. Samples of the migrants were obtained in a net flown from a kite, and M.separata populations in the surrounding region were monitored with a trap network. 2. The radar regularly detected echoes which were of the type characteristic of large insects, and three out of four large insects in the aerial samples were noctuid moths, including one M.separata. Catches of armyworm moths in the regional trap network peaked during the period of radar observations. 3. Migration occurred at night. It commenced with a take-off flight at dusk and generally continued until dawn, with numbers often being highest around midnight. Most migration took place at altitudes below 500 m, with strong layer concentrations forming at 200–400 m during the middle part of some nights. 4. Migration was approximately downwind. The net movement was overwhelmingly to the northeast because southwesterly winds occurred most frequently and were relatively strong, and because migration was more intense and prolonged on these winds. Orientation tended to be to the left of the downwind direction, and was most often to the north or northeast. 5. Migration into northeastern China was accomplished in a series of night-time movements of 100–300 km rather than by a single non-stop flight. 6. The net movement of insects towards the northeast was sufficient to produce the observed regional infestation of M.separata moths. Oviposition by immigrant armyworm moths in vulnerable crops would have been at a level where economically significant damage would be expected from the resulting larval population. 7. Analogous springtime migrations of noctuids leading to temporary colonizations of habitats at higher latitudes occur in other continents. Such colonizations may be unproductive if, as appears possibly the case for northeastern China, prevailing winds later in the season are generally unfavourable for a return migration towards overwintering areas at lower latitudes.