The Jurassic thrips Liassothrips crassipes (Martynov, 1927) and its taxonomic position in the order Thysanoptera (Insecta)

The Late Jurassic thrips Liassothrips crassipes (Martynov) is redescribed, and its taxonomic position discussed. It is shown that the male genitalia of Liassothrips are similar to the terebrantian type, while the female genitalia resemble the tubuliferan type. Therefore, the Liassothripidae shows the possible evolutionary pathway of tubuliferan thrips. Liassothrips is treated as the oldest known member of the suborder Tubulifera (previously known beginning from the Eocene), the ancestors of which belonged to the family Aeolothripidae (Terebrantia) rather than Thripidae.     

The potential of flower odours for use in population monitoring of Western flower thrips Frankliniella occidentalis Perg. (Thysanoptera: Thripidae)

Sticky blue traps are a suitable and important tool for Western Flower Thrips population monitoring in greenhouses. They can be used in vegetables and in ornamentals, and provide important information on the current status of the pest population. However, such traps cannot be used in some susceptible plant species when they are flowering because at that stage the plants are more attractive to Western Flower Thrips than the traps. We therefore tried to increase trap attractiveness by combining the colour cue with an attractive odour cue. In laboratory experiments, we found a significant additive effect on attractiveness for two odours in traps provided with both the visual and the olfactory cues as compared to traps with either cue alone. However, these results could not easily be reproduced in greenhouses. The main factors responsible for this failure seem to be (1) the only moderate, additive increase of trap attractiveness when using combined visual and olfactory cues, and (2) the problems associated with odour diffusion. Unless a more attractive odour is found and a suitable odour dispenser is available, the use of odours to enhance sticky blue trap attractiveness for Western Flower Thrips cannot be recommended and, given the added cost for the trap, may not be affordable for growers.     

入侵害虫西花蓟马及其他8种常见蓟马的分子鉴定

用PCR产物直接测序法对入侵害虫西花蓟马和其他8种蓟马的线粒体 COⅠ基因433 bp片段测序，获得62个个体的序列。分子数据分析显示： 种内个体间平均遗传距离在0～0.005之间，2003年在北京发现的西花蓟马与欧洲等地区报导的西花蓟马不存在明显的遗传差异； 9种蓟马种间平均遗传距离为0.213。构建的NJ树可以很好的显示蓟马的聚类，物种各单元型最初分支自展值均达到100%。结果表明，基于PCR及直接测序技术的分子鉴定可以达到准确鉴定蓟马物种之目的。     

The effect of photoperiod on walking, feeding, and oviposition in the western flower thrips

The western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is a major pest in glasshouses, where light and photoperiod are often manipulated to grow crops. The effect of five photoperiods (L0:D24, L6:D18, L12:D12, L18:D6, and L24:D0) on the behaviour of adult females was investigated in the laboratory at 25 °C. The amount of walking, pollen consumption, and oviposition all increased with increasing photophase. The three behaviours occurred at a low rate in continuous darkness, and are therefore not exclusively diurnal. Three out of 16 thrips (19%) showed weakly rhythmic walking activity in continuous darkness, with an average circadian period of 25.3 ± 1.5 h. It is proposed that the length of the photophase determines the amount of nutrient intake, which in turn determines oviposition rate and thus affects population increase.     

寄主植物接种番茄斑萎病毒对西花蓟马种群的影响

【目的】西花蓟马Frankliniella occidentalis (Pergande)是一种入侵我国的重要害虫, 而番茄斑萎病毒是以西花蓟马传播为主的一种极具危害性的世界性病毒, 通过研究西花蓟马与番茄斑萎病毒之间的互作将有助于进一步深入理解西花蓟马以及番茄斑萎病毒的发生与猖獗机制, 同时也将为制定合理、可持续的控制西花蓟马及其传播的植物病毒防控策略提供理论依据。【方法】利用应用特定年龄-龄期及两性生命表方法, 研究了西花蓟马在辣椒3种处理（健康CK、机械损伤MD、机械接种番茄斑萎病毒MI）叶片上的生长发育、存活及种群增长。【结果】健康、机械损伤和机械接毒叶片上的发育历期依次为12.45, 11.97和11.18 d。雌雄成虫寿命和雌虫产卵量在不同处理植株叶片上差异显著(P<0.05), 在机械接毒叶片上寿命最长(雌13.51 d, 雄12.69 d); 繁殖能力最强, 产子代数高达33.01头1龄若虫/雌。健康、机械损伤和机械接毒叶片上西花蓟马内禀增长率分别为-0.009, 0.153和0.190 d-1, 净生殖率依次为0.84, 14.54和21.79。【结论】番茄斑萎病毒诱导寄主植物辣椒反应使西花蓟马发育历期缩短, 成虫寿命延长, 繁殖能力提高, 种群增长加速。     

Systematics of thrips (Insecta: Thysanoptera) associated with mosses

The systematic relationships between phlaeothripine Thysanoptera species suggest that moss-feeding is an uncommon and highly derived habit. It is restricted to a single sub-tribe, the Williamsiellina, which includes two genera, Lissothrips with 17 species and Williamsiella with 25 species. Although widely distributed, these genera are particularly common in the New World. Structural variation within and between populations of these small wingless insects is discussed and the conclusion reached that species cannot be defined satisfactorily in the common North American L. muscorum -group without experimental rearing. Trisclerothrips is synonymized with Lissothrips , and Prolissothrips, Microlissothrips and Phthirothrips are synonymized with Williamsiella . One specific synonym is established, and four new species are described: L. clayae from Trinidad, L. okajimai from Japan, W. tambopata from Peru and W. zaps from Fiji.     

寄主植物对椰心叶甲生长发育和繁殖力的影响

研究了5种棕榈科寄主植物椰子(Cocos nucifera)、酒瓶椰子(Hyophorbe lageni-caulis)、老人葵(Washingtonia filifera)、大王棕(Roystonea regia)和槟榔(Areca catechu)未展开心叶对椰心叶甲实验种群生长发育和繁殖力的影响.结果表明:在取食不同的寄主植物心叶的情况下,椰心叶甲完成1个世代所需的时间差异显著,其中取食老人葵所需时间最长,为72.8d,取食酒瓶椰子所需时间最短,为39.8d;酒瓶椰子上的平均蛹质量较其它4种寄主植物大;取食老人葵的椰心叶甲平均产卵量最高,为157.6粒,而取食槟榔的最少,为65.2粒;取食酒瓶椰子的椰心叶甲成虫寿命为207.5d,远比寄生于其它寄主的成虫寿命长.5种寄主植物上的实验种群趋势指数分别为53.57、54.98、48.56、20.46和11.54.     

The fecundity, development and host relationships of Ceratobaeus spp. (Hymenoptera: Scelionidae), parasites of spider eggs

Abstract. 1. Ceratobaeus spp. enter the nest of their host spider and oviposit into eggs through the thin silk eggsac.
2. Temperatures below 15° C limit oviposition by slowing parasites down.
3. Males emerge prior to females and mate with their sibs. Sex ratios of 6.6–6.0:1 in favour of females were observed in the field and laboratory for two species.
4. Even though females can oviposit almost immediately after emergence their full complement of eggs (= 65) is not reached until several days later.
5. Superparasitism is low and appears to occur from subsequent accidental ovipositions. No marking of the external surface of hosts was observed.
6. Parasites overwinter as adults under bark. They do not feed as adults nor do they reabsorb their eggs, but rather oviposit as soon as host eggs become available in spring.
7. Successful oviposition occurs in later stages of host eggs reared at 15° C and 20° C than it does at 25°C. Different rates of development between host and parasite is proposed as an explanation for this phenomenon.
8. The species studied show varying degrees of specificity but each has a dominant host. Location of hosts involves cues from the habitat (bark), silk nests of spiders, and some factor associated with host eggs.     

Determining the host specificity of the biological control agent Trichomalus perfectus (Hymenoptera: Pteromalidae): the importance of ecological host range

We determined the host range of the parasitoid Trichomalus perfectus (Walker), a candidate for classical biological control of cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham), an important pest of canola in Canada. Studies were conducted in Europe and in North America. In laboratory experiments, the levels of parasitism (acceptance) of Ceutorhynchus turbatus Schultze, C. cardariae Korotyaev, C. omissus Fall and C. querceti (Gyllenhal) by T. perfectus were not significantly different than of the target host C. obstrictus. Although C. typhae (Herbst), C. pallidactylus (Marsham), C. americanus Buchanan, C. neglectus Blatchely and Ceutorhynchus sp. nr. nodipennis were parasitised by T. perfectus, the levels of parasitism were significantly lower on these species than on C. obstrictus. Ceutorhynchus peyerimhoffi Hustache, C. erysimi (Fabricius), C. alliariae H. Brisout, C. roberti Gyllenhal, Mogulones borraginis (Fabricius), Mononychus vulpeculus (Fabricius) and the leaf-mining fly Scaptomyza flava (Fallén) were not attacked. Ecological host range surveys in Europe corroborated the prediction that T. perfectus would attack C. cardariae at similar rates to C. obstrictus. In North America, the recent discovery of T. perfectus in a C. omissus population suggests that laboratory findings predicting that C. omissus is a preferred host may be the case in the field. We found that T. perfectus attacks larvae of some Ceutorhynchus spp. feeding on Brassicaceae and does not attack species outside of that host range. Thus, the parasitoid can be defined as narrowly oligophagous. These results demonstrate the value of ecological host range studies in the area of origin to validate hypotheses generated through laboratory host range experiments.     

Rapid preliminary characterisation of host specificity of leaf-beetles (Coleoptera: Chrysomelidae)

Rapid characterisation of host specificity is important both in biological control of weeds and studies in ecology and evolution. A means for doing this was developed and tested on four species of leaf beetles of interest for biological control of the weed Mimosa pigra (Mimosaceae). We identified the most promising for the more detailed tests necessary to obtain release approval. The impact of time-dependent effects and effects of experience were also investigated as part of this study but were not detected. Short-term host specificity tests on adult feeding accurately predicted the results of longer term trials. The long-term trial showed that survival on a plant species depended on feeding on it. Hence short-term feeding trials can predict the longer term survival of adults on other plant species. Different feeding results were obtained in cut foliage versus entire plants but no consistent pattern was shown: of the two insect species tested, one species ate more of the cut material while the opposite was demonstrated for the second species. Species in order of priority for further consideration as biocontrol agents were Syphrea bibiana, Genaphthona sp., Syphrea sp. and Paria sp. The latter three species were probably not sufficiently specific for release. The tests done here allow the identification of the most likely species upon which to conduct the more laborious and difficult larval developmental tests, saving considerable resources.     

Effects of temperature and diet on oviposition rate and development time of the New Zealand flower thrips, Thrips obscuratus

The life history of New Zealand flower thrips (Thrips obscuratus (Crawford), Thysanoptera: Thripidae) was studied using a simple laboratory rearing method. The effects of temperature and diet on oviposition rate and development time were examined. Oviposition rate increased with increasing temperature between 10°C and 25°C. Development time for individual instars and for total development decreased with increasing temperature between 10°C and 27°C. Total development time ranged from 50 days at 10°C (female) to 10 days at 27°C (male). The relationship between temperature and development rate was expressed as a straight line such that lower thresholds of development of between 4.2°C and 6.3°C were established for life stages. Adult lifespan increased with decreasing temperature between 10°C and 25°C and females lived longer than males. At 10°C and 25°C females lived for an average of 34 and 3 weeks respectively. Thrips supplied with pollen exhibited highest and sustained levels of egg production in comparison to other diets. Larval mortality was lowest and development time fastest on diets of pollen and sucrose or fruit juice in comparison to other plant tissues. Larval development time was similar on four species of pollen.     

Effect of elevated CO2 on interactions betwe en the western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae) and the common milkweed, Asclepias syriaca

We measured the effect of elevated CO₂ on populations of the western flower thrips, Frankliniella occidentalis and on the amount of leaf damage inflicted by the thrips to one of its host plants, the common milkweed, Asclepias syriaca. Plants grown at elevated CO₂ had significantly greater aboveground biomass and C:N ratios, and significantly reduced percentage nitrogen. The number of thrips per plant was not affected by CO₂ treatment, but the density of thrips (numbers per gram aboveground biomass), was significantly reduced at high CO₂. Consumption by thrips, expressed as the amount of damaged leaf area per capita, was significantly greater at high CO₂, and the amount of leaf area damaged by thrips was increased by 33%. However overall leaf area at elevated CO₂ increased by 62%, more than compensating for the increase in thrips consumption. The net outcome was that plants at elevated CO₂ had 3.6 times more undamaged leaf area available for photosynthesis than plants at ambient CO₂, even though they had only 1.6 times the overall amount of leaf area. This study highlights the need for measuring the effects of herbivory at the whole-plant level and also the importance of taking herbivory into account when predicting plant responses to elevated CO₂. Received: 9 January 1996 /Accepted: 30 July 1996     

Temperature and host plant effects on development and fecundity of Brevicoryne brassicae (L.) (Homoptera: Aphididae)

The development, survival and reproduction of the cabbage aphid, Brevicoryne brassicae (L.) were evaluated at three constant temperatures (20, 25 and 30°C) on cabbage, cauliflower, red cabbage, turnip and radish. The development periods of immature stages ranged from 10.7 d at 20°C to 7.60 d at 30°C for red cabbage. Total percentages of survivorship of immature stages varied from 39.40 and 82.50 within the temperature range of 25–30°C on radish. The average progeny per female was 31.15, 28.95 and 23.77 at 20, 25 and 30°C on cabbage.     

Species composition of thrips (Thysanoptera: Thripidae) and spider mites (Acari: Tetranychidae) on cultivated chrysanthemum (Asteraceae) in Okinawa,southwestern Japan

We investigated the species composition of phytophagous thrips and spider mites on cultivated chrysanthemum in Okinawa, southwestern Japan. Eight thrips species belonging to the genera Frankliniella, Microcephalothrips, Scirtothrips and Thrips were found on chrysanthemum leaves. Among them, Thrips nigropilosus was the predominant species irrespective of season, island or cultivation environment (meshed greenhouse or open field), with its infestation frequency being 89% of the fields in which thrips occurred. This high frequency of occurrence suggests that T. nigropilosus is a major pest of chrysanthemum in Okinawa, even though this species has rarely been regarded as an important pest of chrysanthemum or other crops in any other areas. Thrips palmi was the second most dominant (infestation frequency 36%) and other species were scarce (<14%). Tetranychus urticae (green form) was the only tetranychid species on chrysanthemum in our survey. This lack of diversity among spider mites on chrysanthemum is peculiar considering that eight Tetranychus species have been found on vegetables in the same area. Since T. urticae (green form) has been shown to be resistant to a number of pesticides, severe pesticide applications might have simplified the spider mite fauna on chrysanthemum in Okinawa.     

Floral display in Vicia faba, and the distribution of a flower thrips, Kakothrips pisivourus

The flower thrips Kakothrips pisivorus (Westwood) (Thysanoptera) breeds in flowers of Vicia faba L. (Leguminosae). The egg and larval stages combined outlast the flowers. Each larva must move between the flowers on a plant at least once. The presence of old larvae in buds demonstrates successful inter-floral movement by larvae. If thrips leaving a dying flower transfer to a new flower nearby, old larvae will accumulate at the end of a spatial sequence of adjacent short-lived flowers. The distribution of K. pisivorus on the plant was investigated. Old larvae did accumulate in flowers at the end of V. faba racemes, as predicted. The relationship between floral lifespan, floral display, and flower inhabitants is discussed. The distribution of the thrips is relevant to sampling procedures.

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Disposition des fleurs de Vicia faba et distribution de Kakothrips pisivorus

Résumé K. pisivorus Westwood (Thysanoptera) se développe dans les fleurs de Vicia faba L. (Leguminosae). Les durées combinées des stades embryonnaires et larvaires dépassent celles des fleurs. Chaque larve doit changer de fleur sur la plante au moins une fois. La présence de larves agées dans les bourgeons provient de l'existence de déplacements larvaires interfloraux réussis. Si les thrips quittant une fleur sénescente gagnent une nouvelle fleur voisine, les vieilles larves s'accumuleront à la fin d'une série de fleurs de courte durée de vie. La distribution de K. pisivorus sur la plante a été examinée; des fleurs du même âge ont été échantillonées dans 3 positions sur les inflorescences. Il n'y a pas eu d'effet significatif de la position des fleurs sur les oeufs et larves 1. Les adultes passent une partie de la journée sur les fleurs les plus proches peut-être parce qu'elles sont les plus hautes. A l'extrémité des inflorescences de V. faba, l'accumulation de larves agées était supérieure à celle prévue. La discussion porte sur les relations entre la durée de vie des fleurs, leur position et les insectes que les occupent. La distribution des thrips influe sur les techniques d'échantillonnage.

     

Temperature-mediated relationship between western flower thrips (Thysanoptera: Thripidae) and chrysanthemum

Modeling the effect of temperature on the sustainability of insect-plant interactions requires assessment of both insect and plant performance. We examined the effect of temperature on western flower thrips, Frankliniella occidentalis (Pergande), a generalist herbivore with a high reproductive rate, and chrysanthemum inflorescences, a high quality but relatively fixed, ephemeral resource for thrips population growth. We hypothesized that different thrips versus plant responses to temperature result in significant statistical interaction of temperature with thrips abundance and flower damage attributes over time. Experiments were conducted at five temperatures between 20.7 and 35.3 degrees C, with thrips infestation and time after infestation as main effects. Only minor, uncontrolled variations in relative humidity and light intensity may otherwise have influenced the results. High temperatures lead to an initially rapid increase in density of thrips followed by abrupt declines in abundance. The rate of floral senescence increased with temperature and thrips infestation, as indicated by a reduced fresh biomass and greater leaching of yellow pigments. Multiple regression indicated that indices of plant damage responded more directly to thrips density at low than high temperature, supporting the conclusion that temperature affected the outcome beyond what was predictable simply from differential plant and insect optima. The relative intensity of damage caused by individual thrips decreased with increasing temperature, likely caused by thrips competition and reduced survival, growth, and fecundity on depleted inflorescences. Reduced per capita damage at high temperature may be common in insects exploiting fixed plant resources that exhibit an accelerated rate of deterioration at high temperatures.     

Flagellar sensilla of the eusocial gall-inducing thrips Kladothrips intermedius and its kleptoparasite, Koptothrips dyskritus (Thysanoptera: Phlaeothripinae)

Insect antennal flagella host a multitude of sensory organs fulfilling different functions. Chemoreception, for example, is essential for insects in many contexts. Both olfaction and contact chemoreception are involved in host-plant selection, as well as in the integrity of insect societies, especially for nestmate recognition. Kladothrips intermedius is a eusocial gall-inducing thrips with two castes: dispersers and soldiers. Koptothrips dyskritus is a specialist in invading Kl. intermedius galls, killing the occupants, and thereby gaining the food and shelter offered by galls. In this study, we compared the morphology and ultrastructure of the flagellar sensilla of Kl. intermedius and Ko. dyskritus via scanning and transmission electron microscopy in order to facilitate future investigations of their sensory ecology, with an emphasis on chemical ecology. The two species show a very similar sensillar array. There are a few mechanosensory trichoid and a second type of mechanosensory sensilla, thermo-hygroreceptive sensilla, olfactory single-walled basiconic and double-walled coeloconic sensilla as well as contact chemoreceptive chaetic sensilla. The latter are sexually dimorphic in Kl. intermedius. Dispersers and soldiers of Kl. intermedius do not present noteworthy morphological differences, but the ultrastructural investigations revealed that soldiers have fewer ORNs, possibly an adaptation to their gall-cloistered lifestyle.