The first record of subtropical insects (Thysanoptera) in central Europe: long‐distance transport of airborne thrips,applying three‐dimensional backward trajectories

相似文献   

Antipredator responses to alarm pheromone in groups of young and/or old thrips larvae

Many prey species suffer from different predators in the course of their ontogeny. Hence, the alarm signal a small prey individual sends can have a different meaning than the signal a large prey individual sends, both for small and for large receivers. Larvae of Western Flower Thrips face predators that attack only small larvae, or predators that attack small larvae and large larvae. Furthermore, thrips larvae release a two‐component alarm pheromone, which varies in composition with larval age. Here, we study whether their response to alarm pheromone varies with composition of the pheromone. First, we confirmed that large and small larvae respond when nearby larvae of both sizes were prodded with a brush to induce alarm pheromone excretion. Subsequently, we tested whether thrips larvae of a given size respond differentially to alarm pheromone excreted by a small or large companion larva. We analyzed two types of behavior used in direct defense against a predator and one type of escape response. Only small (not large) larvae attempted to escape more frequently in response to excretions from a large larva. This difference in response could have been due to the alarm pheromone or to the companion larva in the vicinity. We subsequently tested for, but did not find, an effect of size of the companion larva on the behavior of the test larva when exposed to synthetic pheromone mimicking that of a large larva. Finally, we tested how pheromone composition affects antipredator behavior by exposing thrips larvae to synthetic pheromones differing in amount and ratio of the two components. Only for small larvae, we found significant changes in escape behavior with pheromone amount, and a trend with the ratio. Overall, we conclude that small thrips larvae respond differentially to alarm pheromones excreted by small and large larvae and that this differential response is due to differences in pheromone quantity and possibly also quality. Our results suggest that responses to alarm signals can vary with the chemical composition of those alarm signals.     

Interaction of trap colour attractiveness with morphological variability of the thrips Frankliniella occidentalis (Pergande 1895)

In the latitude of Kiev, 80% of Frankliniella occidentalis (Pergande 1895) population was caught on the colour traps from 11 a.m. to 5 p.m. in summer and from 11 a.m. to 3 p.m. in winter. Meanwhile, 10% of the population did not react to the colour traps at all (“passive” individuals), whereas for 20% of the population it was impossible to determine the clear colour with attractive properties. The thrips attracted with blue and yellow color traps, had more massive and variable body parts to be connected with their flight. Their antennae and segment sizes were significantly smaller than compared to the control variant, which could be explained by eyesight domination over other organs of sensory orientation. The indices of heterogeneity of morphological features can be used as evaluation criteria for the adaptive variability and stability of the thrips population.     

The spread of the western flower thrips Frankliniella occidentalis (Pergande)

Abstract 1 Since the late 1970s, the western flower thrips has spread from its original distribution in western North America to become a major worldwide crop pest. 2 A wide range of data sources have been used to map the original distribution in the U.S.A. and Canada, and the progress of the spread in the U.S.A., Canada, Europe, northern Africa and Australia. 3 The possible reasons for the start of the spread are discussed. The most likely reason is that intensive insecticide use in horticulture in the 1970s and 1980s selected an insecticide resistant strain or strains. These then established in glasshouses across North America and spread from there to Europe, Asia, Africa and Australia. 4 The international spread of the western flower thrips occurred predominantly by the movement of horticultural material, such as cuttings, seedlings and potted plants. Within Europe, an outward spread from the original outbreak in the Netherlands is discernible. The speed of spread was 229 ± 20 km/year. 5 The spread has not been restricted to glasshouses. The western flower thrips has established outdoors in areas with milder winters; for example, across the southern U.S.A., southern Europe and Australia. It also overwinters in some regions with colder winters. 6 Polyphagous phytophagous thrips have many factors predisposing them to become worldwide crop pests, particularly in glasshouses. Some other species that might spread in a similar way to the western flower thrips are listed.     

西花蓟马抗辛硫磷种群的抗性机制及交互抗性

为明确西花蓟马对辛硫磷的抗性风险,研究了西花蓟马抗辛硫磷种群对其他杀虫剂的交互抗性及其对辛硫磷的抗性机制.交互抗性测定结果表明,西花蓟马抗辛硫磷种群对辛硫磷与毒死蜱、高效氯氟氰菊酯和灭多威存在中等水平的交互抗性,对溴虫腈、吡虫啉、甲维盐和多杀菌素存在低水平交互抗性,对啶虫脒和阿维菌素不存在交互抗性.酶抑制剂与辛硫磷的增效剂测定结果表明,胡椒基丁醚(PBO)、三丁基三硫磷酸酯(DEF)和磷酸三苯酯(TPP)对西花蓟马抗辛硫磷种群(XK)、田间种群(BJ)和敏感种群(S)均起到了显著的增效作用(P＜0.05),马来酸二乙酯对西花蓟马抗辛硫磷种群和敏感种群增效作用均不显著,但对田间种群增效作用显著(P＜0.05).生化测定发现:除田间种群西花蓟马乙酰胆碱酯酶活性提高不显著外,西花蓟马抗辛硫磷种群和田间种群的细胞色素P450含量(2.79和1.48倍)、细胞色素b5含量(2.88和1.88倍)及O-脱甲基酶活性(2.60和1.68倍)、羧酸酯酶活性(2.02和1.61倍)和乙酰胆碱酯酶活性(3.10倍)均显著高于敏感种群(P＜0.05);谷胱甘肽-S-转移酶酶活性也有一定程度提高(1.11和1.20倍),但不显著(P＞0.05).表明其体内解毒代谢酶和靶标酶活性提高是西花蓟马对辛硫磷产生抗性的重要原因.     

Density, dispersal, and feeding impact of western flower thrips (Thysanoptera: Thripidae) on flowering chrysanthemum at different spatial scales

Abstract.  1. This study evaluated the effect of dispersal on the density and feeding impact of a phytophagous insect in relation to the spatial distribution of its host plants.
2. The interaction between density, dispersal, and feeding impact of western flower thrips on flowering chrysanthemum was quantified at three spatial scales, with infested and uninfested plants either isolated in 0.25 m² individual cages, or enclosed together in 2.25 m² communal cages or 75 m² greenhouses.
3. In individual cages, the rate of dispersal from chrysanthemum plants to blue sticky traps increased with the density of thrips for females but not males. Uninfested plants consistently had fewer thrips when they were individually caged rather than enclosed with plants infested with adults, indicating that dispersal mediates inter-plant distribution of thrips.
4. The feeding impact of thrips on inflorescences was evaluated using the absorbance of ethanol extracts at wavelengths characteristic of yellow carotenoid pigments associated with chrysanthemum inflorescences (415, 445, and 472 nm). Increasing absorbance of extracts with increasing density of thrips per inflorescence suggests that feeding by thrips results in ruptured cells leaching carotenoid pigments.
5. In communal cages, the distribution of thrips was uniform for infested and uninfested plants, whereas the density and feeding impact of thrips in greenhouses were higher for infested than uninfested plants. These results suggest that short-range dispersal by adults homogenises the density and feeding impact of thrips among host plants only on a small spatial scale.     

Cross‐resistance of chrysanthemum to western flower thrips,celery leafminer,and two‐spotted spider mite

Chrysanthemum [Chrysanthemum × morifolium Ramat. (Asteraceae)] is one of the economically most important greenhouse ornamentals worldwide. A major constraint in chrysanthemum production is adequate pest management, requiring the use of different tactics, such as improving host plant resistance, in the framework of an integrated pest management (IPM) approach. In this study, we investigated cross‐resistance of chrysanthemum to its three major pests: western flower thrips [Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)], celery leafminer [Liriomyza trifolii (Burgess) (Diptera: Agromyzidae)], and two‐spotted spider mite [Tetranychus urticae Koch (Acari: Tetranychidae)]. We quantified resistance to each pest by performing greenhouse bioassays with a broad range of chrysanthemum types from commercial germplasm provided by Dutch breeding companies. Considerable variation was detected among the chrysanthemum cultivars in thrips silver damage and growth damage, leafminer damage, measured as number of mines and pupae, and spider mite numbers and damage. We observed significant positive correlations between thrips damage (both silver and growth damage) vs. leafminer numbers (both mines and pupae), and between leafminer numbers (both mines and pupae) vs. spider mite numbers. Our results indicate an overlap in resistance to all three herbivores. The important implications of this result for chrysanthemum breeding are discussed.     

西花蓟马高毒力虫生真菌筛选及其生防应用潜力的研究进展

西花蓟马是一种外来入侵的世界性害虫,对农林业危害巨大。查阅国内外相关文献,综述了当前防治西花蓟马的虫生真菌的种类、高毒力菌株的筛选及防治现状。现已知西花蓟马的寄生病原真菌有5种,包括蜡蚧轮枝菌(半知菌:丝孢目)、球孢白僵菌(半知菌:丝孢目)、金龟子绿僵菌(半知菌:丝孢目)、玫烟色棒束孢(半知菌:束梗孢目)和小孢新接霉。其中,球孢白僵菌、金龟子绿僵菌在西花蓟马的生物防治中应用最广,具有良好的开发应用潜力,部分防效好的虫生真菌已申请专利及实现工厂化生产。     

Acquisition of lethal doses of Beauveria bassiana conidia by western flower thrips, Frankliniella occidentalis, exposed to foliar spray residues of formulated and unformulated conidia

Secondary acquisition of Beauveria bassiana conidia was recorded on the whole bodies and selected body parts of second-instar nymphs and adult female western flower thrips exposed to foliar spray residues of three differently formulated conidial preparations, for 24 h. Conidia were formulated in emulsifiable oil or with clay (wettable powder), or were essentially unformulated conidia (technical grade powder suspended in water with a surfactant). Formulation had no significant effect on dose acquisition and no effect on virulence of acquired conidia. The mean nymphal LC50/LD50 was 116 conidia/mm2 and 52conidia/insect, respectively; the values for adults were 19 conidia/mm2 and 5conidia/insect. Greatest numbers of conidia were recorded on the legs and abdomens of nymphs and on the legs, wings, and thoraces of adults. As would be expected, numbers of conidia acquired increased with residue concentration (application rate). However, an inverse relationship was noted between acquisition rate (conidia acquired/total conidia applied) and residue concentration. The mechanism underlying this response was not determined. However, there was no indication that any body parts (e.g., tarsi) became saturated with spores, which suggests that either the thrips were repelled by the conidial residues or that as the concentrations of conidia on the substrate increased, conidia somehow became more difficult to acquire. Slopes of the LC probit regressions were lower than those of the LD regressions (mean 1.14 vs 1.78), suggesting that the low slopes often obtained in fungal pathogen assays could be partly an artifact of unequal rates of dose acquisition at low vs high application rates.     

Herbivore arthropods benefit from vectoring plant viruses

Plants infected with pathogens often attract the pathogens’ vectors, but it is not clear if this is advantageous to the vectors. We therefore quantified the direct and indirect (through the host plant) effects of a pathogen on its vector. A positive direct effect of the plant‐pathogenic Tomato spotted wilt virus on its thrips vector (Frankliniella occidentalis) was found, but the main effect was indirect; juvenile survival and developmental rate of thrips was lower on pepper plants that were damaged by virus‐free thrips than on unattacked plants, but such negative effects were absent on plants that were damaged and inoculated by infected thrips or were mechanically inoculated with the virus. Hence, potential vectors benefit from attacking plants with virus because virus‐infected plants are of higher quality for the vector's offspring. We propose that plant pathogens in general have evolved mechanisms to overcome plant defences against their vectors, thus promoting pathogen spread.