昆虫寄主选择行为的进化机制

昆虫的寄主选择行为受到遗传、可传承的环境因素或学习行为的调控。尽管大量实验已证实昆虫寄主选择中的遗传变异,但在实际中很难将其与温度、营养、条件作用和可传承的环境因素的作用区别开来。一些报道已证实可传承的环境因素会影响昆虫的寄主选择行为。幼虫期和成虫期对寄主的经历可以改变该虫态的取食和产卵寄主偏嗜行为。虽然巴甫洛夫条件反射和神经组织移植实验初步揭示了幼虫经历对成虫气味选择行为的影响,但寄主选择行为中的前印象条件作用尚需进一步验证。在城市垃圾生态系统中,杂食性的蝇类的取食和产卵选择行为较腐食性的蝇类更易受到学习经历的重塑。     

Was Hopkins right? Influence of larval and early adult experience on the olfactory response in the granary weevil Sitophilus granarius (Coleoptera,Curculionidae)

Abstract The induction of olfactory preferences by larval and early adult experience for odour from wheat or maize grain was examined for the granary weevil Sitophilus granarius L. in a static four-chamber olfactometer. Weevils were reared on either wheat or maize grain and received different early adult experience. It turned out that weevils that were reared in wheat and isolated as pupae from the kernels preferred wheat odour in the olfactometer when they emerged without any odour or in the presence of maize odour. Weevils that emerged in the presence of wheat odour preferred both wheat and maize odour. When weevils emerged normally as adults from the wheat kernel in which they developed, maize odour was avoided. In contrast, for weevils that were reared in maize no preferences were found in most experiments. Only weevils that emerged in the presence of wheat odour preferred the maize odour over the controls. These results demonstrate that host-selection behaviour in S. granarius weevil is shaped by experience according to the Hopkins host-selection principle or the chemical legacy hypothesis and the neo-Hopkins principle.     

Asymmetry of larval diet breadth and oviposition preference in Leptinotarsa undecimlineata

The relationship between preference and performance was studied under laboratory conditions for larvae and adult females of Leptinotarsa undecimlineata (Stål) (Coleoptera: Chrysomelidae). Leptinotarsa undecimlineata feeds exclusively on Solanum lanceolatum L. (Solanaceae) in the centre of Veracruz, Mexico. A common sympatric species, Solanum myriacanthum Dunal, is not used as host. We conducted a series of laboratory experiments to detect reasons for the exclusive use of one host plant. Leptinotarsa undecimlineata larvae were reared under laboratory conditions on both plant species, Solanum lanceolatum and S. myriacanthum . Length of larval stages, pupal weight, and percent adult eclosion were compared, and larval preference for both Solanum species was tested. Upon eclosion, adult females were exposed to each of the plants, and the effect of larval diet on adult preference was determined. Oviposition on both Solanum species was observed in no-choice tests. Larvae showed no significant preferences for either plant species. Pupal weight, however, was significantly higher on S. lanceolatum . Female beetles significantly preferred S. lanceolatum leaves, and no effect of preimaginal conditioning was found. Females reproduced in lower numbers after feeding on S. myriacanthum , oviposition initiated later, and females laid fewer eggs than females fed with S. lanceolatum . No female accepted S. myriacanthum for oviposition. Results obtained suggest that the potential host breadth of L. undecimlineata is broader in larvae than in female beetles.     

Larval food affects oviposition preference,female fecundity and offspring survival in Yponomeuta evonymellus

1. Yponomeuta evonymellus is a monophagous moth that feeds on Prunus padus which is native to Europe. In recent years, larval feeding and egg clusters have also been observed on non‐native Prunus serotina plants; however, survival of larvae on this new host is very low. 2. The objective of the present study was to determine how the feeding of larvae on each of the two host plants impacts oviposition, offspring survival and fecundity in Y. evonymellus. Our hypothesis was that, under controlled conditions, females will lay eggs on the host on which they fed as larvae. We also hypothesised that the lower survival of young larvae feeding on P. serotina was due to the smaller buds and leaves present in this species, relative to those of P. padus. 3. A dual‐choice experiment conducted under laboratory conditions demonstrated that females preferentially chose to oviposit on the plant species on which they fed as larvae. In the experiment, potential fecundity and offspring survival were significantly higher on P. padus than on P. serotina. The reduced performance of Y. evonymellus on P. serotina was correlated with a smaller bud mass and volume, lower leaf mass and surface area, and difficulty in constructing a protective tent against unfavourable weather conditions. 4. In summary, the identity of the host plant species during larval feeding determines adult oviposition preference for that host species. The survival of larvae on P. serotina growing in the nature is low, but for phenology‐related reasons.     

吞咽障碍治疗仪的作用原理及效果

介绍了吞咽障碍严重损害人类健康,吞咽障碍治疗仪是通过电刺激方式来促进受损神经复苏,加强吞咽肌群的运动,提高病人吞咽能力,从而达到治疗目的,取得了良好的效果。     

Life history phenology differences between southern and northern populations of the apple maggot fly, Rhagoletis pomonella

The textbook version of sympatric host race formation in Rhagoletis pomonella (Walsh) (Diptera: Tephritidae) features an ancestral hawthorn-infesting race and a derived apple race differing in life-history timing and response to host fruit odor. However, previous research has focused largely on northeastern North America. To investigate life-history timing in poorly studied southeastern North American populations with very diverse hosts, we performed common garden experiments on emergence time on six southern R. pomonella populations and four other R. pomonella species-group populations. Findings were: (1) the diverse adult emergence times of southern populations resulted largely from genetic differences; (2) some southern populations had bimodal emergence curves; (3) correlations of allozyme markers and emergence times were uncommon in southern populations; and (4) mean emergence times from common garden rearings and dates of field collection of the populations were strongly correlated.     

The effect of host plant on larval survivorship of the Alaskan swallowtail butterfly (Papilio machaon aliaska)

The Alaskan swallowtail butterfly, Papilio machaon aliaska (Lepidoptera: Papilionidae), uses three plant species as host plants. Cnidium cnidiifolium (Turcz.) Schischk. belongs to the family Apiaceae, the ancestral host‐plant family of the P. machaon group. Artemisia arctica Less. and Petasites frigidus (L.) Franch, in contrast, belong to the distantly related Asteraceae family and were colonized relatively recently by this group of butterflies. Previous work has shown that larval survival is highest on the novel host plants when natural enemies are present in the field. Here I examine whether P. m. aliaska fitness varied when individuals were reared on the three host plants in a common environment, free of environmental and ecological complications such as predation. I collected 12 P. m. aliaska females and measured their reproductive success when their progeny were reared on each of the three host plants. I assessed larval fitness on each of the hosts by recording the percentage pupation and percentage emergence as well as by measuring pupal mass. I found that larvae reared on the ancestral host plant, C. cnidiifolium, had higher fitness than did larvae reared on either of the novel host plants, A. arctica or P. frigidus. Larvae reared on C. cnidiifolium were more likely to pupate, achieved a greater pupal mass, and had higher emergence rates than larvae reared on the novel hosts. I interpret these results to mean that, in the absence of predation, the ancestral host plant is a better host for P. m. aliaska larvae than either novel host and I contend that this result does not appear to support the hypothesis that P. m. aliaska populations in central Alaska are divided into host races.     

The Role of Adaptation to Host Plants in the Evolution of Reproductive Isolation: Negative Evidence from Tetranychus Urticae Koch

Reproductive isolation between demes of a phytophagous arthropod population that use different host plant species could evolve in two different ways. First, adaptation to different host species might result in reproductive isolation as a pleiotropic by-product. Second, if adaptation to one host species strongly reduces fitness on others, selection could favour mechanisms, such as host fidelity and assortative mating, that restrict gene flow between host-adapted demes. A laboratory selection experiment on the broadly polyphagous spider mite Tetranychus urticae gave information on these possibilities. A population allowed to adapt to tomato plants showed increased survival, development rate and fecundity on tomato relative to the base population from which it was derived. In spite of the large difference between the tomato-adapted and base populations in performance on tomato plants, the two populations showed no evidence of reproductive isolation, as measured by the hatching rate of eggs laid by F1 hybrids between the lines. Furthermore, a genetically variable population formed by hybridizing the tomato-adapted and base populations did not show evidence for a decline in ability to survive on tomato after more than ten generations of mass rearing on lima bean, indicating that tomato-adapted genotypes suffered little or no selective disadvantage on bean. These results give no support for the role of host plants in the evolution of reproductive isolation in T. urticae.     

The genetics and ecology of sympatric speciation: A case study

Mating occurs on the larval host plant in allRhagoletis species (Diptera: Tephritidae). We show how this attribute, when coupled with certain differences in other biological traits, strongly influences the mode of speciation. In species of thesuavis species group, host shifts have never occurred during speciation, and larvae feed in the husks of any walnut species(Juglans spp.), which are highly toxic. Taxa are allopatric or parapatric and exhibit deep phylogenetic nodes suggesting relatively ancient speciation events. Traits responsible for species and mate recognition, particularly in parapatric species, are morphologically distinct and strongly sexually dimorphic. All aspects of their biology, genetics and distribution are consistent with a slow rate of allopatric speciation followed by morphological divergence in secondary contact. In contrast, speciation in thepomonella species group has always involved a shift to a new, usually unrelated, non-toxic host, and all taxa within these groups are sympatric, monophagous and morphologically indistinguishable from one another. Phylogenetic nodes are very shallow, indicating recent sympatric speciation. Sympatric divergence is promoted by genetic variation which allows a portion of the original species to shift to a new habitat or host. Evidence suggests that changes in a few key loci responsible for host selection and fitness on a new host may initiate host shifts. By exploiting different habitats, competition for resources between diverging populations is reduced or avoided. We provide evidence that in phytophagous and parasitic insects sufficient intrinsic barriers to gene flow can evolve between sister populations as they adapt to different habitats or hosts to allow each population to establish independent evolutionary lineages in sympatry.     

Spatial and genetic structure of host‐associated differentiation in the parasitoid Copidosoma gelechiae

Host‐associated differentiation (HAD) appears to be an important driver of diversification in the hyperdiverse phytophagous and parasitoid insects. The gallmaking moth Gnorimoschema gallaesolidaginis has undergone HAD on two sympatric goldenrods (Solidago), and HAD has also been documented in its parasitoid Copidosoma gelechiae, with the intriguing suggestion that differentiation has proceeded independently in multiple populations. We tested this suggestion with analysis of Amplified Fragment Length Polymorphism (AFLP) markers for C. gelechiae collections from the midwestern and northeastern United States and eastern Canada. AFLP data were consistent with the existence of HAD, with between‐host F_ST significant before Bonferroni correction in two of seven sympatric populations. amova analysis strongly rejected a model of HAD with a single historical origin, and thus supported the repeated‐HAD hypothesis. Copidosoma gelechiae shows significant host‐associated divergence at a number of allozyme loci ( Stireman et al., 2006 ), but only weak evidence via AFLPs for genome‐wide differentiation, suggesting that this species is at a very early stage of HAD.     

The influence of oviposition phenology on survival in host races of Eurosta solidaginis

Phenological differences between host plants can contribute to allochronic isolation of host races of phytophagous insects. Host races of the gallmaking fly, Eurosta solidaginis, that live on different species of goldenrod (Solidago altissima and S. gigantea) exhibit different emergence phenologies. These differences could result from adaptation to corresponding phenological differences between the hosts in periods of optimal suitability for gall formation and survival to adulthood. In order to test this, some flies of each host race were allowed to emerge naturally while the emergence times of others were manipulated to correspond to the emergence and oviposition periods of the other host race. Percent gall formation and survival to adulthood were examined for three oviposition periods: the peak time of emergence and oviposition of the earlier-emerging host race (that from S. gigantea), that of the later-emerging host race (that from S. altissima), and a week after the peak emergence of the host race from S. altissima. Flies of both host races were allowed to ovipuncture plants of the appropriate species during each of these periods. Plant relative growth rates were measured during each of these periods. The experiment was repeated twice over a two-year period. Relative growth rates of both host species were highest during the earliest oviposition period (the period during which the host race from S. gigantea normally emerges). Percent gall formation was significantly correlated with plant relative growth rate, but the coefficient of determination was low. In both years of the study, percent gall formation of both host races was highest during the earliest oviposition period (the period during which the host race from S. gigantea normally oviposits). Likewise, percent survival to adulthood in both host races was highest during the earliest oviposition period. There was no significant effect of oviposition period on the percent of larval death due to parasitism by Eurytoma gigantea or predation by Mordellistena unicolor. These results suggest that the host race from S. altissima does not emerge at the time that its host is optimally suited for gall formation or survival to adulthood. Therefore, differences in emergence phenologies do not appear to be due to corresponding phenological differences between the host species in suitability for gall formation or survival to adulthood.     

Life Cycle of Cystoisospora felis (Coccidia: Apicomplexa) in Cats and Mice

Cystoisospora felis is a ubiquitous apicomplexan protozoon of cats. The endogenous development of C. felis was studied in cats after feeding them infected mice. For this, five newborn cats were killed at 24, 48, 72, 96, and 120 h after having been fed mesenteric lymph nodes and spleens of mice that were inoculated with C. felis sporulated sporocysts. Asexual and sexual development occurred in enterocytes throughout the villi of the small intestine. The number of asexual generations was not determined with certainty, but there were different sized merozoites. At 24 h, merogony was seen only in the duodenum and the jejunum. Beginning at 48 h, the entire small intestine was parasitized. At 24 h, meronts contained 1–4 zoites, and at 48 h up to 12 zoites. Beginning with 72 h, the ileum was more heavily parasitized than the jejunum. At 96 and 120 h, meronts contained many zoites in various stages of development; some divided by endodyogeny. The multiplication was asynchronous, thus both immature multinucleated meronts and mature merozoites were seen in the same parasitophorous vacuole. Gametogony occurred between 96 and 120 h, and oocysts were present at 120 h. For the study of the development of C. felis in murine tissues, mice were killed from day 1 to 720 d after having been fed 10⁵ sporocysts, and their tissues were examined for the parasites microscopically, and by bioassay in cats. The following conclusions were drawn. (1) Cystoisospora felis most frequently invaded the mesenteric lymph nodes of mice and remained there for at least 23 mo. (2) It also invaded the spleen, liver, brain, lung, and skeletal muscle of mice, but division was not seen based on microscopical examination. (3) This species could not be passed from mouse to mouse.     

碲化镉（CdTe）探测器的原理及医学应用

本文介绍了一种新型的化合物半导体探测器——CdTe探测器,它具有灵敏度高,探测效率高、能量分辨率好、可以在室温下使用,以及对湿度不敏感和体积小等优点,并介绍了该探测器在医学应用方面的前景。     

Genetically based polymorphisms in morphology and life history associated with putative host races of the water lily leaf beetle,Galerucella nymphaeae

A host race is a population that is partially reproductively isolated from other conspecific populations as a direct consequence of adaptation to a specific host. The initial step in host race formation is the establishment of genetically based polymorphisms in, for example, morphology, preference, or performance. In this study we investigated whether polymorphisms observed in Galerucella nymphaeae have a genetic component. Galerucella nymphaeae, the water lily leaf beetle, is a herbivore which feeds and oviposits on the plant hosts Nuphar lutea and Nymphaea alba (both Nymphaeaceae) and Rumex hydrolapathum and Polygonum amphibium (both Polygonaceae). A full reciprocal crossing scheme (16 crosses, each replicated 10 times) and subsequent transplantation of 1,001 egg clutches revealed a genetic basis for differences in body length and mandibular width. The heritability value of these traits, based on midparent-offspring regression, ranged between 0.53 and 0.83 for the different diets. Offspring from Nymphaeaceae parents were on average 12% larger and had on average 18% larger mandibles than offspring from Polygonaceae parents. Furthermore, highly significant correlations were found between feeding preference of the offspring and the feeding preference of their parents. Finally, two fitness components were measured: development time and survival. Development time was influenced by diet, survival both by cross type and diet, the latter of which suggest adaptation of the beetles. This suggestion is strengthened by a highly significant cross x diet interaction effect for development time as well as for survival, which is generally believed to indicate local adaptation. Although no absolute genetic incompatibility among putative host races was observed, survival of the between-host family offspring, on each diet separately, was lower than the survival of the within-host family offspring on that particular host. Survival of offspring of two Nymphaeaceae parents was about two times higher on Nymphaeaceae than on Polygonaceae, whereas survival of offspring of two Polygonaceae parents was 11 times higher on Polygonaceae than on Nymphaeaceae (based on untransformed data). Based on these results, we conclude that genetically determined polymorphisms in morphology and feeding preference exist in G. nymphaeae, resulting in differential performance. Furthermore, in each diet separately, offspring of between-host family crosses were less fit than offspring of within-host family crosses. These results support the hypothesis that within this species two host races can be distinguished.