Unmated Females Research Articles

Investigating the effects of symbiotic fungi on the flight behaviour ofSirex noctilio(Hymenoptera: Siricidae)

AbstractThe invasive woodwaspSirex noctilioFabricius (Hymenoptera: Siricidae) is obligately associated with the symbiotic white rot fungusAmylostereum areolatum(Chaillet ex Fries) Boidin (Basidiomycota: Amylosteraceae), and shows positive chemotaxis to volatiles emitted by this symbiont. After introduction to North America,S. noctiliowas collected carrying another fungus speciesAmylostereum chailletii(Persoon) Boidin, used symbiotically by native North AmericanSirexLinnaeus. We conducted flight behaviour studies in a walk-in flight tunnel to evaluate specificity of the attraction of mated and unmatedS. noctilioto its primary symbiont,A. areolatum, versus the alternative symbiont,A. chailletii. Fewer unmated than matedS. noctiliofemales responded to either of the fungi. Unmated females showed no landing preference but matedS. noctiliofemales were attracted toA. areolatumalthough avoidance ofA. chailletiiwas not complete. Chemical analysis demonstrated major differences in the volatile profiles of the two fungal species. Sesquiterpenes dominated theA. areolatumsamples, whereas only two aromatic volatiles were consistently present in the nativeA. chailletii.

Influence of mating and age on susceptibility of the beetle Anoplophora glabripennis to the fungal pathogen Metarhizium brunneum

The age and life history of an insect can influence its susceptibility to pathogens. Reproduction can be costly and may trade off with immunity while it is generally assumed that immunity will decrease with increasing age through a process called immunosenescence. Fungal pathogens are used as biological control agents for a variety of insect pests, and Metarhizium brunneum is being developed to control the Asian longhorned beetle (Anoplophora glabripennis), an invasive wood-borer. Because adult female A. glabripennis take 1–2weeks to mature after eclosion and both sexes can be long-lived, we investigated how age and mating status would influence susceptibility of A. glabripennis to M. brunneum. Young (6.5day-old) unmated, mature (27–33day-old) mated and unmated, and old (57–71day-old) unmated and mated adults were inoculated with a lethal dose of M. brunneum. The presence of M. brunneum in the hemolymph was quantified and beetle mortality was monitored daily. There was a cost to reproduction for mated mature male and female beetles which died a median of 1.6–1.9days earlier than unmated beetles, while there was no effect of mating on susceptibility for old beetles. We found no evidence for immunosenescence in old beetles, as they did not die faster than young or mature beetles. Young unmated males however were more susceptible than mature or old unmated males, while there was no effect of age on susceptibility of unmated females.

The use of the cannibalistic habit and elevated relative humidity to improve the storage and shipment of the predatory mite Neoseiulus californicus (Acari: Phytoseiidae).

This study investigated the feasibility of using the cannibalistic habits of the mite Neoseiulus californicus (McGregor) and controlling the relative humidity (RH) to prolong the survival time during the storage or shipment of this predatory mite. Three-day-old mated and unmated females were individually kept at 25±1°C in polypropylene vials (1.5mL), each containing one of the following items or combinations of items: a kidney bean leaf disk (L), N. californicus eggs (E), and both a leaf disk and the eggs (LE). Because the leaf disk increased the RH in the vials, the RH was 95±2% under the L and LE treatments and 56±6% under the E treatment. The median lethal time (LT50) exceeded 50days for the mated and unmated females under the LE treatment. However, it did not exceed 11 or 3days for all females under the L or E treatments, respectively. Under the LE treatment, the mated and unmated females showed cannibalistic behavior and consumed an average of 5.2 and 4.6 eggs/female/10days. Some of the females that survived for LT50 under each treatment were transferred and fed normally with a constant supply of Tetranychus urticae Koch. Unmated females were provided with adult males for 24h for mating. Only females previously kept at LE treatment produced numbers of eggs equivalent to the control females (no treatment is applied). The results suggested that a supply of predator eggs and leaf material might have furnished nutrition and water vapor, respectively, and that this combination prolonged the survival time of N. californicus during storage. Moreover, this approach poses no risk of pest contamination in commercial products.

Life history of the spider parasitoid Zatypota percontatoria (Hymenoptera: Ichneumonidae)

AbstractThe life history of polysphinctine parasitoids is poorly understood. As a result, their effect on their host has not been evaluated. Here, we present the phenology of Zatypota percontatoria, an ectoparasitoid wasp of theridiid spiders, using rich field, semi‐field and laboratory investigations of selected life‐history parameters. The wasps overwintered as larva attached to the spider abdomen and the imagos of the first generation emerged at the beginning of May. The sex ratio (F/M) of overwintered wasp larvae was 1.4. The wasp spent an average of 6.4 days in the egg stage, 27.67 days in the larval stage and 9.6 days in the pupal stage. Adult longevity was on average 14.34 days. Oviposition occurred on average 8.44 days following maturity. The wasp laid on average 0.35 eggs/day. The total fecundity was on average 7.4 eggs per wasp and decreased with age (data from unmated females). The developmental rate increased with experimental temperature up to 28 °C. The lower developmental threshold for pupae was estimated at 6.6 °C. The sum of effective temperatures for pupae was estimated at 157.8 degree days. Using daily temperature records from the Czech Republic over the last 41 years, we estimated an average of 3.5 generations of Z. percontatoria per year. Mortality was 48% in semi‐field conditions and 23% in the laboratory. The incidence of mortality was highest during egg and larval stages caused by the detachment of eggs or larvae during spider molting, the mortality of the spider‐host and egg deposition on the spider prosoma.

Stable coexistence of ecologically identical species: conspecific aggregation via reproductive interference

Stable coexistence of ecologically identical species is not possible according to the established ecological theory. Many coexistence mechanisms have been proposed, but they all involve some form of ecological differentiation among the competing species. The aggregation model of coexistence would predict coexistence of identical species if there would be a mechanism that generates spatially aggregated distributions that are not completely correlated among the species. Our aim is to demonstrate that continued dispersal, triggered by reproductive interference between ecologically identical species, is such a mechanism. This study has been motivated by species using ephemeral patchy resources, such as decomposing fruits, fungal sporophores, carrion, and dung. We analyse an individual-based model with sexual reproduction, in which the progeny develops in ephemeral resource patches and the new generation disperses to a new set of patches. We assume spatially restricted dispersal, that patches differ in detectability, and that unmated females continue dispersal. In the model, reproductive interference (males spend some time searching for and/or attempting to mate with heterospecific females) reduces the mating rate of females, especially in the less common species, which leads to increased dispersal and reduces spatial correlation in species' distributions. For a wide range of parameter values, coexisting species show a systematic difference in their relative abundances due to two opposing forces: (1) uncommon species have reduced growth rate (Allee effect), which decreases abundance; (2) an abundance difference between the species reduces interspecific spatial correlation, which in turn reduces interspecific competition and allows the rarer species to persist at low density. Our results demonstrate a new mechanism for coexistence that is not based on ecological differentiation between species.

<p class="Body"><strong>Prey</strong><strong> diet quality affects predation, oviposition and conversion rate of the predatory mite <em>Neoseiulus barkeri</em> (Acari: Phytoseiidae)</strong></p>

Biological characteristics of a predator can be affected by the nutritional history of its prey, e.g., change in the nutritional components of prey may influence the development and reproduction of its predator. In this study, the predation, reproduction and conversion rate of a native predatory mite, Neoseiulus barkeri were compared when fed with two colonies of the flour mite Tyrophagus putrescentiae, the one reared on common wheat bran (TPA) and the other on a mixture of wheat bran and yeast (TPB). The experiments were conducted under laboratory condition at 25°C, 80% relative humidity, and 16:8 light:dark photoperiod. The daily consumption of unmated and mated N. barkeri females fed with TPB was 1.30 and 1.93 times higher than those fed with TPA. The daily and cumulative fecundity of mated predator females fed with TPB were 1.55 and 2.47 times, and their eggs being 1.20 times as those of females fed with TPA. The daily consumption of unmated females gradually decreased with age. For both mated and unmated females fed with TPA or TPB, we observed a wave pattern curve of daily prey consumption. The mean difference between two wave peaks was 3.55±0.23 days. It seems a periodic trend instead of random vibration due to the relative consist differences between wave peaks and similar sizes of the peaks. About 82% and 74% overall consumption of mated females offered TPA and TPB were allocated to reproduction, with corresponding conversion rate being 0.39 and 0.28, respectively. Overall, adding yeast to the diet of T. putrescentiae led to increased fecundity of N. barkeri mainly through stimulating its predation.

Temperature-dependent development and life history of Oligonychus litchii (Acari: Tetranychidae), on wax apple

The litchi spider mite Oligonychus litchii Lo & Ho is one of the major pests of fruit crops in Taiwan. This study investigated the life history of the litchi spider mite on wax apple (Syzygium samarangense Merr. & Perry) at five constant temperatures (16, 20, 25, 30, and 32°C) under 70±5% RH and a 12L:12D photoperiod. Ninety-five percent of the eggs hatched at 20, 25, and 30°C, respectively. The entire developmental period was 40.3days at 16°C and only 9.3days at 32°C. The low developmental threshold temperature for development from egg to adult was 10.1°C, and the effective accumulated temperature was 197.5degree–days (DD). Unmated female mites had the longest life span although the oviposition period shortened as temperature increased. Mated female mites produced significantly more eggs than unmated females. At most, a mated female could produce an average of 3.5 eggs per day at 25°C and a maximum of 60.3 eggs over the entire oviposition period at 20°C. Unmated females exclusively produce male offspring, indicating that litchi spider mites are arrhenotokous. At 25°C, the intrinsic rate of increase (r) was 0.1610day−1, the net reproductive rate (R0) was 19.58 offspring, the finite rate of increase (λ) was 1.1747day−1, and the mean generation time (T) was 18.50days. The results obtained in this study provide useful information to aid in the development of phenological models for pest monitoring programs of O. litchii in Taiwan.

Asymmetric effects of adult nutrition on reproductive success of male and female Diaeretiella rapae (Hymenoptera: Aphidiidae)

AbstractThe role of diet supplements (honey, water or no supplements) on egg maturation, oviposition strategy and longevity of the parasitic wasp Diaeretiella rapae McIntosh (Hymenoptera: Aphidiidae) is investigated. Parasitoids feed as larvae on hosts to acquire nutrition for growth and development, and further gain additional resources during their adult stage by feeding on either host or nonhost resources. The additional resources acquired by adults can help them to increase their reproductive activity or life expectancy, or both. Diaeretiella rapae females emerge with some developed eggs and no additional resources are required for egg maturation or successful oviposition. Females are able to oviposit and produce viable offspring immediately after emergence, and the number of eggs left in the ovaries of females decreases with subsequent oviposition, suggesting that ovigeny index of D. rapae is inclined towards pro‐ovigenic status. When unmated males and females are offered honey solution, females are attracted to it, whereas males display courtship and make mating attempts but then feed on honey after mating. The oviposition efficiency of female D. rapae increases by 30% when they feed on honey compared with when starved. Honey‐fed D. rapae adults live significantly longer (almost twice as long) than starved adults. Honey‐fed females deprived of hosts live longer than those offered hosts regularly. The positive effects of honey‐feeding on longevity are greater in females than in males. Taken together, the results of the present study suggest that the provision of additional resources to adult D. rapae parasitoids could enhance their life expectancy and parasitism efficiency in biological control programmes.

Biology of mealybug,Phenacoccus solenopsistinsley onParthenium

Results revealed that males and females of mealybug, Phenacoccus solenopsis Tinsley went through four and three nymphal instars, with total life cycle of 14.06± 1.09 and 15.53± 0.83 days, respectively. Pre-mating, pre-ovipositional, ovipositional and post ovipositional periods were observed to be 2.11 ± 1.26, 7.66 ± 0.70, 10.22 ± 2.68 and 3.77 ± 1.71 days, respectively. The adult longevity was 47.125 ± 7.01 (for unmated females), 3.66 ± 0.81 (for unmated males), 24.66 ± 4.5 (for mated females) and 1.33 ± 0.50 days (for mated males). Reproduction was sexual and ovoviviparous, wherein only mated females laid eggs (167.77 ± 25.57/female). Life span (life cycle duration and adult longevity) was obseverd to be as 61.5 ± 6.95, 18.66 ± 0.82, 38.44 ± 4.95 and 17.13 ± 0.97 days for unmated females, unmated males, mated females and mated males, respectively.

Selection for costly sexual traits results in a vacant mating niche and male dimorphism.

The expected strong directional selection for traits that increase a male's mating ability conflicts with the frequent observation that within species, males may show extreme variation in sexual traits. These male reproductive polymorphisms are usually attributed to direct male-male competition. It is currently unclear, however, how directional selection for sexually selected traits may convert into disruptive selection, and if female preference for elaborate traits may be an alternative mechanism driving the evolution of male polymorphism. Here, we explore this mechanism using the polyandric dwarf spider Oedothorax gibbosus as a model. We first show that males characterized by conspicuous cephalic structures serving as a nuptial feeding device ("gibbosus males") significantly outperform other males in siring offspring of previously fertilized females. However, significant costs in terms of development time of gibbosus males open a mating niche for an alternative male type lacking expensive secondary sexual traits. These "tuberosus males" obtain virtually all fertilizations early in the breeding season. Individual-based simulations demonstrate a hitherto unknown general principle, by which males selected for high investment to attract females suffer constrained mating opportunities. This creates a vacant mating niche of unmated females for noninvesting males and, consequently, disruptive selection on male secondary sexual traits.

Annual Migration of Agrotis segetum (Lepidoptera: Noctuidae): Observed on a Small Isolated Island in Northern China.

Migration behavior of the turnip moth, Agrotis segetum (Lepidoptera: Noctuidae), is not well known by far. Here, we present the data from an 11-year study on A. segetum by means of searchlight trapping and ovarian dissection on Beihuang (BH) Island, which located in the center of the Bohai Strait in northern China. The data showed a large number of A. segetum flight across the strait each year, which provides direct evidence that A. segetum is a long-distance migrant, migrating at least 40 - 60 km to reach the trapping site. The migration period during 2003-2013 ranged from 115 to 172 d. Among the catches, the proportion of females was significantly higher than that of males in each month from May to September. Ovarian dissection showed that the proportion of mated females and the proportion of sexually mature females was significantly higher than that of unmated females and sexually immature females in early summer, respectively, but conversely in autumn. The early summer populations migrate in a south-north direction, which might undertake a long-distance flight on several successive nights. The autumn populations migrate in a north-south direction, which might originate not far from the trapping site. Based on these findings, the migratory physiology of A. segetum was discussed.

Sexual signalling by females: do unmated females increase their signalling effort?

Theory predicts that females should invest least in mate searching when young, but increase their effort with age if they remain unmated. Few studies have examined variation in female sexual signalling. Female Dawson's burrowing bees (Amegilla dawsoni) search for males by signalling their receptivity on emergence, but many leave the emergence site unmated and must attract males at feeding sites. Female bees prevented from mating on emergence had more extreme versions of cuticular hydrocarbon profiles that make them attractive to males, lending empirical evidence of adaptive shifts in female mating effort.

Pheromone Bouquet of the Dried Bean Beetle, Acanthoscelides obtectus (Col.: Chrysomelidae), Now Complete

AbstractMale‐specific volatile components, released by the dried bean beetle, Acanthoscelides obtectus, were identified as methyl (E,R)‐2,4,5‐tetradecatrienoate, methyl (2E,4Z,7Z)‐2,4,7‐decatrienoate, methyl (2E,4Z)‐2,4‐decadienoate, octadecanal and the sesquiterpenes (3Z,6E)‐ and (3E,6E)‐α‐farnesene. In olfactometer bioassays, pure methyl (E,R)‐2,4,5‐tetradecatrienoate was only weakly attractive to unmated females. However, a blend of the six identified compounds released in physiologically relevant ratios and doses proved to be as active as headspace odours collected from live males.

Response to conspecific and heterospecific semiochemicals by Sesamia nonagrioides (L.) (Lepidoptera: Noctuidae) gravid females.

The Mediterranean corn borer, Sesamia nonagrioides, occurs sympatrically in the northeast of Spain with other lepidopteran pests such as Ostrinia nubilalis and Mythimna unipuncta. In this study, we evaluated the electrophysiological and behavioural response of mated and unmated females and males of S. nonagrioides to their own complete pheromone blend, to its own four components separately, and to the pheromone components of the sympatric species O. nubilalis and M. unipuncta. Results of the electroantennogram recordings revealed that females of S. nonagrioides can detect their own pheromone blend and its individual components. Moreover, our results show that unmated females and males of S. nonagrioides are more sensitive to the female pheromone, showing higher electrophysiological response than the mated females and males. Electroantennogram recordings showed that males and females can detect the major sexual pheromone component of O. nubilalis (Z)-11-tetradecenyl acetate and the minor component of the pheromone of M. unipuncta (Z)-9-hexadecenyl acetate. When the sex pheromone stimulus was presented in the dual-choice assays, gravid females of S. nonagrioides were attracted to both their own complete pheromone blend and one of their own minor pheromone components, (Z)-11-hexadecenal, but the major sexual pheromone component of O. nubilalis acts as a behavioural antagonist to the females.

Contact pheromones mediate male preference in black widow spiders: avoidance of hungry sexual cannibals?

Males often exercise mate choice when mating frequency is constrained, costs of choice are low and variation in female quality and/or expected paternity can be reliably detected. Across invertebrates, males use sex pheromones to discern female mating status, but there are few demonstrations that information about expected fecundity (‘quality’) is encoded in pheromones alone. Here we examine whether females' sex pheromones allow males to detect differences in female food intake and mass in two species of widow spiders (Latrodectus hesperus and Latrodectus hasselti) in which chemicals are deposited by females in silk. Recent work shows that male L. hesperus prefer well-fed females, and that these females produce more silk than hungry females. Thus, changes in diet could be mechanistically linked to changes in silk-bound pheromonal signals. We show that unmated females of both species lose more than half of their mass when food is withheld, and silk production is reduced by 48% (L. hesperus) to 67% (L. hasselti). Males had a significant sexual response to pheromones extracted from the females' silk in both species, although this response was not directly correlated with silk or female mass. In L. hesperus, but not in L. hasselti, males were less responsive to sex pheromones from food-deprived females compared to well-fed females. While females on good diets provide the benefit of higher fecundity in both species, the risk of being cannibalized by hungry females during courtship exists only in L. hesperus. We conclude that sex pheromones alone can provide information about recent female feeding history, possibly reducing the costs of males expressing choice in the field. The species difference in male response also suggests that male preferences in these spiders may depend less on the benefit of seeking a highly fecund female and more on avoiding the cost of risky mating attempts with a likely cannibal.

Chemoreception and mating behaviour of a tropical Australian skink

In many reptile groups, molecular systematics is currently revealing high levels of cryptic diversity (i.e. genetically distinct lineages that are difficult to distinguish morphologically). One obvious mode for mate discrimination in these cryptic species is chemoreception. We hypothesise that diversity in these groups is not cryptic for pheromones, and mate recognition via chemoreception may be the primary reproductive isolating mechanism. Here, we present a preliminary study of chemoreception in Lampropholis coggeri, a rainforest skink of north-eastern Australia. We first describe the mating behaviour of captive pairs, showing that tongue-flicking is an important component for both males and females, and find that L. coggeri mate more readily when paired with a conspecific from their own population vs. from a nearby population. Based on the assumption that tongue-flicking represents the lizard’s interest, we then experimentally tested scent discrimination using lizard-swabbed cotton buds presented to captive individuals. We found both sexes tongue-flicked more to conspecific scent than to unscented controls. Males tongue-flicked more to female scent than to male scent but did not discriminate between mated and unmated females. While females showed greater interest in conspecific scent, they showed no greater interest in scent from males than females. This lack of discrimination was true for both mated and unmated females. Unexpectedly, however, mated females tongue-flicked substantially more than unmated females. Finally, males tended to tongue flick more often to female scents from their own population than to a nearby population that is moderately genetically divergent. Our results suggest that chemoreception plays a role in mate recognition in this species. Further work should extend to establishing mate recognition between the highly divergent cryptic lineages within this species and the pheromones underlying mate recognition.

副珠蜡蚧阔柄跳小蜂的寄生影响因子

PDF HTML阅读 XML下载 导出引用 引用提醒 副珠蜡蚧阔柄跳小蜂的寄生影响因子 DOI: 10.5846/stxb201312253019 作者: 作者单位: 中国热带农业科学院环境与植物保护研究所,海南大学环境与植物保护学院,中国热带农业科学院环境与植物保护研究所,中国热带农业科学院环境与植物保护研究所,中国热带农业科学院环境与植物保护研究所,中国热带农业科学院环境与植物保护研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 农业部发展南亚热带作物办公室项目(12RZBC-20, 13RZBC-15, 14RZBC-15);中国热带农业科学院基本业务费(1630042012005) Factors influencing the parasitism of Metaphycus parasaissetiae (Hymenoptera: Encyrtidae) Author: Affiliation: Environment and Plant Protection Institute,CATAS,,Environment and Plant Protection Institute,CATAS,Environment and Plant Protection Institute,CATAS,Environment and Plant Protection Institute,CATAS,Environment and Plant Protection Institute,CATAS Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:副珠蜡蚧阔柄跳小蜂Metaphycus parasaissetiae是橡副珠蜡蚧Parasaissetia nigra成虫的重要内寄生蜂。寄生蜂的寄生效果受多种因素影响,就温度、光周期、寄主成虫日龄、雌蜂日龄及交配等因子对副珠蜡蚧阔柄跳小蜂的寄生率、每头寄主的出蜂量及后代雌性率的影响进行研究,以期探明几种因子对该蜂寄生效果的影响。结果表明:温度为27-30 ℃时寄生率最高为91.7%,出蜂量以27 ℃最高为7.5头,雌性率以24 ℃条件最高为72.1%,其次27 ℃为62.6%,说明24-30 ℃是寄生效果较好的适温范围;光周期对副珠蜡蚧阔柄跳小蜂的影响明显,光暗比为12 h : 12 h条件下,其寄生率、出蜂量、后代雌性率均最大,分别为70.6%、5.3头、68.3%;副珠蜡蚧阔柄跳小蜂寄生用20-21日龄橡副珠蜡蚧成虫的寄生率、出蜂量及后代雌性率均为最高,分别为87.0%、5.6头、51.2%,说明20-21日龄的橡副珠蜡蚧成虫是副珠蜡蚧阔柄跳小蜂最适合寄生的阶段;雌蜂日龄对寄生效果的影响明显,3日龄的出蜂量最多为5.6头,4日龄的小蜂寄生率最高为81.7%, 5日龄的雌性率最大为55.2%;交配是另一影响寄生效果及性比的重要因子,已交配的寄生率及出蜂量显著高于未交配的,分别为91.7%、7.5头,交配的雌性率为62.1%,而未交配所育后代均为雄蜂。综合以上结果分析,可考虑选用20-21日龄橡副珠蜡蚧成虫、充分交配的3-6日龄小蜂、温度27 ℃及光周期L : D=12 : 12作为室内扩繁副珠蜡蚧阔柄跳小蜂的理想条件组合。 Abstract:Metaphycus parasaissetiae is a dominant endoparasitoid found in Parasaissetia nigra adults; however, various factors influence the efficiency of the parasite. The parasitic rate, emergence amount per host, and the sexes of its progeny were used to evaluate the effects of temperature, photoperiods, ages of P. nigra adults, adult ages, and female M. parasaissetiae mating success on parasitic efficiency. The results showed that the parasitic rate peaked (91.7%) at 27-30 ℃, but decreased to 88.3% at 33 ℃. In the temperature range of 21 to 27 ℃, the emergence levels of M. parasaissetiae gradually increased with temperature, increasing 7.5 at 27 ℃. This emergence level was significantly higher than that recorded at other temperatures. However, in the temperature range of 27 to 33 ℃, the emergence level decreased with temperature, declining to 5.1 at 33 ℃. The highest female ratio was 72.1% at 24 ℃, followed by 62.6% at 27 ℃; thus, a temperature range of 24 to 30 ℃ is suitable for the parasitoid. Parasitic efficiency gradually increased as the illumination duration was increased from 8 h to 12 h. After 12 h illumination, the number of parasitized hosts, parasitic rate, emergence level, and female progeny ratio of M. parasaissetiae were the highest in all groups, i.e., 21.2, 70.6%, 5.3, and 68.3%, respectively. However, these factors decreased after 16 h illumination, i.e., 9.0, 30.0%, 1.7, and 34.1%, respectively. In parasitized P. nigra adults aged 20 and 21 days, the highest parasitic rate (87.0%), number of emerging parasitoids (5.6), and female progeny ratio (51.2%) of M. parasaissetiae was recorded. In comparison, in parasitized hosts aged 1 and 2 days, these factors were 33.0%, 0.9, and 46.6% respectively. This result indicates that adult P. nigra hosts aged 20 and 21 days are the most compatible for M. parasaissetiae, while those aged 1 to 2 days were not optimal. The age of female parasitoid adults represented another important factor that influences the parasitic efficiency of M. parasaissetiae. The number of parasitized host, emergence level of the offspring, and parasitic rate increased with the age of female adults (in the age range of 2-4 days), reaching 16.3, 5.2, and 81.7%, respectively, at 4 days. These values were higher than those observed at ages 2, 6, 7, and 8 days. In M. parasaissetiae females of >4 days of age, the number of parasitized hosts and parasitic rate decreased gradually. At the age of 8 days, the lowest parasitic ratio, emergence level, and number of parasitized hosts was recorded, i.e., 25.0%, 1.5, and 5, respectively. However, the ratio of female offspring was the highest (55.2%) at 5 days. Mating also significantly affected the parasitic efficacy and sex ratio of M. parasaissetiae. The parasitic rate (91.7%) and emergence (7.5) induced by mated parasitoids were greater than that by unmated parasitoids. The female ratio of mated female parasitoid offspring was 62.1%, whereas unmated females produced no female offspring. We concluded that a combination of factors are required for the optimum conditions for M. parasaissetiae, including P. nigra adults aged 20-21 days, mated female parasitoids aged 3–6 days, temperature conditions of 27 ℃, and a light : dark photoperiod of 12 : 12 h. 参考文献 相似文献 引证文献

The Role of Olfactory Cues for the Search Behavior of a Specialist and Generalist Butterfly

Searching for resources is often a challenging task, especially for small organisms such as insects. Complex stimuli have to be extracted from the environment and translated into a relevant behavioral output. A first step in this process is to investigate the relative roles of the different senses during search for various resources. While the role of olfaction is well documented in nocturnal moths, the olfactory abilities of the closely related diurnal butterflies are poorly explored. Here we investigated how olfactory information is used in the search for host plants and asked if these abilities varied with levels of stimulus complexity. Thus, we tested two nymphalid butterfly species with divergent host plant range in a two-choice olfactometer testing different combinations of host and non-host plants. The experiments show both the monophagous Aglais urticae and the polyphagous Polygonia c-album could navigate towards an odor source, but this ability varied with context. While mated females exhibited a preference for their host plant, unmated females of both species did not show a preference for host plant cues. Furthermore, both species showed inabilities to make fine-tuned decisions between hosts. We conclude that olfactory cues are important for butterflies to navigate towards targets. We argue that there are limitations on how much information can be extracted from host volatiles. These results are discussed in the light of neural processing limitations and degree of host plant specialization, suggesting the necessity of other sensory modalities to sharpen the decision process and facilitate the final oviposition event.

Embryonic expression of shuttle craft, a Drosophila gene involved in neuron development, is associated with adult lifespan.

Despite the progress in aging research that highlights the role of the nervous system in longevity, whether genes that control development and consequently structure of the nervous system affect lifespan is unclear. We demonstrated that a mutation inshuttle craft, a gene involved in the nervous system development, increased the lifespan of unmated females and decreased the lifespan of mated females, without affecting males. Precise reversions of the mutation lead to the restoration of the lifespan specific to control females. In mutant unmated females, increased lifespan was associated with elevated locomotion at older ages, indicating slowed aging. In mutant mated females, reproduction was decreased compared to controls, indicating a lack of tradeoff between this trait and lifespan. No differences in shuttle craft transcription were observed between whole bodies, ovaries, and brains of mutant and control females of different ages, either unmated or mated. The amount of shuttle craft transcript appeared to be substantially decreased in mutant embryos. Our results demonstrated that a gene that regulates development of the nervous system might also influence longevity, and thus expanded the spectrum of genes involved in lifespan control. We hypothesize that this "carry-over" effect might be the result of transcription regulation in embryos.

Effects of starvation and molting on the metabolic rate of the bed bug (Cimex lectularius L.).

The bed bug (Cimex lectularius L.) is a common hematophagous pest in the urban environment and is capable of surviving extended periods of starvation. However, the relationship between starvation and metabolism in bed bugs is not well understood. To better understand this relationship, we measured the metabolism of all life stages for >900 h after feeding (starvation) using closed-system respirometry. Measurements were made around molting for the immature life stages, which occurs only after a blood meal. In addition, both mated and unmated adults were measured. Starvation and molting had significant effects on the metabolism of the bed bug. Mass-specific metabolic rate (V(O2); mL g(-1) h(-1)) declined in a curvilinear fashion with the period of starvation for adults and with the postmolting period for immature bed bugs (used to standardize all immature life stages). A standard curve was developed to depict the generalized pattern of metabolic decline observed in all life stages that molted. Individual metabolic comparisons among life stages that molted revealed some differences in metabolic rate between unmated males and females. In addition, the mass scaling coefficient was found to decline with starvation time (postmolting time) for all life stages that molted. In most life stages, the ratio of V(CO2) to V(O2) (respiratory exchange ratio) declined over time, indicating a change in metabolic substrate with starvation. Finally, daily percent loss in body mass declined in a pattern similar to that of V(O2). The observed patterns in metabolic decline are evaluated in relation to the life history of bed bugs. In addition, the evolutionary development of these patterns is discussed. The metabolic pattern after feeding was also found to share several similarities with that of other ectothermic species.