Geographic variation in male courtship acoustics and genetic divergence of populations of the Cotesia flavipes species complex

Courtship behaviors of insect populations can vary across the range of a species. Populations exhibiting divergent courtship behavior may indicate genetic divergence or cryptic species. Courtship acoustic signals produced by male wing fanning and genetic structure (using amplified fragment length polymorphisms) were examined for seven allopatric populations of the Cotesia flavipes (Hymenoptera: Braconidae) species complex, using four C. sesamiae (Cameron) and three C. flavipes Cameron populations. Members of this species complex parasitize lepidopteran pests in gramineous crops including sugarcane, maize, and rice . Significant variation was detected in courtship acoustic signals and genetic structure among populations of both species. For C. sesamiae, courtship acoustic signals varied more between populations of two biotypes that were collected near an area of sympatry. The two biotypes of C. sesamiae were also genetically divergent. For C. flavipes, significant differences in acoustic signals and genetic structure occurred among allopatric populations; these differences support the recent designation of one population as a new species. Courtship acoustics play a role in reproductive isolation in this species complex, and are likely used in conjunction with chemical signals. Ecological factors such as host range and host plant use may also influence the divergence of both courtship acoustic signals and genetic structure among populations in the C. flavipes complex.     

Variation in behavioural response to oxygen stress by egg-tending males of parapatric fluvial and lacustrine populations of a landlocked goby

The behavioural response of egg-tending males from parapatric fluvial and lacustrine populations of a landlocked goby Rhinogobius sp. (the orange form) to oxygen stress was compared in laboratory experiments. The natural spawning locations of these populations (rapids of tributary rivers and lakeshore of Lake Biwa, respectively) differ in dissolved oxygen concentration and its variability. Males of both populations spent a longer period of time in fanning behaviour under low dissolved oxygen conditions (4·5–5·0 mg l⁻¹), where >90% of eggs without paternal care died before reaching eyed stage, relative to fully saturated dissolved oxygen conditions (8·0–8·5 mg l⁻¹). Lacustrine males, who occasionally encounter oxygen stress (<2 mg l⁻¹) in their natural habitat, fanned eggs for a longer time period than fluvial males. The time difference in fanning behaviour between the two oxygen conditions was greater for lacustrine than fluvial males. Survival rate in the lower oxygen condition was higher for eggs tended by lacustrine males than those tended by fluvial males, probably due to this difference in fanning activity. These results showed that the response to oxygen stress differs between the two populations and, moreover, as both populations behaved adaptively in responding to the reduction in dissolved oxygen, contiguous habitats may have distinct natural selective pressures. It is suggested that regulation of egg fanning activity is strongly favoured by natural selection in unpredictable environments.     

Effects of a low oxygen environment on parental effort and filial cannibalism in the male sand goby, Pomatoschistus minutus

In fish, brood cycling parental males sometimes eat some orall of their eggs, a behavior termed filial cannibalism. Wetested predictions of filial cannibalism models related to thecost of parental care in the male sand goby, Pomatoschistusminutus, by increasing the parental effort (fanning expenditure)through reduced levels of dissolved oxygen to 39% in an experimentalgroup, whereas a control group had fully saturated water. Malesshowed both full-clutch cannibalism and partial-clutch cannibalismin both treatments. Giving the males one to three females tospawn with, we found that small clutches were completely eatenmore often than were larger ones, whereas partial-clutch cannibalismwas not affected by clutch size. Although treatment did notaffect filial cannibalism, it did affect a male's energy statesuch that males in the low oxygen treatment lost more body fat,indicating a greater fanning effort. This shows that males inthe low oxygen treatment allocated more energy to the presentbrood, potentially at the expense of future reproductive success.Our study strongly suggests that filial cannibalism in malesand gobies represents a strategic life-history decision asan investment in future reproductive success, and is not triggeredby a proximate need for food necessary for the male's own survival.Furthermore, males in the low oxygen treatment built nests withlarger entrances, and were less likely to rebuild their nestsafter destruction. Presumably, this makes fanning easier butthe nest more vulnerable to predators, suggesting a trade-offbetween fanning and nest defense.     

鸭稻共作生态农业模式的功能与效益分析

对鸭稻共作生态农业模式的结构、功能和效益进行了综合分析。结果表明,鸭子和水稻可以较好地全天候地同生共长在稻田生态系统中,平均每公顷大约300-375只鸭子。利用鸭子的野性和杂食性在一定程度上可防除病、虫、草害,提高土壤肥力,因而可代替人耕耙田、施肥、施药等,避免了农药和化肥的大量投入;鸭群的活动可刺激和促进水稻的生长发育。利用这种模式可以生产出有机食品或绿色稻米,其经济效益比常规稻作高。鸭稻共作系统的每公顷净收入比常规稻作系统要高出808.5元。若按绿色食品价格高出同类商品市场价格的20%计算,则鸭稻共作系统每公顷比常规稻作系统大约多增加2000元左右的收入。这种模式的推广应用可产生良好的生态-经济-社会效益。     

我国人工养麝研究进展及养麝效益问题

我国人工养麝已历经半个世纪,人工养麝研究取得了重要进展,但从整体上看,疾病控制、产香量及养麝的整体效益仍是有待深入研究的课题.为进一步推进我国人工养麝研究和养麝业的发展,现就一些主要的研究进展进行了综述,提出了麝场的经济效益公式,认为在现有的管理体制下,养麝规模越大,经济效益反而越低.鉴于我国养麝业的特殊性及其存在的具体问题,国家应该将养麝业作为一项公益性的事业予以特殊的政策和资金方面的扶持.同时,鼓励医药企业积极投身于养麝研究与麝场建设,以共同推进养麝业的持续健康发展,从而使人工养麝能够为我国麝资源的保护和传统中药的传承做出应有的贡献.     

Parental Responses to Changes in Costs and Benefits Along an Environmental Gradient

We evaluated the effects of dissolved oxygen on offspring survival, parental costs, and the pattern of parental care in Florida flagfish, Jordanella floridae (Cyprinodontidae). Specifically, we quantified (1) embryonic development and survival in the absence of parental care, (2) behavior of non-reproductive adults, and (3) behavior of parental males across a gradient in dissolved oxygen. Embryo developmental rates and survivorship increased with dissolved oxygen, with a relatively sharp increase in survival between medium and high oxygen treatments. Non-reproductive adults increased their frequency of aquatic surface respiration, reduced overall activity, and increased opercular beat rate as oxygen declined, suggesting increased costs of activity with reduced oxygen. Taking these cost measures together, costs appear to increase slowly as oxygen starts to decline and then increase sharply as conditions approach hypoxia. In contrast, parental effort increased gradually with dissolved oxygen. We conclude that the increase in care from low to medium oxygen primarily results from a sharp decline in physiological costs, whereas the continued increase in care from medium to high oxygen primarily results from an increase in offspring value. In addition, our results highlight that the benefits of fanning for offspring are not well understood and that they may increase with oxygen, contrary to what has been previously assumed.     

旱作条件下不同苜蓿品种光合作用的日变化

晴天,利用LI-6400光合仪研究了旱作条件下4年生紫花苜蓿新疆大叶、巨人201、牧歌401和路宝再生草初花期（2004年6月23日）的光合作用日变化特征.结果表明：①4个苜蓿品种Pn、Tr和Gs的日变化曲线均呈“双峰”型,12：00左右存在明显的光合＂午休＂现象,但不同品种Pn、Tr和Gs的高峰和低谷出现的时刻和高低不同.WUE日进程,除路宝呈“单峰”型外,新疆大叶、巨人201和牧歌401呈“双峰”型,4个品种在8：00左右的WUE均达到全天的最高值,14：00左右的峰值不明显.②根据Pn、Ci、Ls的变化方向,推测4个品种的光合“午休”主要受气孔因素限制.③国外苜蓿品种巨人201、牧歌401和路宝日平均Pn、Tr和WUE均优于国内地方品种新疆大叶,尤其是巨人201是一种高光合、高蒸腾、高水分利用率的品种.④相关分析结果表明,对Pn影响最显著的因子是PAR,其次是Gs、RH、Ta和VPD;对蒸腾速率影响最显著的因子为PAR,其次是RH、Ta、Gs和VPD.     

水产养殖动物遗传连锁图谱及QTL定位研究进展

自1997年美国农业部启动5种水产养殖动物基因组计划以来,在不到10年的时间里,世界各国都相继开展了本国主要水产养殖动物基因组研究。截至2005年底,有近17种海淡水养殖动物公布了遗传连锁图谱：属于高密度连锁图谱的有虹鳟和大西洋鲑（标记数超过1000）;属于中密度遗传连锁图谱的有罗非鱼、沟鲶、黑虎虾、日本牙鲆和欧洲海鲈（标记数为400-1000）;属于低密度遗传连锁图谱的有泰国的胡鲶,中国的栉孔扇贝、鲤鱼,日本的黄尾鲕,美国的牡蛎等近10种养殖种类（标记数少于400）。水产养殖动物遗传连锁图谱的构建和发展,促进了一些与经济性状（如生长、抗逆、发育等）相关的数量性状位点（QTL）的定位研究。然而,QTL定位研究目前只在具有中高密度遗传连锁图谱的鲑科鱼类（虹鳟、大西洋鲑和北极嘉鱼）、罗非鱼、沟鲶和日本牙鲆等种类中开展,而且定位研究仍处在初级水平。遗传连锁图谱的高分辨率和QTL在图谱上的精确定位,是今后能否实现对主要水产养殖动物的经济性状进行遗传操作的技术保证,同时也是实现分子标记或基因辅助育种在水产养殖动物中成功运用的制胜法宝。     

Evidence for acoustic communication in the parasitoid wasp Glyptapanteles flavicoxis

Females of the parasitoid wasp Glyptapanteles flavicoxis (Marsh) (Hymenoptera: Braconidae) deposit sex pheromone on substrate that elicits attraction and wing fanning in conspecific males. We tested the hypothesis that wing fanning sound induces a behavioral response from females which, in turn, affects the males’ orientation toward them. Females exposed to playback of the males’ wing fanning sound engaged in short flights, with sound characteristics different from those of the males’ wing fanning sound. In two‐choice bioassays, playback of the females’ flight sound attracted significantly more males than a silent control stimulus, and in combination with pheromone‐containing body extract of females it attracted more males than female body extract alone. Our data support the conclusion that the males’ wing fanning induces sound and visual reply signals from females that help males orient toward them.     

Substrate influences mating success and transmission of courtship vibrations for the parasitoid Cotesia marginiventris

The influences of artificial and natural rearing substrates on mating success were investigated for the parasitoid wasp Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae), a candidate for augmentative biological control of various lepidopteran pests. Five rearing substrates were tested: plastic, glass, chiffon fabric, and leaves of two host plants, bean [Vigna unguiculata (L.) (Fabaceae)] and maize [Zea mays L. (Poaceae)]. Mating success was highest on chiffon, lowest on plastic and glass, and intermediate on maize and bean. The transmission characteristics of one component (buzz 1) of the courtship vibrations produced by male wing fanning were investigated using laser vibrometry. The duration of buzz 1 was longer on maize, bean, and chiffon than on plastic and glass. The fundamental frequency of buzz 1 (~300 Hz) was lowest on bean and highest on glass, and intermediate among other substrates. The relative amplitude of buzz 1 was higher on chiffon than on plastic, glass, or bean, and intermediate on maize. The relative importance of airborne sound and substrate vibration as courtship signals was also investigated with experiments that manipulated the production of courtship vibrations and the mating substrates. The amplitude of courtship vibrations on chiffon was significantly higher for winged males than for dealated males. The mating success of males was impacted by both the presence of wings and the mating substrate. These findings suggest that mating success and transmission of courtship vibrations are influenced by the rearing substrate, and that courtship vibrations are critical to mating success in C. marginiventris. Future efforts to mass rear this parasitoid and other insects should consider the potential influences of rearing substrates on mating.