长白山北坡访花昆虫研究(Ⅳ)——访花昆虫的访花行为

2004—2005年盛花期(7~8月份)对长白山北坡昆虫的访花行为进行了研究。经初步鉴定,在22种蜜源植物上共捕捉38种访花昆虫,其中双翅目、膜翅目为主要访花昆虫。经观察,在整个花期拜访的访花昆虫中,意大利蜜蜂和乌苏熊蜂是最有效而稳定的访花者,而且拜访频率非常高。此外,气温下降、阴天降雨等都能使访花昆虫的访花频率降低。     

昆虫对冬季显花植物蜜粉组合的选择偏好

为探明昆虫的授粉行为与不同粉蜜组合模式植物间的关系,采用野外考察法研究冬季昆虫对油菜(含大量花蜜与适量花粉)、芥蓝(含大量花蜜与少量花粉)、蚕豆(含少量花蜜和大量花粉)等不同花蜜和花粉组合模式显花植物的选择偏好。结果表明:相同条件下,昆虫对油菜的访花频次为(591±11.83)只/d,显著高于蚕豆的(127±1.90)只/d和芥蓝的(180±2.53)只/d。蜜粉组合方式(油菜)比仅提供粉源(蚕豆)更能吸引授粉者。优势访花昆虫1d的最大访花量及其出现时间存在差异,中蜂和食蚜蝇的最大访花量分别为(34±9.80)只和(14±0.56)只,出现在12:00~13:00;意蜂为(39±9.17)只,出现在12:30~14:30;家蝇为(12±1.34)只,出现在16:00~18:00。最大访花量及其出现时间的差异能减少授粉者间的取食竞争,提高显花植物的授粉率。     

中国养蜂业现代化发展的路径探析

养蜂业是我国传统农业, 也是现代农业的重要组成部分。蜜蜂为农作物提供授粉支持并附加产出蜂产品, 其在现代农业中的地位逐渐受到重视。养蜂业的稳定发展对促进农民增收、提高农作物产量和维护生态平衡作出了突出贡献。但我国蜂业生产及科技水平与发达国家相比仍有一定差距。本文从蜜蜂授粉对农作物生产和蜜蜂在农业生态环境监测和保护中的作用方面分析了养蜂业与现代农业发展的关系, 同时分析总结我国目前蜂业存在的问题, 包括重产品、轻授粉, 重原料和半成品生产、轻深加工开发, 重转地饲养、轻定地饲养, 重单一饲养、轻立体种养, 科技方面重实际应用、轻基础研究。在此基础上提出了我国养蜂业发展的措施, 如建立规模化昆虫授粉产业, 建立蜂业循环经济发展模式, 确立定地辅以转地养蜂方式, 进行蜂产品的深度开发和加强蜂业理论的研究等。     

Development of a new dispenser for microbiological control agents and evaluation of dissemination by bumblebees in greenhouse strawberries

BACKGROUND: To date, in modern agriculture, biological control strategies are increasingly becoming the preferred pest management approach. However, the success of microbiological control agents (MCAs) largely depends on efficient dissemination into the crop. The pollinator‐and‐vector technology employs pollinating insects like bees for a better dissemination. In this study, a new dispenser for bumblebee workers of Bombus terrestris L. was developed. Binab‐T‐vector and Prestop‐Mix were used as two typical MCA products for dissemination. RESULTS: In a first series of experiments in the laboratory for optimisation, the newly developed dispenser was a two‐way type dispenser, 20 cm long, with two rectangular compartments and different entrance and exit holes. In addition, the amounts of MCA loaded on the workers were 10 times higher with the new dispenser as compared with the side‐by‐side passageway (SSP) dispenser. Typically, the highest amounts were recovered from the thorax and legs of the workers. In a second series of experiments under greenhouse conditions with the use of queen‐right B. terrestris hives, successful dissemination in strawberry flowers was obtained at different distances from the hive (0–8 m, 8–18 m and 18–21 m), and the workers inoculated the first, second and third flowers that were consecutively visited. In addition, the new dispenser caused no adverse effects on worker foraging intensity, whereas a dramatic reduction was scored with an SSP dispenser. Finally, the data suggested that it is necessary to refill the newly developed dispenser at 3 day intervals. CONCLUSIONS: The results demonstrated that, with the use of the newly developed dispenser, bumblebee workers carried high amounts of MCA, and this resulted in a successful dissemination of MCA into strawberry flowers. Copyright © 2010 Society of Chemical Industry     

Reproduction of Hedysarum scoparium (Fabaceae) in patched habitat is pollen limited, but not just pollinator limited

Pollen limitation of plant reproduction occurs across Angiosperms,particularly those in patched habitats.We investigated the relationship between pollen limitation and patch variables (patch size,visitation frequency) in the desert plant Hedysarum scoparium (Fabaceae),which is an important xerophyte in the arid and semi-arid regions of Northwest China and can grow well as a pioneer plant in shifting sand dunes.We observed insect visitation to H.scoparium over two flowering seasons and estimated pollen limitation using fruit set and seed production.Our results indicate that fruit set and seed production increased significantly with pollen supplementation compared with open pollination.Hedysarum scoparium was pollinated by over 8 species of bees,with 88.4% of visits made by introduced honeybees (Apis mellifera).Bee visitation varied significantly among the patches of habitats,but not associated with patch size of habitat.In general,pollen limitation occurred more strongly during fruit set than during seed production.The patches that received higher rates of pollinator visits were less pollen limited for fruit set.Pollen limitation for seed production,however,was not associated with pollinator visitation frequency.We conclude that pollen limitation in H.scoparium was caused by more than one reason,not just pollinator visits.     

Evidence for Bombus occidentalis (Hymenoptera: Apidae) Populations in the Olympic Peninsula,the Palouse Prairie,and Forests of Northern Idaho

Since the mid-1990s, Bombus occidentalis (Green) has declined from being one of the most common to one of the rarest bumble bee species in the Pacific Northwest of the United States. Although its conservation status is unresolved, a petition to list this species as endangered or threatened was recently submitted to the U.S. Fish and Wildlife Service. To shed light on the conservation situation and inform the U.S. Fish and Wildlife Service decision, we report on the detection and abundance of B. occidentalis following bumble bee collection between 2012 and 2014 across the Pacific Northwest. Collection occurred from the San Juan Islands and Olympic peninsula east to northern Idaho and northeastern Oregon, excluding the arid region in central Washington. B. occidentalis was observed at 23 collection sites out of a total of 234. With the exception of three sites on the Olympic peninsula, all of these were in the southeastern portion of the collection range.     

The Life Span and Levels of Oxidative Stress in Foragers Between Feral and Managed Honey Bee Colonies

Molecular damage caused by oxidative stress may lead to organismal aging and result in acute mortality to organisms. Thus, oxidative stress resistance and longevity are closely linked. Honey bees (Apis mellifera) are the most important managed pollinator in agriculture, but the long-term survival of honey bees is seriously threatened. Feral honey bee colonies can be used as natural resources to improve honey bee health. One question we ask here is whether feral honey bees are stress resistant or survive longer than managed bee populations. More work is needed to determine the impact of oxidative stress on honey bee health and survival. In this study, we used paired colony designs to compare the life span of worker bees (foragers) between feral and managed colonies and their levels of oxidative stress. Each pair of colonies shared similar foraging resources. The results indicated that foragers in feral colonies had longer survival times and life spans than those in managed colonies. The levels of oxidative stress from lipid damage content in feral colonies were higher than those in managed colonies, indicating that they used a tolerance mechanism rather than a repair mechanism to survive. Our study provides new insights into a colony difference in the physiology and oxidative stress resistance of feral honey bees compared with managed colony stocks.     

Development of a hybrid variety system in marjoram (Origanum majorana L.)

20 accessions of marjoram (Origanum majorana L.)were characterized in two field experiments in Quedlinburg, Germany in 1997. The variation was assessed both on single plants as a base for the development of pollinator inbred lines of a prospective hybrid variety system and also on plots on a larger scale. The characterization comprised yield of leaf-flower fraction, content of essential oil and its proportion of cis-sabinene hydrate. The anther status of the regrowth after the herb harvest was used as an indicator of male fertility. The investigations revealed a high variability between and within accessions. The correlation of some traits is discussed as a clue to indirect selection. The yield rises with increasing bush diameter of the single plants and with longer vegetation periods caused by late flowering. Relations between the essential oil content and the duration of the vegetation period were not consistent and could be caused by the environment. There were no relations between the anther status and agronomical or physiological traits. This revised version was published online in July 2006 with corrections to the Cover Date.     

Plant‐pollinator interactions in a biodiverse meadow are rather stable and tight for 3 consecutive years

Plant–pollinator interactions can be highly variable across years in natural communities. Although variation in the species composition and its basic structure has been investigated to understand the dynamic nature of pollination networks, little is known about the temporal dynamic of interaction strength between the same plant and pollinator species in any natural community. Pollinator‐mediated selection on the evolution of floral traits could be diminished if plant–pollinator interactions vary temporally. To quantify the temporal variation in plant–pollinator interactions and the interaction strength (observed visits), we compared weighted networks between plants and pollinators in a biodiverse alpine meadow in Shangri‐La, southwest China for 3 consecutive years. Although plant–pollinator interactions were highly dynamic such that identical interactions only accounted for 10.7% of the total between pair years, the diversity of interactions was stable. These identical interactions contributed 41.2% of total visits and were similar in strength and weighted nestedness. For plant species, 72.6% of species were visited by identical pollinator species between pair years, accounting for over half of the total visits and three‐quarters at the functional group level. More generalized pollinators contributed more connectiveness and were more central in networks across years. However, there was no similar or even opposite trend for plant species, which suggested that specialized plant species may also be central in pollinator networks. The variation in pollinator composition decreased as pollinator species numbers increased, suggesting that generalized plants experienced stable pollinator partition. The stable, tight interactions between generalized pollinators and specialized plants represent cornerstones of the studied community.