乙基多杀菌素和联苯肼酯对地熊蜂的毒性及风险评估

【目的】明确乙基多杀菌素和联苯肼酯对地熊蜂Bombus terrestris的毒性, 探讨这两种农药亚致死浓度对地熊蜂体内乙酰胆碱酯酶(AchE)、谷胱甘肽-S-转移酶(GST)和羧酸酯酶(CarE) 3种解毒酶活性的影响。【方法】采用饲喂法测定60 g a.i./L乙基多杀菌素和43%联苯肼酯对地熊蜂采集蜂的急性经口毒性,依据农药对蜜蜂生态风险的危害熵(hazard quotient, HQ)值评估这两种农药对地熊蜂的风险。同时测定了这两种农药亚致死剂量(LD₅₀和LD₈₀)处理后地熊蜂AchE, GST和CarE的活性变化。【结果】60 g a.i./L乙基多杀菌素和43%联苯肼酯对地熊蜂采集蜂的急性经口毒性测定48 h时LD₅₀值分别为3.590和1 447 μg a.i./蜂,其中60 g a.i./L乙基多杀菌素表现为中毒,43%联苯肼酯表现为低毒。两种农药对地熊蜂采集蜂的HQ值均低于50,表现为低风险。LD₅₀和LD₈₀剂量的乙基多杀菌素处理组与对照组相比,3 h时地熊蜂AchE活性被激活,显著高于对照组(P＜0.05),分别为对照组的1.45和1.23倍,24 h后活性受到抑制,两个剂量处理组AchE活性均显著低于对照组(P＜0.05);CarE活性3 h时同样被激活,显著高于对照组(P＜0.05),LD₅₀和LD₈₀剂量处理组CarE活性分别为对照组的1.24和1.53倍, 24 h后活性受到抑制,其中LD₅₀剂量处理组CarE活性显著低于对照组(P＜0.05),LD₈₀剂量处理组CarE活性与对照组差异不显著(P＞0.05);LD₅₀和LD₈₀剂量处理组GST活性3 h被激活,显著高于对照组(P＜0.05),分别为对照组的2.24和2.58倍,24 h后活性降低,但两个剂量处理组GST活性仍显著高于对照组(P＜0.05)。43%联苯肼酯处理后,与对照组相比3 h时LD₅₀和LD₈₀剂量处理组AchE活性与对照组差异不显著(P＞0.05),24 h后AchE活性降低,显著低于对照组(P＜0.05),分别是对照组的75%和80%;CarE活性3 h时被抑制,LD₅₀剂量处理组CarE活性显著低于对照组(P＜0.05),LD₈₀剂量处理组CarE活性低于对照组,但差异不显著(P＞0.05),24 h后CarE活性被激活,其中LD₅₀剂量处理组CarE活性高于对照组,但差异不显著(P＞0.05),LD₈₀剂量处理组CarE活性显著高于对照组(P＜0.05);LD₅₀剂量处理组GST活性3 h时被激活,显著高于对照组(P＜0.05),24 h后活性降低,但仍显著高于对照组(P＜0.05),3 h和24 h的活性分别为对照组的2.04和1.72倍,LD₈₀剂量处理组3 h的GST活性与对照组无显著差异(P＞0.05),24 h后活性降低,显著低于对照组(P＜0.05)。【结论】乙基多杀菌素和联苯肼酯对地熊蜂的HQ 评估均表现为低风险,其中联苯肼酯对地熊蜂的安全性较高,在熊蜂授粉过程中可以按照推荐剂量应用,但过量施用或者长期施用可能会造成熊蜂体内药剂积累引起生理或者行为的变化,乙基多杀菌素在温室及大田授粉期的使用剂量和方法有待进一步研究。     

11种常用农药对地熊蜂工蜂的毒性和风险评估

【目的】评估常用农药对地熊蜂Bombus terrestris的生态风险,为设施大棚合理施用农药提供科学依据。【方法】分别采用饲喂法和接触法测定了6种杀虫剂(虫螨腈、高效氯氟氰菊酯、氟吡呋喃酮、螺虫乙酯、异丙威和除虫脲)、3种杀螨剂(丁氟螨酯、唑螨酯和联苯肼酯)及2种杀菌剂(春雷霉素和啶酰菌胺)共11种常用农药对地熊蜂成年工蜂的急性经口和急性接触毒性,并评估其生态风险性。【结果】11种农药经饲喂法测定,对地熊蜂工蜂的急性经口毒性除高效氯氟氰菊酯、异丙威和虫螨腈为高毒,氟吡呋喃酮和唑螨酯为中毒外,其余药物均为低毒。经接触法测定,对地熊工蜂的急性接触毒性除高效氯氟氰菊酯和异丙威为高毒,虫螨腈为中毒外,其余药物均为低毒。生态风险评估表明,对地熊蜂工蜂而言,异丙威和高效氯氟氰菊酯的经口与接触毒性为中风险,氟吡呋喃酮、啶酰菌胺、除虫脲、唑螨酯、联苯肼酯、螺虫乙酯、春雷霉素、丁氟螨酯的经口与接触毒性为低风险;虫螨腈的经口毒性为中风险,接触毒性为低风险。【结论】在设施作物花期使用地熊蜂授粉时,建议禁用异丙威、高效氯氟氰菊酯和虫螨腈这3种存在中风险的农药,慎重使用氟吡呋喃酮和唑螨酯这2种农药,以避免对地熊蜂造成危害,而另外6种低毒农药可根据田间情况合理施用,并可采取通风晾晒、设置间隔期等方式降低农药对地熊蜂的生态风险。     

Intraspecific Variation of the Cephalic Labial Gland Secretions in Bombus terrestris (L.) (Hymenoptera: Apidae)

Variations of secretions of the cephalic part of the labial glands from four different subspecies of Bombus terrestris, B. t. terrestris, B. t. lusitanicus, B. t. sassaricus, and B. t. dalmatinus, were investigated. 95 compounds were detected in the whole data set: 54 in B. t. terrestris, 54 in B. t. lusitanicus, 48 in B. t. sassaricus, and 44 in B. t. dalmatinus. The (E)‐2,3‐dihydrofarnesol is the main compound in B. t. dalmatinus and B. t. sassaricus, while it is dihydrofarnesyl dodecanoate in B. t. terrestris and B. t. lusitanicus. A principal component analysis produced a pattern showing three well distinct groups corresponding to dalmatinus, sassaricus, and terrestris+lusitanicus.     

Genetic differentiation of continental and island populations of Bombus terrestris (Hymenoptera: Apidae) in Europe

Ten microsatellite loci and a partial sequence of the COII mitochondrial gene were used to investigate genetic differentiation in B. terrestris, a bumble bee of interest for its high-value crop pollination. The analysis included eight populations from the European continent, five from Mediterranean islands (six subspecies altogether) and one from Tenerife (initially described as a colour form of B. terrestris but recently considered as a separate species, B. canariensis). Eight of the 10 microsatellite loci displayed high levels of polymorphism in most populations. In B. terrestris populations, the total number of alleles detected per polymorphic locus ranged from 3 to 16, with observed allelic diversity from 3.8 ± 0.5 to 6.5 ± 1.4 and average calculated heterozygosities from 0.41 ± 0.09 to 0.65 ± 0.07. B. canariensis showed a significantly lower average calculated heterozygosity (0.12 ± 0.08) and observed allelic diversity (1.5 ± 0.04) as compared to both continental and island populations of B. terrestris. No significant differentiation was found among populations of B. terrestris from the European continent. In contrast, island populations were all significantly and most of them strongly differentiated from continental populations. B. terrestris mitochondrial DNA is characterized by a low nucleotide diversity: 0.18%± 0.07%, 0.20%± 0.04% and 0.27%± 0.04% for the continental populations, the island populations and all populations together, respectively. The only haplotype found in the Tenerife population differs by a single nucleotide substitution from the most common continental haplotype of B. terrestris. This situation, identical to that of Tyrrhenian islands populations and quite different from that of B. lucorum (15 substitutions between terrestris and lucorum mtDNA) casts doubts on the species status of B. canariensis. The large genetic distance between the Tenerife and B. terrestris populations estimated from microsatellite data result, most probably, from a severe bottleneck in the Canary island population. Microsatellite and mitochondrial DNA data call for the protection of the island populations of B. terrestris against importation of bumble bees of foreign origin which are used as crop pollinators.     

Reduced cephalic labial glands in the male bumblebees of the subgenus Rhodobombus Dalla Torre (Hymenoptera: Apidae: Bombus Latreille)

Until now, all males of bumblebees are known to attract conspecific females by marking places with a chemical signal secreted by their cephalic labial gland. The specific combination of patrolling flight and scentmarking is of outmost importance to bumblebees as it is their main species specific recognition system. We report here the lack of that recognition system in species of the subgenus Rhodobombus by comparing the morphology and histology of the cephalic labial glands of Bombus (Rhodobombus) mesomelas with those of a well known species, B. (Bombus) terrestris (L.) The cephalic labial glands are much smaller in B. mesomelas than in other bumblebees species and most likely non-functional. This morphology is also observed in B. pomorum and B. brodmanni which also belong to the subgenus Rhodobombus. Our morphological observations are consistent with the chemical analyses of the secretions in B. mesomelas and B. pomorum which are very limited and of most unusual composition for a bumblebee. In addition, whereas other species are thought to use their barbae mandibularis to spread their secretion onto the substrate, these structures are absent in all Rhodobombus. All these observations would mean that the males of Rhodobombus do not attract females from far away by the use of their cephalic labial gland secretions.     

小峰熊蜂工蜂触角感器的扫描电镜观察

利用扫描电镜对小峰熊蜂Bombus hypocrita的触角形态和感器进行了观察。结果表明:小峰熊蜂触角呈膝状,由柄节、梗节和鞭节组成。工蜂的柄节约为触角全长的三分之一,其长度约为(2099.40±112.26)μm,梗节呈方圆形,最短,长度为(212.86±12.51)μm。鞭节全长为(3861.43±137.86)μm,共由10节组成。触角上广布11种类型的感受器,即板形感器、坛形感器、钟形感器、锥形感器、腔锥形感器、毛形感器、刺形感器、芽形感器、端指形感器、缘感器和刚毛,不同感器在触角上的分布部位不同。其中,芽形感器和端指形感器在膜翅目昆虫中属首次发现。     

小峰熊蜂访花偏爱性

传粉昆虫在访花时,通常会表现出对某一类型花的偏爱性。本研究利用人工制作的大小、颜色、形态和气味不同的9种类型的花来研究小峰熊蜂Bombus hypocrita的访花偏爱性。结果表明：当增加花的大小、形态、气味等附加特征数时,小峰熊蜂的偏爱性程度与花朵附加特征数有显著相关性（P<0.01）。当花朵颜色由2种增加到4种,熊蜂对紫色花的偏爱性程度降低,但花朵颜色的种类与小峰熊蜂的访花偏爱性没有相关性（P>0.05）,花颜色的种类对熊蜂访紫色花的偏爱性影响不大。大小为5 cm的紫花被访次数（108±9次）明显高于大小为3 cm的紫花被访次数（40±4次）（P<0.01）,说明熊蜂明显喜欢访大花瓣的紫花。完全盛开的紫花被访次数（129±13次）显著高于刚绽放的花被访次数（26±3次）（P<0.01）,说明熊蜂喜欢访盛开的紫花。柠檬味的紫花被访次数（63±8次）明显低于草莓味的紫色花被访次数（88±2次）（P<0.05）,说明熊蜂喜欢访草莓味的花朵。     

Kin-selected conflict in the bumble-bee Bombus terrestris (Hymenoptera: Apidae)

Kin selection theory predicts conflict in social Hymenoptera between the queen and workers over male parentage because each party is more closely related to its own male offspring. Some aspects of the reproductive biology of the bumble-bee Bombus terrestris support kin selection theory but others arguably do not. We present a novel hypothesis for how conflict over male parentage should unfold in B. terrestris colonies. We propose that workers delay laying eggs until they possess information showing that egg laying suits their kin-selected interests. In colonies where queens start to lay haploid eggs early, we hypothesize that this occurs when workers detect the presence of queen-produced male brood in the brood's larval stage. In colonies where queens start to lay haploid eggs late, we hypothesize that it occurs when workers detect a signal from the queen to female larvae to commence development as queens. Our hypothesis accounts for previously unexplained aspects of the timing of reproductive events in B. terrestris, provides ultimate explanations for the results of a recent study of mechanisms underlying queen-worker conflict and helps explain this species' characteristic bimodal (split) sex ratios. Therefore, kin selection theory potentially provides a good explanation for reproductive patterns in B. terrestris.     

A method for year-round rearing of cuckoo bumblebees (Hymenoptera: Apoidea: Bombus subgenus Psithyrus)

Summary. The study of the social interactions between host bumblebees and their inquiline species requires rearing them. Here we provide a simple method for rearing of cuckoo bumblebees (Bombus subgenus Psithyrus) in the laboratory. Two bumblebee cuckoo-host systems are used: Bombus (Psithyrus) vestalis hosted by B. (Bombus) terrestris and B. (Psithyrus) sylvestris hosted by B. (Pyrobombus) pratorum. First, the invasion of the Psithyrus female is performed in species-specific host colonies containing approximately 10 young workers. On average, a parasitized colony of B. terrestris produced 90 ± 9 young males and 21 ± 3 young females of B. vestalis, whereas a parasitized colony of B. pratorum produced 16 ± 2 young males and 5 ± 1 young females of B. sylvestris. One week after emergence, Psithyrus virgin females are placed in a flight cage exposed to natural light, with Psithyrus males of other colonies. After successful mating, the females are isolated and overwintered in a cold room at 4°C for 2–4 months. This method enables a year-round and mass breeding of Psithyrus species to facilitate studies of these rare species.     

密林熊蜂雄性成蜂生殖系统发育动态

为了研究密林熊蜂Bombus patagiatus Nylander雄蜂出房后生殖系统发育变化过程, 本研究首次对密林熊蜂雄性成蜂（1-15日龄）生殖系统的精液量、 精子数、 性腺大小、 储精囊大小等进行了测定。结果显示： 雄性成蜂在1日龄时精液量最大, 达到5.95±0.39 μL; 镜检精子数在2日龄最多; 而精液中活动精子数出现波浪式的循环趋势, 9日龄达到最大值, 为25.93±1.06个; 精液中精子总数在9日龄达到最大值, 为160.67±17.11万个; 活动精子百分比以8、 9日龄最高, 分别达到86.38%±2.02%及86.45%±2.50%; 性腺长度在1日龄时最小, 为1 522.01±37.93 μm; 储精囊的中部宽度在7日龄最宽, 达86.38±2.96 μm, 但与9日龄相比无显著差异。由此可见, 8-9日龄雄性成蜂个体各指标较为稳定, 该日龄即为雄性成蜂性成熟且可以交配的时期。本研究结果为密林熊蜂人工繁育提供了理论依据。     

Effect of worker number and diapause duration on colony parameters of the bumblebee,Bombus terrestris (Hymenoptera: Apidae)

Bumblebee, Bombus terrestris queens undergo winter diapause and show a great difference in diapause duration in natural conditions. Queens emerged from diapause initiate colonies by producing a batch of diploid (fertilised) eggs that develop into workers. In this study we investigated the effects of both the duration of queen diapause (2, 3, 4, or 5 months) and colony size (artificially limited to 50, 100, 150, and 200 workers) on the number of sexuals (males or new queens — gynes) produced, when gynes are produced and the longevity of both the foundress queen and the colony. Both worker population and diapause duration showed significant effect on sexual gyne production, foundress queen longevity and colony longevity but their interaction effect was insignificant. The worker number and diapause duration, respectively showed significant effect on sexual male production and gyne emergence period, but their interaction effects were insignificant.     

Improvement of almond production using Bombus terrestris (Hymenoptera: Apidae) in Mediterranean conditions

Almond trees are one of the most important crops in the Balearic Islands. The pollination of almonds is limited to the activity of insects, and cross‐pollination is necessary for fruit development. Currently, honey bees and wild bee populations are declining considerably due to multiple causes, such as the use of pesticides, diseases and habitat loss. An alternative to increase the almond production is the use of commercial pollinators. In this long‐term (3 years) study, the effect of the introduction of Bombus terrestris colonies on almond production was evaluated in two orchards. Two experimental designs were carried out to study the best management of this pollinator. For 2 years, all bumble bee colonies were placed in the middle of the plot and during the last year, the bumble bee colonies were distributed homogenously in the plot. Fruit set and the foraging behaviour of bumble bees during the blossoming period was determined, and the effect of different environmental variables on the visitation rate of bumble bees was assessed by means of a generalized linear mixed model (GLMM). Moreover, for the first time, the spatial distribution of fruit set was evaluated. Our results show that fruit set was significantly higher in the fields where B. terrestris had been introduced than in the control plots. This increased production resulted in a positive economic balance for the farmer. Moreover, bumble bees showed to prefer trees in a southwest orientation that were close to their colony. The activity of bumble bees showed to be significantly influenced by wind speed (the higher the speed the more flowers are visited by B. terrestris) and time after flowering (visitation rate decreased with days after flowering). In order to improve its management and obtain the highest possible almond production, it is important to understand the activity and behaviour of this pollinator.     

An overview of the Bombus terrestris (L. 1758) subspecies (Hymenoptera: Apidae)

Bombus terrestris is one of the most abundant bumblebee species in the West-Palaearctic. Its widespread domestication results in the movement of many colonies. The aim of this paper is to describe the 9 subspecies currently recognised and to list some of their most obvious characteristics. Bombus terrestris is not declining anywhere, on the contrary, its synanthropic spread through domestication may be expected. However, its autumn and winter populations rely on a restricted choice of flowers so they may be threatened locally by scrub clearance and the destruction of their favourite autumnal flowers.     

First report of Bombus terrestris xanthopus Kriechbaumer on the Italian peninsula (Hymenoptera: Apidae)

A male specimen of Bombus terrestris (L. 1758) showing an intermediate colour between the subspecies xanthopus Kriechbaumer 1870 endemic to Corsica and the subspecies terrestris ubiquitous in the mainland was found within samples collected in 1999 on the Tuscan coast. Hybrid specimens between these subspecies are common on some of the islands of the Tuscan archipelago, while others only have pure populations. The finding is significant as it could signal the spread of the subspecies xanthopus_to the mainland. We consider and discuss the circumstances of the finding.     

Factors influencing Nosema bombi infections in natural populations of Bombus terrestris (Hymenoptera: Apidae)

Bumblebees are of profound ecological importance because of the pollination services they provide in natural and agricultural ecosystems. Any decline of these pollinators is therefore of great concern for ecosystem functioning. Increased parasite pressures have been discussed as a major factor for the loss of pollinators. One of the main parasites of bumblebees is Nosema bombi, an intracellular microsporidian parasite with considerable impact on the vitality of the host. Here we study the effect of host colony density and host genetic variability on N. bombi infections in natural populations of the bumblebee Bombus terrestris. We sampled males and workers from six B. terrestris populations located in an agricultural landscape in Middle Sweden to determine the prevalence and degree of N. bombi infections. All individuals were genotyped with five microsatellite markers to infer the colony densities in the sampled populations and the genetic variability of the host population. We confirmed that genetic variability and sex significantly correlate with the degree of infection with N. bombi. Males and workers with lower genetic variability had significantly higher infection levels than average. Also colony density had a significant impact on the degree of infection, with high density populations having higher infected individuals.     

Observations of Successful Bombus terrestris (L.) (Hymenoptera: Apidae) Colonies in Southern Tasmania

Early attempts to acclimatise Bombus spp. to Australia were not successful but a pre-1992 introduction of the bumble bee B. terrestris has succeeded and the species is slowly spreading in southern Tasmania. It is likely that the genetic base of the Tasmanian population is limited if, as is thought, only a few queens were brought from New Zealand. This may affect the rate of dispersal through the island, which presently averages 12.5 km/year. In 1995–96 18 feral colonies found in and around Hobart were transferred to nest boxes, where colony development could be monitored. All of the colonies produced queens, and the ratio of queens to workers (1:4.71) compares favourably with the upper end of colony performance scale in New Zealand (1:5.19). At least two generations are produced during warmer months and there is no indication of genetic impediments to further dispersal in Tasmania or possibly even mainland Australia. External influences such as predatory habits of birds, availability of food, competition from other insects and deliberate introduction by people into new areas make the rate of spread unpredictable.     

Hazards of imidacloprid seed coating to Bombus terrestris (Hymenoptera: Apidae) when applied to sunflower.

Seed coating treatments of sunflower by the systemic insecticide imidacloprid was suspected of affecting honey bees and bumblebees. The hypothesis raised was whether imidacloprid could migrate into nectar and pollen, then modify flower attractiveness, homing behavior, and colony development. Our greenhouse and field experiments with Bombus terrestris L. were aimed at the following: the behavior of workers foraging on treated and control plants blooming in a greenhouse, the homing rate of colonies placed for 9 d in a treated field compared with colonies in a control field, and the development of these 20 colonies under laboratory conditions when removed from the fields. In the greenhouse, workers visited blooming heads of treated and control plants at the same rate and the mean duration of their visits was similar. In field colonies, analysis of pollen in hairs and pellets of workers showed that in both fields 98% of nectar foragers visited exclusively sunflowers, whereas only 25% of pollen gatherers collected sunflower pollen. After 9 d, in the control and treated field, 23 and 33% of the marked foragers, respectively, did not return to hives. In both fields, workers significantly drifted from the center to the sides of colony rows. During the 26-d period under field and laboratory conditions, the population increase rate of the 20 colonies was 3.3 and 3.0 workers/d in hives of the control and treated field, respectively. This difference was not significant. New queens were produced in eight colonies in either field. The mean number of new queens per hive was 17 and 24 in the control and treated field, respectively. Their mating rate was the same. It was concluded that applying imidacloprid at the registered dose, as a seed coating of sunflowers cultivated in greenhouse or in field, did not significantly affect the foraging and homing behavior of B. terestris and its colony development.     

Population structure and inbreeding in a rare and declining bumblebee, Bombus muscorum (Hymenoptera: Apidae)

Owing to habitat loss populations of many organisms have declined and become fragmented. Vertebrate conservation strategies routinely consider genetic factors, but their importance in invertebrate populations is poorly understood. Bumblebees are important pollinators, and many species have undergone dramatic declines. As monoandrous social hymenopterans they may be particularly susceptible to inbreeding due to low effective population sizes. We study fragmented populations of a bumblebee species, on a model island system, and on mainland Great Britain where it is rare and declining. We use microsatellites to study: population genetic structuring and gene flow; the relationships between genetic diversity, population size and isolation; and frequencies of (sterile) diploid males - an indicator of inbreeding. We find significant genetic structuring (theta = 0.12) and isolation by distance. Populations > 10 km apart are all significantly differentiated, both on oceanic islands and on the mainland. Genetic diversity is reduced relative to closely related common species, and isolated populations exhibit further reductions. Of 16 populations, 10 show recent bottlenecking, and 3 show diploid male production. These results suggest that surviving populations of this rare insect suffer from inbreeding as a result of geographical isolation. Implications for the conservation of social hymenopterans are discussed.     

西方蜜蜂和兰州熊蜂在设施桃园的访花偏好性比较

【目的】为了比较西方蜜蜂 Apis mellifera 和兰州熊蜂 Bombus lantschouensis 在设施桃园内对不同时期桃花的访花偏好性、以及这种偏好性与花粉活力和采集花粉花蜜之间的关系。【方法】记录2种蜂在温室桃园内访问早期花、中期花和晚期花的比例,测定桃花不同时期的花粉活力以及2种蜂携带的花粉活力,观察2种蜂采集花蜜和采集花粉的成功率,统计2种蜂访花过程中桃花所处的枝条数及植株数。【结果】桃花不同时期的花粉活力差异显著,早期花花药未开裂,花粉未释放,中期花花粉活力（58.3%）显著高于晚期花花粉活力（34.2%）（P<0.01）;西方蜜蜂更加偏好访问中期花,对中期花的访问率高达75.3%,显著高于兰州熊蜂对中期花的访问率（49.2%）（P<0.01）;西方蜜蜂携带的花粉活力（92.1%）显著高于兰州熊蜂携带的花粉活力（72.9%）,但是西方蜜蜂采集花粉和采集花蜜的成功率均低于兰州熊蜂（P<0.01）;在访问一定数量的桃花过程中,兰州熊蜂在设施桃园内访问的枝条数和植株数较多,分布范围较广（P<0.01）。【结论】和兰州熊蜂相比,西方蜜蜂对活力花粉的辨别能力更强,更加偏好访问花粉活力较高的花朵,这种偏好性导致其采集花粉花蜜的成功率降低。