The ectoparasitic mite Tropilaelaps mercedesae (Acari, Laelapidae) as a vector of honeybee viruses

The ectoparasitic mites Varroa destructor and Tropilaelaps mercedesae share life history traits and both infect honeybee colonies, Apis mellifera. Since V. destructor is a biological vector of several honeybee viruses, we here test whether T. mercedesae can also be infected and enable virus replication. In Kunming (China), workers and T. mercedesae mites were sampled from three A. mellifera colonies, where workers were exhibiting clinical symptoms of deformed wing virus (DWV). We analysed a pooled bee sample (15 workers) and 29 mites for the presence of Deformed wing virus (DWV), Black queen cell virus (BQCV), Sacbrood virus (SBV), Kashmir bee virus (KBV), Acute bee paralysis virus (ABPV), and Chronic bee paralysis virus (CBPV). Virus positive samples were analysed with a qPCR. Only DWV +RNA was found but with a high titre of up to 10⁸ equivalent virus copies per mite and 10⁶ per bee. Moreover, in all DWV positive mites (N= 12) and in the bee sample virus–RNA was also detected using RT-PCR and tagged RT-PCR, strongly suggesting virus replication. Our data show for the first time that T. mercedesae may be a biological vector of DWV, which would open a novel route of virus spread in A. mellifera. Received 6 June 2008; revised 14 August 2008; accepted 10 September 2008.     

Esterases of Varroa destructor (Acari: Varroidae), parasitic mite of the honeybee

Varroa destructor is an ectoparasite that causes serious damage to the population of the honeybee. Increasing resistance of the parasite to acaricides is related, among others, to metabolic adaptations of its esterases to facilitate decomposition of the chemicals used. Esterases are a large heterogeneous group of enzymes that metabolize a number of endogenous and exogenous substrates with ester binding. The aim of the present study was to determine the activity of esterases in the body extracts (BE) and excretion/secretion products (E/SP) of the mite. The enzymes contained in the E/SP should originate mainly from the salivary glands and the alimentary system and they may play a particularly important role in the first line of defence of the mite against acaricides. Activity of cholinesterases (ChEs) [acetylcholinesterase (AChE) and butyrylcholinesterase], carboxylesterases (CEs) and phosphatases [alkaline phosphatase (AP) and acid phosphatase (AcP)] was investigated. The activity of all the enzymes except AChE was higher in the E/SP than in the BE. ChEs from the BE and from the E/SP reacted differently on eserine, a ChE inhibitor. Eserine inhibited both enzymes from the BE, increased decomposition of acetylcholine, but did not influence hydrolysis of butyrylcholine by the E/SP. Activity of the CEs from the BE in relation to the esters of carboxylic acids can be presented in the following series: C10 > C12 > C14 > C8 > C2 > C4 = C16, while activity of the CEs from the E/SP was: C4 > C8 > C2 > C14 > C10 > C12 > C16. The inhibitor of CEs, triphenyl phosphate, reduced the activity of esterases C2–C8 and C14–C16; however, it acted in the opposite way to CEs C10 and C12. The activity of both phosphatases was higher in the E/SP than in the BE (AcP about twofold and AP about 2.6-fold); the activities of AP and AcP in the same material were similar. Given the role of esterases in resistance to pesticides, further studies are necessary to obtain complete biochemical characteristics of the enzymes currently present in V. destructor.     

Non-reproduction in the honeybee mite Varroa jacobsoni

This study brings together the results of investigations into both the causes and subsequent consequences of mites which fail to produce viable female offspring. These showed that the premature death of the male offspring within the host cell leads to unfertilized adult female offspring emerging from the cell. These unfertilized mites cannot mate and so never produce viable offspring, although they do enter cells and attempt to reproduce. Therefore, virgin females cannot account for females which normally only produce male offspring, suggesting that these males are not produced parthenogenically. In the majority of mites, the type of reproductive behaviour does not change, i.e. once abnormal always abnormal. The possible role of premature male mite death in the resistance of (Africanized) bees is discussed.     

Response of foster Asian honeybee (Apis cerana Fabr.) colonies to the brood of European honeybee (Apis mellifera L.) infested with parasitic mite,Varroa jacobsoni oudemans

The response of Asian honeybee (Apis cerana Fabr.) colonies toward the introduced worker brood of the European honeybee (Apis mellifera L.) infested with the parasitic mite Varroa jacobsoni Oudemans was investigated. When no mites were present, 40% of the healthy open brood and 3% of the healthy capped brood of the European honeybees were rejected by the Asian honeybee colonies. When the brood was infested, brood rejection was significantly higher for open (P < 0.05) and capped broods (P < 0.01). The brood removal activity decreased with time. The quantity of brood removed was also correlated with mite infestation level for open (r² = 0.933) and sealed broods (r² = 0.918). The feasibility of using heterospecific colonies to control Varroa mite is unclear and is discussed from behavioral and ecological points of view.     

小蜂螨的研究现状

小蜂螨,是亚洲地区蜜蜂重要的经济害螨之一。小蜂螨以吸食蜜蜂封盖子的血淋巴为生,能导致大量封盖幼虫和蛹变形或死亡,勉强出房的工蜂也出现体型畸形,致使蜂群的生产力严重下降,直接影响蜂群的发生发展。本文就小蜂螨的分类分布、繁殖生物学、流行病学及行为学、危害防治及其蜂螨、蜜蜂与病毒直接的关系等展开阐述。旨在有助于将来更深入的探索小蜂螨,对今后小蜂螨的防治提供理论参考。     

Validity of species status of the parasitic mite Otodectes cynotis

A combined molecular and phenotypic approach was used to determine whether ear mites of the genus Otodectes (Acari: Psoroptidae) belong to a single species. The second internal transcribed spacer (ITS 2) of the rDNA of 16 isolates from 11 cats, two dogs, one arctic fox and two ferrets originating from four different continents was characterized. In addition, mites from dog, cat and arctic fox were investigated morphologically. Sequence comparisons revealed five different, but closely related genotypes which did not segregate according to host species or geographical origin. Morphologically, mites of the three host species did not differ significantly in their body or leg sizes. These investigations support the view that ear mites of the genus Otodectes from different hosts and geographical origins belong to a single species, Otodectes cynotis (Hering).     

中华真地鳖寄生螨的初步研究

在地鳖虫的饲养中发现 ,中华真地鳖EupolyphagasinensisWalker被螨类寄生较严重 ,可造成巨大的损失。经鉴定该寄生螨为伯氏嗜木螨Caloglyphusberlesei,并对其进行了形态描述。通过饲养观察 ,总结了该寄生螨的发育历期、寄生部位、寄主带螨率和单头带螨量 ,并调查了该寄生螨在饲养土中的分布规律。根据该寄生螨的生物学特性 ,该文提出了几种防除该螨的措施和方法。     

Grooming behaviour ofApis cerana,Apis mellifera andApis dorsata and its effect on the parasitic mitesVarroa jacobsoni andTropilaelaps clareae

OneApis mellifera and oneApis cerana observation hive were used to test the response to individually introducedVarroa jacobsoni mites. Within 60s, 88.6% of the involved cerana worker bees (n=44) showed auto-grooming behaviour. Within 5 min, allo-grooming behaviour, involving up to four nestmates, was observed in 33.3% of the infested bees. Successful mite removal was observed in 75% of the not-prematurely discontinued observations (n=36); 32% of the mites removed were caught with the mandibles.For mellifera auto-grooming behaviour was observed in most cases but delayed in comparison to cerana, and allo-grooming behaviour was rarely observed. Within 5 min, 48% of the mites in notprematurely discontinued observations (n=25) were removed, but none of the mites was caught with the mandibles.ForApis dorsata auto-grooming behaviour in response to the infestation withTropilaelaps clareae andVarroa mites is reported for the first time.Varroa was removed at a higher rate thanTropilaelaps. The higher survival chance ofTropilaelaps seems to be due to differences in mite behaviour and the preference for certain parts of the bee-body.     

大猿叶虫交配行为的观察

大猿叶虫Colaphellus bowringi Baly是十字花科上的重要害虫,一生能多次交配。本试验在25℃,光周期L∶D=12∶12条件下观察了大猿叶虫成虫连续7d的交配行为。结果表明:(1)每日平均交配(5.67±0.26)次,最高可达11次,不同日龄间的交配次数存在显著差异。(2)平均每日用于交配的时间为(238±10)min,占总时间的33.5%,最长可达493min,占总时间的68.5%,不同日龄间的交配时间有极显著差异。(3)交配持续时间最短8min,最长达289min,平均为(48±2)min;同一日内,随着交配次数增加,交配持续时间逐渐缩短;不同日龄间的交配持续时间存在显著差异。(4)相邻两次交配之间的间隔时间最短5min,最长300min,平均交配间隔(75±3)min;交配间隔时间随日龄的增加而明显延长。     

Mating flight causes genome-wide transcriptional changes in sexually mature honeybee queens

In this study, we analyzed the gene and miRNA expression differences between the courted virgin queen (CVQ) and non-courted virgin queen (NCVQ) of Apis mellifera using a high-throughput sequencing method. Through Digital Gene Expression (DGE) sequencing, 452 genes were differentially expressed, out of which, 90 genes were up-regulated and 362 genes were down-regulated in CVQ compared with NCVQ. Through small RNA sequencing, 27 miRNAs showed significant expression difference between these two samples. Moreover, 9 of the differentially expressed genes are the targets of the 11 differentially expressed miRNAs. Besides, 47 novel miRNA candidates were predicted in these two samples. Our results provided valuable information for understanding the molecular mechanism of the transition to functional queens.     

Impact of parasitic mite infection on a terrestrial snail

Summary

Although parasitic infections have been shown to be critical for growth, reproduction and survival of many vertebrates, little is known about the impact of parasites on invertebrate hosts and particular on molluscs. Therefore, it is of interest how parasites may affect their invertebrate hosts and how hosts can manage the detrimental effect of infections. In the present study, the naturally widespread parasitic mite Riccardoella limacum, which has been suggested to play an important role in the ecology of the land snail Arianta arbustorum, was artificially transferred to A. arbustorum. We experimentally examined the effect of the parasite on the food consumption, shell growth, and survival of its host. Surprisingly, we found minor impacts in some traits, i.e. we found that infected and uninfected snails similarly completed their shell growth, attained sexual maturity, and allocated equal energy into their albumen glands. However, infected snails consumed less and showed a significantly higher mortality after winter than uninfected snails.     

Mating behavior of the squid Loligo opalescens

In the laboratory, the squid Loligo opalescens exhibits dominance behavior during spawning. A single dominant male keeps other male squid from coming near the egg mass he is guarding. Females are allowed to approach the egg mass. The dominant squid uses postural and color displays directed toward challenging males. Similar dominance behavior and displays have not been observed in natural spawns in the ocean.     

Mating modifies female life history in a haplodiploid spider mite

Mating usually modifies females' resource allocation pattern, often as a result of conflicts between male and female partners. Can such a switch occur even in the absence of sexual conflicts? We addressed this issue in the haplodiploid spider mite Tetranychus urticae, whose biology and population structure considerably reduce conflicts between males and females over reproductive decisions. Comparing virgin and mated females, we tested the hypothesis that mated females modify their allocation pattern so as to maximize their probability of producing daughters. Mated females produced fewer but larger eggs, resulting in an overall similar reproductive effort but an increased probability of producing daughters, since in this species larger eggs are more likely to be fertilized and thus to become female. Moreover, mated females concentrated their reproduction early in life. Again, this might be a way to produce more daughters, since sperm is more abundant early in life. For virgins, spreading reproductive investment might be a way to save resources to extend life span, thus increasing their probability of encountering a sexual partner. Females with multiple opportunities for mating produced fewer eggs and a less female-biased sex ratio than once-mated females, raising the question of why multiple mating often occurs in this species.     

Mating behaviour of the water mite Arrenurus manubriator (Acari: Arrenuridae)

Water mites of the genus Arrenurus vary in male sexual dimorphism and in sperm transfer behaviour. Although it is a very large genus (≈800 spp.), mating behaviour has been described for only a few species. Here sperm transfer behaviour is described for the first time in a North American species, Arrenurus manubriator. Behaviour patterns can be divided into pre-pairing (readiness posture and cauda presentation), pre-deposition (high vertical jerking, low vertical shaking, striking/stroking and slow lateral waving), spermatophore deposition, sperm translocation, post-deposition (striking/stroking. slow lateral waving, 'tick-rock', shuttling, violent shaking), and separation. Males deposited 8–21 spermatophores in a mating. Pairs remained together for up to 31/2h. Possible adaptive functions of male courtship behaviour are discussed, including the hypothesis that male intromittant organs evolved in Arrenurus to circumvent female choice.     

The chemosensory bases of host discrimination in a parasitic mite

Summary Behavioral observations, preference tests, and physiological studies show thatProctolaelaps nauphoetae, an ectoparasitic mite, bases its choice of host on chemical information. Behavioral observations characterized searching patterns used to detect chemical cues. Preference tests showed that mites are attracted by three kinds of chemical cues: general cues — feces and detritus, apposite cues — cockroach expectorants, and a host-specific cue. This last cue, nauphoetamine, was isolated by gel filtration and high voltage paper electrophoresis. Preliminary analysis shows that it is a macromolecular amine (mw = 1,500–6,500) and may be a glycosaminoglycan. Electrophysiological experiments showed that nauphoetamine is detected by contact chemoreceptors located on the tarsi of the first pair of legs; these records are the first reported for a mite. The process of host discrimination is discussed in terms of a general model first proposed for hymenopteran parasites.This research effort profitted from the several contributions of Abby Shapiro, Robert Barth, Frank Hanson, G. Barrie Kitto, Rudy Morales, Ted Hollingsworth, E.E. Lindquist, K.P. Bland, Bill Clavert, A. Gelperin, USPHS Grant No. GM 00386-07, and the faculty and staff of the Zoology Department at the University of Texas. All are greatfully acknowledged. Figures 10 and 13 are used with the permission ofNature.     

蜜蜂采集及其信息传递的行为机制研究进展

蜜蜂的采集行为是蜜蜂众多社会行为中一种较复杂的行为,涉及信息评估、信息传递、学习记忆及能量代谢等不同的行为过程。研究蜜蜂采集及信息交流系统的分子机制,不仅利于蜜蜂的理论研究和蜂产业的发展,还为人类语言及信息交流系统的研究提供借鉴。本文从行为、感觉基础及分子机制等不同研究层面,综述了近年来对蜜蜂采集及信息传递行为的研究进展,并提出了研究设想,以期为深入研究蜜蜂的采集行为及其信息传递行为的分子机制提供参考。