The effects on domestic infestations of Cimex lectularius bedbugs of interspecific mating with C. hemipterus

Interspecific mating between male Cimex hemipterus and female C. lectularius bedbugs (Hemiptera: Cimicidae) occurs freely in the laboratory, even when many female C. hemipterus are available. Longevity and fertile egg production of female C. lectularius are reduced by mating with male C. hemipterus. In KwaZulu, South Africa, a correlation exists between the percentage of C. lectularius females which are interspecifically mated and the predominance of C. hemipterus in mixed domestic infestations of these bedbugs. When C. hemipterus constitutes over 75% of the infestation, the majority of C. lectularius females lay only sterile eggs.     

Production of a hybrid between the bedbugs Cimex hemipterus and Cimex lectularius

Of 479 eggs laid by female Cimex lectularius Linnaeus and C.hemipterus (Fabricius) mated by males of the other species, one was fertile and gave rise to a first stage nymph. The egg showed sculpturing typical of C.hemipterus, the female parent, and the nymph conformed to the narrow pronotum and abdomen of this species, being significantly different from C.lectularius in the width of the abdomen. Because the orientation and lengths of the bristles on the sides of the abdomen were distinctly different from C.hemipterus and closely resembled C.lectularius, the single nymph obtained from the cross C.hemipterus x lectularius was interpreted as being a hybrid rather than a product of parthenogenesis.     

Alarm pheromones and chemical communication in nymphs of the tropical bed bug Cimex hemipterus (Hemiptera: Cimicidae)

The recent resurge of bed bug infestations (Cimex spp.; Cimicidae) and their resistance to commonly used pesticides calls for alternative methods of control. Pheromones play an important role in environmentally sustainable methods for the management of many pest insects and may therefore be applicable for the control of bed bugs. The tropical bed bug, Cimex hemipterus, is a temporary ectoparasite on humans and causes severe discomfort. Compared to the common bed bug, Cimex lectularius, little is known about the chemical signalling and pheromone-based behaviour of the tropical species. Here, we show that the antennal morphology and volatile emission of C. hemipterus closely resembles those of C. lectularius and we test their behavioural responses to conspecific odour emissions. Two major volatiles are emitted by male, female and nymph C. hemipterus under stress, (E)-2-hexenal and (E)-2-octenal. Notably, nymph emissions show contrasting ratios of these compounds to adults and are further characterized by the addition of 4-oxo-(E)-2-hexenal and 4-oxo-(E)-2-octenal. The discovery of this nymph pheromone in C. hemipterus is potentially the cause of a repellent effect observed in the bio-tests, where nymph odours induce a significantly stronger repellent reaction in conspecifics than adult odours. Our results suggest that pheromone-based pest control methods developed for C. lectularius could be applicable to C. hemipterus, with the unique nymph blend showing promising practical properties.     

聚四氟乙烯对温带臭虫爬行能力的影响

温带臭虫Cimex lectularius L.是一种重要的卫生害虫,严重影响人们的生活和健康。目前有关该虫的防治措施主要以喷洒化学杀虫剂为主,而杀虫剂的使用不当极易导致该虫抗药性的产生或进一步加重,还将对人身安全构成极大的威胁。因此,探索高效、安全的防治方法成为当前温带臭虫防治过程中亟待解决的问题。本研究在实验室条件下采用行为观察法评估了高分子聚合物-聚四氟乙烯对温带臭虫垂直和水平爬行能力的影响。结果表明,随着聚四氟乙烯涂层宽度的增加,温带臭虫的垂直攀爬能力逐渐降低,当涂层宽度为6 cm时可100%阻隔温带臭虫垂直攀爬,且涂层的持效期可达112 d以上。而聚四氟乙烯涂层无法阻止温带臭虫的水平扩散。研究结果可为温带臭虫的高效、安全物理预防提供理论依据和技术支持。     

Trauma, disease and collateral damage: conflict in cimicids

The bed bugs and bat bugs (Hemiptera: Cimicidae) are unusual in being a gonochorist (separate male and female genders) taxon with obligate traumatic insemination. Males of all the species in this family have a lanceolate paramere (intromittent organ) which they use to pierce the female's body wall and inseminate directly into her haemocoel, despite the presence of a functional female genital tract. Mating is tightly linked to the feeding cycle in Cimex lectularius, the common bed bug. In this paper, I examine key aspects of the reproductive anatomy and behaviour of C. lectularius that underpin the nature of the conflict over mating rate in this species. I then examine the consequences of traumatic insemination for female fitness and examine potential mechanisms that might underpin those costs. Finally, the collateral consequences of the male reproductive tactic on other males of C. lectularius and the African bat bug, Afrocimex constrictus are examined.     

温带臭虫生活史中各龄若虫及成虫形态的进一步描述

本通过对温带臭虫生活史中各龄若虫及成虫形态的进一步描述,首次提出臭虫度量的长度随虫龄的成熟而逐步增大。身长与体宽之比基本保持在1：1.8左右,前胸宽及前胸长之比在3：1左右;除一龄若虫外,其基本基缘毛丛的数量。每增加一龄,其毛从根数也增加一根,即n 1,这在臭虫形态分类及对臭虫的进一步研究和防治有着重要的意义。     

大黄蝠锥虫生活史的研究

大黄蝠锥虫进入实验媒介体——热带臭虫胃内后2小时变为上鞭毛体,第3天起在后肠形成后循环型锥虫。传播方式为污染。在大黄蝠体内潜伏期为1—2天,第6—7天虫体充分长大。未见分裂及细胞内的锥虫。本虫可感染小黄蝠;但末感染埤、螨和白纹伊蚊、致乏库蚊。虫体在NNN培养基中的发育和在热带臭虫中的发育相似。实验结果有力地提示本虫的天然媒介是臭虫,并很可能是Cimex flavifuscus。     

Pyrethroid resistance in tropical bedbugs,Cimex hemipterus,associated with use of treated bednets

When Tanzanian villages were provided with pyrethroid-treated bednets, bedbugs (Cimicidae) disappeared; however, after about 6 years they have re-appeared in these villages. Using a newly devised test-kit, susceptibility tests of bedbugs Cimex hemipterus (Fabricius) from five of these villages showed that there is resistance to permethrin and alphacypermethrin in bedbugs from each of the villages, in contrast to those from five villages without treated nets. Circumstantial evidence indicates that bedbug resistance to pyrethroid insecticides may evolve more readily in villages with incomplete coverage rates of treated bednets, allowing bedbug infestations to become re-established. Bedbugs have not returned to a village where nearly all the beds have been provided with pyrethroid-treated bednets for 14 years.     

Estimating the feeding rate of the bedbug Cimex lectularius in an infested room: an inexpensive method and a case study

The common bedbug, Cimex lectularius L. (Hemiptera: Cimicidae), is a globally re-emerging pest that is playing an increasing role in legal disputes and compensation claims as a result of its unpleasant feeding activity. However, there is little information about the feeding frequency of bedbugs outside controlled laboratory cultures. Here, we present a simple method of estimating the average time since the last bloodmeal of individual female bedbugs in a single sampling event, applicable to a single bedbug harbourage or an entire room. Using the temperature-dependent rate of decrease in the abdomen size of the bedbug after a bloodmeal, we found that, in a highly infested room kept at a constant temperature of 26°C, females fed every 2.5 days on average. Our method corrects for variations in body size across different populations and determines the shrinkage that occurs when individuals are preserved in ethanol. This method should, therefore, be widely applicable. It is cheap, rapid and, if coupled with information on the total number of bedbugs present in a room, allows for the estimation of the minimum number of times persons lodging in a room have been bitten by bedbugs. This method can also be used to calculate the feeding rate of other blood-sucking insects on their hosts. The sex ratio in the infestation was female-biased. Finally, our case study suggests that individual female bedbugs within a harbourage do not seem to feed at a regular rate, but tend to synchronize feeding patterns.     

A matter of taste: direct detection of female mating status in the bedbug

Males of the bedbug, Cimex lectularius, traumatically inseminate females by inserting a needle-like intromittent organ (penis) through the female's abdominal wall after she has fed. We demonstrate that: (i) mating duration determines ejaculate size; (ii) a female's first copulation in a bout of copulations always lasts longer than subsequent copulations; (iii) the intromittent organ bears sensillae; (iv) males use their intromittent organ to 'taste' whether their current mate has recently copulated; and (v) the consequence of detecting female mating status is the reduction of copulation duration and ejaculate size. We discuss why male bedbugs might show this pattern of ejaculate-size adjustment.     

Reducing a cost of traumatic insemination: female bedbugs evolve a unique organ

The frequent wounding of female bedbugs (Cimex lectularius: Cimicidae) during copulation has been shown to decrease their fitness, but how females have responded to this cost in evolutionary terms is unclear. The evolution of a unique anatomical structure found in female bedbugs, the spermalege, into which the male's intromittent organ passes during traumatic insemination, is a possible counteradaptation to harmful male traits. Several functions have been proposed for this organ, and we test two hypotheses related to its role in sexual conflict. We examine the hypotheses that the spermalege functions to (i) defend against pathogens introduced during traumatic insemination; and (ii) reduce the costs of wound healing during traumatic insemination. Our results support the 'defence against pathogens' hypothesis, suggesting that the evolution of this unique cimicid organ resulted, at least partly, from selection to reduce the costs of mating-associated infection. We found no evidence that the spermalege reduces the costs of wound healing.     

Temporary feeding inhibition caused by artificial abdominal distension in the bedbug, Cimex lectularius

Abdominal distension of haematophagous insects caused by ingested blood has been recognised as an important contributor to triggering meal termination, feeding inhibition and further susceptibility to host signals. Factors that regulate feeding behaviour of the common bedbug, Cimex lectularius, are poorly understood. By injecting air directly into the body cavity of virgin female C. lectularius we artificially induced abdominal distension without providing chemical cues of the blood meal and without applying gut distension. Body length increased to 138% after feeding and 147% after inflation. The early decline in body volume is similar in blood-fed bugs but after between 8 and 24h became faster in inflated than fed bedbugs. Artificially inflated individuals remained feeding-inhibited at lower abdominal distensions than those that terminate blood ingestion (to ca. 135% initial body length, or up to about 5h). Feeding activity resumed earlier in inflated than blood-fed bugs. These results suggest that artificial abdominal distension has an inhibitory effect on feeding but is not the sole mechanism in preventing further feeding.     

Bedbug infestations recorded in Central Italy

In summer 2003 two separate infestations due to the common bedbug (Cimex lectularius) occurred in Pisa, Italy. Cutaneous reaction was evident and one patient developed a severe bullous eruption. In both cases there was circumstantial evidence for association with international travel.     

Control of Cimex lectularius using heat combined with dichlorvos resin strips

Successful management of the bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), is difficult because of its pesticide resistance, which can allow a reduction in population, but not elimination. We evaluated the effect of heat and/or air circulation on the efficacy of dichlorvos resin strips in the control of bed bugs. Treatments were performed in unoccupied dormitory rooms and consisted of dichlorvos resin strips containing 18.6% active ingredient, the same strips + fan, and strips + fan + heat. The mortality of recently fed bed bugs and weight loss of the dichlorvos strips were evaluated over 7 days. Dichlorvos resin strips killed bed bugs and eggs in just over 7 days. The addition of a fan or a fan + heat decreased time to 100% mortality to 3 days and 36 h, respectively. Eggs located in treated rooms did not hatch. Resin strips in the strips + fan treatment and the strips + fan + heat treatment volatilized 10 and 70 times, respectively, faster than strips in the strips-only treatment. The addition of heat in treatments with dichlorvos resin strips enhances the overall efficacy of the volatile insecticide and reduces the time required to eliminate live bed bugs and eggs.     

Situation exploitation: higher male mating success when female resistance is reduced by feeding

Optimal male and female mating rates rarely coincide. Males often shift the rate in their favor by either increased signaling and by overcoming female resistance to copulation. The concept of sensory exploitation posits that males produce signals that mimic naturally selected benefits and so deceitfully attract females. However, males also have to overcome female resistance to actual copulation. Males may do so by copulating during situations when the female's ability to resist is decreased because of competing naturally selected demands. Males of the common bedbug, Cimex lectularius , an obligate blood feeder, mate at a rate, and in a manner that is harmful to females. Females have to feed regularly to produce eggs, and during feeding female body volume increases by 300%. Choice trials using unfed and either fed or experimentally enlarged but unfed females showed that the increased postfeeding body volume of females attracted more male mating attempts, strongly reduced female resistance to male mating attempts and resulted in a net increase in female mating rate. Our results, therefore, suggest that males have increased mating success in a situation that females cannot avoid because it is naturally selected. Such "situation exploitation" of low resistance may be a common phenomenon.     

臭虫的再猖獗、生物学及防治研究进展

由于DDT等现代杀虫剂的问世,臭虫在20世纪40-50年代以后在全球大部分地区尤其是发达国家和地区销声匿迹,但近10多年来臭虫在部分国家和地区重新出现.本文对其再猖獗原因、生物学和行为、饲养、抗药性、监测与防治策略进行了综述,旨在引起国人的重视,对今后臭虫的监测和防治起到抛砖引玉的作用.本文分析了近15年有关温带臭虫Cimex lectulariusL.和热带臭虫C.hemipterus(F.)的研究文献.臭虫再猖獗被认为是因为它对目前使用的杀虫剂例如拟除虫菊酯类等产生抗性以及频繁的地区及国际交往等因素造成的.简单、经济和大规模臭虫种群饲养方法——人工膜饲喂法的研发为我们开展臭虫生物学和生态学研究提供了便利.控制和根除臭虫目前仍较困难,采用害虫综合治理(integrated pest management,IPM)策略,包括臭虫知识宣传、主动监测、非化学防治方法(例如:经常洗涤床上用品、蒸汽熏蒸、热处理、使用床垫罩、在家具腿下放置臭虫拦截装置)、有选择使用杀虫剂以及定期监测及反复防治等措施,可达到很好的防控效果.在我国部分地区,臭虫发生也呈上升趋势,工人宿舍和火车车厢是常见的臭虫为害环境.有必要对我国臭虫发生现状及其抗药性进行调查与监测.还应借鉴国际先进技术,研制出我国适用的、有效的监测工具和防治方法,并根据我国具体国情制定出切实可行的防治标准.同时积极开展臭虫科普宣传,做到早发现、早防治,防止臭虫再猖獗和扩散.     

Effect of vitamin A acid on papillomas induced by irradiated bed bugs in rabbit skin

The preventive effect of vitamin A acid (13-cis-retinoic acid) on skin papillomas induced in rabbits (Oryctolagus cuniculus) by the bite of bed bugs (Cimex lectularius) pre-irradiated with gamma rays was investigated. Painting the papillomas with an oily 13-cis-retinoic acid suspension twice a week in a dose of 25 mg/kg body weight leads to significant regression of these structures.     

Permethrin-impregnated bednets reduce nuisance arthropods in Gambian houses

The prevalence of bedbugs (Cimex hemipterus L.), chicken ticks (Argas persicus Oken) and headlice (Pediculus capitis De Geer) was surveyed in a rural area of The Gambia. At the beginning of the study 37.5% of children's beds were infested with bedbugs and 3.9% with chicken ticks, whilst the prevalence rate of pediculosis in children under 10 years old was 28.8%. Both bedbugs and headlice were clustered within compounds. Headlice prevalence increased with hair length and they were more common on girls than boys. Following this cross-sectional survey all bednets in the sixteen hamlets were either dipped in permethrin or a placebo. About 4 months later it was found that bedbugs and chicken ticks had disappeared from homes in which the bednets had been impregnated with permethrin. There was no reduction in hamlets with placebo-treated bednets. The rate of acquiring headlice between the two surveys was reduced by 91.1% in children who slept under insecticide-treated bednets compared with children with placebo-treated bednets. There were also significantly fewer day-flying and crawling insects, except earwigs, in homes of children who slept under insecticide-treated bednets compared with those with placebo-treated nets. These additional benefits of permethrin-treated bednets should contribute to their widespread acceptance and utilization by the community for personal protection.     

Acoustic indicators for targeted detection of stored product and urban insect pests by inexpensive infrared, acoustic, and vibrational detection of movement

Crawling and scraping activity of three stored-product pests, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), and Stegobium paniceum (L.) (Coleoptera: Anobiidae), and two urban pests, Blattella germanica (L.) (Blattodea: Blattellidae) and Cimex lectularius L. (Hemiptera: Cimicidae), were monitored individually by infrared sensors, microphones, and a piezoelectric sensor in a small arena to evaluate effects of insect locomotory behavior and size on the ability of an inexpensively constructed instrument to detect insects and distinguish among different species. Adults of all species could be detected when crawling or scraping. The smallest insects in the study, first-fourth-instar C. lectularius nymphs, could not be detected easily when crawling, but could be detected when scraping. Sound and vibration sensors detected brief, 3-10-ms impulses from all tested species, often grouped in distinctive trains (bursts), typical of impulses in previous acoustic detection experiments. To consider the potential for targeting or focusing detection on particular species of interest, indicators were developed to assess the likelihood of detection of C. lectularius. Statistically significant differences were found between C. lectularius and other species in distributions of three measured variables: infrared signal durations, sound impulse-burst durations, and sound pressure levels (energy) of impulses that best matched an averaged spectrum (profile) of scraping behavior. Thus, there is potential that signals collected by an inexpensive, polymodal-sensor instrument could be used in automated trapping systems to detect a targeted species, 0.1 mg or larger, in environments where servicing of traps is difficult or when timeliness of trapping information is important.     

Ability of bed bug (Hemiptera: Cimicidae) defensive secretions (E)‐2‐hexenal and (E)‐2‐octenal to attract adults of the common bed bug Cimex lectularius

Accurate and timely surveillance of bed bug infestations is critical for the development of effective control strategies. Although the bed bug‐produced volatiles (E)‐2‐hexenal and (E)‐2‐octenal are considered as defensive secretions, the present study demonstrates, using ethovision® video‐tracking software (Noldus Information Technology Inc., Leesburg, Virginia), that low amounts of these commercially‐obtained aldehydes function as attractants, and high amounts function as local repellents, against the common bed bug Cimex lectularius L. In behavioural assays, both males and female C. lectularius are attracted to 0.04 µg of an aldehyde blend (1 : 1) for up to 1 h after initial treatment of filter paper disks. Males differ from females in their response to higher amounts of aldehydes, with females and males exhibiting maximum local repellency at 40 µg and 400 µg, respectively. The results suggest that these bed bug secretions may be candidates for lures and monitors.