The common bedbug Cimex lectularius in African huts

First official report of bed bug (Hemiptera, Cimicidae) infestations in Algeria

Background

Bed bugs are hematophagous insects with a long history of presence in human communities. Over the last three decades, infestations by bed bugs in human dwellings have drastically increased, leading to a rise in bed bug concerns. Nevertheless, very little is known about the bed bug species and their population diversity in Algeria.

Method

A pilot entomological inventory was performed in May 2019 in Tizi Ouzou, in northern Algeria. The gathered bed bug specimens were identified by morphological and molecular approaches, followed by neighbor-joining and network phylogenetic analyses.

Results

A total of seven out of 12 requested locations were allowed to inspect for bed bug infestation. Of these, three locations were found with active bed bug infestations. A total of 145 specimens belonging to different life stages [egg (21), nymph (74), adult male (17), and female (33)] were collected and analyzed using morphological and molecular approaches. The adult specimens were identified as Cimex lectularius according to specific morphological criteria, most importantly the pronotum laterally expanded with more flattened extreme margins. Morphological identification of the adults was confirmed further by conventional PCR targeting 450 bp fragment of the COI gene. All the nymphs and eggs were also molecularly identified as C. lectularius. Neighbor-Joining phylogenetic tree reconstructed with the collected specimens provides clues on the presence of two closely phylogenetic groups. The first one gathers our samples of Algeria with previously reported COI haplotype sequences from Asian, European, and North American countries. The second group encompasses a lesser-documented haplotype reported in Europe and Central America. These findings were further confirmed by network analysis.

Conclusions

These results provide evidence of established C. lectularius infestation in Algeria and its potential dispersal capacity by travelers or immigrants and will help future management of these ectoparasites.

Morphological and Molecular Identification of Cimex hemipterus Fabricius, 1803 (Hemiptera: Cimicidae) and First Report of C. lectularius Linnaeus, 1758, in Madagascar

Bed bugs are hematophagous insects with a long history of presence in human communities. Over the last three decades, infestations by bed bugs in human dwellings have drastically increased, leading to a rise in bed bug concerns. This study was conducted in May 2019 in the Miarinarivo district of Madagascar. Eight locations with suspected infestations were inspected. Of these, five locations were found with active bed bug infestations. Overall, 23 (19 adults and four nymphs) specimens with numbers per apartment ranging from 2 to 6 were collected and analyzed using morphological and molecular approaches. Of 19 adults collected, 18 were morphologically identified as Cimex hemipterus (Hemiptera: Cimicidae), with the final adult identified as C. lectularius. Morphological identification of adults was confirmed by sequencing 450 bp fragment of COI gene. All four nymphs were also identified molecularly as C. hemipterus. Maximum likelihood phylogenetic tree of COI gene and sequence alignment of C. hemipterus specimens revealed the presence of two groups (first group clustered with previously reported haplotype from Asian and African countries and the second group encompassed a lesser known haplotype exclusively from Africa (Kenya and Senegal). This study presents low genetic diversity among C. hemipterus specimens and, for the first time, reports the occurrence of C. lectularius, known as temperate species, in Madagascar. These results can be helpful in control management strategies against these ectoparasites in this country.

Bed bugs are associated with anemia

INTRODUCTION

Bed bugs are hematophagous insects that can be problematic in some urban emergency departments. The objective was to determine if red blood cell (RBC) and coagulation indices of bed bug-infested emergency department (ED) patients differed from those of noninfested control patients.

METHODS

A chart review from a single health system was performed for ED patients between February 1, 2011, and February 1, 2017. Bed bug-infested patients were matched to noninfested control patients on the basis of age, sex, and the presenting ED. Variables were analyzed with the t-test and Pearson χ² test and were modeled with multivariable logistic regression.

RESULTS

The study had 332 bed bug-infested patients and 4952 controls. Infested patients had lower hemoglobin (11.7 g/dL vs 12.8 g/dL), hematocrit (35.0% vs 37.9%), RBC counts (4.1 × 10⁹/L vs 4.4 × 10⁹/L), mean corpuscular volume (86.0 vs 87.5 fL/cell), and mean corpuscular hemoglobin concentrations (33.2 vs 33.7 g/dL) and higher RBC distribution width-coefficient of variation (RDW-CV) (15.2% vs 14.2%) than noninfested patients (all P ≤ .003). Infested patients were more likely to be anemic (59.5% vs 36.9%) and to have severe anemia (4.4% vs 0.7%) (P < .001 for both). Blood transfusions were more common in those with bed bugs (5.1%) than those without bed bugs (2.3%) (P < .001).

CONCLUSION

Bed bug infestated patients in the ED are associated with anemia.

Potential population growth and harmful effects on humans from bed bug populations exposed to different feeding regimes

Effects of host availability and feeding period on bed bugs, Cimex lectularius (L.) (Hemiptera: Cimicidae), were measured. Population growth and the potential harmful effect of bed bug populations on human hosts were modelled. Bloodmeal sizes were affected by both feeding length and frequency, with >2-fold difference between insects fed daily or weekly. Blood consumption increased >2-fold between bed bugs fed occasionally and often, and 1.5-fold between occasional and daily feeding. Bed bugs fed more often than once a week, potentially every 2-4 days. Egg production was associated with nutrition, being strongly correlated with blood consumption in the previous week. Bed bug populations can grow under different feeding regimes and are hard to control with <80% mortality. Bed bugs can survive and grow even in locations with a limited blood supply, where bed bug persistence may be important for the continual spread of populations. Persistence in non-traditional locations and a potential association with human pathogens increase the health risks of bed bugs. Potential blood loss as a result of a bed bug can have serious consequences because uncontrolled populations can reach harmful levels in 3-8 months. The reproduction potential of bed bug populations suggests serious consequences to human health and the need for efficacious control measures.

"My children and I will no longer suffer from malaria": a qualitative study of the acceptance and rejection of indoor residual spraying to prevent malaria in Tanzania

Background

The objective of this study was to identify attitudes and misconceptions related to acceptance or refusal of indoor residual spraying (IRS) in Tanzania for both the general population and among certain groups (e.g., farmers, fishermen, community leaders, and women).

Methods

This study was a series of qualitative, semi-structured, in-depth interviews and focus group discussions conducted from October 2010 to March 2011 on Mainland Tanzania and Zanzibar. Three groups of participants were targeted: acceptors of IRS (those who have already had their homes sprayed), refusers (those whose communities have been sprayed, but refused to have their individual home sprayed), and those whose houses were about to be sprayed as part of IRS scale-up. Interviews were also conducted with farmers, fishermen, women, community leaders and members of non-government organizations responsible for community mobilization around IRS.

Results

Results showed refusers are a very small percentage of the population. They tend to be more knowledgeable people such as teachers, drivers, extension workers, and other civil servants who do not simply follow the orders of the local government or the sprayers, but are skeptical about the process until they see true results. Refusal took three forms: 1) refusing partially until thorough explanation is provided; 2) accepting spray to be done in a few rooms only; and 3) refusing outright. In most of the refusal interviews, refusers justified why their houses were not sprayed, often without admitting that they had refused. Reasons for refusal included initial ignorance about the reasons for IRS, uncertainty about its effectiveness, increased prevalence of other insects, potential physical side effects, odour, rumours about the chemical affecting fertility, embarrassment about moving poor quality possessions out of the house, and belief that the spray was politically motivated.

Conclusions

To increase IRS acceptance, participants recommended more emphasis on providing thorough public education, ensuring the sprayers themselves are more knowledgeable about IRS, and asking that community leaders encourage participation by their constituents rather than threatening punishment for noncompliance. While there are several rumours and misconceptions concerning IRS in Tanzania, acceptance is very high and continues to increase as positive results become apparent.

Swahili Abstract

Usuli

Malengo mahususi ya utafiti huu ni kutambua tabia na imani potofu zinazopelekea kukubali au kutakaa upuliaziaji wa dawa ya kuua mbu majumbani (IRS) katika Tanzania kwa watu wote kwa ujumla na kwa makundi maalumu ya watu (kama wakulima, wavuvi, viongozi wa jamii na wanawake).

Njia

Utafiti huu ni mfululizo wa tafiti stahilifu zenye sehemu ya muundo, tafiti za kina na majadilianao ya vikundi vya walengwa yaliyofanyika Tanzania bara na Zanzibar kuanzia mwezi Oktoba, 2010 hadi mwezi Machi, 2011. Yalikuwepo makundi matatu ya walengwa: wanaokubali IRS (wale ambao nyumba zao zilikwisha kupulizwa dawa ya kuua mbu) wasiokubali (hii ni jamii iliyokwisha kupulizwa dawa na wale watu waliokataa dawa isipulizwe kwenye nyumba zao) na wale ambao nyumba zao zilikuwa zinakaribia kupulizwa dawa ikiwa ni kama sehemu ya kusambaza IRS. Usaili ulifanyika pia kwa wakulima, wavuvi, wanawake na viongozi wa jamii vile vile na kwa wanachama wa asasi zisizo za kiserikali waliokuwa wakiwajibika kwa IRS.

Matokeo

Matokeo yalionyesha kuwa waliokataa walikuwa ni asilimia ndogo sana ya watu wote. Walikuwa ni watu waelewa kama vile walimu, madereva, wafanyakazi katika miradi na watumishi wengine wa serikali ambao wanafuata amri kutoka kwa serikali yao au kwa wapuliza dawa lakini walikuwa na wasiwasi kuhusu mchakato huo mpaka waone matokeo yake. Waliokataa walikuwa katika maainisho matatu: 1) waliokataa kidogo mpaka wapewe maelezo; 2) waliokubali dawa ipulizwe kwenye vyumba vichache tu; 3) waliokataa katu katu. Mara kwa mara wengi wa wasailiwa waliokataa, walitoa sababu zao za kukataa nyumba zao zisipuliziwe, bila kukubali kuwa wamekataa kupuliziwa. Sababu za kukataa mwanzoni zilikuwa ni pamoja na; kutokuwa na uhakika kuhusu dawa inavyofanya kazi, kutoelewa matokeo yake, kuongezeka kwa kuenea kwa wadudu wengine. Athari nyingine mbaya zilizoonekana ni: harufu, tetesi kuhusu kemikali zinazoathiri urutubishwaji, aibu ya kutolewa vitu vyao vyenye thamani duni kutoka kwenye nyumba zao na imani kuwa dawa hiyo ilihamasishwa kisiasa zaidi.

Hitimisho

Ili kuongeza kukubalika kwa IRS, washiriki wanasisitiza zaidi kuzitoa dawa hizo kwa kuwaelimisha watu kwanza, kuhakikisha kuwa wanaonyunyuza dawa hiyo wana ujuzi wa kutosha kuhusu dawa yenyewe, kuwaomba viongozi wa jamii wawatie moyo wanajamii katika kaya zao badala ya kuwatishia na kuwalazimisha. Pamoja na kwamba kuna tetesi na watu kuelewa visivyo kuhusu IRS, kukubalika ni kukubwa na kunaendelea kuonyehsa kuwa na mafanikio chanya.

Bed Bug (Cimex lectularius L.) Population Composition as Determined by Baited Traps

Two established field populations of bed bugs were sampled using host-mimicking traps baited with a combination of CO₂, heat and a synthetic kairomone. The proportion of first instar nymphs (between 52% and 78% of all captured insects) was significantly higher than reported in previous studies, which had employed different sampling methods. The proportion of adults was correspondingly much lower than previously reported, between 5% and 7% of total capture. As many as 120 bed bugs were captured in a single trap in one night; the variation in catches between sampling locations within the same room and between days at the same location indicates that multiple nights of trapping may be required to obtain an accurate representation of population structure.

Insecticides Susceptibility Status of the Bedbugs (Cimex lectularius) in a Rural Area of Magugu, Northern Tanzania

The recent spread of bedbugs, Cimex lectularius L. (Heteroptera: Cimicidae), has received attention of the public health sector for designing of effective plan of action for control. Several studies have focused on determining the distribution and abundance of bedbug populations in tropical areas. This study establishes baseline information on deltamethrin, permethrin, alphacypermethrin, lambdacypermethrin and K-O tab susceptibility status in a bedbug population collected from Magugu area in northern Tanzania. The evolution of insecticide resistance could be a primary factor in explaining this resurgence of bedbugs in many areas, both rural and urban. Evaluation of the bedbug population from houses in Magugu indicates that the population of bedbugs is susceptible to pyrethroid insecticides, which are commonly used. Without the development of new tactics for bedbug resistance management, further escalation of this public health problem should be expected when resistant gene spreads within the population. These results suggest that although all concentrations kill bedbugs, more evaluations should be done using WHO kits and mechanisms involved in pyrethroid resistance should be evaluated, such as metabolic and knockdown resistance gene, to have a broad picture for better design of control methodologies.

Effect of population structure and size on aggregation behavior of Cimex lectularius (Hemiptera: Cimicidae)

The bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), occurs in aggregations until the conditions are no longer beneficial, leading to dispersal. Active and passive bed bug dispersal causes migrations from main aggregations either within a room, from room to room within a building, or from building to building. Because bed bug movement is an important factor in the spread of infestations, we wanted to determine how population structure and size affect bed bug aggregations. Engorged bed bugs were placed in glass petri dish arenas at varying densities, sex ratios, and population compositions. Nymphs had a high tendency to aggregate, varying between 94 and 98%, and therefore were not the likely dispersal stage of the bed bug. At densities of 10 and 40 adults at a 1:1 sex ratio, there were significantly more lone females than lone males. When the population composition was varied, the percentage of lone females was significantly higher than that of males and nymphs at population compositions of 40 and 80% adults. When the sex ratio of adults was varied, there were significantly more lone females than males in arenas with 20, 50, and 80% males. Females, being found away from aggregations significantly more often than any other life stage, are potentially the dispersal stage of the bed bug. Active female dispersal away from main aggregations can potentially lead to treatment failures and should be taken into account when using control methods.

Biology of the bed bugs (Cimicidae)

The cimicids, or bed bugs, belong to a highly specialized hematophagous taxon that parasitizes primarily humans, birds, and bats. Their best-known member is the bed bug, Cimex lectularius. This group demonstrates some bizarre but evolutionarily important biology. All members of the family Cimicidae show traumatic insemination and a suite of female adaptations to this male trait. Cimicids therefore constitute an ideal model system for examining the extreme causes and consequences of sexual selection. Our dual goal in re-examining the extensive literature on this group is to identify issues relevant to pest control, such as dispersal ecology and the recent global spread, and to understand the selective forces that have shaped the unique aspects of this insect's biology.

Bed bug infestations in an urban environment

Bed bug infestations adversely affect health and quality of life, particularly among persons living in homeless shelters.

Until recently, bed bugs have been considered uncommon in the industrialized world. This study determined the extent of reemerging bed bug infestations in homeless shelters and other locations in Toronto, Canada. Toronto Public Health documented complaints of bed bug infestations from 46 locations in 2003, most commonly apartments (63%), shelters (15%), and rooming houses (11%). Pest control operators in Toronto (N = 34) reported treating bed bug infestations at 847 locations in 2003, most commonly single-family dwellings (70%), apartments (18%), and shelters (8%). Bed bug infestations were reported at 20 (31%) of 65 homeless shelters. At 1 affected shelter, 4% of residents reported having bed bug bites. Bed bug infestations can have an adverse effect on health and quality of life in the general population, particularly among homeless persons living in shelters.

Historical review of malarial control in southern African with emphasis on the use of indoor residual house-spraying

Indoor residual house-spraying (IRS) mainly with dichlorodiphenyltrichloroethane (DDT) was the principal method by which malaria was eradicated or greatly reduced in many countries in the world between the 1940s and 1960s. In sub-Saharan Africa early malarial eradication pilot projects also showed that malaria is highly responsive to vector control by IRS but transmission could not be interrupted in the endemic tropical and lowland areas. As a result IRS was not taken to scale in most endemic areas of the continent with the exception of southern Africa and some island countries such as Reunion, Mayotte, Zanzibar, Cape Verde and Sao Tome. In southern Africa large-scale malarial control operations based on IRS with DDT and benzene hexachloride (BHC) were initiated in a number of countries to varying degrees. The objective of this review was to investigate the malarial situation before and after the introduction of indoor residual insecticide spraying in South Africa, Swaziland, Botswana, Namibia, Zimbabwe and Mozambique using historical malarial data and related information collected from National Malaria Control Programmes, national archives and libraries, as well as academic institutions in the respective countries. Immediately after the inception of IRS with insecticides, dramatic reductions in malaria and its vectors were recorded. Countries that developed National Malaria Control Programmes during this phase and had built up human and organizational resources made significant advances towards malarial control. Malaria was reduced from hyper- to meso-endemicity and from meso- to hypo-endemicity and in certain instances to complete eradication. Data are presented on the effectiveness of IRS as a malarial control tool in six southern African countries. Recent trends in and challenges to malarial control in the region are also discussed.

The cost and cost-effectiveness of malaria vector control by residual insecticide house-spraying in southern Mozambique: a rural and urban analysis

OBJECTIVES

To compare two separately funded, but operationally similar, residual household-spraying (RHS) initiatives; one rural and one peri-urban in southern Mozambique.

METHODS

The rural programme is a regional project involving the participation and co-ordination of organizations across three countries in southern Africa and is focussed on control in an area in Mozambique of 7552 km2. The second programme focuses on spraying a peri-urban community within a 10-km radius around MOZAL, an aluminium smelter plant of area 410 km2. An ingredients approach was used to derive unit costs for both the rural and peri-urban spraying programmes using detail retrospective cost data and effectiveness indicators.

RESULTS

The economic cost per person covered per year using Carbamates for indoor residual spraying (IRS) in the rural area, excluding the costs of project management and monitoring and surveillance was $3.48 and in the peri-urban area, $2.16. The financial costs per person covered in the rural area and peri-urban area per year were $3.86 and $2.41, respectively. The economic costs per person covered were respectively increased by 39% and 31% when project management and monitoring and surveillance were included. The main driving forces behind the costs of delivering RHS are twofold: the population covered and insecticide used. Computed economic and financial costs are presented for all four insecticide families available for use in RHS.

CONCLUSIONS

The results from both these initiatives, especially the rural area, should be interpreted as conservative cost estimates as they exclude the additional health gains that the newly introduced programmes have had on malaria rates in the neighbouring areas of South Africa and Swaziland. Both these initiatives show that introducing an IRS programme can deliver a reduction in malaria-related suffering providing financial support, political will, collaborative management and training and community involvement are in place.

Susceptibility of the bedbug, Cimex lectularius, to selected insecticides and various treated surfaces

Adult bedbugs, Cimex lectularius, were exposed for 24 h (25 degrees C) to filter paper treated with various dilutions of the technical grade of nine insecticides dissolved in acetone to determine the concentration-response relationships. The order of toxicity, from most to least based on the LC50's was: dichlorvos, pirimiphos methyl, lambda-cyhalothrin, bendiocarb, permethrin, malathion, carbaryl, tetrachlorvinphos, and fenvalerate. The residual toxicities of commercial formulations of six of the chemicals diluted with water and applied to wood, cardboard, cloth and galvanized metal, were determined by exposing adult bedbugs at 3, 7 and 12 weeks after treatment. The formulation of bendiocarb (FICAM 76% W) had little residual activity on all surfaces at 12 weeks after treatment. The formulation of carbaryl (SEVIN 21.5% L) was toxic to bedbugs on all surfaces at 12 weeks after treatment, but required high concentrations on wood, cardboard, and cloth. The formulation of pirimiphos methyl (ACTELLIC 57% EC) had no residual activity on any of the surfaces at 12 weeks after treatment. The formulation of tetrachlorovinphos (RABON 50% W) had residual activity for 12 weeks on all surfaces except metal. The formulation of permethrin (ATROBAN 11% EC) had residual activity on only metal and wood while the formulation of lambda-cyhalothrin (KARATE 13.1% EC) had residual activity 12 weeks on all surfaces.

The tropical bedbug Cimex hemipterus near the southernmost extent of its range

The average degree of infestation of Cimex hemipterus in Zulu huts in South Africa is the same as that of C. lectularius. Nymphal stages of C. hemipterus can be distinguished by head-width measurements and numbers of lateral pronotal hairs.

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.