Blattella germanica (German cockroach)
Index
- Pictures
- Identity
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Description
- Distribution
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat
- Habitat List
- Host Plants and Other Plants Affected
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Impact Summary
- Economic Impact
- Environmental Impact
- Social Impact
- Risk and Impact Factors
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- References
- Contributors
- Distribution Maps
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Top of pagePreferred Scientific Name
- Blattella germanica Linnaeus
Preferred Common Name
- German cockroach
Other Scientific Names
- Blatta germanica Linnaeus
- Blatta transfuga
- Ectobia germanica Linnaeus
- Periplaneta germanica (L.)
- Phyllodromia germanica
- Phyllodromica germanica (L.)
International Common Names
- English: croton bug; Russian roach; steam fly
- Spanish: cucaracha alemana; cucaracha europea; cucaracha pequena de las casas
- French: blatte germanique
Local Common Names
- Denmark: køkkenkakerlak; tysk kakerlak
- Germany: Deutsche Schabe; Hausschabe
- Israel: hatikan hagermani
- Netherlands: duitsche kakkerlak; Huiskakkerlak; kleine kakkerlak
- Norway: tysk kakerlakk
- Turkey: alman hamam bocegi
EPPO code
- BLTTGE (Blattella germanica)
Summary of Invasiveness
Top of pageB. germanica is one of the most widespread cockroaches in the genus Blattella. It is native to North Africa (Ethiopia and Sudan) and has since spread rapidly around the world facilitated by international trade. This species is not tolerant of cold conditions and lives in close association with humans and/or human activities. B. germanica can be a major pest species which is both a nuisance and can cause health problems (allergies and infections). This species can also vector a number of potentially harmful pathogens and is linked with the spread of pathogens in hospitals and can lead to food borne illnesses. The ability of this species to spread rapidly is exacerbated by a resistance to chemicals for control.
Taxonomic Tree
Top of page- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Dictyoptera
- Suborder: Blattaria
- Family: Blattellidae
- Genus: Blattella
- Species: Blattella germanica
Notes on Taxonomy and Nomenclature
Top of pageCockroaches have an evolutionary history going back 350 million years and have one of the most consistent fossil records of all terrestrial arthropods (Vrsansky, 2008). There are 49 species in the genus Blattella and B. germanica is said to be probably the most important pest and the most widespread in the genus (Roth, 1985). B. germanica was designated the type-species of the genus Blattella in the 1980s (International Commission on Zoological Nomenclature, 1982). The International Commission on Zoological Nomenclature ruled that germanica (published in 1767 as Blatta germanica L.) was to be given precedence over transfuga, whenever the two names were considered to be synonymous (International Commission on Zoological Nomenclature, 1982).
B. germanica is most widely referred to as the German cockroach, but in Germany it is known as the Russian roach (Berenbaum, 1989).
During a study on the saltatory changes in ribosomal gene clusters during the evolution of Blattella species, it was noted that B. germanica is closely related to B. lituricollis and B. vaga (Mukha et al., 1999). This was based on the similarity between species in the 1270-bp fragment of 28S ribosomal RNA, which was 94.5% for B. germanica and B. lituricollis and 88.0% for B. germanica and B. vaga.
Description
Top of pageAn adult B. germanica is 10-15 mm long, brown to black, with two distinct parallel bands running the length of the pronotum. The males have thin, slender bodies, the posterior abdomen is tapered, the terminal segments of the abdomen are visible and not covered by tegmina. In contrast, the female has a stout body, the posterior abdomen is rounded and the entire abdomen is just covered by tegmina (Valles, 1996).
Ramaswamy and Gupta (1981) studied the sensilla of the antennae and the labial and maxillary palps of B. germanica. They reported that all these organs contain thick-walled chemoreceptors with fluted shafts and articulated bases. The flaggellar segments of the antennae and the distal segments of the palps contain thin-walled receptors without fluted shafts or articulated bases. The adult male antennae have more thin-walled chemoreceptors than those of the females. At the joints of segments on the palps, scape-head and scape pedicel, hair-plate sensilla can be found. The distal margin of the pedicel, the scape, pedicel and flagellar segments of the antennae and the first segment of the maxillary palps are all sites of campaniform sensilla. Sensilla coeloconica and cold-receptor sensilla are sometimes found on the antennal flagellum.
The nymphs of B. germanica are dark-brown to black, with dark parallel bands running the length of the pronotum. The most frequently reported number of moults required to reach adulthood is six, but the number of moults can vary. Development of the nymphs at room temperature takes approximately 60 days (Valles, 1996). The nymphs eat the moulted skins (Precise Pest Control, 2014).
Distribution
Top of pageB. germanica is probably the most widespread species to occur in the genus Blattella (Roth, 1985). Early documentation considered B. germanica to be native to Europe (Cory and McConnell, 1917) however it is now thought to be a native of Ethiopia and Sudan (Hill, 2002) or elsewhere in North Africa (Eaton and Kaufmann, 2007). This species has since been widely introduced around the world into parts of Australia, Africa, North America and the Oceanic Islands. The distribution presented in the Distribution Table, is likely an underestimate of the actual distribution of B. germanica.
Distribution Table
Top of pageThe distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
Last updated: 10 Jan 2020Continent/Country/Region | Distribution | Last Reported | Origin | First Reported | Invasive | Reference | Notes |
---|---|---|---|---|---|---|---|
Africa |
|||||||
Botswana | Present | ||||||
Egypt | Present | ||||||
Ethiopia | Present | Native | |||||
Namibia | Present | ||||||
Sudan | Present | Native | |||||
Asia |
|||||||
China | Present | Introduced | |||||
-Beijing | Present | Introduced | |||||
-Fujian | Present | Introduced | |||||
-Gansu | Present | Introduced | Lanzhou | ||||
-Guangdong | Present | Introduced | |||||
-Hainan | Present | Introduced | Haikou city | ||||
-Hebei | Present | Introduced | Handan city; Original citation: Wang et al. (2012) | ||||
-Heilongjiang | Present | Introduced | |||||
-Henan | Present | Introduced | Kaifeng city | ||||
-Hubei | Present | Introduced | Wuhan city | ||||
-Jiangsu | Present | Introduced | Changzhou | ||||
-Jiangxi | Present | Yichun | |||||
-Jilin | Present | Introduced | Tonghu | ||||
-Liaoning | Present | Introduced | Dalian city | ||||
-Shaanxi | Present | Introduced | Yulin urban area | ||||
-Shandong | Present | Introduced | Qufu city | ||||
-Shanghai | Present | Introduced | Original citation: Liang et al. (1981, recd. 1984) | ||||
-Sichuan | Present | Introduced | Panzhihua | ||||
-Zhejiang | Present | Introduced | Wenzhou | ||||
India | Present | Introduced | |||||
Indonesia | Present | Introduced | |||||
Iran | Present | Introduced | Yasuj City, southwestern Iran | ||||
Japan | Present | Present based on regional distribution. | |||||
-Honshu | Present | Introduced | |||||
Malaysia | Present | Introduced | Animal facility in Kuala Lumpur | ||||
Philippines | Present | Introduced | Original citation: Gonzales JC Jr (1980, publ. 1981, recd. 1982) | ||||
Saudi Arabia | Present | Introduced | |||||
Singapore | Present | Introduced | Jurong city; Original citation: Wang et al. (2012) | ||||
South Korea | Present | Introduced | |||||
Taiwan | Present | Introduced | |||||
Thailand | Present | Introduced | |||||
Turkey | Present | Introduced | |||||
Europe |
|||||||
Bulgaria | Present | Introduced | |||||
Croatia | Present | Introduced | |||||
Czechia | Present | ||||||
Czechoslovakia | Present | Introduced | |||||
Denmark | Present | Introduced | |||||
Estonia | Present | Introduced | |||||
Finland | Present | Introduced | |||||
France | Present | Introduced | |||||
Germany | Present | Introduced | |||||
Ireland | Present | Introduced | |||||
Netherlands | Present | Introduced | Original citation: Jonge de (1982) | ||||
Poland | Present | Introduced | |||||
Russia | Present | Introduced | |||||
Spain | Present | Present based on regional distribution. | |||||
-Canary Islands | Present | Tenerife | |||||
Sweden | Present | Introduced | |||||
Switzerland | Present | Introduced | |||||
United Kingdom | Present | Introduced | |||||
-Scotland | Present | Introduced | |||||
North America |
|||||||
Barbados | Present | Introduced | |||||
Bermuda | Present | Introduced | |||||
Canada | Present | Present based on regional distribution. | |||||
-Alberta | Present | Introduced | |||||
-British Columbia | Present | Introduced | |||||
-Manitoba | Present | Introduced | |||||
-New Brunswick | Present | Introduced | |||||
-Newfoundland and Labrador | Present | Introduced | |||||
-Nova Scotia | Present | Introduced | |||||
-Ontario | Present | Introduced | |||||
-Prince Edward Island | Present | Introduced | |||||
-Quebec | Present | Introduced | Original citation: Kevan and Vickery (1977, publ. 1978) | ||||
-Saskatchewan | Present | Introduced | |||||
Costa Rica | Present | Introduced | |||||
Mexico | Present | Introduced | |||||
Panama | Present | Introduced | |||||
Puerto Rico | Present | Introduced | |||||
United States | Present | Introduced | |||||
-Alabama | Present | Introduced | |||||
-Alaska | Present | Introduced | |||||
-Arizona | Present | Introduced | |||||
-Arkansas | Present | Introduced | |||||
-California | Present | Introduced | |||||
-Colorado | Present | Introduced | |||||
-Connecticut | Present | Introduced | |||||
-Delaware | Present | Introduced | |||||
-Florida | Present | Introduced | |||||
-Georgia | Present | Introduced | Original citation: Haines and Palmer (1956) | ||||
-Hawaii | Present | Introduced | |||||
-Idaho | Present | Introduced | |||||
-Illinois | Present | Introduced | |||||
-Indiana | Present | Introduced | Original citation: Runstrom and Bennett (1990) | ||||
-Kansas | Present | Introduced | |||||
-Kentucky | Present | Introduced | |||||
-Louisiana | Present | Introduced | |||||
-Maine | Present | Introduced | |||||
-Maryland | Present | Introduced | |||||
-Massachusetts | Present | Introduced | |||||
-Michigan | Present | Introduced | Original citation: International Commission Zoological Nomenclature on (1982) | ||||
-Minnesota | Present | Introduced | |||||
-Mississippi | Present | Introduced | |||||
-Missouri | Present | Introduced | Original citation: International Commission Zoological Nomenclature on (1982) | ||||
-Montana | Present | Introduced | |||||
-Nebraska | Present | Introduced | Original citation: Ballard et al. (1984) | ||||
-New Hampshire | Present | Introduced | |||||
-New Jersey | Present | Introduced | |||||
-New Mexico | Present | Introduced | Original citation: International Commission Zoological Nomenclature on (1982) | ||||
-New York | Present | Introduced | |||||
-North Carolina | Present | ||||||
-North Dakota | Present | Introduced | |||||
-Ohio | Present | Introduced | |||||
-Oklahoma | Present | Introduced | |||||
-Oregon | Present | Introduced | |||||
-Pennsylvania | Present | Introduced | |||||
-Rhode Island | Present | Introduced | |||||
-South Carolina | Present | Introduced | |||||
-South Dakota | Present | Introduced | |||||
-Texas | Present | Introduced | Houston | ||||
-Utah | Present | Introduced | |||||
-Vermont | Present | Introduced | |||||
-Virginia | Present | Introduced | |||||
-Washington | Present | Introduced | |||||
-West Virginia | Present | Introduced | |||||
-Wisconsin | Present | Introduced | |||||
-Wyoming | Present | Introduced | |||||
Oceania |
|||||||
Australia | Present | Introduced | |||||
-New South Wales | Present | Introduced | |||||
-Northern Territory | Present | Introduced | |||||
-South Australia | Present | Introduced | |||||
-Tasmania | Present | Introduced | |||||
-Victoria | Present | Introduced | |||||
Cook Islands | Present | Introduced | |||||
French Polynesia | Present | Introduced | |||||
New Zealand | Present | Introduced | |||||
Papua New Guinea | Present | Introduced | |||||
South America |
|||||||
Brazil | Present | Present based on regional distribution. | |||||
-Amazonas | Present | Introduced | |||||
Chile | Present | Introduced | Magallanes region | ||||
Ecuador | Present | Introduced | |||||
Uruguay | Present | Introduced |
History of Introduction and Spread
Top of pageB. germanica is thought to have originated from Ethiopia and Sudan, but is now the most widely distributed cockroach after being spread by humans and commerce (Hill, 2002). It is spread as far north as Canada and Scandinavia; it has also been reported in Alaska in heated buildings (Hill, 2002). B. germanica is susceptible to cold temperatures and therefore dependent upon humans or human activity and hence why it is only found in heated buildings in Alaska (Valles, 1996).
A survey carried out in 1989 in the UK, suggested an increase in the known ranges of B. germanica (and Blatta orientalis) with new vice-county records for Scotland (including the Western Isles), England and Wales (Alexander et al., 1991).
Risk of Introduction
Top of pageIt is likely that the distribution of B. germanica will increase and be introduced into new countries. This is a result of urbanisation and commerce providing the opportunity and favourable conditions encouraging an increase in the range of B. germanica (Sommer, 1974; Hill, 2002). For example, the structural features of a building can assist in the dispersal of cockroaches. In addition to this globalisation and increased trade between countries increases the likelihood of it spreading between countries.
Habitat
Top of pageB. germanica is unable to survive in locations away from humans or human activity (Valles, 1996). This pest is therefore found in hotels, residential areas, farm produce markets, catering establishments (Jia et al., 2011), swimming baths (Rivault, 1989), hospitals, shops, stores, restaurants, food manufactures’, nurseries, crèches (Engelbrecht and Buske, 1983) and grain stores (Stejskal et al., 2006). They are gregarious during their resting period and research by Ame et al. (2004) suggested that different strains are able to aggregate at the same site.
The major limiting factor for survival of B. germanica appears to be cold temperatures. They are unable to colonise inactive ships during cool temperatures and survival in northern climates is dependent on the presence of central heating installations (Valles, 1996). In contrast to this, Vater (1979) studied B. germanica found in a refrigerator in Germany where the temperature ranged from 7-12°C. The first to sixth larval instars were found to be mobile in this environment.
Habitat List
Top of pageCategory | Sub-Category | Habitat | Presence | Status |
---|---|---|---|---|
Other | Stored products | Principal habitat | Harmful (pest or invasive) | |
Terrestrial | Managed | Urban / peri-urban areas | Principal habitat | Harmful (pest or invasive) |
Terrestrial | Managed | Urban / peri-urban areas | Principal habitat | Natural |
Host Plants and Other Plants Affected
Top of pagePlant name | Family | Context | References |
---|---|---|---|
Oryza sativa (rice) | Poaceae | Unknown |
Biology and Ecology
Top of pageGenetics
Xiao et al. (2012) reported that the complete mtDNA nucleotide sequence of B. germanica is 15,584 bp.
Reproductive Biology
B. germanica has panoistic ovaries (Irles et al., 2013), meaning that the ovarian follicle is formed exclusively by one germinal cell (the oocyte) surrounded by a monolayer of follicular cells (the most basal ovarian type in insects) (Piulachs, 2013). B. germanica breeds continuously (Valles, 1996) and during a study under laboratory conditions females were shown to oviposit up to five oothecae during their lifetime (Aguilera et al., 1996). The egg case is approximately 8 mm long, 3 mm high and 2 mm wide, brown and purse-shaped and thirty to forty eggs are usually held in a typical egg case (Valles, 1996). The eggs are carried by the female in egg cases (ootheca) until just before egg hatch. The egg case protrudes from the posterior of the adult female and the nymphs often hatch from the case while the female is carrying it.
Typical field populations consist of 80% nymphs and 20% adults (Valles, 1996). B. germanica has a short lifecycle and under optimum conditions one female could, in theory, produce over 10 million females within one year and over 10 billion females in 11/12 years (Hill, 2002).
Longevity
On average, male B. germanica live for up to 130 days and females for 150 days (Hill, 2002). However, a study by Aguilera et al. (1996) found that under laboratory conditions mean development time of the six nymphal stages was 114.71 days at 29+/-1°C and 80.9% RH. The average longevity of the males (77.23 days) was lower than that of the females (98.40 days). Dambach and Goehlen (1999) showed that humidity affects survival times of nymphs when deprived of food and drinking water. The longevity was found to be inversely proportional to saturation deficiency.
Activity Patterns
B. germanica demonstrates aggregation behaviour, where individuals accumulate due to a mutual attraction (Sommer, 1974; Jeanson et al., 2005). The aggregation pheromone is both emitted and perceived using antennae. Various physiological and ecological factors determine the spatial-temporal patterns of aggregation (Sommer, 1974). At lower relative humidity grouping is denser than under higher humidity (Dambach and Goehlen, 1999).
In a survey of B. germanica in Yichun city, Jiangxi, China, a peak in activity was recorded from June to August (Wu et al., 2009). In South Korea, the peak densities of B. germanica occurred between May and September in hospitals (Lee, 1995).
When Stein and Haschemi (1994) studied dispersal and emigration of B. germanica in a rubbish tip in Germany, they reported that movement was influenced by the sun which resulted in a southward dispersal. Rivault (1989) studying the spatial distribution of B. germanica in a swimming bath in France, found it to be contiguous. Insects move from the centre to the periphery in a circular motion within an aggregate and vice versa, which is dependent on lifecycle stage. New larvae explore further afield to the border of the aggregate; considered as the spreading phase when they need to forage or find new shelters. Older larvae tend to gather in the middle of the aggregate and newly-moulted adults search for a sexual partner. The females remain in the shelters during maturation of the oothecae.
Durier and Rivault (2003) reported when familiar with their environment B. germanica does not follow edges, rather it exploits different parts of accessible surfaces within their range. When placed into a new environment they showed a tendency to follow edges.
Heating and food supply are said to be factors that influence the distribution and population of B. germanica in buildings (Tanaka et al., 1993) and male adults tend to seek new space more actively than female adults (Takahashi et al., 1998). Starvation increases the distance travelled, velocity and the proportion of time in motion of adult males and final instars, but not adult females (Barclay and Bennett, 1991).
Nutrition
B. germanica are omnivorous and eat items such as table scraps, pet food and book bindings (Valles, 1996). When three different diets of poultry feed, sugar and wheat flour and rusk were investigated for their effect on biological parameters of B. germanica, it was found that individuals which fed on poultry feed showed maximum hatching and male and female longevity (Khuhro et al., 2007). The minimum mean incubation period and minimum mean nymphal development period was also recorded on a poultry diet.
Associations
Blattabacterium are mutualistic endosymbiont bacteria which inhabit specialised cells in the body fat of B. germanica and all species of cockroach except those in the genus Nocticola (Bandi et al., 1994).
Environmental Requirements
B. germanica is unable to survive in locations away from humans or human activity, but the major limiting factor for survival appears to be cold temperatures (Valles, 1996). It is reported that this species is unable to colonise inactive ships during cool temperatures. In northern climates survival of B. germanica is dependent on the presence of central heating installations (Valles, 1996). Therefore this species is often found in temperate and tropical environments. Due to cold temperatures, B. germanica is found at elevations of 1,200 m and rarely found above 2000 m (Encyclopedia of Life, 2015).
Natural enemies
Top of pageNatural enemy | Type | Life stages | Specificity | References | Biological control in | Biological control on |
---|---|---|---|---|---|---|
Ampulex compressa | Predator | Menke and Yustiz, 1983 | ||||
Aprostocetus hagenowii | Parasite | Eggs | Cook Islands Biodiversity Database, 2016 | Yes | ||
Blatticola blattae | Predator | Rizvi and Jairajpuri, 2002 | ||||
Cephalobellus ovumglutinosus | Predator | Waerebeke DVan, 1978 | ||||
Herpomyces ectobiae | Pathogen | Kesel A de, 2001 | ||||
Metarhizium anisopliae | Pathogen | Quesada-Moraga et al., 2004 | ||||
Neoaplectana carpocapsae | Predator | Zukowski, 1984 | ||||
Ripidius pectinicornis | Predator/parasite | Falin, 2001 | ||||
Steinernema carpocapsae | Predator | Manweiler et al., 1993 |
Notes on Natural Enemies
Top of pageThe natural enemies of B. germanica include nematodes (Blatticola blattae and Cephalobellus ovumglutinosus) (Waerebeke, 1978; Rizvi and Jairajpuri, 2002), parasitoids (Ripidius pectinicornis) (Falinm 2001), predators (Ampulex compressa) (Menke and Yustiz, 1983) and parasitic fungi (Herpomyces ectobiae) (Kesel, 2001).
The parasitic wasp Aprostocetus hagenowii lays its eggs in the egg cases of B. germanica and have been used as a biocontrol agent (Cook Islands Biodiversity Database, 2016). The fungus Metarhizium anisopliae has been studied under laboratory conditions as a potential biocontrol agent (Quesada-Moraga et al., 2004). Other reports suggest that entomophilic nematodes such as Neoaplectana carpocapsae and Steinernema carpocapsae could provide control of B. germanica (Zukowski, 1984; Manweiler et al., 1993).
Means of Movement and Dispersal
Top of pageNatural Dispersal
B. germanica will disperse naturally to new locations. Their dispersal is influenced by environmental conditions and starvation (Barclay and Bennet, 1991).
Accidental Introduction
The spread of B. germanica into new countries is likely to have occurred accidentally through the globalisation and increased trade between countries.
Pathway Causes
Top of pageCause | Notes | Long Distance | Local | References |
---|---|---|---|---|
Food | Yes | Yes | Angeli Adegli, 1979 | |
Garden waste disposal | Yes | Valles, 1996 | ||
Hitchhiker | Yes | Yes | Rockman, 1992 | |
Live food or feed trade | Yes | Yes | Valles, 1996 | |
Military movements | Yes | Wright and McDaniel, 1973 | ||
People sharing resources | Yes | Sommer, 1974 |
Pathway Vectors
Top of pageVector | Notes | Long Distance | Local | References |
---|---|---|---|---|
Consumables | Yes | Yes | Mouchtouri et al., 2008 | |
Containers and packaging - wood | Yes | Yes | Nigam et al., 1969 | |
Debris and waste associated with human activities | Yes | Valles, 1996 | ||
Livestock | Yes | Booth et al., 2011 | ||
Luggage | Yes | Yes | Schulze, 1977 | |
Ship structures above the water line | Yes | Mouchtouri et al., 2008 |
Economic Impact
Top of pageB. germanica is a serious pest of urban and rural areas and although it has been the subject of many research projects due to its pest status, it is difficult to put a price on its economic impact. B. germanica is resistant to pesticides (Briggs et al., 1984) and this poses obvious costs associated with research for alternative control measures and application of available chemicals. Although studies have shown Integrated Pest Management (IPM) methods to be more effective at controlling cockroach infestations, they are also significantly more costly than conventional methods (Miller and Meek, 2004; Shahraki et al., 2011). A study by Shahraki et al. (2011) found that the cost for IPM could be up to 363.2% more than conventional methods. A survey of residents of public housing in Virginia, USA found that on average they spent between 0.4 and 1.0% of their annual income on pesticides to supplement the pest control programme provided by the housing authorities (Wood et al., 1981).
Environmental Impact
Top of pageIn Japan, B. germanica has been shown to be an intermediate host of Protospirura muris, a parasitic nematode of Rattus norvegicus (brown rat) in both the wild and under laboratory conditions (Shogaki et al., 1972). The impact of this however is unknown.
Social Impact
Top of pageB. germanica regularly inhabits areas of food preparation and storage; thus food left out overnight and food preparation surfaces are likely to become contaminated during the course of foraging (Brenner, 1992). This could lead to digestive upsets of consumers due to the ingestion of insect excreta, indigestible cast skins or moulds developing (Angeli, 1979; Gore and Schal, 2004). In a study of food-borne pathogens in Ethiopia, Tachbele et al. (2006) identified a species of Salmonella, Shigella flexneri, Escherichia coli, Staphylococcus aureus and Bacillus cereus from B. germanica. This indicates that B. germanica may be a possible reservoir and potential vector of some food-borne pathogens. In addition to this they are carriers of human pathogens, which can be problematic in hospitals. A study of bacterial loads of B. germanica in hospitals in Alergia found a large number of bacteria present including species of Pseudomonas, Enterobacter and Citrobacter.B. germanica has also been shown to be a possible vector of Klebsiella pneumonia (Cotton at al., 2000).
B. germanica is known to cause sensitisation of people with asthma around the world (Rosenstreich et al., 1997).
Other impacts to humans caused by infestations of B. germanica include anxiety caused by the potential health hazards and the repulsive nature of the species (Davies and Petranovic, 1986).
Risk and Impact Factors
Top of page- Invasive in its native range
- Proved invasive outside its native range
- Abundant in its native range
- Highly adaptable to different environments
- Tolerant of shade
- Capable of securing and ingesting a wide range of food
- Highly mobile locally
- Benefits from human association (i.e. it is a human commensal)
- Fast growing
- Has high reproductive potential
- Gregarious
- Negatively impacts agriculture
- Negatively impacts human health
- Negatively impacts livelihoods
- Reduced amenity values
- Damages animal/plant products
- Negatively impacts trade/international relations
- Causes allergic responses
- Pest and disease transmission
- Herbivory/grazing/browsing
- Rapid growth
- Highly likely to be transported internationally accidentally
- Difficult to identify/detect in the field
- Difficult/costly to control
Detection and Inspection
Top of pageThe presence of B. germanica in food stuffs can be detected by visual inspection for filth and extraneous material using microscopy; however, this can be time-consuming and inaccurate. Jones et al. (2013) sequenced DNA from common pests, including B. germanica and generated DNA barcodes for each one. The authors suggested that this could be a powerful tool to aid the mission of the U.S. Food, Drug and Cosmetic Act, which is to prohibit the distribution of adulterated food.
Similarities to Other Species/Conditions
Top of pageB. germanica, B. asahinai and B. vaga are morphologically similar species of cockroach, therefore there has been much research carried out into different ways of reliably identifying them. The tenth tergite (T10) of male B. asahinai is narrower than that of B. germanica; a trait that is intermediate in F1 hybrids (Ross, 1992). The oothecae of B. asahinai are also smaller than those of B. germanica; first instars of B. asahinai are smaller and the number of the antennal annuli is less in B. asahinai. In addition, the abdominal margins of late-instar nymphs and the spots on each side of the mid-dorsal line are colourless in B. asahinai, as opposed to lightly pigmented in B. germanica (Ross and Mullins, 1988).
Carlson (1988) reported on the use of hydrocarbons for identifying these species and reported that the hydrocarbon components of the three species were consistently different, independent of geography, sex or age.
Prevention and Control
Top of pageDue to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
Prevention and Control
Public Awareness
Infestations of B. germanica are exacerbated by poor hygiene, therefore it is important to create public awareness on how to prevent and control the spread of this public health pest. Shahraki et al. (2010) studied the efficacy of sanitation and sanitary factors against B. germanica infestations and the effectiveness of educational programmes on sanitation in Iran. Pamphlets, posters and lectures were used to describe the importance of sanitation and the comprehensive education programme led to a reduction in infestations.
Control
Cultural Control and Sanitary Measures
B. germanica live where humans and human activity is, feeding on scraps of food (Valles, 1996) and their presence is associated with poor hygiene. However they can also occur in the cleanest and most hygiene-conscious dairies and cheese factories (Rockman, 1992). By eliminating food and water sources and clutter, the risk of encouraging new infestations and population increase is decreased (Valles, 1996). Sealing cracks and crevices can be effective in reducing harbourage space and population size (Valles, 1996) because B. germanica are smaller than most other cockroaches, with the ability to conceal themselves in many places inaccessible to larger species (Jacobs, 2013).
Beccaloni (1991) reported that freshly cut plants of Tagetes minuta placed into the wooden walls and thatched roofs of dwellings in Papua New Guinea repelled B. germanica.Tabaru and Mochizuki (2005) reported that B. germanica was repelled by ethanol extracts of some herbs under laboratory conditions. Herbs showing the most repellent effect were Anethum graveolens (dill), Apium graveolens (celery), Carum carvi (caraway), Cuminum cymimum (cumin), Coriandrum sativum (coriander), Cinamomum zeylanicum (cinnamon), Myristica fragrans (mace) and Capsicum annuum (chili pepper).
Physical/Mechanical Control
Sticky traps can be used to monitor and/or reduce population size of B. germanica (Valles, 1996); however, Ballard and Gold (1983) reported that sticky traps did not reduce populations in Nebraska, USA. Ballard and Gold (1983) evaluated two different types of traps for the control of B. germanica: tent-shaped sticky traps and electrified traps, in Macy, Nebraska, USA. It was found that the sticky traps did not reduce populations, but the electrified traps caused a 76% reduction in catch after two months of trapping.
Biological Control
Pathogens and in particular fungi, appear to be the most promising group for the biological control of B. germanica, according to a review of different methods published by Suiter (1997). Ren et al. (2005) reported successful infection rates of B. germanica using Metarhizium anisopliae under laboratory conditions. Infected B. germanica were erratic in their movements and hyphae of the fungi were found in most parts of the body 4-5 days post-infection. Other reported symptoms of infection by M. anisopliae are a reduction in the mean number of oothecae laid by females, oothecal production, hatchability and nymphal production (Quesada-Moraga et al., 2004).
Other reports suggest that entomophilic nematodes such as Neoaplectana carpocapsae and Steinernema carpocapsae could provide acceptable control of B. germanica (Zukowski, 1984; Manweiler et al., 1993). The parasitic wasp Aprostocetus hagenowii lays its eggs in the egg cases of B. germanica and other species of cockroach and have been used as a biocontrol agent (Cook Islands Biodiversity Database, 2016).
Chemical Control
Due to the speed at which B. germanica reproduces and thus the rapidity of developing resistance to chemicals, much of the early work on chemical control is out of date.
Resistance of B. germanica to insecticides poses a serious concern; they have been shown to be resistant to organophosphorous insecticides (Ge at al., 2009) and tetramethrin (Deng et al., 2013). The extent to which they are resistant has been studied in the Chaoyang District, Beijing, China and it was found that the highest resistance was observed for organophosphorous insecticides. Resistance differed between the eight sites sampled, indicating that control methods should be modified accordingly (Ge et al., 2009).
In a review of B. germanica, Jacobs (2013) indicated that the use of baits containing hydramethylnon, fipronil, sulfluramid, boric acid or abamectin is a successful method of chemical control. Also insecticidal dusts such as boric acid, silica aerogel and diatomaceous earth can provide additional control. Populations of B. germanica were observed to rapidly evolve to become repelled by the glucose present in bait traps rather than attracted to it, a process known as bait aversion (Silverman and Bieman, 1993). This highlights the ability of B. germanica to rapidly change in response to environmental pressures.
Jacobs (2013) indicated that residual insecticidal sprays or aerosol foggers are of little value and may actually disperse B. germanica, hampering control. Bacterial insecticides based on Bacillus thuringiensis were evaluated against B. germanica (Zukowski, 1994). Thuridan (based on B. thuringiensis subsp. thuringiensis) was reported as the most effective and males were more sensitive than females.
IPM
Alternative methods for controlling cockroaches have been the focus of numerous studies (Miller and Meek, 2004; Shahraki et al., 2011), particularly with the advent of resistance to chemicals used in conventional control methods (Nasirian et al., 2006) and the fact that cockroaches live in close proximity to humans. Methods used in IPM include the provision of education using pamphlets and lectures and hydramethylnon gel baits (Shahraki et al., 2011), vacuuming and insect growth regulator devices (Miller and Meek, 2004).
Monitoring and Surveillance
It is important to survey populations by setting traps before applying control measures to ascertain the level of infestation (Jacobs, 2013). Sticky traps can be used to both monitor population sizes (Valles, 1996). Jacobs (2013) suggested that one week of trapping at approximately ten or more trapping sites usually provides sufficient information for effective control.
Passenger ships provide a suitable environment for populations of B. germanica and a Hazard Analysis Critical Control Point (HACCP) system is employed on vessels to ensure food safety is adhered to. Mouchtouri et al. (2008) reported a negative association between infestations and the application of HACCP on board ferries.
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Distribution References
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CABI, Undated b. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
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Ge T, Ji Z, Yuan S, Tang L, Liu Y, 2010. Surveillance of disease vectors in Heilongjiang Province from 2006 to 2008. In: Chinese Journal of Vector Biology and Control, 21 (2) 143-145.
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Jia Y, Zhang S, Ning J, Jiang H, Liu X, 2011. Cockroach dynamics in Lanzhou from 2006 to 2010. In: Chinese Journal of Vector Biology and Control, 22 (6) 601-602.
Klobucar A, Benic N, Krajcar D, 2012. Proceedings, 24th Scientific and Educational Seminar, DDD and ZUPP 2012, Disinfection, Disinsection, Deratization and Protection of Stored Agricultural Products, Split, Croatia, 20-23 March, 2012., [ed. by Zbornik Radova]. 165-174.
Landcare Research, 2016. German cockroach., New Zealand: http://www.landcareresearch.co.nz/resources/identification/animals/bug-id/alphabetic-list-of-bugs/german-cockroach
Martin K, Jensen V, 1993. Proceedings of the 1st International Conference on Urban Pests., [ed. by Wildey KB, Robinson WmH]. 135-139.
Rafael JA, Silva NMda, Dias RMNS, 2008. Syanthropic cockroaches (Insecta, Blattaria) from Manaus, Amazonas, Brazil. In: Acta Amazonica, 38 (1) 173-178.
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Wu H, Long H, Long Q, He Q, Cheng X, Gao H, 2009. Investigation on cockroach population distribution and the infestation situation on Yichun city in 2008. In: Chinese Journal of Vector Biology and Control, 20 (6) 593-594.
Zhou Z, Zhuang H, Wang Y, Fang Q, Cao L, Lin B, 2012. Analysis of surveillance results of main vectors in Shenzhen Universiade venues from 2010 to 2011. In: Chinese Journal of Vector Biology and Control, 23 (6) 564-566.
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