View source for Biology:German cockroach

{{Short description|Species of cockroach}}
{{Speciesbox
| name = German cockroach
| image =
| genus = Blattella
| species = germanica
| authority = [[Biography:Carl Linnaeus|Linnaeus]], [[Biology:12th edition of Systema Naturae|1767]]
| display_parents = 4
}}

The '''German cockroach''' ('''''Blattella germanica'''''), colloquially known as the '''croton bug''', is a [[Biology:Species|species]] of small [[Biology:Cockroach|cockroach]], typically about {{convert|1.1| to|1.6|cm|in|abbr=on}}<ref name="isbn1-86872-713-0">{{cite book |author1=Alan Weaving |author2=Mike Picker |author3=Griffiths, Charles Llewellyn |title=Field Guide to Insects of South Africa |publisher=New Holland Publishers, Ltd |year=2003 |isbn=1-86872-713-0 }}</ref><ref name="JackmanDrees1998">{{cite book|author1=John A. Jackman|author2=Bastiaan M. Drees|title=A Field Guide to Common Texas Insects|url=https://books.google.com/books?id=sTH5AQAAQBAJ&pg=PA28|date=1 March 1998|publisher=Taylor Trade Publishing|isbn=978-1-4616-2291-8|pages=28–}}</ref> long. In color it varies from tan to almost black, and it has two dark, roughly parallel, streaks on the [[Biology:Prothorax|pronotum]] running [[Biology:Anatomical terms of location#Anterior and posterior 2|anteroposteriorly]] from behind the head to the base of the wings. Although ''B. germanica'' has wings, it can barely fly, although it may glide when disturbed.<ref name="BellRoth2007">{{cite book|author1=William J. Bell|author2=Louis M. Roth|author3=Christine A. Nalepa|title=Cockroaches: Ecology, Behavior, and Natural History|url=https://books.google.com/books?id=R7eVRP08kasC&pg=PA33|date=26 June 2007|publisher=JHU Press|isbn=978-0-8018-8616-4|pages=33–}}</ref> Of the few species of cockroach that are domestic pests, it probably is the most widely troublesome example.<ref name="BonnefoyKampen2008">{{cite book|author1=Xavier Bonnefoy|author2=Helge Kampen|author3=Kevin Sweeney|title=Public Health Significance of Urban Pests|url=https://books.google.com/books?id=uruktyYMGpAC&pg=PT35|year=2008|publisher=World Health Organization|isbn=978-92-890-7188-8|pages=35–}}</ref> It is very closely related to the [[Biology:Blattella asahinai|Asian cockroach]], and to the casual observer, the two appear nearly identical and may be mistaken for each other. However, the Asian cockroach is attracted to light and can fly like a moth, while the German cockroach cannot.

== Biology and pest status ==
The German cockroach occurs widely in human buildings, but is particularly associated with [[Finance:Restaurant|restaurant]]s, [[Engineering:Food processing|food processing]] facilities, [[Social:Hotel|hotel]]s, and institutional establishments such as nursing homes and hospitals.<ref>{{cite journal |last1=Menasria |first1=Taha |last2=Moussa |first2=Fatima |last3=El-Hamza |first3=Souad |last4=Tine |first4=Samir |last5=Megri |first5=Rochdi |last6=Chenchouni |first6=Haroun |title=Bacterial load of German cockroach (Blattella germanica) found in hospital environment |journal=Pathogens and Global Health |date=April 2014 |volume=108 |issue=3 |pages=141–147 |doi=10.1179/2047773214Y.0000000136 |pmid=24766338 |pmc=4083176 |language=English}}</ref> They can survive outside as well, though they are not commonly found in the wild.<ref name="Mallis1982">{{cite book |last1=Mallis |first1=Arnold |title=Handbook of Pest Control: The Behavior, Life History, and Control of Household Pests |date=1982 |publisher=Franzak & Foster |isbn=978-0-942588-00-2 |page=114 |language=English}}</ref> In cold climates, they occur only near human dwellings, because they cannot survive severe cold. However, German cockroaches have been found as [[Biology:Inquiline|inquiline]]s ("tenants") of human buildings as far north as [[Place:Alert, Nunavut|Alert, Nunavut]].<ref>{{Cite web |url=https://www.pensoft.net/book/6332/the-insects-and-arachnids-of-canada-part-14 |title=The insects and arachnids of Canada, part 14, The Grasshoppers, Crickets, and related insects of Canada and adjacent region |access-date=2018-01-15 |archive-date=2015-09-24 |archive-url=https://web.archive.org/web/20150924091300/http://www.pensoft.net/book/6332/the-insects-and-arachnids-of-canada-part-14 |url-status=dead }}</ref> Similarly, they have been found as far south as southern [[Place:Patagonia|Patagonia]].<ref>Faúndez, E. I. & M. A. Carvajal. 2011. Blattella germanica (Linnaeus, 1767) (Insecta: Blattaria) en la Región de Magallanes. Boletín de Biodiversidad de Chile, 5: 50-55.</ref>

Previously thought to be a native of Europe, the German cockroach later was considered to have emerged from the region of Ethiopia in Northeast Africa,<ref>{{cite book|last1=Cory|first1=EN|last2=McConnell|first2=HS|title=Bulletin No. 8: Insects and Rodents Injurious to Stored Products|url=https://books.google.com/books?id=qcU2AQAAIAAJ&pg=PA135|year=1917|publisher=Maryland State College of Agriculture Extension Service|location=College Park, Maryland|page=135}}</ref><ref name="Hill2002">{{cite book|last=Hill|first=Dennis S. |title=Pests of Stored Foodstuffs and their Control|url=https://books.google.com/books?id=r6j1oFOdewwC&pg=PA146|date=30 September 2002|publisher=Springer|isbn=978-1-4020-0735-4|pages=145–146}}</ref> but more recent evidence suggests that it actually originated in Southeast Asia.<ref name="BonnefoyKampen2008" /><ref name="EatonKaufman2007">{{cite book|last1=Eaton|first1=Eric R. |last2=Kaufman|first2=Kenn |title=Kaufman Field Guide to Insects of North America|url=https://books.google.com/books?id=aWVi0IF_jcQC&pg=PA62|year=2007|publisher=Houghton Mifflin Harcourt|isbn=978-0-618-15310-7|page=62}}</ref> Whatever the truth of the matter, the cockroach's sensitivity to cold might reflect its origin from such warm climates, and its spread as a domiciliary pest since ancient times has resulted from incidental human transport and shelter. The species now is [[Biology:Cosmopolitan distribution|cosmopolitan]] in distribution, occurring as a household pest on all continents except Antarctica, and on many major islands, as well. It accordingly has been given various names in the cultures of many regions.

Though [[Biology:Nocturnality|nocturnal]], the German cockroach occasionally appears by day, especially if the population is crowded or has been disturbed. However, sightings are most frequent in the evening, when someone suddenly brings a light into a room deserted after dark, such as a kitchen where they have been scavenging.<ref name="MullenDurden2002">{{cite book|author1=Gary R. Mullen|author2=Lance A. Durden|title=Medical and Veterinary Entomology|url=https://books.google.com/books?id=6R1v9o-uaI4C&pg=PA33|date=27 September 2002|publisher=Academic Press|isbn=978-0-08-053607-1|pages=33–}}</ref> When excited or frightened, the species emits an unpleasant odor.

== Diet ==
German cockroaches are omnivorous [[Earth:Scavenger|scavenger]]s. They are attracted particularly to meats, [[Chemistry:Starch|starch]]es, sugars, and fatty foods. Where a shortage of foodstuff exists, they may eat household items such as [[Chemistry:Soap|soap]], glue, and [[Medicine:Toothpaste|toothpaste]]. In famine conditions, they turn cannibalistic, chewing at each other's wings and legs.<ref name="CaliforniaWisconsin1994">{{cite book|first1=Michael K. |last1=Rust |first2= John M. |last2=Owens |first3=Donald A. |last3=Reierson |title=Understanding and Controlling the German Cockroach|url=https://books.google.com/books?id=4j8n8hIBEa0C&pg=PA388|date=30 November 1994|publisher=Oxford University Press|isbn=978-0-19-534508-7|pages=388–}}</ref> The German cockroach is an [[Biology:Host#Types of hosts|intermediate host]] of the [[Biology:Acanthocephala|Acanthocephala]]n parasite ''[[Biology:Moniliformis kalahariensis|Moniliformis kalahariensis]]''.<ref name="Amin2014">{{cite journal|doi=10.1654/4664.1|title=Description of ''Moniliformis'' kalahariensis(Acanthocephala: Moniliformidae) from the South African Hedgehog,Atelerix frontalis(Erinaceidae) in South Africa|year=2014|last1=Amin|first1=Omar M.|last2=Heckmann|first2=Richard A.|last3=Halajian|first3=Ali|last4=El-Naggar|first4=Atif|last5=Tavakol|first5=Sareh|journal=Comparative Parasitology|volume=81|pages=33–43}}</ref>

== Reproduction ==
The German cockroach reproduces faster than any other residential cockroach,<ref name="Ebeling">{{cite web
 |last=Ebeling
 |first=Walter
 |title=Urban entomology
 |url=http://www.precisepestcontrol.com/learn/cockroaches/
 |archive-url=https://archive.today/20130717145436/http://www.precisepestcontrol.com/learn/cockroaches/
 |url-status=dead
 |archive-date=17 July 2013
 |access-date=17 July 2013
 }}</ref> growing from egg to reproductive adult in roughly 50 – 60 days under ideal conditions.<ref>http://museumpests.net/wp-content/uploads/2014/03/German-Cockroach.pdf Museumpests.net Accessed July 15, 2015}</ref>  Once fertilized, a female German cockroach develops an [[Biology:Ootheca|ootheca]] in her abdomen. The abdomen swells as her eggs develop,  until the translucent tip of the ootheca begins to protrude from the end of her abdomen, and by that time the eggs inside are fully sized, about 1/4 inch long with 16 segments.  The ootheca, at first translucent, soon turns white and then within a few hours it turns pink, progressively darkening until, some 48 hours later, it attains the dark red-brown of the shell of a chestnut.  The ootheca has a keel-like ridge along the line where the young emerge, and curls slightly towards that edge as it completes its maturation.  A small percentage of the nymphs may hatch while the ootheca is still attached to the female, but the majority emerge some 24 hours after it has detached from the female's body.  The newly hatched 3-mm-long black nymphs then progress through six or seven [[Biology:Instar|instar]]s before becoming sexually mature, but [[Biology:Ecdysis|ecdysis]] is such a hazardous process that nearly half the nymphs die of natural causes before reaching adulthood.  Molted skins and dead nymphs are soon eaten by living nymphs present at the time of molting.<ref name="Ebeling" />

== Pest control ==
The German cockroach is very successful at establishing an [[Biology:Ecological niche|ecological niche]] in buildings, and is resilient in the face of many pest-control measures. Reasons include:
* lack of natural predators in a human habitat
* prolific reproduction
* short reproductive cycle
* the ability to hide in very small refuges
* sexual maturity attained within several weeks, and
* adaptation and resistance to some chemical pesticides<ref>{{Cite journal|last1=Fardisi|first1=Mahsa|last2=Gondhalekar|first2=Ameya D.|last3=Ashbrook|first3=Aaron R.|last4=Scharf|first4=Michael E.|date=2019-06-05|title=Rapid evolutionary responses to insecticide resistance management interventions by the German cockroach ( Blattella germanica L.)|journal=Scientific Reports|language=en|volume=9|issue=1|page=8292|doi=10.1038/s41598-019-44296-y|issn=2045-2322|pmc=6549143|pmid=31165746|bibcode=2019NatSR...9.8292F}}</ref> 

The German cockroach is resistant to 42 active ingredients from most major groups of synthetic insecticides such as organochlorides, organophosphates, carbamates, synthetic pyrethroids, neonicotinoids, oxadiazines, and phenyl pyrazoles.<ref>{{cite journal |last1=Zhu |first1=F |last2=Lavine |first2=L |last3=O'Neal |first3=S |last4=Lavine |first4=M |last5=Foss |first5=C |last6=Walsh |first6=D |title=Insecticide Resistance and Management Strategies in Urban Ecosystems. |journal=Insects |date=6 January 2016 |volume=7 |issue=1 |page=2 |doi=10.3390/insects7010002 |pmid=26751480 |doi-access=free }}</ref><ref>{{cite journal |last1=Tang |first1=Qian |last2=Bourguignon |first2=Thomas |last3=Willenmse |first3=Luc |last4=De Coninck |first4=Eliane |last5=Evans |first5=Theodore |title=Global spread of the German cockroach, Blattella germanica |journal=Biological Invasions |date=1 March 2019 |volume=21 |issue=3 |pages=693–707 |doi=10.1007/s10530-018-1865-2 |bibcode=2019BiInv..21..693T |s2cid=254284641 |url=https://doi.org/10.1007/s10530-018-1865-2 |language=en |issn=1573-1464}}</ref>  
German cockroach resistance was first observed with chlordane in 1952. <ref>{{cite journal |last1=Heal |first1=Ralph E. |last2=Nash |first2=Kenneth B. |last3=Williams |first3=Michele |title=An Insecticide-Resistant Strain of the German Cockroach from Corpus Christi, Texas |journal=Journal of Economic Entomology |date=1 April 1953 |volume=46 |issue=2 |pages=385–386 |doi=10.1093/jee/46.2.385a}}</ref><ref>{{cite journal |last1=Tang |first1=Qian |last2=Bourguignon |first2=Thomas |last3=Willenmse |first3=Luc |last4=De Coninck |first4=Eliane |last5=Evans |first5=Theodore |title=Global spread of the German cockroach, Blattella germanica |journal=Biological Invasions |date=1 March 2019 |volume=21 |issue=3 |pages=693–707 |doi=10.1007/s10530-018-1865-2 |bibcode=2019BiInv..21..693T |s2cid=254284641 |url=https://doi.org/10.1007/s10530-018-1865-2 |language=en |issn=1573-1464}}</ref>

German cockroaches are thigmotactic, meaning they prefer confined spaces, and they are small compared to other pest species, so they can hide within small cracks and crevices that are easy to overlook, thereby evading humans and their eradication efforts. Conversely, the seasoned pest controller is alert for cracks and crevices where it is likely to be profitable to place baits or spray surfaces.

To be effective, control measures must be comprehensive, sustained, and systematic; survival of just a few eggs is quite enough to regenerate a nearly exterminated pest population within a few generations, and recolonization from surrounding populations often is very rapid, too.<ref name="CaliforniaWisconsin1994" />

[[File:Blatella germanica cdc.jpg|thumb|right|200px|Female German cockroach with ootheca]]Another problem in controlling German cockroaches is the nature of their population behavior. Though they are not social and practice no organized maternal care, females carry oothecae of 18-50 eggs (average about 32) during incubation until just before hatching, instead of dropping them as most other species of cockroaches do. This protects the eggs from certain classes of predation. Then, after hatching, nymphs largely survive by consuming excretions and molts from adults, thereby establishing their own internal microbial populations and avoiding contact with most insecticidal surface treatments and baits.  One effective control is insect growth regulators (hydroprene, methoprene, etc.), which act by preventing molting, thus prevent maturation of the various instars. Caulking baseboards and around pipes may prevent the travel of adults from one apartment to another within a building.

As an [[Biology:Adaptation|adaptive]] consequence of pest control by poisoned sugar baits, a strain of German cockroaches has emerged that reacts to glucose as distastefully bitter. They refuse to eat sweetened baits, which presents an obstacle to their control, given that baits are an economical and effective means of control.<ref>{{Cite journal |last1=Wada-Katsumata |first1=A. |last2=Silverman |first2=J. |last3=Schal |first3=C. |year=2013 |title=Changes in Taste Neurons Support the Emergence of an Adaptive Behavior in Cockroaches |journal=Science |volume=340 |issue=6135 |pages=972–5 |bibcode=2013Sci...340..972W |doi=10.1126/science.1234854 |pmid=23704571 |s2cid=30957375}} ([https://www.bbc.co.uk/news/science-environment-22611143 summary at BBC News])</ref>

Once a pest control professional has completed the treatment, it’s still important for the homeowner to follow certain steps to ensure the effectiveness of the service. There are three main points to keep in mind after a pest control treatment: letting the treatment work, avoiding cleaning treated areas for four weeks, and maintaining general housekeeping.

==Comparison of three common cockroaches==
{| class="wikitable"
|'''Roach''' || German cockroach || [[Biology:Oriental cockroach|Oriental cockroach]] || [[Biology:American cockroach|American cockroach]]
|-
|'''Size''' || {{convert|13|–|16|mm|in|abbr=on}}<ref name="Robinson2005"/> || {{convert|18|–|29|mm|in|abbr=on}}<ref name="Robinson2005">{{cite book|last=Robinson|first=William H.|title=Urban Insects and Arachnids: A Handbook of Urban Entomology|url=https://books.google.com/books?id=aluUgDVYJ8wC&pg=PA51|date=14 April 2005|publisher=Cambridge University Press|isbn=978-0-521-81253-5|pages=45–46, 51–54}}</ref> || {{convert|29|–|53|mm|in|abbr=on}}<ref name="Robinson2005"/>
|-
|'''Preferred temperature''' || {{convert|15|–|35|C|abbr=on}}<ref name="Bassett2012">{{cite book|last=Bassett|first=W.H. |title=Clay's Handbook of Environmental Health|url=https://books.google.com/books?id=ck2qO5Gyj40C&pg=PT317|date=12 October 2012|publisher=Routledge|isbn=978-1-135-81033-7|page=317}}</ref> || {{convert|20|–|30|C|abbr=on}}<ref name="Robinson2005"/> || {{convert|20|–|29|C|abbr=on}}<ref name="Bassett2012"/>
|-
|'''Nymphal development'''<ref group="note">Dependent on several factors, including temperature (significantly), sex, and nutrition.</ref> || 54–215 days<br/>(at {{convert|24|–|35|C|abbr=on}})<ref name="Robinson2005"/> || 164–542 days<br/>(at {{convert|22|–|30|C|abbr=on}})<ref name="Robinson2005"/> || 150–360 days<br/>(at {{convert|25|–|30|C|abbr=on}})<ref name="Robinson2005"/>
|-
|'''Lifespan''' || Around 200 days<ref name="Robinson2005"/> || 35–190 days<ref name="Robinson2005"/> || 90–706 days<ref name="Robinson2005"/>
|-
|'''Able to fly?''' || Uncommon<ref group="note">German cockroaches can glide, especially males, but powered flight is uncommon.</ref><ref name="Robinson2005"/> || No<ref name="Robinson2005"/> || Yes<ref group="note">American cockroaches can fly short distances, usually starting from high places, but real flight is uncommon, despite popular belief.</ref><ref name="Robinson2005"/>
|}

== Genome ==
The genome of the German cockroach was published in February 2018 in ''Nature Ecology and Evolution''.<ref name="Harrison2018">{{cite journal|last1=Harrison|first1=Mark C.|last2=Jongepier|first2=Evelien|last3=Robertson|first3=Hugh M.|last4=Arning|first4=Nicolas|last5=Bitard-Feildel|first5=Tristan|last6=Chao|first6=Hsu|last7=Childers|first7=Christopher P.|last8=Dinh|first8=Huyen|last9=Doddapaneni|first9=Harshavardhan|last10=Dugan|first10=Shannon|last11=Gowin|first11=Johannes|last12=Greiner|first12=Carolin|last13=Han|first13=Yi|last14=Hu|first14=Haofu|last15=Hughes|first15=Daniel S. T.|last16=Huylmans|first16=Ann-Kathrin|last17=Kemena|first17=Carsten|last18=Kremer|first18=Lukas P. M.|last19=Lee|first19=Sandra L.|last20=Lopez-Ezquerra|first20=Alberto|last21=Mallet|first21=Ludovic|last22=Monroy-Kuhn|first22=Jose M.|last23=Moser|first23=Annabell|last24=Murali|first24=Shwetha C.|last25=Muzny|first25=Donna M.|last26=Otani|first26=Saria|last27=Piulachs|first27=Maria-Dolors|last28=Poelchau|first28=Monica|last29=Qu|first29=Jiaxin|last30=Schaub|first30=Florentine|last31=Wada-Katsumata|first31=Ayako|last32=Worley|first32=Kim C.|last33=Xie|first33=Qiaolin|last34=Ylla|first34=Guillem|last35=Poulsen|first35=Michael|last36=Gibbs|first36=Richard A.|last37=Schal|first37=Coby|last38=Richards|first38=Stephen|last39=Belles|first39=Xavier|last40=Korb|first40=Judith|last41=Bornberg-Bauer|first41=Erich|title=Hemimetabolous genomes reveal molecular basis of termite eusociality|journal=Nature Ecology & Evolution|date=2018|volume=2|issue=3|pages=557–566|doi=10.1038/s41559-017-0459-1|pmid=29403074|pmc=6482461|bibcode=2018NatEE...2..557H }}</ref> The relatively large genome (2.0 Gb) harbours a very high number of proteins, of which most notably one group of chemoreceptors, called the ionotropic receptors, is particularly numerous. These chemoreceptors possibly allow the German cockroach to detect a broad range of chemical cues from toxins, food, pathogens, and pheromones.<ref name="Harrison2018" />
<!-- ==See also==
* [[Biology:Cockroach|Cockroach]]
* [[Biology:Oriental cockroach|Oriental cockroach]]
 -->

== See also ==
* [[Chemistry:Blattellaquinone|Blattellaquinone]], a sex pheromone of the German cockroach

== Notes ==
{{reflist|group=note}}

== References ==
{{Reflist|2}}

== External links ==
{{Commons|Blattella germanica}}
* [http://entomology.ifas.ufl.edu/creatures/urban/roaches/german.htm German cockroach] on the [[Organization:University of Florida|UF]] / IFAS Featured Creatures Web site
* [http://www.ento.psu.edu/extension/factsheets/german_cockroach.htm German cockroach fact sheet] from the [[Organization:Pennsylvania State University|Penn State]] Extension

{{Taxonbar|from=Q466194}}

{{DEFAULTSORT:German cockroach}}
[[Category:Cockroaches]]

{{Sourceattribution|German cockroach}}