German cockroach: Difference between revisions

The '''German cockroach''' ('''''Blattella germanica'''''), colloquially known as the '''croton bug''', is a [[species]] of small [[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 [[Prothorax|pronotum]] running [[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 [[Pest (organism)|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 [[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.

}}</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 [[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 [[instar]]s before becoming sexually mature, but [[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" />

* 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>

[[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.

== Comparison of three common cockroaches ==

|'''Preferred temperatureSize''' || {{convert|1513|–|3516|mm|Cin|abbr=on}}<ref name="Bassett2012Robinson2005"/> || {{convert|18|–|29|mm|in|abbr=on}}<ref name="Robinson2005">{{cite book|last=BassettRobinson|first=W.William H. |title=Clay'sUrban Insects and Arachnids: A Handbook of EnvironmentalUrban HealthEntomology|url=https://books.google.com/books?id=ck2qO5Gyj40CaluUgDVYJ8wC&pg=PT317PA51|date=1214 OctoberApril 20122005|publisher=RoutledgeCambridge University Press|isbn=978-10-135521-8103381253-75|pagepages=31745–46, 51–54}}</ref> || {{convert|2029|–|3053|mm|Cin|abbr=on}}<ref name="Robinson2005" /> || {{convert|20|–|29|C|abbr=on}}<ref name="Bassett2012" />

|'''NymphalPreferred developmenttemperature'''{{efn|Dependent on several factors, including temperature (significantly), sex, and nutrition.}} || 54–215 days<br />(at {{convert|2415|–|35|C|abbr=on}})<ref name="Robinson2005Bassett2012" />{{cite book|last=Bassett|first=W.H. 164–542|title=Clay's days<brHandbook 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>(at || {{convert|2220|–|30|C|abbr=on}})<ref name="Robinson2005" /> || 150–360 days<br />(at {{convert|2520|–|3029|C|abbr=on}})<ref name="Robinson2005Bassett2012" />

|'''LifespanNymphal development'''<ref group="note">Dependent on several factors, including temperature (significantly), sex, and nutrition.</ref> || Around 20054–215 days<br/>(at {{convert|24|–|35|C|abbr=on}})<ref name="Robinson2005" /> || 35–190164–542 days<br/>(at {{convert|22|–|30|C|abbr=on}})<ref name="Robinson2005" /> || 90–706150–360 days<br/>(at {{convert|25|–|30|C|abbr=on}})<ref name="Robinson2005" />

|'''Able to fly?Lifespan''' || Uncommon{{efn|German cockroaches can glide, especially males, but powered flightAround is200 uncommon.}}days<ref name="Robinson2005" /> || No35–190 days<ref name="Robinson2005" /> || Yes90–706 days<ref name="Robinson2005" />

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" />