Editing Aphid (section)

====Anti-predator defences====
[[File:Aphid-sap2.jpg |right|thumb|Aphid secreting defensive fluid from the cornicles]]

Most aphids have little protection from predators. Some species interact with plant tissues forming a [[gall]], an abnormal swelling of plant tissue. Aphids can live inside the gall, which provides protection from predators and the elements. A number of galling aphid species are known to produce specialised "soldier" forms, sterile nymphs with defensive features which defend the gall from invasion.<ref name=Stroyan/><ref>{{cite journal |author=Aoki, S. |year=1977 |title=''Colophina clematis'' (Homoptera, Pemphigidae), an aphid species with soldiers |journal=[[Japanese Journal of Entomology]] |volume=45 |issue=2 |pages=276–282 |url=http://ci.nii.ac.jp/els/110003500318.pdf?id=ART0006019385&type=pdf&lang=en&host=cinii&order_no=&ppv_type=0&lang_sw= }}{{Dead link|date=September 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name="Kutsukake2012">{{Cite journal |last1=Kutsukake |first1=M. |last2=Meng |first2=X.Y. |last3=Katayama |first3=N. |last4=Nikoh |first4=N. |last5=Shibao |first5=H. |last6=Fukatsu |first6=T. |doi=10.1038/ncomms2187 |title=An insect-induced novel plant phenotype for sustaining social life in a closed system |journal=Nature Communications |volume=3 |pages=1187–1193 |year=2012 |pmid=23149732 |pmc=3514493 |bibcode=2012NatCo...3.1187K }}</ref> For example, Alexander's horned aphids are a type of soldier aphid that has a hard [[exoskeleton]] and [[pincer (biology)|pincer]]-like mouthparts.<ref name="I&S"/>{{rp |144}} A woolly aphid, ''[[Colophina clematis]]'', has first instar "soldier" nymphs that protect the aphid colony, killing larvae of ladybirds, hoverflies and the flower bug ''[[Anthocoris nemoralis]]'' by climbing on them and inserting their stylets.<ref name="Preston">{{cite book |author1=Preston-Mafham, Rod |author2=Preston-Mafham, Ken |title=The Encyclopedia of Land Invertebrate Behaviour |url=https://archive.org/details/encyclopediaofla0000pres |url-access=registration |year=1993 |publisher=MIT Press |isbn=978-0-262-16137-4 |page=[https://archive.org/details/encyclopediaofla0000pres/page/281 281]}}</ref>

Although aphids cannot fly for most of their life cycle, they can escape predators and accidental ingestion by herbivores by dropping off the plant onto the ground.<ref>{{Cite journal |last1=Gish |first1=M. |last2=Dafni |first2=A. |last3=Inbar |first3=M. |editor1-last=Heil |editor1-first=Martin |title=Young Aphids Avoid Erroneous Dropping when Evading Mammalian Herbivores by Combining Input from Two Sensory Modalities |doi=10.1371/journal.pone.0032706 |journal=PLOS ONE |volume=7 |issue=4 |pages=e32706 |year=2012 |pmid=22496734 |pmc=3322135 |bibcode=2012PLoSO...732706G |doi-access=free }}</ref> Others species use the soil as a permanent protection, feeding on the vascular systems of roots and remaining underground all their lives. They are often attended by ants, for the honeydew they produce and are carried from plant to plant by the ants through their tunnels.<ref name="Capinera2011"/><!--this page number is wrong but I cannot find the correct one-->

Some species of aphid, known as "woolly aphids" ([[Eriosomatinae]]), excrete a "fluffy wax coating" for protection.<ref name=Stroyan/> The cabbage aphid, ''[[Brevicoryne brassicae]]'', sequesters secondary metabolites from its host, stores them and releases chemicals that produce a violent [[chemical reaction]] and strong [[mustard oil]] smell to repel predators.<ref>{{cite journal |author=Kazana, Eleanna |author2=Pope, Tom W. |author3=Tibbles, Laurienne |author4=Bridges, Matthew |author5=Pickett, John A. |author6=Bones, Atle M. |author7=Powell, Glen |author8=Rossiter, John T. |year=2007 |title=The cabbage aphid: a walking mustard oil bomb |journal=Proceedings of the Royal Society B |volume=274 |issue=1623 |pages= 2271–2277|doi=10.1098/rspb.2007.0237 |pmid=17623639 |pmc=2288485 }}</ref> Peptides produced by aphids, [[Thaumatin]]s, are thought to provide them with resistance to some fungi.<ref>{{cite book|author=Vilcinskas, Andreas|chapter=Aphid Immunity.|title= Biology and Ecology of Aphids |year=2016|page=131|publisher=CRC Press}}</ref>

It was common at one time to suggest that the cornicles were the source of the honeydew, and this was even included in the ''[[Shorter Oxford English Dictionary]]''<ref>{{cite journal |author=Edwards, John S. |year=1966 |title=Defence by smear: supercooling in the cornicle wax of aphids |journal=[[Nature (journal)|Nature]] |volume=211 |pages=73–74 |doi=10.1038/211073a0 |issue=5044|bibcode=1966Natur.211...73E |s2cid=4295930 }}</ref> and the 2008 edition of the ''[[World Book Encyclopedia]]''.<ref>{{cite encyclopedia |title=Aphid |author=Martinson, Candace |encyclopedia=[[World Book Encyclopedia]] |year=2008 |isbn=978-0-7166-0108-1}}</ref> In fact, honeydew secretions are produced from the anus of the aphid,<ref>{{cite journal |author=Way, M.J. |year=1963 |title=Mutualism between ants and honeydew-producing Homoptera |journal=[[Annual Review of Entomology]] |volume=8 |pages=307–344 |doi=10.1146/annurev.en.08.010163.001515}}</ref> while cornicles mostly produce defensive chemicals such as waxes. There also is evidence of cornicle wax [[Kairomone|attracting aphid predators]] in some cases.<ref>{{cite journal |author1=Grasswitz, Tessa R. |author2=Paine, Timothy D. |year=1992 |title=Kairomonal effect of an aphid cornicle secretion on ''Lysiphlebus testaceipes'' (Cresson) (Hymenoptera: Aphidiidae) |journal=[[Journal of Insect Behavior]] |volume=5 |issue=4 |pages=447–457 |doi=10.1007/BF01058190|bibcode=1992JIBeh...5..447G |s2cid=25298742 }}</ref>

Some clones of ''[[Aphis craccivora]]'' are sufficiently toxic to the invasive and dominant predatory ladybird ''[[Harmonia axyridis]]'' to suppress it locally, favouring other ladybird species; the toxicity is in this case narrowly specific to the dominant predator species.<ref name="Lenhart Jackson White p=20180523">{{cite journal | last1=Lenhart | first1=Paul A. | last2=Jackson | first2=Kelly A. | last3=White | first3=Jennifer A. | title=Heritable variation in prey defence provides refuge for subdominant predators | journal=Proceedings of the Royal Society B: Biological Sciences| volume=285 | issue=1879 | date=2018 | doi=10.1098/rspb.2018.0523 | pmid=29848647 | page=20180523| pmc=5998095 }}</ref>