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A gall-inducing insect is any

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

that can cause the growth of

gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants. Plant galls are abnormal outgrowths of plant tissues, similar to benign tumors or war ...

s within

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

s. There are several groups of insects that meet this description. They include the

gall wasp Gall wasps, also traditionally called gallflies, are hymenopterans of the family Cynipidae in the wasp superfamily Cynipoidea. Their common name comes from the galls they induce on plants for larval development. About 1,300 species of this gene ...

s, scales,

gall midge Cecidomyiidae is a family of diptera, flies known as gall midges or gall gnats. As the name implies, the larvae of most gall midges feed within plant tissue, creating abnormal plant growths called galls. Cecidomyiidae are very fragile small in ...

aphid Aphids are small sap-sucking insects in the Taxonomic rank, family Aphididae. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Eriosomatinae, woolly ...

psyllid Psyllidae, the jumping plant lice or psyllids, are a family of small plant-feeding insects that tend to be very host-specific, i.e. each plant-louse species only feeds on one plant species (monophagous) or feeds on a few closely related plants ( ...

s and certain species of leafminer

flies Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwin ...

. Galls are growth deformities induced in certain plants by various insects which are mostly species-specific. Galls induced by insects can be viewed as an extended

phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological propert ...

of the inducing insect, and gall-inducing insects specialize on their host plants, often to a greater extent than insects that feed on the same plant without creating galls. The gall's form or type depends on what organism is attacking the plant and where the plant is being attacked. Based on the form, there are two classification systems used to identify the cause of galls: causative agents located outside plant tissues, and those agents located inside plant tissues. Causative outside agents include: * ''Krebs gall'' is caused by surface agents. * ''Filz gall'' is caused by agents among surface hairs. * ''Fold/roll gall'' is caused by agents within turned-over leaf blades. * ''Pouch gall'' is caused by agents within a cup-like structure that occurs when opposite ends of the infected structure arch upward and form a spherical oval. Causative inside agents include: * ''Covering gall'' is caused by agents embedded within a gall when plant tissues rise up and surround the parasite. * ''Lysenchyme gall'' is caused by agents that sink into the plant when the plant cells dissolve away and close around the parasite. * ''Mark gall'' is caused by agents burrowing within plant tissue before gall develops. This

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

relationship is rather one-sided, with not much research verifying any benefit given to the plant species; therefore such insects are most likely

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

s of their host plant. The insect that causes the gall formation gets an entire microenvironment or

microhabitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

provided to it, safe from climate and predation, to grow within, and with a rich supply of food formed within the gall for the insect to feed upon. Ecologically, gall-inducing insects, because of their creation of a

, are often attacked by

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

inquiline In zoology, an inquiline (from Latin ''inquilinus'', "lodger" or "tenant") is an animal that lives commensally in the nest, burrow, or dwelling place of an animal of another species. For example, some organisms, such as insects, may live in the ...

insects that take advantage of the excess resources the gall-inducer causes the plant to create, often leading to more

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

in the ecosystem than what would exist without the presence of gall-inducers. Thus gall-inducing insects are examples of

ecosystem engineer An ecosystem engineer is any species that creates, significantly modifies, maintains or destroys a habitat. These organisms can have a large impact on species richness and landscape-level heterogeneity of an area. As a result, ecosystem engine ...

References

Sources

* Darlington, Arnold (1975) ''The Pocket Encyclopaedia of Plant Galls in Colour''. Poole: Blandford Press. . {{DEFAULTSORT:Gall-Inducing Insect

See also

References

Sources