Definitions

Ichneumonidae Solitary, parasitic wasp.
Imago The adult insect.
impunctate lacking punctures
inbreeding the mating or crossing of individuals more closely related than average mating pairs in the population
inchworm the caterpillar of a moth in the Geometridae family, so-called for its manner of locomotion
incipient about to become or happen; used of the initial stages of an event or structure
incompatibility the inability to unite, fuse or form a viable association
incompatible the failure of cross- or self-fertilisation because of genetic, structural or physiological barriers
incubation the maintenance of eggs under conditions favourable for hatching, e.g. as in a bumblebee nest
indeterminate growth growth that continues throughout the life of the individual so that body size and age are correlated
indicator a organism, species or community characteristic of a particular habitat or set of environmental conditions, e.g. the presence of certain insect aquatic larva (e.g. stoneflies and caddis flies) indication or high water quality.
indicator species a species whose presence or absence is an indicative of a particular habitat, community or set of environmental conditions, e.g. stoneflies of high water quality
Indigenous Organisms that are native to a particular region - not introduced.
industrial melanism an increase in dark morphs as a response to changes in selection in habitats blackened by industrial pollution
inert inactive, quiescent
infertile not fertile, non-reproductive
infestation invasion by parasites or pests
ingestion the action of taking in food, feeding
inheritance the transmission of genetic information from ancestors or parents to descendants or offspring
inhibition any process that acts to restrain actions or behaviour
innate inherited, present at birth, not learned behaviour
Inoculation the insertion of a pathogen into a host organism by a vector, or of an organism into an experimental culture
Inorganic pertaining to, or derived from non-biological material; used of non-carbon compounds
Inquilinism symbiosis in which one organism (the inquiline) lives with another (either inside its body, or outside, or in its nest) without causing any harm to the host, e.g. certain mites which live in bumblebee nests
insecta the insects
insecticide a chemical used to kill insects, but commonly used of any chemical used to kill invertebrates
Insectivora an order of small mammals including hedgehogs, moles, shrews which include insects as a large part of their diet
Insectivorous feeding on insects
Insemination the introduction of sperm into the genital tract of the female
Instar the stages between moults of arthropods
Instinctive behaviour complex, stereotyped behaviour in response to an environmental stimulus
Integument an external covering or layer
intensity of infection the number of individuals of a parasite species in each infected host
interbreeding mating or hybridisation between individuals, species, populations etc.
intermediate host the host in which some development of a parasite occurs, but not sexual reproduction or maturity
Internal fertilisation In reproduction a form of fertilisation that takes place inside the female's body. Internal fertilisation is a characteristic of many land animals.
Interstitial living in the spaces between sand grains, small crevices, cells.
Intertidal zone the shallow zone where land meets water, also known as the littoral zone.
intraspecific within a species; between individuals or populations of the same species
Introduced species A species that humans have accidentally or deliberately brought into an ecosystem in which it does not naturally occur.
Intromittent organ a male copulatory structure that is inserted into the body of the female
Introvert a retractable body region, as seen in the peanut worms
Invagination an infolding of a layer of tissue to form a sac-like structure
invasion the mass movement of organisms from one area into another
Invertebrate lacking a backbone
Isolation the separation of 2 populations so that they are prevented from interbreeding
Isopods a group of crustaceans that includes woodlice
Isoptera termites
Ixodida a group of ticks which includes the castor bean tick or sheep tick
Juvenile hormone In arthropods a hormone secreted by the corpora allata which promotes the retention of the larval state.
Keystone predator the dominant predator (often the top predator), in a food web; this predator will have a major influence on the community structure
Keystone species A species whose disappearance from a community transforms the populations of the other species in the community.
Kin selection Selection acting on one or more individuals and favouring or disfavouring the survival and reproduction of relatives (not offspring) that possess the same genes by common descent. As happens in selection for altruistic behaviour between genetically related individuals, e.g. the social insects.
Kingdom The highest category in taxonomic classification
Kinorhyncha A phylum of tiny marine invertebrates