Insect ecology (defenition) Insect ecology is the scientific study of how insects, individually or as a community, interact with the surrounding environment or ecosystem. Interspecific interaction Species interactions vary considerably in their form, strength and effect, and create quite complex networks among species. The web of interactions, direct and indirect, and having positive or negative feedback, determines the structure and dynamics of the community Classes of interaction Species interact with other species in various ways and with varying degrees of intimacy (interaction strength). Individuals compete with other organisms, may prey on other organisms, are prey for other organisms, and may be involved in stronger interactions with particular species . Categories of interactions generally have been distinguished on the basis of their direct effects, i.e., positive, neutral or negative effects on growth or mortality of each species. Interspecific positive interactions Interspecific positive interactions are defined as relationships between different species that result in better growth, reproduction and/or survival for at least one species involved in the interaction without negatively affecting the other species. http://www.els.net/WileyCDA/ElsArticle/refId-a0021901.html Interspecific negative interaction In negative interaction one of the interacting population is benefited and the other is harmed. In negative interaction one population may eat members of the other population, compete for food or excrete harmful wastes. http://www.easybiologyclass.com/biological-interactions-positive-negative-interactions-ecosystem-ppt/ Classes of interaction Competition Predation Symbiosis Parasitism Commensalism Mutualism Competition Competition is the struggle for use of shared, limiting resources. Resources can be limiting at various amounts and for various reasons. Any resource can be an object of interspecific competition, e.g., food resources, basking or oviposition sites, etc. Interspecific competition takes two general forms they are Exploitation competition Interference competition Exploitation competition Exploitation competition occurs when all individuals of the competing species have equal access to the resource. Species that can find or exploit a resource more quickly, develop or reproduce more rapidly, or population having increased efficiency to use the resource are favoured under such circumstances. plants consume nitrogen by absorbing it into their roots, making nitrogen unavailable to nearby plants. Plants that produce many roots typically reduce soil nitrogen to very low levels, eventually killing neighboring plants. Read more: http://www.biologyreference.com/Ce- Co/Competition.html#ixzz4qk4tcjef Interference competition Interference competition involves pre-emptive use, and often defence, of a resource. This allows more aggressive species to increase their access to, and share of, the resource, to the detriment of other species. Many species avoid resources that have been exploited previously, thereby losing access to them. Parasitic wasps frequently avoid hosts that are already parasitized by other wasps. An example of this can be seen between the ant Novomessor cockerelli and red harvester ants, where the former interferes with the ability of the latter to forage by plugging the entrances to their colonies with small rocks. https://en.wikipedia.org/wiki/Competition_(biology) Novomessor cockerelli Red harvester ants Predation Predation has been defined either as a general process of feeding on other (prey) organisms or as a more specific process of killing and consuming prey. Predation is generally considered to have positive effects for the predator, but negative effects for the prey. Insects are important prey for a variety of other organisms. Carnivorous plants generally are associated with nitrogen- poor habitats and depend on insects for an adequate supply of nitrogen. A variety of mechanisms for entrapping insects has evolved among carnivorous plants, including water-filled pitchers (pitcher plants), Some carnivorous plants show conspicuous ultraviolet patterns that attract insect prey, in a manner similar to floral attraction of some pollinators. Insects also are prey for other arthropods (e.g., predaceous insects, spiders, mites), and vertebrates. Many fish, amphibian, reptile, bird and mammal taxa feed largely or exclusively on insects Symbiosis Symbiosis involves an intimate association between two unrelated species. Three types of interactions are considered symbiotic,. Parasitism Commensalism Mutualism Parasitism Parasitism affects the host (prey) population. parasites exploit living prey. Parasitoidism is unique to insects, especially flies and wasps, and combines attributes of both predation and parasitism. The adult parasitoid typically deposits eggs or larvae on, in, or near multiple hosts, and the larvae subsequently feed on their living host and eventually kill it. Parasites must be adapted to long periods of exposure to the defenses of a living host. Therefore parasitic interactions tend to be relatively specific associations between co-evolved -parasites and their particular host species and may involve the modification of host morphology, physiology or behavior to benefit parasite development or transmission. Ectoparasites These are the insects that feed externally, by inserting mouthparts into the host( Eg: lice, flea, mosquito, ticks) Endoparasites These are the insects that feed internally, within the host’s body (Eg: bot flies, wasps, etc) Primary parasites These are the insects that develop on or in a non parasitic hosts. hyperparasites These are insects which develop on or in another parasite. Eg. Hymenoptera (wasps, sawflies, etc.) Sawfly Autoparasitism Some parasites parasitize other members of the same species Eg: as seen in hymenoptera, the female of Coccophagus scutellaris parasitize scale insects and the male is an obligate parasite of the female. Coccophagus scutellaris Superparasitism This occurs when more individuals occupy a host and compete to develop to maturity. One dominant individual completely suppresses others and develops to maturity. Eg. Insect larva such as a catterpillar Insects are parasitized by a number of organisms, including viruses, bacteria, fungi, protozoa, nematodes, flatworms, mites, as well as by other insects . Some parasites cause sufficient mortality to have been exploited as agents of biological control . monarch butterflies, Danaus plexippus, that were parasitized by the protozoan, Ophryocystis, lost 50% more body mass per kilometer flown and exhibited 10% slower flight velocity, 14% shorter flight duration, and 19% shorter flight distance, compared to uninfected butterflies. These data, suggest that the long distance migration of this species may eliminate infected individuals and reduce rates of parasitism. Commensalism Commensalism is a relatively rare type of interaction, because hosts are completely unaffected by their symbionts. Epiphytes, plants that use their hosts for aerial support but gain their resources from the atmosphere, A number of insect and other arthropod species are commensal in ant or termite nests. Such species are called myrmecophiles or termitophiles, respectively. These symbionts gain shelter, from their host colonies, but have little, effect on their hosts. This relationship is distinct from those interactions like parasitism. Bark beetle galleries provide habitat and resources for a variety of invertebrate and microbial commensals, most of which have little or no effect on the bark beetles. Mutualism Mutualistic interactions tend to be relatively specific associations between co-evolved partners, and they often involve modification of host morphology, physiology or behaviour to provide habitat or food resources for the symbiont. In return, the symbiont provides necessary services, resources or protection from competitors or predators. some mutualists are less dependent on each other. Mutualism can be viewed as mutual exploitation or manipulation. Mutualism (example) The cecropia plant provides shelter and food for the ant, and the ant protects the plant from herbivore predators. In order for most plants to make seeds, pollen from one plant must be transferred to another plant. Butterflies, bees and other insects often suck sweet nectar from flowers for food and pick up pollen as they do so. Intraspecific competition Intraspecific competition occurs when members of the same species compete for the same resources in an ecosystem. Intraspecific competition is an interaction in population ecology, wherby members of the same species compete for limited resources Intraspecific competition would select for as diverse as an array of qualities as possible within a population to minimise competition. An obvious evolutionary solution to reduce the intraspecific competition would be by broadening the exploitation pattern by developing a polymorphic population Eg: Sexual dimorphism Sexual dimorphism Due to sexual dimorphism the species population has modified or adapted to survive in population. Eg:In insects in particular, females are often larger than the males. It is thought that the reason lies in the huge number of eggs that insects lay; a larger body size enables a female insect to lay more eggs. In some cases, sexual dimorphism enables males and females to exploit different food resources, thus increasing their collective ability to find food. https://www2.nau.edu/~gaud/bio300b/sexdi.htm