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The Insects - Outline of Entomology 3th Edition - Chapter 13

Chapter 13 INSECT PREDATION AND PARASITISM We saw in Chapter 11 that many insects are phytophagous, feeding directly on primary producers, the algae and higher plants. These phytophages comprise a substantial food resource, which is fed upon by a range of other organisms. | TIC13 5 20 04 4 41 PM Page 327 Chapter 13 INSECT PREDATION AND PARASITISM Scorpionfly feeding on a butterfly pupa. After a photograph by P.H. Ward S.L. Ward. TIC13 5 20 04 4 41 PM Page 328 328 Insect predation and parasitism We saw in Chapter 11 that many insects are phytophagous feeding directly on primary producers the algae and higher plants. These phytophages comprise a substantial food resource which is fed upon by a range of other organisms. Individuals within this broad carnivorous group may be categorized as follows. A predator kills and consumes a number of prey animals during its life. Predation involves the interactions in space and time between predator foraging and prey availability although often it is treated in a one-sided manner as if predation is what the predator does. Animals that live at the expense of another animal a host that eventually dies as a result are called parasitoids they may live externally ectopara-sitoids or internally endoparasitoids . Those that live at the expense of another animal also a host that they do not kill are parasites which likewise can be internal endoparasites or external ectoparasites . A host attacked by a parasitoid or parasite is parasitized and parasitization is the condition of being parasitized. Parasitism describes the relationship between parasitoid or parasite and the host. Predators parasitoids and parasites although defined above as if distinct may not be so clear-cut as parasitoids may be viewed as specialized predators. By some estimates about 25 of insect species are predatory or parasitic in feeding habit in some lifehistory stage. Representatives from amongst nearly every order of insects are predatory with adults and immature stages of the Odonata Mantodea Manto-phasmatodea and the neuropteroid orders Neuro-ptera Megaloptera and Raphidioptera and adults of the Mecoptera being almost exclusively predatory. These orders are considered in Boxes 10.2 and 13.213.5 and the vignette for this chapter .