Biochemical Coevolution between Parasitoids and their Hosts

Abstract

The coevolution of a predator and its prey suggests that the prey is selected for predator avoidance and escape while the predator is selected for more efficient prey-finding and capture. The predator attacks and consumes its host and, thus being successful, would be expected to propagate. The parasite-host relationship is a similar reciprocating evolutionary relationship with one important difference--the host should not be killed. The parasite must not only locate the host but must constantly adapt to a developing and changing host, a situation resulting in a closely interwoven relationship. The continued development of a host in accord with the evolutionary development of the host species is of benefit to the parasite. It is probably advantageous for the parasite to evolve towards a condition where the parasite has a minimal affect on the host species. This would insure the continued existence of a viable host population.The parasitoid-host relationship is akin to the predator-and parasite-host relationship, but with some unique aspects. The term parasitoid is used for arthropods where the egg and early larval stages are parasitic, but where the host is eventually killed. The adult is free living. In the parasitoid-host relationship, the parasitoid must not only locate the host, but must utilize the host for the progeny's benefit. Once the host has been parasitized, the parasitoid's progeny grow and develop at the expense of the host; ultimately killing the host. The host's future development is only of importance to the parasitoid. Thus the evolutionary strategy of the parasitoid is different from that of a parasite or predator. The parasitized host can no longer be considered as a member of the host species, but must be viewed as a container for the parasitoid. The evolutionary development of the parasitized host towards a

Understanding and Manipulating Plant Attributes to Enhance Biological Control

“…Most compounds emanating from herbivores (other than pheromones) are slightly volatile or nonvolatile and can only be detected at close range (Vet and Dicke, 1992). Therefore, to restrict prospected areas, parasitoids often first search for habitats where hosts are likely to be present (Salt, 1935;Doutt, 1964;Vinson, 1975Vinson, , 1981; van Alphen and Vet, 1986). For parasitoids of herbivorous insects, many studies document the key role of volatile allelochemicals emitted by plants in this process (e.g., Elzen et al, 1983Elzen et al, , 1984 Mattiacci et al, 1994).…”

Optimal Selection and Exploitation of Hosts in the Parasitic Wasp Colpoclypeus Florus (Hym., Eulophidae)

“…Following an encounter with a complex of host and host plant, the female wasp shows an arrestment response (Vinson, 1975), which is most likely in response to olfactory stimuli. This response consists of short periods of immobility during which the antennae may be alternately slowly moved up and down, alternated with periods of walking during which the antennae are moved quickly.…”

Factors affecting the potential increase rate (eλ, PIR), as defined by Hughes, in populations of Sitobion αvenαe (F.) (Hemiptera: Aphididae

“…However, the first-instar larva lowered the food uptake which returned to a level simi lar to that of non-parasitized aphids when the second-instar larva of the parasite was present and dropped again when the parasite larva reached the third instar. The physiological dis turbance is attributed to the fact that insect parasites affect carbohydrate metabolism, lipid metabolism and the endocrine system of their host (Vinson 1975). This has also been de monstrated by Johnson (1959Johnson ( , 1965 in parasitized aphids.…”