Info

Olfaction is the major sense by which insects search for and locate their host, whether it is a plant or another animal. The host's odor, or less commonly its taste, is therefore serving as a kairomone for the searching insect (Chapter 23, Sections 3.3.1 and 4.2.2). Insects that prey on or parasitize other insects are especially adept at locating their host using chemical cues. These cues may include the odor of the prey insect's host plant, the odor or taste of the prey itself, and pheromones or, rarely, allomones released by the prey during the course of other activities.

Pheromones, in particular, have been exploited by predators and parasites in order to locate their host, as the following examples illustrate. The oviposition-deterring pheromone placed on fruit by the apple maggot fly (Section 4.1.6) allows the braconid parasitoid Opius lectus to locate its host's eggs. Likewise, the spacing pheromone released by larvae of Anagasta kUhniella enables their predator, the ichneumonid Nemeritis canescens, to determine their position. Aggregation pheromones are widely used by predators for prey-finding. Thus, clerid and trogositiid beetles are strongly attracted to trees under early attack by bark beetles as a result of the aggregation pheromone that the latter emit (Haynes and Birch, in Kerkut and Gilbert, 1985). Predators or egg parasitoids often "eavesdrop" on the sex attractants released by female Lepidoptera: the predators locate and feed on the adult moths, while the parasitoids "hang around" until the moth lays its eggs soon after mating (Stowe et al., 1995; Boo and Yang, 2000).

The pheromones of social insects are exploited in various ways by predaceous and parasitic insects, as well as by other social species, for example, slave-making ants. Some beetle predators, having located a pheromone trail, simply ambush passing foragers or rob them of their food. Many "guests" of ant nests, including species of beetles, flies, and Thysanura, find their way to the host colony using the ants' trail pheromones. (Further, some "guests" produce cuticular hydrocarbons identical to those of their hosts, enabling themselves to remain unrecognized while they feed on, or are fed by, the ants!)

Remarkably, in rare instances, allomones released by the host as a means of defending itself are used by some predators and parasites to locate the emitter. Thus, a number of aphid species emit (E)-p-farnesene as a defensive compound from their cornicles. However, the compound is used by searching seven-spot ladybird beetles, Coccinella septempunctata, as an aphid-locating cue (Al Abassi et al., 2000).

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

Get My Free Ebook


Post a comment