Introduction

Abstract

Venoms are employed by many arthropods for defense or for offense as in subduing prey for food or oviposition. Since fast action is obviously helpful, it is not surprising that many arthropod venoms contain neurotoxic constituents. Often the venoms contain complex mixtures of substances which may contribute both immediate and persisting actions or which have potency for a wide spectrum of target organisms. Although many arthropods produce secretions or possess spines that affect chemoreceptors or cause pain, it is usual to restrict the term venom to substances injected by a bite or sting. Since salivary glands are designed to secrete enzymes and are under neural control, it is reasonable that salivary neurotoxins are mainly proteins or neural transmitters. Venoms associated with the sting apparatus are more complex and may include components derived from pheromones or tanning reagents as well as proteins. Neural transmitters and related small molecules such as acetylcholine, serotonin and histamine have been identified in several venoms; their actions are well known. The volatile alkaloids of fire ant venoms that will be discussed by Schimdt apparently act post-synaptically to dissociate transmitter reception from ionic conductance change.