Toxicity of heteropteran 2-alkenals and their derivatives

2-Alkenals of 6, 8 and 10 carbon chain lengths and their derivatives are frequently found from Heteroptera as pheromones or defensive compounds. These compounds are thought to function as either nonspecific irritants or specific toxins. Although some studies have been done on the toxicity of these aldehydes, their mechanism of toxicity of the compounds is still largely missing. We investigated the mode of action of these compounds using crickets. When the crickets were exposed to either (E)-2-hexenal or 4-oxo-(E)-2-hexenal, they became paralyzed. Specifically, 4-oxo-(E)-2-hexenal causes the permanent paralysis. On the other hand, (E)-2-octenal did not affect the crickets. These results suggest that C₆ 2-alkenals can potentially function as neurotoxins. The relationships between toxicity and chemical structure will be discussed.