Egg‐laying in response to prostaglandin injections in the Australian field cricket, Teleogryllus commodus

Abstract

ABSTRACT. We report the effects of prostaglandin (PG) injection on egg‐laying by sexually mature virgin crickets, Teleogryllus commodus Walker. High egg‐laying activity is associated with PGE1 PGE2, 6‐keto‐PGE1 and 15‐keto‐PGE2, compounds that share the basic prostanoid backbone (C20 substituted fatty acid, 5 membered ring, a 7‐ and an 8‐carbon aliphatic chain), and 9‐keto, 11‐hydroxyl ring substitutions. PGs without these ring features and other compounds that lack the prostanoid backbone have no or only intermediate egg‐laying effects. Adding oxygen functionalities or an aliphatic double bond tends to increase egg‐laying activity. Hence, 15‐keto‐PGF2 and TxB2, both of which have an additional backbone oxygen compared with their less active analogues, are highly active compounds. Two of the most active PGs, 15‐keto‐PGE2 and 15‐keto‐PGE2α, are the products of inactivating metabolism in mammalian systems, describing a fundamental difference in PG biochemistry with respect to mammals and insects.