Factors affecting submerged oviposition in a water strider: level of dissolved oxygen and male presence

A large variation in dissolved oxygen (DO) concentration of water is expected to limit activities of semiaquatic insects, including submerged oviposition. Female water striders Aquarius paludum insularis (Heteroptera: Gerridae) perform submerged oviposition either in tandem pairs (with males on their backs) or singly. We allowed A. paludum females to oviposit in high- or low-DO water to examine the effects of DO concentration and the method of submersion (tandem pair or single female) on submerged oviposition. The duration of submersion and the number and depth of eggs oviposited were all greater in the high-DO water, but the females performed more bouts of submerged oviposition in the low-DO water. The duration of submersion was longer for tandem pairs than for single females in both the high- and low-DO water. In the high-DO water, the number and depth of eggs oviposited were greater for tandem pairs than for single females. The DO concentration did not affect the frequency of submerged oviposition by tandem pairs or by single females. We suggest that submerged oviposition with an accompanying male is beneficial for both sexes, because submersion is longer than for single females.