Nesting strategies in some southern African species of Ammophila (Hymenoptera: Sphecidae)

Abstract

Nest provisioning strategies were worked out for eight southern African Ammophila and related to those of extra-limital species. All of them hunted after digging their nests except for A. dolichodera, the first Afrotropical species reported to hunt first. This species, A. beniniensis, A. vulcania and A. braunsi provided each nest with one large caterpillar. The remaining four species, A. dolichocephala, A. conifera, A. ferrugineipes and A. insignis provisioned with several smaller caterpillars, the last species being the only mass provisioner. A. ferrugineipes practised a form of progressive provisioning and maintained several nests at a time, the only Afrotropical species, and the fifth species worldwide, known so far to do so.

The selective advantages of these strategies are discussed in relation to foraging efficiency and nest parasitism. Failure of nests of single-prey species was greater due to the latter, but data were inadequate to show whether progressive provisioning reduced cleptoparasitism more effectively than mass provisioning.

The sex of offspring was related to mass of provision in A. insignis but not in A. ferrugineipes. The reason for this was not established.

Keywords :

• Ammophila
• Sphecidae
• nesting strategy
• mass provisioning
• progressive provisioning
• delayed provisioning
• cleptoparasite