The Comparative Population Dynamics of Eight Solitary Bees and Wasps (Aculeata; Apocrita; Hymenoptera) Trap-Nested in Jamaica

Abstract

Six thousand and eighty-three trap nests recovered from 9158 placed in St. Catherine, Jamaica, contained 6738 cells built by 11 solitary wasps and bees (Hymenoptera; Apocrita; Aculeata). These species normally nest in hollow stems or other cavities in wood. Analyses for eight of these species showed developmental mortalities between 48 and 69 percent, set ratios near 1:1 (except two Megachile species where there were about 2.5 males per female), and fecundities between 5.6 and 13.1 eggs/female. A comparison with temperate solitary Aculeata is made. MOST INSECT POPULATION STUDIES have been on pest species that exist at high numbers, a circumstance which makes it difficult to derive general principles, since insufficient work has been done on the majority of species that exist at low numbers. The present work, which includes information on several uncommon Aculeata, attempts to redress this situation, and makes a comparison between members of this large group of wasps and bees in the tropics and in temperate regions. Solitary wasps and bees show many affinities in their nesting biology. Females construct cells, frequently of mud or plant material such as leaves, petals, or resin, in each of which a single egg is laid. The wasps stock the cells with paralyzed insects or spiders, while the bees stock with pollen and nectar. The larval progeny consume these provisions, and metamorphosis takes place within the cells. The emerging adults chew their way out of the cells and fly almost immediately. Few publications exist on the population ecology of these insects. One difficulty is that their populations are almost always extremely sparse (Danks 1971a) compared with those of most other insects. While it is often difficult to locate their nesting sites and qbtain enough cells to construct accurate life tables, conversely, they can provide excellent data because the developmental history of each instar within the cell may easily be determined and the adult emergence may be ascertained by the exit hole. Furthermore, the behavior of nesting females necessarily links them to their nests so that estimates of their survival and fecundity may be facilitated (Freeman 1973). The retrospective life tables produced cover many amalgamated generations whose properties have been discussed by Freeman (1973, 1976) and Freeman and Taffe (1974).