Territorial behavior of Centris adani and its reproductive function in the Costa Rican dry forest (Hymenoptera: Anthophoridae).

Abstract

Territorial behavior in males of the anthophorid bee Centris adani Cockerell was investigated primarily in 1975, 1976 and 1980 in the Costa Rican dry forest. The study revealed that territories were commonly established in certain dry grassy habi tats and to a lesser extent in the crowns of flowering trees that are visited by conspecific females for pollen and/or nectar. Regardless of site there was a high turnover of bees in the territories, which suggested active competition among the males. A citral-like chem ical was deposited systematically by males on grass stems that surrounded given territories in grassy habitats. It is suggested that territorial behavior in this bee serves a mating function. Observations and experiments also indicate that an im portant odor communication exists between male and female bees associated with the territories. This communication may be im portant in consummating a mating event. Ecological and evolutionary aspects of mating behavior in bees have re ceived considerable attention by workers in recent years (see reviews in Alcock et al., 1978; and Eickwort and Ginsberg, 1980). Several distinct mating strategies exist in the Apoidea, and some attempt has been made to classify the strategies as to type (Alcock et al., 1978; Alcock, 1980). It is noteworthy that many researchers are now providing greater insight on the role played by males in their respective mating systems (Alcock et al., 1978; Eickwort and Ginsberg, 1980). Males of one group, genus Centris (family: Anthophoridae), are known to display diverse reproductive behavior. In Arizona, males of Centris pal uda exhibit dimorphic behavior that is correlated with their body size (Al cock et al., 1976, 1977). Large males fly over nesting areas and locate emerg ing females by odor. Upon locating the odor, males dig down and mate with females as they emerge. Smaller males hover within territories at the periphery of nesting areas, waiting for females that escape unmated from the digger males. Raw (1975) described four different behavioral patterns 1 Department of Entomological Sciences, University of California, Berkeley 94720. Department of Entomology, Texas AM Dodson, 1962; Hurd and Linsley, 1975; Batra and Schuster, 1977). In this paper we present results of a study that was conducted in Costa Rica primarily during 1975-76 and 1980 on male territorial behavior in Cen tris adani Cockerell. We provide an overview of male territorial behavior in grassy habitats and in trees and results of experimental manipulations on territorial males in the former habitat. We also provide evidence to show how territorial activity in this bee is related to mating and foraging.