Population dynamics of the solitary digger bee Andrena vaga Panzer (Hymenoptera, Andrenidae) studied using mark‐recapture and nest counts

Abstract

The population size of the solitary digger bee Andrena vaga was documented using mark‐recapture methods during 4 consecutive years (1996–1999). Additionally, the numbers of the parasitoids Nomada lathburiana and Bombylius major were estimated. For calculations of the daily population size, the Jolly‐Seber model for open populations with time‐dependent survival and capture rates was used. The mean daily population size corresponded well to the number of nests marked in the aggregation of A. vaga. The method of mark‐recapture achieved the most accurate data when the number of sampling periods and the capture probability was high. The results document a decrease in population size of the investigated A. vaga aggregation during 4 successive years. A population increase of its parasitoids B. major is considered to be one reason for the population decline of A. vaga in 1999. The sex ratio of A. vaga was biased toward females, contrary to the expected higher number of males. Results of the mark‐recapture studies showed that up to 50% of females left the aggregation or died at the beginning of the season. The females probably colonized new aggregations at distances further than 200 m away from their birth aggregation, as no marked females were observed in the environs of the study area. This behavior is interpreted as a parasite avoidance strategy. The bee populations in the study area form a web of interconnected aggregations. Apparently a flux of extinction and recolonization exists between the different aggregations.

Are landscape structures insurmountable barriers for foraging bees? A mark-recapture study with two solitary pollen specialist species

“…While recapture rates found in the present study are well within the range of recaptures measured for species of other insect groups in search of their key resources (Toepfer et al, 1999(Toepfer et al, , 2000Haddad et al, 2008), they are lower than those reported in other studies with pollen specialist bee species (Bischoff, 2003;Franzen et al, 2009).…”

Strong genetic exchange among populations of a specialist bee, Andrena vaga (Hymenoptera: Andrenidae)

“…Hence, a high rate of dispersal might compensate for local extinctions. This hypothesis is supported by the fact that about 50% of the emerging females of Andrena vaga are known to emigrate (Bischoff 2003).…”

Nectar-foraging behavior of Euglossine bees (Hymenoptera: Apidae) in urban areas

“…Mark-recapture experiments are widely used in population ecology for estimating parameters such as population size, survival rates, longevity and dispersal (Andres and Rivera, 2001;Bischoff, 2003) among others. However, these parameters have not been estimated for euglossine populations because of the low or non-existent recapture rates when bees are marked at chemical baits (Kroodsman, 1975;Janzen, 1981;Ackerman and Montalvo, 1985;Folsom, 1985;Raw, 1989;Eltz et al, 1999;Otero and Sandino, 2003;Tonhasca et al, 2003).…”