Floral Visitor Guilds of Five Allochronic Flowering Asteraceous Species in a Xeric Community in Central Mexico

In this research, we determined: 1) the insect guilds visiting the ßower heads of Þve Asteraceae species (Eupatorium petiolare Mociño ex De Candolle, Senecio praecox [Cavanilles] De Candolle, Dahlia coccinea Cavanilles, Tagetes lunulata Ortega, and Verbesina virgata Cavanilles); 2) the role of ßoral phenology and ßoral morphology on species composition and frequency of visits of different insect order; and 3) the diurnal schedules of anthophilous visitors and their relationship to temperature and relative humidity. Collections and observations of ßoral visitors for each species were made over 24 h per day. The Þve Asteraceae were visited by 137 Diptera, Hymenoptera, Coleoptera, andLepidoptera species.Tagetes lunulatahad the highest species richness of ßoral visitors (41 species), while V. virgata had the lowest (23 species). Apis mellifera L. (Hymenoptera) was the only visitor found visiting all Þve species. Species composition of insect visitors was closely related to plantphenology.Order-level frequencyofvisitswasclosely related toßoralmorphology.Twoseparate principal component analyses based on frequency of visits and ßoralmorphology showed similar plant species groupings. Two groups of insects (Formicidae and Coleoptera) and two ßoral traits (ligulae length and presence of a cylindrical-campanulate involucre), respectively, were the variables determining these groupings. The highest frequency of anthophilous visitors coincided with the highest temperatures and the lowest relative humidity levels on ßowers of all species, except S. praecox. The combination of diurnal activity and guild visitor analyses in this study showed the importance of including both characteristics in pollination studies.