Nesting ecology of Polistes gallicus (Hymenoptera: Vespidae) in South-Western Spain

Among the numerous factors that contribute to the success of social wasps, colony productivity is the most important and depends on ecological and environmental factors, such as the nest site. Consequently, nest-site choice should be determined by nest-site characteristics. The objective of this study was to determine on which species of plants Polistes gallicus wasps build their nests and identify the possible preferred features of plants used during nest-site selection by the foundress. From February to October 2017-2019 we recorded details of the nests in natural areas in south-western Spain (at 38 degrees latitude). Nests of P. gallicus were recorded on 49 species of plants belonging to 23 families, with Scirpoides holoschoenus, Epilobium hirsutum and Foeniculum vulgare the most common. Significantly more wasps built their nests on herbaceous than on shrub and arboreal plants, and on "green" than "brown-grey" plants. Most of the nests were 21 to 189 cm above the ground, with a nest azimuth of about 102 degrees. Nests were located at a mean distance of 43.51 +/- 123.79 m from the nearest source of water. The length of the nesting season in the area studied was between 30 and 33 weeks, and more colonies were founded by a single foundress than several foundresses. Furthermore, a greater percentage of the single foundress colonies failed than of the multiple-foundress colonies.