Daily foraging activity of Polybia diguetana Buysson 1905 (Hymenoptera, Vespidae, Polistinae)

Abstract

It is important to study the foraging activity of Polistinae in order to understand their impact on ecosystems. In this work we describe the activity of one nest in post-emergence state of Polybia diguetana in relation to temperature and relative humidity. The study area is a university campus in Mérida, México, with warm sub - humid climate. Sampling were taken in the following dates of 2019: January 30 and 31, February 5 and 6 and April 9 and 10, the 9 it rained from 9:00 to 11:45 hours. A video lasting 3:40 min was taken every half an hour, beginning at 7:30 and finishing at 14:45. Eighty-three videos were recorded with an accumulated time of 308.5 minutes. When the video recording was beginning, temperature (°C) and relative humidity (%) were measured at a distance of 3 meters from the nest. Partial correlation analysis were carried out, with temperature and relative humidity as independent variables and wasp departures and arrivals frequencies as response variables, April 9th was excluded from this analysis for excluding the effect of the rain. In the rainy days the highest frequency of arrivals and departures was at 7:30, when the temperature was the highest and the humidity the lowest. In other days departure frequency was higher at 11:00 and arrivals at 14:00. Temperature was positively correlated to departures (r=0.21, p=0.05) and arrivals (r= 0.44, p<0.0001). Relative humidity was c orrelated to arrivals only (r=-0.27, p=0.01). Temperature was the main factor influencing foraging activity, and humidity did in lesser degree. The pattern was different in the rainy day, due to raises in humidity and the risk of being impacted by raindrops.