Sampling Aerially Dispersing Arthropods: A High-Volume, Inexpensive, Automobile- and Aircraft-Borne System

Densities of aerially dispersing arthropods are on the order of only hundredths to single individuals per 1,000 m3. Therefore, an understanding of the atmospheric dynamics of dispersal requires active sampling of high volumes of air. We describe a system for active sampling in the surface boundary layer, from which arthropods ascend, and the planetary boundary layer, in which arthropods are transported by winds. The sampler, a net with a diameter of 0.62 m, was carried by an automobile in the surface boundary layer and a slowflying fixed-wing aircraft (Piper Cub) in the planetary boundary layer. The slow airspeeds characteristic of this aircraft permit large sampling rates without the need for expansion chambers in the samplers, which would require aircraft modification. It is also one of the least expensive aircraft to maintain and fly. At 72.4 km/h, a speed that does not destroy small specimens as traditional aircraft sampling speeds may, the two aircraft nets sampled at the rate of 38,910 m3/h. At the same speed, the single automobile net sampled at the rate of 21,420 m3/h.