Sequential Plans for Sampling Aphids on Sugar Beets in Kern County, California

Abstract

An efficient sampling plan, to aid in the timing of treatments, is essential to the development of a practical insecticidal program for possible, use in the control of Myzus persicae (Sulzer), the major vector of the beet yellows viruses. Sequential sampling, in which decisions are made upon the accumulated results of each unit sampled, in many eases can save both time and money. Although the tendency of aphids to colonize individual plants leads to what is known as over-dispersed, or contagious, distributions, critical population levels (assumed to be approximately one aphid per plant) are reached before 100% of the plants are infested. This fact permits the use of sequential sampling plans based upon either the mean number of aphids per plant or the number of plants found to be infested. In situations of very light or very heavy populations the use of a sequential sampling plan should allow rapid decisions to be made as to whether critical population levels have been reached.