An experimental design encountered in vector-borne disease transmission research involves moving s > 1 insect vectors (perhaps aphids, whitefly, or planthoppers) from an infected source to each of n uninfected test (host) plants. Each of the host plants is then observed for developing symptoms of infection. In plant pathology, such designs are called multiple-vector transfers. In the statistical literature, such transfers are known as an application of group testing. Even though vectors are tested in groups of size s, the goal is still to estimate p, the probability of disease transmission for an individual vector. The use of a single-vector transfer (s = 1) is usually not possible due to limitations in the number of host plants, greenhouse space, screened cages, or some other factor. In fact, when dealing with low-prevalence diseases, the use of group testing in vector-transfer experiments can make otherwise impossible experiments feasible (Swallow, 1985; Tebbs and Swallow, 2003).
Examples of insect vectors:
Example greenhouse where an experiment takes place:
