Probing Behavior of the Pea Aphid, Acyrthosiphon pisum. IV. EfEects of Starvation on Certain Probing Activities1

Abstract

Individuals from 1 group of A. pisum (Harris) were starved for 1, 4, or 24 hr prior to their access to leaves of Vicia faba L. Other individuals from the same group were not starved prior to access. Following the starvation treatments, the aphids were permitted to probe until they had made 5 probes or until they ingested fluid from the plants. The time of ingestion was restricted to 10 min. Six parameters of probing activities were statistically analyzed. There were statistically significant differences between unstarved aphids and starved aphids in all but 1 parameter. More starved aphids ingested fluid from the sieve elements than did aphids that were not starved. The plant tissues from which ingestion took place were determined by using histological procedures. Individuals from another group of pea aphids were starved for 24 hr. Other individuals from the same group were not starved. Following starvation or nonstarvation, the aphids were permitted a 24-hr access to leaves of V. faba . Nine parameters of aphid-probing activities were analyzed statistically. Significant differences were evident in the following parameters: mean number of probes, mean base time, mean total X waveform time, mean total ingestion time, and mean total probe time. The results of 7 of the 9 above-mentioned probing activities were plotted as a function of time. A lag effect appeared between the activities of starved and unstarved aphids. At least 4 hr passed before the probing behavior of starved aphids was similar to the behavior of unstarved aphids. Preacquisition starvation is discussed in relation to its effect on the length of the latent period of a circulatiye or propagative plant virus within the aphid vector. It is suggested that the length of the latent period may be directly correlated with the magnitude of a virus charge and the rapidity with which the virus is accumulated by the aphid vector.