Symbionts contribute nutrients that allow insects to feed on plants. The whitefly Bemisia tabaci Middle East-Asia Minor 1 (MEAM1) is a polyphagous pest that depends on symbionts to provide key nutrients that are deficient in the diet. Here, we established three whitefly populations on eggplants, cucumbers, and tomatoes and observed that they harbored the same symbiont taxa in different quantities. The amount of the primary symbiont, Portiera, decreased with increasing concentrations of host-plant essential amino acids (EAAs). Whitefly populations transferred to different plant species exhibited fluctuations in Portiera amounts in the first three or four generations; the amount of Portiera increased when whitefly populations were transferred to plant species with lower EAAs proportions. As for the secondary symbionts, the whitefly population of eggplants exhibited lower quantities of Hamiltonella and higher quantities of Rickettsia than the other two populations. The changes of both symbionts' abundance in whitefly populations after host-plant-shifting for one generation showed little correlation with the EAAs' proportions of host plants. These findings suggest that host-plant nitrogen nutrition, mainly in the form of EAAs, influences the abundance of symbionts, especially Portiera, to meet the nutritional demands of whiteflies. The results will inform efforts to control pests through manipulating symbionts in insect-symbiont associations.
Keywords: biotype B; essential amino acids; host plant; nutrition; symbiont; whitefly.