Assessment of relative host plant quality for three cryptic species of the Bemisia tabaci species complex in Australia

Abstract

Host plant relationships of Australian native and invasive whitefly species in the Bemisia tabaci species complex, namely AUSI and AUSII and Bemisia argentifolii (also called B. tabaci Middle East-Asia Minor 1 (MEAM1), were investigated with three approaches: ecologically in the field with surveys, experimentally in the laboratory, and using population genetics to assess any host-associated differentiation within whitefly species. AUSII and B. argentifolii were collected from various host plant species to test for gene flow using microsatellite genotyping. Neither species showed evidence of population structuring associated with host plant species. Host plant testing in the laboratory showed that only some host plants are reproductive hosts for these three whitefly species. Most individuals of all three species settled on tomato over the other host plant species in a cage with several host species presented simultaneously. Nevertheless, tomato was not a reproductive host for AUSI, and cassava did not support adult survival or nymphal production in any species. AUSI reproduced successfully on cotton, chia, and golden crownbeard. AUSII reproduced best on chia, followed by golden crownbeard, cotton, and tomato. Bemisia argentifolii reproduced well on tomato, followed by cotton, chia, and golden crownbeard. In summary, host plant testing supported the hypothesis that AUSI, AUSII, and B. argentifolii have different host plant relationships from one another and confirmed that the invasive B. argentifolii can use more host plant species for reproduction than the indigenous Australian species. Discrete host associations across cryptic species complexes are likely to be common amongst herbivorous insects.