EPG-recorded Feeding Behaviors Reveal Adaptability and Competitiveness in Two Species of Bemisia tabaci (Hemiptera: Aleyrodidae)

The tobacco whitefly, Bemisia tabaci , is a fast-evolving complex species consisting of more than 35 cryptic species (biotypes). Among these species, the Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) are the most widely distributed and often cooccurrent. Field investigations showed that MED has eventually replaced MEAM1in most areas in China, but MEAM1still exists alone or together with MED in some areas. There are several hypotheses for species replacement in B. tabaci , but underlying mechanisms need further investigation. In this study, we focused to compare their adaptability and competitiveness of the two species under insecticide-free conditions by using electrical penetration graph (EPG). Feeding behaviors of the two species were recorded on each other’s pre-infested cotton or cucumber plants to mimic their interactions. Fourteen EPG variables indicated that two B. tabaci species performed remarkably differently on both pre-infested cotton and cucumber plants. Specifically, MEAM1 adults exhibited a shorter pathway for probing and a longer phloem sap ingestion than MED on either healthy or pre-infested plants. Both species had more efficient on its own pre-infested plants than on plants pre-infested by the other B. tabaci species. However, MEAM1 showed an advantage on pre-infested plants than MED under the same conditions. Our results clearly indicated that MEAM1 had stronger adaptability and competitiveness than MED on either cotton or cucumber plants without insecticide stresses.