Development of Bemisia tabaci MEAM1 and MED on Tomato (Solanum lycopersicum) Alone and in a Mixed Population

Abstract

The invasive whitefly species Bemisia tabaci MED (Gennadius) (Hemiptera: Aleyrodidae) has demonstrated the ability to develop higher levels of insecticide resistance than B. tabaci MEAM1, leading MED to displace MEAM1 in some regions when insecticide resistance management is not practiced. Displacement of MEAM1 by MED is influenced also by host plant. MED established recently in the Florida landscape, making it necessary to evaluate the risk that MED will displace MEAM1 on tomato and other economically important crops. The development of MEAM1 and MED was observed on tomato (cv. ‘Florida 91') 30, 45, and 70 d after inoculation separately and in the presence of the other species. MEAM1 were more abundant than MED on plants where both were combined 30, 45, and 70 d after inoculation. MEAM1 reached higher numbers than MED on plants where they were established separately 30 and 70 d after inoculation. At 70 d after inoculation, there were significantly more MED on tomato plants where MEAM1 was not present than on plants infested with both species. Our results indicate that MEAM1 has a competitive advantage over MED on tomato in the absence of insecticide applications. In addition, we tested 13 populations of MEAM1 from commercial vegetable fields and 2 populations of MED from residential hibiscus for tolerance to imidacloprid and thiamethoxam. The 2 MED populations did not demonstrate high levels of tolerance to these insecticides relative to the MEAM1 populations. Our results suggest that the displacement of MEAM1 by MED in Florida tomato fields is unlikely at the present time.