| The ecological and biological characteristics of the two important pest insects of greenhouse-grown ornamental plants, greenhouse whitefly (GHWF), Trialeurodes vaporariorum (Westwood), and sweetpotato whitefly (SPWF), Bemisia tabaci (Gennadius), were investigated on some ornamental plants under greenhouse and environment-controlled conditions.;The external morphological characters of all developmental stages of the two whitefly species were described and illustrated. These characters can be used to identify the species without mounting the specimens on microscope slides to be examined under a phase microscope.;The spatial distribution patterns of immature and adult stages of both whitefly species were highly aggregated within and between plants as measured using Taylor's power law and Iwao's patchiness regression methods. Both within- and between-plant distributions were less aggregated following applications of insecticides. The effectiveness of the insecticides, application methods and equipment, and plant height may affect the distribution patterns.;Diel flight activities of the two whitefly species were monitored using yellow sticky traps in greenhouse conditions and growth chambers under different temperatures. Under greenhouse conditions, the flight activity of GHWF was unimodal with a peak in the morning or mid-day. Flight activity of SPWF was unimodal when ventilation fans were running constantly, and was bimodal when ventilation fans were shut off with temperature at or below 26.7;When the two whitefly species were present on the same leaf of a plant at the same time interspecific competitive exclusion occurred, and one species displaced the other depending upon the host plant on which they fed. Competition results were similar at temperatures of 20, 25 and 30... |
