Abstract
The relative suitability of three prey organisms, Bemisia tabaci (Gennadius) eggs, B. tabaci nymphs, and Myzus persicae (Sulzer), to the ladybird Propylea japonica (Thunberg) was evaluated under laboratory conditions. The larvae developed fastest when fed M. persicae, and slowest on B. tabaci eggs. When fed M. persicae, all larvae successfully developed into adult with a growth index (i.e., percent pupation/larval period in days) of 13.16 and development rate of 0.096. The longevity of starving adults was 4.7 ± 0.2 days. In contrast, when fed B. tabaci eggs, all larvae survived to the second instars, 56.7% of which survived to the third instars, 13.3% to the fourth instars; only 6.7% of larvae survived to the pupal stage and the pupae developed into abnormal adults that died shortly. When fed B. tabaci nymphs, all larvae survived and successfully developed into adults with a growth index of 10.71 and development rate of 0.083. The adult body mass was greater when larvae fed M. persicae, compared to adults eclosing from larvae fed B. tabaci nymphs. On the basis of these findings, the order of suitability of three prey organisms for P. japonica is M. persicae > B. tabaci nymph > B. tabaci egg. This is the first record that P. japonica can complete its development when feeding exclusively on whitefly nymphs.
Highlights
The cotton whitefly Bemisia tabaci (Gennadius), occurring worldwide in tropical and subtropical climates (Jiang et al, 1999; Hilje et al, 2001) as well as in protected agricultural systems in temperate regions (Brown et al, 1995), is a severe pest of numerous field and vegetable crops in many parts of the world (Gerling et al, 2001), attacking more than 600 plant species (Secker et al, 1998)
The third instars took longer time to develop on B. tabaci eggs than on M. persicae or B. tabaci nymphs (F = 39.871; df = 2, 89; P < 0.001)
The complete developmental period was significantly shorter when feeding on M. persicae than on B. tabaci nymphs (F = 69.9027; df = 1, 59; P < 0.001)
Summary
The cotton whitefly Bemisia tabaci (Gennadius), occurring worldwide in tropical and subtropical climates (Jiang et al, 1999; Hilje et al, 2001) as well as in protected agricultural systems in temperate regions (Brown et al, 1995), is a severe pest of numerous field and vegetable crops in many parts of the world (Gerling et al, 2001), attacking more than 600 plant species (Secker et al, 1998). The whitefly causes damage through feeding, honeydew production and resultant sooty mold, and disease transmission (Jones, 2003). This pest has been known as a sporadic pest of cotton in China for a long time, its B-biotype has not become an important pest in northern China until 2000 (Wu et al, 2002) and has spread to 19 provinces to date (Ren et al, 2001). Many attempts have been made to control B. tabaci Because of their high reproductive rate, multiple generations per year (Byrne & Bellows, 1991; Brown et al, 1995), and ability to rapidly develop resistance to insecticides (Palumbo et al, 2001), the whitefly is very difficult to control through conventional approaches. Biological control becomes the primary method to suppress whitefly populations in agroecosystems
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