Performance of the tobacco aphid Myzus persicae (Hemiptera : Aphididae) on Oriental and Virginia tobacco varieties

Abstract

1 The life parameters of one red and one green clone of Myzus persicae reared on 11 Oriental tobacco type varieties (KP7, K63, KZ10/z, MA13/b, BX2/a, N34/4, KP14/a, Kolindros, S79, TA21 and BX81) and on five Virginia ones (VE9, VE3, SPG28-VE2, Kleio-KN1 and Niki-NK3) at 20degreesC and LD 16: 8 h were examined. 2 In general, the clones, performed better on Oriental than on Virginia type varieties. The varieties TA21 and Kolindros could be considered as the most resistant among the Oriental ones. Aphids on Virginia varieties showed longer developmental time (9.1-9.6days), a lower intrinsic rate of increase (0.2347-0.2647) and higher nymphal mortality (27.9-52.5%) than on Oriental varieties. The corresponding values in the latter were 7.3-9.0 days, 0.2784-0.3302 and 10.0-47.9%. 3 The leaves of Virginia type varieties (188-471 hairs/cm(2)) and one Oriental (K63) 273 hairs/cm(2) were more hairy than the other Oriental type varieties (61-150 hairs/cm(2)). The Virginia type varieties showed also a lower level of reducing sugars (3.5-7.2%) than the Oriental ones (7.0-9.8%). Trichome density and level of reducing sugars were significantly negatively correlated with developmental time and intrinsic rate of increase. 4 An interclonal variation in performance, possibly related to the colour of aphids, was observed. The red clone performed better than the green one. The same trend was observed when the results of the previous clones on the variety KP14/a were analysed with the data obtained on the same variety from two other clones (one red and one green).