Temperature-Dependent Pathogenicity of the X-Disease Mycoplasma-Like Organism to its Vector, Paraphlepsius irroratus (Homoptera: Cicadellidae

Abstract

The effect of the X-disease mycoplasma-like organism (MLO) on the longevity of Paraphlepsius irroratus (Say) was investigated at four fluctuating temperatures averaging 15, 20, 25, and 30°C. The X-disease MLO in diseased leafhoppers was assayed with a radiolabeled cDNA probe. At the two lower temperatures, the X-disease MLO is pathogenic to P. irroratus . At 15 and 20°C, healthy leafhoppers lived 62 ± 16 ( |$\bar x$| ± SE) and 52 ± 22 d, respectively, whereas X-diseased leafhoppers lived 35 ± 21 and 23 ± 9 d, respectively. In the 25–30°C temperature range, MLO pathogenicity was masked by the temperature effect on leafhopper survival. At 25 and 30°C, longevity of healthy leafhoppers was 15 ± 9 and 7 ± 3 d, respectively, whereas X-diseased leafhoppers lived 14 ± 4 and 7 ± 4 days, respectively. Below 20°C, the MLO accounted for a 32% reduction in leafhopper longevity compared with <6% above 25°C. The MLO acquisition ranged from 32.4 to 36.9% with no difference ( P ≤ 0.05) between temperature regimes.