TEMPERATURE-DEPENDENT PATHOGENICITY OF THE X-DISEASE MYCOPLASMA-LIKE ORGANISM TO ITS VECTOR, PARAPHLEPSIUS-IRRORATUS (HOMOPTERA, CICADELLIDAE)

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-degrees-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-degrees-C, healthy leafhoppers lived 62 +/- 16 (xBAR +/- SE) and 52 +/- 22 d, respectively, whereas X-diseased leafhoppers lived 35 +/- 21 and 23 +/- 9 d, respectively. In the 25-30-degrees-C temperature range, MLO pathogenicity was masked by the temperature effect on leafhopper survival. At 25 and 30-degrees-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-degrees-C, the MLO accounted for a 32% reduction in leafhopper longevity compared with < 6% above 25-degrees-C. The MLO acquisition ranged from 32.4 to 36.9% with no difference (P less-than-or-equal-to 0.05) between temperature regimes.