[Host selection of ectoparasitic gamasid mites on Tylonycteris pachypus and T. robustula]

Correlations of two species of gamasid mites (Macronyssus pararadovskyi and M. radovskyi) and their bat hosts (Tylonycteris pachypus and T. robustula) were studied by field surveys and indoor behavioral experiments. The wild data indicated that mite load was positively correlated with body condition index of female T. pachypus hosts (Spearman: r (s)=0.55, P<0.01, n=24). Whereas, mite loads had no correlation with body condition indexes of male T. pachypus and all T. robustula hosts (P>0.05). Indoor original host infection showed that mites preferred male T. pachypus and T. robustula hosts. The infection percentages on male hosts were significantly higher than those on female hosts [T. pachypus: male (58±12)%, female (42±12)%, (t=-3.6, df=31, P<0.01); T. robustula: male (63±11)%, female (37±11)%, (t=-6.1, df=26, P<0.001)]. Using M. pararadovskyi (original host T. pachypus) to across infect T. pachypus and T. robustula, we found that mites significantly preferred the original host (t=9.1, df=29, P<0.001). The infection percentages of T. pachypus, and T. robustula were (71±13)% and (29±13)%, respectively. Our results indicated that mite loads of the two bat species were not correlated with body condition indexes of hosts. However, these mites presented different host sexual preferences, and the mites of T. pachypus presented specific host species preferences.