59-05-032 Proceeding

370 Proceedings of the Princess Maha Chakri Sirindhorn Congress and have co-evolution. This bee species can limit the population growth of T. mercedesae in its colony by developingmany defensivemechanisms such as colonymigrations, grooming behavior, hygienic behavior and broodless periods (Wongsiri et al., 1989; Burgett and Rossignol, 1990; Rath and Delfinado-Baker, 1990; Koeniger et al., 1993, 2002; Kavinseksan et al., 2003; Woyke et al., 2004; Kavinseksan, 2006, 2011; Khongphinitbunjong et al., 2012). The result here showed that A. dorsata has developed a high level of genetic trait to be resistant to its natural parasite by limiting the reproduction of T. mercedesae . Non-reproduction of mites is a mite-bee interaction in colonies in which mites show impaired reproductive ability (Anderson, 1994). The cause of this non-reproduction is exactly unknown. However, evidence suggests that certain factors can be possible causes. Harbo andHarris (1999, 2001) reported that a genetic characteristic of bees causedmites to become non-reproductive and is a heritable characteristic of honeybees. Chemicals from larva and prepupa’s haemolymph stimulate Varroa mites to produce and lay eggs (Harris andHarbo, 2001). Several researchers have reported on the role of juvenile hormone as a trigger for Varroa mite reproduction. Exogenous application of juvenile hormone to bee larvae increased reproduction of Varroa mites (Hanel, 1983, 1986; Hanel and Koeniger, 1986). However, endogenous juvenile hormone titers are similar in bee larvae from races and species of bees that differ dramatically in their abilities to support mite reproduction (Rosenkranz et al., 1989, 1993). Woyke (1989) reported that the thickness of T. mercedesae females in brood cells after cell sealing 48 to 96 h increased to be double of mites moving freely on the combs because they feed on haemolymph of larva and pupa bees. Hence, it is possible that some substances in bee’s haemolymph may affect reproduction of T. mercedesae . However, the affect of juvenile hormone in bee’s blood to reproduction of T. mercedesae has not been studied. From the data obtained, 98.6% of non-reproductive mites did not lay eggs (Table 2). This suggests that non-reproduction could be related to non-mating of the mites. T. mercedesae mates by podospermy and multiple mating was observed in males whereas such a circumstance was not found in females (Rath et al., 1991). Harris and Harbo (2001) reported that many non-laying egg Varroa mites had no stored sperm, and Varroa females used the stored sperm to produce eggs after entering brood cells for reproductive cycles. Possibly, non-laying egg Tropilaelaps femalesmay not mate or fail to store sperm like in non-laying egg Varroa females. Various environmental factors affect the percentage of non-reproductive Varroa mites in colonies of bees. High temperatures and relative humidity increased the percentage of non-reproductive Varroa mites (Le Cont et al., 1990; Kraus and Velthuis, 1997). A higher percentage of non-reproductive Varroa mites occurred in colonies from tropical climates than in those from moderate climates (Harris and Harbo, 2001). However, the affect of environmental factors to non-reproductive Tropilaelaps mites in bee colonies has yet been studied. In this study, 1.4% of non-reproductive mites produced too young progeny to mature before emerging of the host bee (Table 2). This finding was inconsistent with the previous report by Ritter and Schneider-Ritter (1988) that all T. mercedesae offspring could develop to be adults