Field and laboratory tests that associate heat with mortality of tracheal mites

SUMMARYTwelve white and 12 dark (unpainted) hives were set up in a sunny location in Baton Rouge, Louisiana, USA, on 7 May 1992. Each hive received a uniform colony of 5 048 ± 125 (mean ± s.d.) honey bees (Apis mellifera) that had been established from a single, artificially mixed population; 38% of the bees were infested with tracheal mites (Acarapis woodi). During June and July, bees produced more brood and honey in white hives than in dark hives. On 5 August, dark hives contained fewer tracheal mites than white hives; mites were found in 1 dark and 10 white hives (P < 0.001). In summer, the temperature in the space between brood combs in the dark hives often exceeded 40°C; maximum temperatures in the brood areas of dark and white hives, were 45°C and 38°C respectively. Laboratory tests showed that heat can kill tracheal mites inside live bees. A single six-hour exposure of bees to 42°C, a condition comparable to the short periods of high temperature encountered in field colonies, significantly reduced ...