-The case of a host-parasite relationship may provide a good model to evaluate the costs and benefits of some behaviors, an area in which field data a currently lacking. European (EHB) and Africanized (AHB) honey bees are two Apis mellifera subspecies that coexist in Mexico, the former highly compatible with Varroa destructor, the latter less compatible. Here we examine two mechanisms that could explain the low compatibility between AHB and V. destructor in Mexico: (1) grooming behavior appeared significantly more intensive in AHB colonies, but was nevertheless ineffective; (2) EHB removed 8.03% of the infested brood, while AHB removed 32.46%, especially between 5 and 7 days post-capping. Though the cost of removing infested brood was not different between subspecies, the result, in terms of the amount of removed infested brood, was significantly higher for AHB. For both bees, there is thus a real cost, since removing a pupa results in a lower number of adult bees. We discuss the possibility that the removal of infested brood corresponds with a threshold above which the cost of removal becomes greater than the benefit.Apis mellifera / Varroa destructor / parasitology / costs and benefits / behavioral resistance

We investigated the relationships between the honey bee, Apis mellifera, and the parasitic mite Varroa jacobsoni in Mexico. In an 18-month survey of European honey bees (EHB) and Africanized honey bees (AHB), we showed that EHB were highly compatible with V. jacobsoni, while AHB were not as compatible. Furthermore, mite infertility ("parasite infectivity" factor), suspected to be the main factor of low AHB/V. jacobsoni compatibility in Brazil, was not observed in Mexico. The "intrinsic rate of natural increase" of mites did not differ significantly between host subspecies, indicating that the cause of low compatibility appears only at high parasite densities. The "carrying capacity" was twice as high in EHB as in AHB, indicating that the cause of low compatibility is possibly linked to honey bees' behavior. We hypothesize that the reason why V. jacobsoni is highly fertile on Mexican AHB (whereas it has low fertility on Brazilian AHB) may be that different strains of V. jacobsoni exist in the two countries.

SVarious insects, especially social insects, possess electric charges. Erickson (1982,1983) shows their involvement in the odor receptor efficiency of honey bee antenna. Also, the author suggests the importance of charges in the transfer of pollen grains from flowers to pollinator insects. To measure directly electric charges, we fit a sensor used to determine the charges of raindrops. Strongly clustered wintering bees and foraging bees were rne.asured. The individual values range between -4OOpC to +600pC (m = 153 +/-105pC) during winter time. The foraging bees possess variable charges, generally 17 Copyright @ 199 1 by Marcel Dekker, Inc Electromagn Biol Med Downloaded from informahealthcare.com by Chinese University of Hong Kong on 12/25/14 For personal use only.i a COLIN, RICHARD, AND CHAUZY smaller than wintering bees (m = 29 +I-40pC). 7.0% of measured bees whole are charged negatively and less than 1% of these have no charges. The presence of electric charges throughout bees yearly cycle is significant for the insect society. Moreover electric forces contribute to explain some aspects of bee-parasite relationships.

The efficiency of Labiatae essential oils was compared with a classical aerosol treatment, including the acaricidic substance amitraz at the 0.25 concentration. The tested concentrations of the experimental mixture were 1 YO of thyme (Thymus vulgaris L.) and 0.5 YO of sage (Salvia oflicinalis L.). These products were also injected into each colony by the aerosol way for one minute. 4 applications in an interval of 3 or 4 days constitute the treatment. The dead mites (Varroajacobsoni Oud.) were counted everyday. The number of surviving mites was estimated by means of a fluvalinate control treatment. No difference in the lobal efficiency was found for the moderately infested colonies (less than 1300 mites, a few mutilatef pu ae), which contained a small brood area. A weak grade of post-therapeutic residues in honey was onry detected by gas chromatography just after aerosol administration.

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