-A one year study was conducted to evaluate the population growth of three kinds of honey bee colonies and Varroa destructor mites in Mexico, and to estimate the relative contributions of three resistance mechanisms of the bees: hygienic behavior, grooming behavior, and reproductive ability of the parasite. Very significant changes over the year were observed in the number of mated female offspring produced per mother mite (Wr), mite fertility and mutilation of V. destructor. These changes were correlated to the total number of mites per colony. A factorial analysis showed that two mechanisms explained the variation in the amount of mites per colony: Wr (r 2 = 0.73) and proportion of mutilated mites (r 2 = 0.51). A multi-factorial model including these two mechanisms was significant (r 2 = 0.97). The mite fecundity and the hygienic behavior could not explain the population changes of the mite, and the different kinds of bees showed no differences in the expression of the resistance mechanisms.Varroa destructor / Africanized honeybees / mite reproduction / hygienic behavior / grooming behavior / resistance / population growth

-The knowledge generated from several studies conducted in Mexico on the susceptibility of European and Africanized honey bees to Varroa jacobsoni is reviewed and compared with the situation in Brazil. There is evidence of genotypic variation for mite population growth, and for tolerance to the mite in honey bee colonies located in Mexico. However, Mexican honey bees seem to be relatively less tolerant to the parasite than bees in Brazil. The main difference is that mite fertility rates in Mexico are higher than those reported from Brazil. Hypotheses for why the situation is different in Mexico than in Brazil are discussed. © Inra/DIB/AGIB/Elsevier, Paris Varroa jacobsoni / tolerance / Apis mellifera / Africanized bee / Mexico

Foraging activity of bees is currently disturbed by treatments with pyrethroid agrochemicals. To discover eventual troubles of spatial orientation of the foragers, we exposed bees to sublethal doses of deltamethrin sufficiently low to avoid motor incoordination or muscular troubles. In an insect‐proof tunnel, bees were trained to forage at a feeder 8 m from their nucleus. When temperature and global radiance conditions were optimal, some foragers were caught, exposed to a deltamethrin dose 27 times lower than its LD50, and released after 20 min of recovering. Among the contaminated bees, 54% took flight toward the sun and 81% did not come back to their nest within 30 s (which is 3 times longer than the mean time of control bees). Because pyrethroids are known to disturb learning and memory, we cannot conclude if this disorientation is due either to a trouble of information storage (wrong spatial perception or phototropism increase), or to a trouble of information retrieval (bad comparison of actual and memorized patterns). Routine chemical analysis of exposed bees does not detect residues of deltamethrin 3 h after bee sublethal exposure, although bees evidenced alteration in the flight.

Summary Traditional tropical agriculture often entails a form of slash‐and‐burn land management that may adversely affect ecosystem services such as pollination, which are required for successful crop yields. The Yucatán Peninsula of Mexico has a >4000 year history of traditional slash‐and‐burn agriculture, termed ‘milpa’. Hot ‘Habanero’ chilli is a major pollinator‐dependent crop that nowadays is often grown in monoculture within the milpa system.We studied 37 local farmers’ chilli fields (sites) to evaluate the effects of landscape composition on bee communities. At 11 of these sites, we undertook experimental pollination treatments to quantify the pollination of chilli. We further explored the relationships between landscape composition, bee communities and pollination service provision to chilli.Bee species richness, particularly species of the family Apidae, was positively related to the amount of forest cover. Species diversity decreased with increasing proportion of crop land surrounding each sampling site. Sweat bees of the genus Lasioglossum were the most abundant bee taxon in chilli fields and, in contrast to other bee species, increased in abundance with the proportion of fallow land, gardens and pastures which are an integral part of the milpa system.There was an average pollination shortfall of 21% for chilli across all sites; yet the shortfall was unrelated to the proportion of land covered by crops. Rather, chilli pollination was positively related to the abundance of Lasioglossum bees, probably an important pollinator of chilli, as well indirectly to the proportion of fallow land, gardens and pastures that promote Lasioglossum abundance. Synthesis and applications. Current, low‐intensity traditional slash‐and‐burn (milpa) agriculture provides Lasioglossum spp. pollinators for successful chilli production; fallow land, gardens and pasture therefore need to be valued as important habitats for these and related ground‐nesting bee species. However, the negative impact of agriculture on total bee species diversity highlights how agricultural intensification is likely to reduce pollination services to crops, including chilli. Indeed, natural forest cover is vital in tropical Yucatán to maintain a rich assemblage of bee species and the provision of pollination services for diverse crops and wild flowers.

-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

The Africanization of the honeybee (Apis mellifera) in South America is one of the most spectacular examples of biological invasions. In this study, we analyzed the Africanization process in Central Mexico along an altitudinal transect from 72 to 2800 m, using both mitochondrial and nuclear DNA markers. The mitochondrial analysis revealed that the two high-altitude populations had a significantly greater percentage of African mitotypes (95%) than the three lowland populations (67%), indicating successful spreading of Africanized swarms to these altitudes. All populations (highland and lowland) had a similar overall proportion of African alleles at nuclear loci (58%). Thus, all populations showed an asymmetric introgression of African nuclear and mtDNA. Colonies with African mitotypes had, on average, significantly more African nuclear alleles (60%) than those with European mitotypes (51%). Furthermore, the three lowland populations showed clear signs of linkage disequilibrium, while the two high-altitude populations did not, indicating recent genetic introgression events into the lowland populations.

The Latin American subcontinent contains some of the world's major honey producing and exporting countries, but the status of bee health in this part of the world has not been clearly documented. There have been no reports of massive colony losses in Latin America, at least from the symptoms of CCD (colony collapse disorder) or in the proportion and extent of the situations in the US and Europe. We examine possible reasons for the difference, and develop hypotheses that this prevailing good bee health could be due to: (1) the management of generally unselected bees with a certain natural resistance to diseases (tropical regions) or the selection of disease resistant bees (temperate regions); (2) a lower proportion of cropland over the total land area, resulting in more abundant or higher-quality pollen resources for bees;(3) the generally small-scale, low-income and little subsidized agriculture, and concomitant lower use of insecticides compared to industrialized countries. These general parameters may act synergistically, resulting in a large number of configurations across the tremendous ecological, social and economic diversity of Latin America. We suggest that the health of honey bees in Latin America may be ultimately due to the practices of low-income agriculture and beekeeping in the region, leading to more sustainable conditions for the bees. However the increasing trend of land use intensification in some parts of Latin America could lead to declines in honey bee health and population size. honey bee health / colony losses / disease resistance / genetic diversity / pollen nutrition

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.