STUDY CASE 02
Varroa research in Brazil
Jong (1), L.S. Gonçalves (2)
The parasitic honey bee mite, Varroa jacobsoni, was first found in Brazil in 1978, and has been the subject of an extensive research program since 1979. Despite considerable economic and political pressure, due to the grave consequences for apiculture in the rest of the world, Brazilian experts avoided the immediate application of control measures. Some of the available chemical controls were tested in Rio Claro, SP, while research on the economic impact of infestations, population dynamics and other biological parameters began in Ribeirão Preto, SP. An attempt was made to establish an economic injury level.
However, the varroa infestations developed much differently from what was known for Europe at that time. While initial infestations quickly reached many thousands of mites, more than 50 mites per 100 bees in many cases, they fluctuated seasonally, never were found to kill any colonies, and within a period of a few years, reached relatively low levels of about five mites per 100 adult bees. We were never able to demonstrate economically measurable damage, so treatments were not recommended or used, except experimentally. Nevertheless Varroa jacobsoni is found in all honey bee colonies, and the interesting contrast between the catastrophic situation in much of the rest of the world and the relatively uneventful coexistence between mites and bees found in Brazil has maintained our interest in investigating this mite and has stimulated considerable collaboration with researchers from other countries, especially Germany and the U.S.A.
Since the research on varroa in Europe in the 80s was concentrated basically on finding ways to control this mite, much of the early information available on varroa biology and its interaction with honey bees, came from Brazil. Since 1979 Varroa jacobsoni has been the subject of numerous M.Sc. and Ph.D. thesis projects. Major research themes include cytogenetics, embryology, reproduction, brood cell invasion behavior, honey bee defensive behavior, comparisons between the development of infestations in Africanized versus European bees, honey bee aggression towards the mites, damaged mites, infested brood removal, the effect of climate and selection of more resistant or tolerant lines. We can say that today (2003) the Brazilian beekeepers have no problems with this mite and we do not recommend any chemical control. Even though the lack of an important economic impact has eliminated any urgency towards dedicating resources to studying this mite, Brazilian researchers will continue to study Varroa jacobsoni (actually called Varroa destructor) to determine how the bees in Brazil can survive without treatments, as part of a world-wide effort to find an effective solution that will eliminate the need to apply chemical controls.
Index terms: Apis mellifera, Varroa jacobsoni and Varroa destructor tolerance, honey bee, Africanized bee.See also: Case Study 01: Review on Africanized Honey Bees (AHB) in Brazil