Sex determination in honey bees (Apinae and Meliponinae) and its consequences

Abstract

The first experiments on sex determination in bees began with Dzierzon, Meves, Nachtsheim, Paulcke, Petrunkewitsch, Manning. Whiting, (1943) found multiple alleles in Bracon xo that are the Rosetta stone of sex determination in Hymenoptera. Whiting also discovered that some species of microhymenoptera do not possess xo sex alleles. Therefore, Hymenoptera apparently presents two types of sex determination superimposed on haplodiploidy. In the panmictic groups hemizygous (xo1, xo2,... xon) and homozygous (xo1xo1, xo2xo2... xonxon) are males while heterozygous (xo1xo2, ... xon-1xon) are females. There is no such series of xon in endogamous Hymenoptera, since the constant elimination of diploid males would be damaging to the population and the mutation of xo to xon would be quickly eliminated. Besides the Whiting hypothesis, four others are discussed. The new hypothesis of genomic imprinting, of Beukeboom, is eliminated since: a) spermatozoa that develop within the egg produce male tissue; b) telitokous parthenogenesis due to the fusion of two haploid cells develop into females; c) last instar larvae treated with juvenile hormone become queens. The Cunha and Kerr hypothesis (female determining genes are totally or partially additive and male determination is totally or partially nonadditive) explains all known cases. The xo is a female determining gene. Sex determination in social bees led to the gradual evolution of two systems of caste determination: one in which queens and workers are similar and males are very different (Apinae), and another in which workers and males are very similar and both very different from the queens (Meliponinae). This second system in stingless bees implies that many of the mutations that improve worker capacities also affect the males that will carry out some activities that in Apis are clearly female ones. Ten of these activities are described.<br>São relatados os primeiros experimentos sobre determinação do sexo em abelhas, iniciando com os de Dzierzon, Meves, Nachtsheim, Paulcke, Petrunkewitsch e Manning. Whiting descobriu em Bracon alelos múltiplos xo que são considerados a pedra Rosetta da determinação do sexo em himenópteros. O próprio Whiting constatou que algumas espécies de micro-himenópteros não têm alelos múltiplos xo1 a xon. Logo, nos himenópteros há aparentemente dois tipos de determinação do sexo superpostos a haplodiploidia. Nos panmíticos há uma série de genes xo1, xo2 ... xon para os quais os hemizigotos xo1 a xon e homozigotos, xo1xo1 até xonxon são machos e os heterozigotos xo1xo2, até xon-1xon são fêmeas. Nos endogâmicos não há essa série de alelos múltiplos, pois a mutação de xo para xn é rapidamente eliminada, a não ser quando o heterozigoto for muito mais viável. Além da hipótese básica de Whiting, discutem-se outras 4 hipóteses que tentam explicar a genética da determinação do sexo nos Hymenoptera. A nova hipótese, da impressão genômica, de Beukeboom, é eliminada pelos seguintes fatos: a) espermatozóides que se desenvolvem em ovos dão origem a tecidos masculinos;...

Workers of the stingless bee Melipona scutellaris are more similar to males than to queens in their cuticular compounds

“…Yet, also, in meliponines, the endocrine system affects caste development, indicating that juvenile hormone became, through many evolutionary steps, gradually more important in expressing femaleness genes in queens, making queens become more different from workers. In line with this argument, workers would also become phenotypically more similar to males (Bonetti and Kerr, 1985;Bonetti et al, 1994;Kerr, 1997).…”

“…There are two modes of caste determination in eusocial bees (Kerr, 1950;1975;Rachinsky et al, 1990;Hartfelder and Rembold, 1991;Kerr, 1997). In Apinae the development of the queen and workers depends on the quantity of food delivered.…”

“…CruzLandim (1963) performed histological studies on the male wax glands and found a striking resemblance between male and worker wax gland morphology. Males are also able to work with the produced wax inside the hive, they collect wax, put it in wax deposits and are even capable of using it for the construction of wax pillars (Kerr, 1997).…”

Sex determination and inbreeding depression in an ant with regular sib-mating

“…Furthermore, selection would be too weak to maintain heterozygosity at many loci, unless they had pleiotropic effects (Crozier, 1971;Bull, 1983), making ml-CSD unlikely. Genomic imprinting (Beukeboom, 1995), genic balance (Cunha and Kerr, 1957;Kerr, 1997), and the maternal effect model (Crozier, 1971;Cook, 1993a) are attractive alternative hypotheses for sex determination in C. obscurior, but cannot be tested without appropriate cytogenetic markers, such as the parental sex ratio chromosome in Nasonia (Beukeboom and Werren, 2000). Unfortunately, such markers are not available for ants.…”

Population structure, mating system, and sex-determining allele diversity of the parasitoid wasp Habrobracon hebetor

“…First, large populations with random mating should harbour many sex-determining alleles because frequency-dependent selection favours alleles when they become rare. Hymenoptera commonly have six or more sex-determining alleles (Whiting, 1943;Adams et al, 1977;Periquet et al, 1993;Ross et al, 1993;Kerr, 1997;Heimpel et al, 1999;Butcher et al, 2000). Second, multiple mating by females decreases the variance in diploid male production among females.…”