José Javier G. Quezada-Euán

Paternity frequency and maternity of males in some stingless bee species

In monogynous hymenopteran societies, the number of mates of a queen strongly influences the potential for conflict between workers and queens over the maternity of males. Queens always ‘prefer’ their own sons to sons of workers, regardless of queen mating frequency. When a queen mates once, workers are more closely related to, and therefore are expected to prefer, their own sons and then sons of sisters to sons of the queen. However, if effective paternity frequency exceeds 2, workers on average should prefer queen‐produced males to males produced by their sisters. We studied the queen mating frequency of seven stingless bee species: the Mexican species Scaptotrigona mexicana, S. pectoralis and the Australian species Austroplebeia symei, Trigona clypearis, T. hockingsi, T. mellipes and T. sapiens. We then determined whether males arise from eggs laid by workers or queens in A. symei, T. clypearis, T. hockingsi and T. mellipes. We show that all seven species investigated are most likely singly mated and that the queen dominates reproduction. This indicates that the queens mating frequency alone does not determine whether workers or the queen produces the males.

Meliponiculture in Mexico: problems and perspective for development

Beekeeping with stingless bees (meliponiculture) in Mexico is an ancient tradition which today is in the process of disappearing as a consequence of changes in cultural, economic and ecological factors. This article reviews the historical background of meliponiculture as well as its potential uses in Mexico. Meliponiculture could be revived, providing an important source of income for peasant farmers in areas where the use of Africanized honey bees is restricted, provided technical and marketing problems are solved. We outline the current weaknesses and the changes needed to exploit these bees to their full potential for honey and wax production and use in other activities such as pollination.

Morphological and molecular characters reveal differentiation in a Neotropical social bee, Melipona beecheii (Apidae: Meliponini)

Morphometrics and DNA microsatellites were used to analyse the genetic structure of populations of the stingless bee M. beecheii from two extremes of its geographic range. The results showed that populations from Costa Rica and Yucatan exhibit substantial phenotypic and molecular differentiation. Bees from Yucatan were smaller and paler than those from Costa Rica. The value of multilocus FST = 0.280 (P < 0.001) confirmed that there were significant molecular genetic differences between the two populations. Populations showed significant deviation from Hardy Weinberg equilibrium and the values of FIS (the inbreeding coefficient) were positive for Costa Rica = 0.416 and the Yucatan Peninsula = 0.193, indicating a lack of hétérozygotes in both populations possibly due to inbreeding. The DNA sequence of 678 bp of the mitochondrial gene COI differed between populations by 1.2%. The results of this study should be considered in conservation programmes, particularly with regard to the movement of colonies between regions.ZusammenfassungDie über 400 Arten umfassenden pantropisch verbreiteten Meliponini sind vergleichsweise wenig untersucht, insbesondere gibt es nur wenige Studien zur Populationsstruktur. Die Art Melipona beechei weist eine geographische Verbreitung von Mexiko bis Costa Rica auf (Abb. 1), so dass es möglich ist, dass lokal adaptierte Ökotypen existieren. Wir nutzen einen morphometrischen Ansatz, sowie DNA Mikrosatellitenloci und Gensequenzen mitochondrialer DNA um die Populationsstruktur von M. beecheii an den Extrempunkten der geographischen Verbreitung zu untersuchen.Die Bienen wurden 1998 an sieben Orten auf der Halbinsel Yucatan (65 Völker) und an einem Ort in Costa Rica (15 Völker) gesammelt. Elf Morphometriemerkmale am Kopf, an Flügeln und Beinen wurden an 10–12 Arbeiterinnen pro Volk vermessen und die einzelnen Standorte wurden mittels ANOVA (gefolgt von Tukey post hoc Tests) verglichen. Populationsunterschiede in Farbmarken am Kopf (Abb. 2) wurden mittels Kontingenz G-Test herausgearbeitet. Anschliessend wurde eine Hauptkomponentenanalyse (PCA auf der Basis einer Korrelationsmatrix) mit allen log-transformierten metrischen Merkmalen durchgeführt.Sechs Mikrosatellitenloci (T4, T7, Mbill, Mb201, B116 und B124) wurden an jeweils einer Arbeiterin pro Volk untersucht. Zusätzlich wurden 678 Basenpaare des mitochondrialen Gens COI für jeweils zwei Individuen aus Costa Rica und Yucatan sequenziert. Die Verknüpfung (linkage) der Mikrosatellitenloci wurde mittels des Programmpakets GENEPOP Version 3.1. getestet. Die Allelfrequenzen und beobachtete sowie Nei’s (1978) unabhängige Erwartungswerte für Heterozygotie an jedem Mikrosatellitenlocus wurden für jede Population mittels des FSTAT Programmpakets ermittelt. Die effektive Anzahl an Allelen (na) wurde als na = 1/gSpi2 berechnet, wobei pi die Frequenz des i-ten Allels darstellt. Abweichungen vom Hardy-Weinberg-Gleichgewicht an jedem Locus und für jede Population wurden mittels in GENEPOP verfügbaren exakten Tests in einem Markov Ketten-Ansatz ermittelt. Der unabhängige Multilocus-Schätzwert für FST zwischen Populationen wurde benutzt, um die Signifikanz der genetischen Differenzierung mittels FSTAT herauszuarbeiten und um den jeweiligen Inzuchtgrad FIS und seine Konfidenzintervalle zu berechnen.Die Populationen aus Costa Rica und Yucatan zeigten eine erhebliche phänotypische und genetische Differenzierung. Dabei bildeten die Völker aus Yucatan eine homogene Gruppe, die sich deutlich (als kleiner und weniger farbkräftig) von den Costa Rica Völkern unterschied (Tab. I, II; Abb. 3). Der Multilocus Wert für FST = 0,280 (P < 0,001) belegt die signifikante molekulargenetische Differenzierung zwischen den beiden Populationen (Tab. IV). Beide Populationen zeigten erhebliche Abweichungen vom Hardy-Weinberg Gleichgewicht. Die FIS — Werte für Costa Rica = 0,416 (P < 0,05) und Yucatan = 0,193 (P < 0,05) waren hochsignifikant, was auf ein vermutlich inzuchtbedingtes Fehlen an Heterozygoten hinweist. In den DNA-Sequenzen für COI unterschieden sich die beiden Populationen um 1,2 %. Die Ergebnisse der vorliegenden Studie sollten in Konservierungsprogramme Eingang finden, vor allem dann, wenn der Austausch von Völkern zwischen Regionen in Betracht gezogen wird.

Comparative toxicity of pesticides to stingless bees (Hymenoptera: Apidae: Meliponini).

ABSTRACT Stingless bees are potential pollinators of commercial tropical crops and their use may increase in the short term. However, studies comparing the toxicity of pesticides to different individuals and species are lacking, making it difficult to evaluate their short- and long-term effects on colonies and populations of these insects. In this work, we tested the lethality of compounds from the main pesticide groups on stingless bees of the species Melipona beecheii Bennett, Trigona nigra Provancher, and Nannotrigona perilampoides Cresson. The LD50 (in micrograms per bee) for each pesticide was calculated for callow workers and foragers of the three species as well as for gynes and drones of M. beecheii. The results showed that all species were highly susceptible to the evaluated compounds. Nicotinoid pesticides were the most toxic, followed in descending order by permethrin, diazinon, and methomyl. We found evidence of a relationship between the body weight of the species and their LD50 for permethrin and methomyl (r = 0.91 and 0.90, respectively) but not for diazinon (r = -0.089). An analysis of contingency tables showed that within each species, callow workers had higher mortalities than foragers (P < 0.01). In M. beecheii at similar pesticide dose more males died compared with females [&khgr;2(0.01),1 = 10.16]. However, gynes were less resistant than workers [&khgr;2(0.01),1 = 8.11]. The potential negative consequences of pesticides to native stingless bees are discussed considering the reproductive biology of these insects. It is important to take actions to prevent damage to these key species for the ecology and agriculture of México and Latin America.

Geometric morphometrics of the wing as a tool for assigning genetic lineages and geographic origin to Melipona beecheii (Hymenoptera: Meliponini)

The stingless bee Melipona beecheii presents great variability and is considered a complex of species. In order to better understand this species complex, we need to evaluate its diversity and develop methods that allow geographic traceability of the populations. Here we present a fast, efficient, and inexpensive means to accomplish this using geometric morphometrics of wings. We collected samples from Mexico, Guatemala, El Salvador, Nicaragua, and Costa Rica and we were able to correctly assign 87.1% of the colonies to their sampling sites and 92.4% to their haplotype. We propose that geometric morphometrics of the wing could be used as a first step analysis leaving the more expensive molecular analysis only to doubtful cases.

Production of greenhouse tomatoes (Lycopersicon esculentum) using Nannotrigona perilampoides, Bombus impatiens and mechanical vibration (Hym.: Apoidea)

Importation of exotic bumblebees for greenhouse pollination may be restricted in México, thus making it necessary to evaluate the potential of native species as pollinators in enclosures. We studied the foraging activity and fruit production of tomato using one colony of Nannotrigona perilampoides (NP) and one colony of Bombus impatiens (BI) in greenhouses with ≈1000 plants. Mechanical vibration (MV) was included as a test treatment.

Evidence of continued European morphometrics and mtDNA in feral colonies of honey bees (Apis mellifera) from the Yucatán peninsula, Mexico.

SUMMARYSixty-five samples of honey bee (Apis mellifera) workers from feral colonies across the Yucatan peninsula, Mexico, were analysed for morphometrics and mtDNA using polymerase chain reaction. Diverse associations between morphotypes and mitotypes were found across the sampled area. Although the feral population now comprises mainly (54%) pure African colonies showing no evidence of European introgression, there is a frequency of European mitotypes in feral colonies (20%). The high frequencies of continued European markers in the feral population of honey bees from the Yucatan could be explained by the population size of resident European honey bees. Further monitoring is necessary to document the persistence of such markers in the feral population and to determine whether there will be a complete replacement of European honey bees by Africanized ones.

The distribution and range expansion of Africanized honey bees (Apis mellifera) in the state of Yucatan, Mexico

SUMMARYAfricanized honey bees (Apis mellifera) first arrived in the neotropical Mexican state of Yucatan in 1987. We documented the distribution and spread of Africanized honey bees at 15 localities across Yucatan by sampling worker honey bees from more than 280 managed colonies per year from 1990 to 1994, and from over 60 feral colonies per year at the same localities from 1992 to 1994. Colonies were classified morphometrically, using the criteria of Rinderer et al. (1993a) for managed colonies and using modified probabilities for feral colonies. Africanized honey bees spread from the south, and by 1991 were found throughout Yucatan in managed colonies. By 1994, 52% of managed colonies were classified as pure Africanized and, assuming linearity in the rate of Africanization, all managed colonies are projected to be Africanized by mid-1997. Feral colonies showed evidence of Europeanization in 1992 but, by 1994, they were classified as Africanized. The slower pace of Africanization of managed colonies than...

Genetic and phenotypic differentiation in endemic Scaptotrigona hellwegeri (Apidae: Meliponini): implications for the conservation of stingless bee populations in contrasting environments

Abstract.  1. The western forests of Mexico are rich in species of stingless bee, possibly a consequence of the diverse habitats found across different altitudes of the Trans‐Mexican Volcanic Belt (TMVB) and the Pacific coast (PAC).

Contribution of native bees and Africanized honey bees (Hymenoptera:Apoidea) to Solanaceae crop pollination in tropical México

In the tropics the contribution of bees as pollinators of important economic indigenous crops remains largely undocumented. We studied the diversity of bee species visiting indigenous tomato (Solanum lycopersicon) and habanero pepper (Capsicum chinense) in subtropical Yucatán, México. The contribution of two native bees, Exomalopsis (E) and Augochloropsis (AG) was compared with that of the introduced Africanized Apis mellífera (HB) for pollinating unvisited flowers in both crops. Apis mellífera and stingless bees were dominant in habanero pepper but solitary bee species were important visitors of tomato. In spite of both crops being autogamic, there was a significant contribution of native bees for pollination of both tomato and habanero pepper. The comparison of fruit weight, number of seeds, and a pollination index based on the latter showed that E and AG were more effective pollinators compared to HB in both crops (ca. Spear’s index of ca. 0.7 vs. 0.35 respectively). In tomato, a further evaluation of the contribution to pollination provided by the three bee species was made using the rate of visits to flowers. Although E and AG were the most efficient pollinators at single flower visits in tomato, none of the three species (including HB) were able to provide single visits to all flowers per unit time to the crop. Our results underline the importance of maintaining diverse assemblages and abundant populations of bee species that can synergically contribute to the productivity of tomato and hot pepper in the Neotropics.