Ricardo Ayala

Diversity of native bee visitors of cucurbit crops (Cucurbitaceae) in Yucatán, México

Native bees in Yucatán, México are treatened by agricultural land uses that limit their food resources, alter their reproductive habitats and increase their mortality. Various species may disappear before their importance for regional agricultural productivity and ecosystem maintenance is known. In order to assess their assemblage as visitors of cucurbit crops, we sampled more than 2000 bee specimens on fourteen fields of pumpkin, cucumber, melon and watermelon from five localities between 1995 and 1997; sample units consisted of all bees collected by net sweeping in a given field during 25–30 accumulated hours on separate days. The fourteen samples comprised bees of six families, 29 genera and 58 species. Composition per sample ranged between 10 and 27 species and abundance between 28 and 444 individuals. Seven species (six genera) of Apidae, Anthophoridae and Halictidae comprised around 80% of all the individuals collected. Yet, diversity measures indicated intermediate to high evenness in most sampled bee assemblages, i.e. despite the frequent abundance of some species of Augochlora, Partamona, Ceratina, Trigona or Peponapis, other bee visitors were also relatively important, particularly in small samples. Individual samples of pumpkin bee visitors had significantly different evenness among themselves and to other cucurbit crops. The percent similarity and number of shared species among the fourteen samples were both usually low; lumping data per crop and locality showed, however, higher evenness and more common species than individual samples. Results are discussed in terms of future research priorities: natural history of tropical native bees and strategies to monitor bee community changes for conservation purposes.

Diversity of the Family Cerambycidae (Coleoptera) of the Tropical Dry Forest of Mexico, I. Sierra de Huautla, Morelos

Abstract The cerambycid fauna of the tropical dry forest of the Sierra of Huautla, Morelos, Mexico, is described. Collections were made between November 1995 and October 1996, during 5 d of every month, and collection methods included light trapping, Malaise trapping, and netting, sweeping and beating. A total of 153 species, 91 genera, 32 tribes, and four subfamilies was recorded. The subfamily with the greatest number of species was Cerambycinae with 78, followed by Lamiinae with 67, Lepturinae with six, and Prioninae with two. The tribes with the largest number of genera and species were Trachyderini with 13 and 17 and Acanthocini with 12 and 23. The genera with the most species were Phaea Newman with 11 and Lepturges Bates with eight. Estimated richness values using the nonparametric estimators ICE and Chao 2 were 251 and 241, respectively. A few species were very abundant, but many were represented by only a few individuals. The diversity value calculated with the Shannon Index over the entire year was 3.86. Species richness and abundance varied with time, with the highest values recorded in the rainy season and lowest values in the dry season. The fauna was more similar to the fauna of Chamela, Jalisco, than to El Aguacero, Chiapas, and consists of 65% species endemic to Mexico.

Mexican Stingless Bees (Hymenoptera: Apidae): Diversity, Distribution, and Indigenous Knowledge

Stingless bees (Apinae: Meliponini) are highly eusocial apine bees commonly encountered in tropical and subtropical areas of the world but are more diverse in the Western Hemisphere. In Mexico, stingless bees represent a relatively small fraction (2.6%) of the large bee fauna of the country, but the economic, social, and cultural impacts they have are like no other in the world. When compared to other countries with more diverse stingless bee faunas, a large percentage (41.3%) of the total number of Mexican stingless bees are exploited by indigenous people in the country at least since pre-Colombian times and possibly well before. Stingless bees played a significant role in Mayan religious views and today they are directly or indirectly used for diverse purposes, including managed pollination, medicine, crafts, and folk art; while honey, wax, and pollen are regularly extracted and sold, thus providing an important source of income for indigenous and non-indigenous populations. Herein, we summarize the diversity, distribution, origin, and traditional uses of the stingless bees in Mexico. We also discuss the challenges and future directions for the study and conservation of this important lineage of bees.

A Faunal Study of Cerambycidae (Coleoptera) from One Region with Tropical Dry Forest in México: San Buenaventura, Jalisco

The results of a study of the fauna of cerambycids of the tropical dry forest of San Buenaventura, Jalisco, México are presented. The study was carried out between November, 1996 and October, 1997. The collections were carried out during five days of every month and the collection methods included light trapping, Malaise trapping and direct collecting. A total of 109 species, 76 genera, 30 tribes and 5 subfamilies were recorded. The subfamily with the greatest number of species was Cerambycinae with 62, followed by Lamiinae with 40, Lepturinae and Prioninae with three and Disteniinae with one. The tribes with the largest number of genera and species were Trachyderini with 14 and 20, Acanthocinini with nine and 18 and Elaphidiini with eight and 15. The genera with the most species were Stenosphenus Haldeman with five and Eburia Lepeletier, Sphaenothecus Dupont, Lepturges Bates and Urgleptes Dillon with four. The richness value using the non-parametric estimator ICE was 151 species. The species abundance pattern showed few very abundant species and many with few individuals. The diversity value calculated with the Shannon Index over the entire year was 3.88. Species richness and abundance varied with time, with the highest values recorded in the rainy season and lowest values in the dry season. The fauna was more similar to the fauna of Chamela, Jalisco than to Sierra de Huautla, Morelos or El Aguacero, Chiapas and consists of 37% species endemic to México.

Morphometric and genetic analyses differentiate Mesoamerican populations of the endangered stingless bee Melipona beecheii (Hymenoptera: Meliponidae) and support their conservation as two separate units

Phenotypic and molecular differences were previously found in populations of the endangered stingless bee Melipona beecheii from two extremes of its geographic range. In this study we combine the use of morphometric and molecular tools, with the aim of investigating patterns of phenotypic and molecular variation in populations across Mesoamerica. Morphometric analyses showed that bees from Mexico have significantly smaller body size compared with populations from Central America, forming two separated groups. Bayesian analysis of the ITS1 spacer of the ribosomal gene also showed the existence of two clusters: one composed by the Mexican populations, and another in which the Central American ones assembled (Guatemala, El Salvador, Nicaragua and Costa Rica). The combined results confirm the presence of two taxonomic units: one distributed in southern Mexico (ranging from the Yucatan peninsula to the north of Guatemala), and a Central American unit found from the southern part of Guatemala down to Costa Rica. These units should be considered separately under conservation programs and therefore, human assisted colony exchange between them should be avoided.

Comparative temperature tolerance in stingless bee species from tropical highlands and lowlands of Mexico and implications for their conservation (Hymenoptera: Apidae: Meliponini)

The objective of this study was to evaluate the temperature sensitivity of three stingless bee species, one from the tropical highland transition Neartic-Neotropical region (Melipona colimana) and two from the tropical lowland regions (Melipona beecheii and Scaptotrigona hellwegeri) of Mexico. The changes in thoracic temperature, behavior, and mortality rate of workers and pupae of the three species submitted to control high and low temperatures were assessed. Workers of highland M. colimana regurgitated water and fanned their wings when submitted to high temperatures, a behavior reported here for the first time in a stingless bee. M. colimana consumed syrup and increased its thoracic temperature in response to cold environment. Workers and pupae of M. colimana experienced lower mortality rates than M. beecheii and S. hellwegeri. The results of this study showed the tolerance of M. colimana to a wider temperature range, possibly as a response to extreme conditions in its native environment. The implications of thermal susceptibility differences for the conservation of highland and lowland stingless bees are discussed.

Sweat bees on hot chillies: provision of pollination services by native bees in traditional slash‐and‐burn agriculture in the Yucatán Peninsula of tropical Mexico

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.

Temporal Variation in Native Bee Diversity in the Tropical Sub-Deciduous Forest of the Yucatan Peninsula, Mexico

Native bee community diversity is known to vary temporally in the Neotropics, but little research has been done to quantify the extent of this variation. We studied monthly variation in native bee diversity in tropical semi-deciduous forest on the Yucatan Peninsula, Mexico, over a twelve-month period in 2007. Hurricane Dean traversed the study area in August of that year, causing some changes in the environment and in the native bee community. A total of 2,335 individual bee specimens were collected, belonging to 102 species from four families. The family Apidae had the highest number of species (46%) and individuals (71%). Species richness, abundance, and diversity varied throughout the study period. Species proportions of lifestyles and nesting behaviors varied from month to month, and absolute numbers changed. Low to moderate similarity values indicated high monthly species turnover, with almost half of species present for only one to two months. Species richness declined after the hurricane, with a loss of 40% of the species present beforehand, but nine new species appeared in September. The hurricane also reduced the number of solitary, parasocial, and social species, mostly those nesting in preexisting cavities and wood. Species composition in August had similarity values nearer to those of months in the dry season than to those in the rainy season. Two months after the hurricane, the native bee community had returned to previous species diversity levels, probably due to the rapid recovery of the vegetation on which the bee community depends. Effective biodiversity conservation programs will need more data on changes in vegetation community structure and how such changes influence Neotropical native bee communities after natural disturbances.

A Pentocellar Female of Caenaugochlora inermis from Southern Mexico (Hymenoptera: Halictidae)

Abstract An unusual deformity is reported for a female of the augochlorine bee Caenaugochlora (Caenaugochlora) inermis (Vachal). The individual has malformations of the vertex which resulted in two additional lateral ocelli near the compound eyes and apparently a forward contraction of the vertex shifting the ocellar triangle further into the upper frons. A brief account and figure of the specimen is provided.

Alpha and beta diversity of bees and their pollination role on Cucurbita pepo L. (Cucurbitaceae) in the Guatemalan cloud forest

Abstract. Cucurbita pepo L. (Cucurbitaceae) was an integral component of the diet of Pre-Columbian Mesoamerican cultures and is an important cash crop with high cultural value in contemporaneous indigenous populations of Guatemala. Despite the increasing attention to native bees as pollinators of cucurbit crops, little is known about the diversity of bees that visit or pollinate these crops in many regions. Based on collections from 11 observational plots of C. pepo established in five localities and maintained by the local community across the Cloud Forest Corridor in Guatemala, we documented 27 bee species belonging to 14 genera in Apidae and Halictidae as floral visitors. Species composition was significantly different among plots and among localities; however, honey bees (Apis mellifera Linnaeus, 1758) (Apidae: Apini) and the stingless bee Partamona bilineata (Say, 1837) (Apidae: Meliponini) were the most abundant flower visitors in all plots and localities, accounting up to 80% of the total number of visits. Two species of squash bees were recorded, Peponapis apiculata (Cresson, 1878) and P. limitaris (Cockerell, 1906) (Apidae: Eucerini), but they were rare (3.4% of total number of specimens) across all plots and localities. Based on pollinator exclusion experiments as well as comparisons of fruit weight and seed number and weight, we confirmed the dependence of this crop on insect pollination and the role of honey bees and P. bilineata as main pollinators in the observational plots. Surveys of bees in the surrounding vegetation of the plots indicated a higher diversity (36 species of 28 genera) than in the plots; about 40% of these species are also common visitors of flowers of C. pepo.