Guaiacum Sanctum Research Articles

La vegetación de Calakmul, Campeche, México: clasificación, descripción y distribución

La región de Calakmul, en el centro de la península de Yucatán, es de gran importancia por contener el área forestal más extensa del trópico mexicano. El objetivo de este trabajo es presentar la clasificación, descripción y distribución espacial de las comunidades vegetales de la región de Calakmul. A pesar del escaso relieve topográfico de la región, la vegetación presenta una elevada heterogeneidad espacial. Las cinco asociaciones que destacan por su relevancia regional, nacional y mundial son la selva de guayacán (Guaiacum sanctum), la selva de jobillo (Astronium graveolens), la selva baja caducifolia, la selva alta y el bajo mixto. Se discuten las principales influencias sobre la vegetación de la región, incluyendo los gradientes de precipitación, el desarrollo del suelo, los disturbios naturales y el factor antropogénico. Se subraya la la necesidad de utilizar clasificaciones de vegetación suficientemente detalladas para evaluar la representatividad y la efectividad de las áreas naturales protegidas.

Toumeyella lignumvitae, a New Species of Scale Insect from the Florida Keys (Homoptera: Coccidae)

Toumeyella lignumvitae, a new species of soft scale insect known only from lignumvitae, Guaiacum sanctum Linnaeus, trees in the Florida Keys, is described and illustrated. Lignumvitae scale feeding is seriously affecting growth of lignum-vitae trees on Lignumvitae Key. Three species of insects are often found associated with lignumvitae scale. Two species of ants, the Florida carpenter ant, Camponotus abdominalis floridanus (Buckley) and the little fire ant, Wasmannia auropunctata (Roger), tend the scale insects for the honeydew they produce, and a predaceous pyralid caterpillar, Laetilia coccidivora (Comstock), is occasionally found feeding on colonies of lignumvitae scale.

Effects of scale insect herbivory and shading on net gas exchange and growth of a subtropical tree species (Guaiacum sanctum L.).

The scale insect, Toumeyella sp., feeds exclusively on the subtropical hammock tree lignum vitae (Guaiacum sanctum L.). The combined effects of scale herbivory and shading on leaf gas exchange characteristics and growth of lignum vitae trees were studied using a factorial design. Trees grown in full sun or in 75% shade were manually infested with scale or left noninfested. Beginning 4 weeks after infestation, net CO2 assimilation, stomatal conductance, transpiration, internal partial pressure of CO2, and water-use efficiency were determined on single-leaves at 4-week intervals for trees in each treatment. At the end of the experiment, net CO2 assimilation was determined for whole plants. Total leaf area, leaf, stem, and root dry weights, and leaf chlorophyll and nitrogen concentrations were also determined. Scale infested trees generally had lower net CO2 assimilation, stomatal conductance, and transpiration rates as well as less leaf area, and root, stem, and leaf dry weights than noninfested trees. Twenty four weeks after the shade treatment was imposed, sun-grown trees had approximately twice the leaf area of shade-grown trees. Shade-grown trees compensated for the reduced leaf area by increasing their photosynthetic efficiency. This resulted in no difference in light saturated net CO2 assimilation on a whole plant basis between sun-grown and shade-grown trees. Chlorophyll and nitrogen concentrations per unit leaf area were greater in leaves of shade-grown trees than in leaves of sun-grown trees. Shading and herbivory by Toumeyella sp. each resulted in decreased growth of Guaiacum sanctum. Scale insect herbivory did not result in greater detrimental effects on leaf gas exchange characteristics for shade-grown than for sun-grown trees. Herbivory by Toumeyella resulted in a greater decrease in tree growth for sun-grown than for shade-grown trees.

Avian Consumption of the Fruit of the Cacti Stenocereus eichlamii and Pilosocereus maxonii in Guatemala

An assemblage of 18 avian species belonging to 17 genera and 11 fami- lies consumed the fruits of the cacti Stenocereus eichlamii and Pilosocereus maxonii in the arid interior of Guatemala. These large, candelabra-shaped, arborescent cacti are syntopic and similar in morphology, but display divergent fruiting phenologies. In 1984, the population of S. eichlamii ripened fruit continuously over an 8-wk period from April to June. The population of P. maxonii displayed synchronized fruiting dur- ing three discrete periods from mid-May to early July; each fruit-ripening pulse lasted about 1 wk and successive pulses were separated by nonfruiting intervals of 2 wk. Fruiting in P maxonii continued at least until early August with less apparent syn- chrony. The fruit of both cactus species is abundant and large and possesses a juicy pulp through which are distributed hundreds of tiny seeds. Avian consumers em- ployed a diversity of harvesting/ingestion procedures that are relevant to potential seed dispersal. Excepting two species of hummingbirds, birds confined their feeding to a single fruit during most visits to cactus plants. No intra- or interspecific aggres- sion was observed among consumers. A major portion of this consumer assemblage also fed at Guaiacum sanctum (Zygophyllaceae), the other conspicuous producer of fleshy fruit in this area.

Avian Consumption of Guaiacum sanctum Fruit in the Arid Interior of Guatemala

Data are provided on consumption of the fruit of the Guayac6n (Guaiacum sanctum, Zygophyllaceae) by 19 avian species of 17 genera in 8 families in the arid interior of Guatemala. G. sanctum is an abundant evergreen tree of the dry deciduous scrub forest of the Motagua River valley in the Departments of Zacapa and El Progreso. Arilloids were exposed in conspicuous displays during 2 distinct fruiting periods, each lasting about 2 mo. During a fruiting period, individual trees bore ripe fruit continuously for as long as 6 wk. Diverse harvesting and handling procedures of Guayacan arilloids were employed by avian consumers, both intraand interspecifically; these are characterized and harvesting procedures are related to tree morphology. Arils and/or arilloids were consumed and/or transported by adult birds to nestlings and fledglings. Thirteen species transported seeds away from G. sanctum parent trees and did not drop seeds beneath these; two other species transported a portion of the seeds they handled away from parent trees.

Defense against Ants in a Caterpillar That Feeds on Ant-Guarded Scale Insects

The lignum vitae trees, Guaiacum sanctum , on Lignumvitae Key, Monroe County, Fla., have recently shown signs of heavy infestation by an apparently new species of scale insect, Toumeyella sp. Living in dense clusters and causing serious defoliation, the scales are tended by swarms of ants, Camponotus floridanus (Buckley), which, in characteristic fashion, stand guard over their hosts (Fig. 1) and protect them against attack. Prodding fingers are promptly bitten (and often sprayed), as, presumably are, predators, entomophagous parasites, and other potential enemies of the scales. On visits to Lignumvitae Key in December 1971 and January 1972, we found several individuals of a small pyralid caterpillar, Laetilia sp., that feeds on the scales (Fig. 2) and is defensively adapted to contend with the ants. When pinched with fine forceps, in simulation of the mandibular bite of an ant, the caterpillar revolves the front end, brings the mouthparts into contact or near contact with the forceps, and regurgitates. The fluid is demonstrably effective against ants. A caterpillar that was placed amidst a group of ants tending a cluster of scales placed for observation under the stage of a stereomicroscope was promptly attacked by 2 ants, but it fended them off with regurgitate, visibly wetting them, and causing them to engage in intensive and protracted cleansing activities.

In vitro Propagation of Albizia guachapele, Cedrela odorata, Platymiscium pinnatum and Guaiacum sanctum

In Costa Rica Albizia guachapele, Cedrela odorata, Platymiscium pinnatum and Guaiacum sanctum are important plant species in both economic and ecological terms and their wood is precious and reported to be highly resistant material. This research has evaluated the in vitro micropropagation as a technology focused to conserve these species. Findings include percentage of germination of seeds and contamination, induction of buds, rooting and growth of micro-cuttings of these four species. Key words: In vitro, Propagation, Albizia guachapele, Cedrela odorata, Platymiscium pinnatum, Guaiacum sanctum D.O.I. 10.3329/ptcb.v18i2.3397 Plant Tissue Cult. & Biotech. 18(2): 151-156, 2008 (December)