Marta Caccavari

Pollen analysis of honeys from the central zone of the Argentine province of Entre Rios

Based on the melissopalynology 38 honey samples collected in the central region of the Argentine province of Entre Ríos were classified by botanical and geographical origin. According to qualitative analysis, 20 honey samples were monofloral and 18 were multifloral. Dominant pollen types were Scutia buxifolia Reissek (Rhamnaceae) in six samples, Baccharis spp. (Asteraceae) in five, Lotus spp. (Fabaceae) in three, Eucalyptus spp. (Myrtaceae) and Eryngium spp. (Apiaceae) in two, Ammi visnaga (L.) Lam. (Apiaceae) and Trithrinax campestris (Burmeist.) Drude & Griseb. (Arecaceae) in one sample. One hundred and nineteen pollen types were identified belonging to 52 families; 75% of which were native species. The families best represented in number of species were Asteraceae and Fabaceae. Pollen types such as Scutia buxifolia, Trithrinax campestris, Schinus spp. (Anacardiaceae), Mimosoideae from Prosopis spp., Acacia spp., Mimosa ostenii Speg. ex Burkart, and M. strigillosa Torr. & A. Gray are considered the indicators for this geographical origin. The studied honeys were also characterized by a high frequency of Apiaceae, Brassicaceae, Astereae, Echium plantagineum L. and cultivated Papilionoideae forage species such as Melilotus albus Desr., Lotus spp. and Trifolium spp. Honeydew elements were scarce.

AN ACCOUNT OF MORPHOLOGICAL AND STRUCTURAL CHARACTERIZATION OF AMERICAN MIMOSOIDEAE POLLEN. PART I: TRIBE ACACIEAE

Abstract The results of a pollen study of 77 American species of Acacia (tribe Acaciae) characterizes pollen among the different New World taxa of the compound‐pollen Mimosoideae on the basis of the most relevant morphologic and structural features. Two pollen types and five subtypes are recognized and summarized in the diagnostic key presented herein. As a result of the species studied, some newly observed structural features are now utilized; these features modify the previous characterization of the pollen of Acacia, and include frequent ornamentation of the suprasubreticulate or supramicrorugulate exine, presence of subpseudocolpi in some species, and presence of a bistratified granular infractectal layer in the subgenus Aculeiferum but not in the section Filicinae.

Pollen morphology and structure of Tropical and Subtropical American genera of the Piptadenia -group (Leguminosae: Mimosoideae)

A survey of the pollen morphology of the American taxa of the Piptadenia -group (Mimoseae) was done including all together 384 species of the following genera: Piptadenia , Parapiptadenia , Pseudopiptadenia , Piptadeniopsis , Microlobius (= Goldmania ), Stryphnodendron , Adenopodia , Anadenanthera and Mimosa . Because of a high morphological and structural variation the definition and characterization of pollen types turned out to be very difficult. Nevertheless the presence and durability of some pollen characters allow a provisional grouping: (1) always tetrads or polyads, (2) small size 6 (20) 40 mum, (3) unstable shape but currently ovoidal and, if biconvex, ellipsoidal in the outline, (4) number of pollen grains of the polyads very variable and unstable; the most frequent numbers are 8-12-16, (5) pollen grains irregularly united in polyads, with homomorphous exine and, (6) pores always located in the angles of the pollen grains in distal-subdistal position, rarely subdistal, (7) without or with pseudocolpi or subpseudocolpi (never colpi) in the distal face, (8) endexine forming an annulus around the endoaperture with ends of free lamellae with a central white line, (9) the tectal stratum above the pores forming a small vestibular space (except in Anadenanthera ). These palynological characters or most of them confirm the affinity among genera in the Piptadenia -group and its distinction from other taxa of the subfamily Misosoideae with tetrads or polyads.

The foraging preferences of two species of Melissodes Latreille (Hymenoptera, Apidae, Eucerini) in farmed sunflower in Argentina

Abstract The present study addresses the pollen preferences of two species of wild bees of the genus Melissodes in the intensively farmed temperate Pampean region of Argentina. The resources used by M. (Ecplectica) tintinnans and M. (Ecplectica) rufithorax were studied in a commercial plot of sunflower and its field margins in the locality of Carlos Casares, province of Buenos Aires. Surveys before, during and after the bloom of sunflower were carried out. The bees emerged synchronously with the beginning of the bloom, but continued foraging for over a month after maturation of the crop. Pollen analyses of scopal loads indicated that sunflower was a major component of the diet. Bees also collected pollen from other Asteraceae during and after the blooming of the sunflowers. Pollen from Ligustrum sp. and Eucalyptus sp., two trees common in the hedgerows, was also collected in significant amounts. The vegetation on the field margins facilitated maintenance of the populations after the blooming of the sunflower. The two species of native Melissodes used pollen of plant taxa that are frequent and widespread in the Pampean agricultural ecosystems. This fact, together with their habit of nesting in aggregations, indicates that these bees represent a valuable resource as crop pollinators.

Depositación polínica anual en el Parque Nacional Pre-Delta (Entre Ríos, Argentina)

Annual pollen deposition in the Pre-Delta National Park (Entre Rios, Argentina). This work aims to analyze the seasonal pattern and the diversity of the Pre-Delta National Park vegetation (Entre Rios, Argentina) as reflected by the deposited pollen along a year. Pollen has been monitored monthly with Tauber traps over one year (since August 2004 to July 2005). The pollen traps were placed in two sub environments within the park: 1) in a tallgrass prairie (P), and 2) in a shrubland next to a forest (A). The high diversity was determined by 83 pollen types (72 in P and 65 in A), but only 3 in P and 5 in A reached more than 5% of the pollen total. Asteraceae Asteroideae (non Ambrosia, non Artemisia), Poaceae and Salix were the most abundant, being related to the Tessaria and Salix forests, and to the prairies of Panicum. In A, the Prosopis pollen (typical taxon of the Espinal vegetation) was also important, as well as the Solanum glaucophyllum pollen type (taxon of the wetland). The deposited annual pollen value was 15186 pollen/cm2 in P and 11552 pollen/cm2 in A. A noticeable seasonal difference was observed between P (the maximum in January and February) and A (maximum in October) due to the flowering of dominant taxa: Poaceae and Asteraceae Asteroideae, respectively. The minimum was registered in July in both sites. In conclusion the plant diversity of the park is represented in both sites, but the seasonal flowering period differs according to the main vegetation sources.

Remoción química como nueva alternativa a la remoción mecánica para el estudio del polen transportado en las escopas de abejas silvestres

Removal new alternative to chemical and mechanical removal for the study of pollen carried on the wild bee scopae. Taxonomic recognition and quantification of the different pollen types collected by bees offer the most direct method to study the diet. To determine the importance of each plant taxon, it is necessary to separate the pollen deposited only in the collecting structures in order to minimize contamination of grains collected passively in other parts of the body. The technique currently applied is based on the mechanical removal of the pollen loads with dissecting needles and repeated washings with ethanol. Metathoracic scopae that underwent this procedure showed traces of pollen in varying amounts when observed under the microscope. As an alternative to this technique chemical removal using HOK is proposed. The leg is removed and treated separatedly to avoid contamination. The deflocculant properties of HOK successfully allowed to separate the pollen adhered to the scopae, which can be then returned to the individual, unaffected by the procedure. Suspend the pollen in a know quantity of mounting fluid permit take the subsamples and determine the total number of pollen grains of each taxon. In this paper, the new technique is presented and its effectiveness is compared to the technique currenty used.