Nemésio & Morato 2004

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Euglossina (Hymenoptera: Apidae: Apini) of theHumait Reserve, Acre state, Brazilian Amazon,with comments on bait trap efficiency

Euglossina (Hymenoptera: Apidae: Apini) da Reserva Humait,

estado do Acre, Amaznia brasileira, com comentrios sobre aeficcia de armadilhas

Andr Nemsio* and Elder F. Morato* *

Abstract

Male euglossine bees attracted to seven chemical baits during eight months

were collected with insect nets and baited traps at different sampling sites in

the Reserva de Humait, Acre state, southwesternBrazilian Amazon. Each

month, three sampling points were selected in a site: one in which collecting

was carried out with an insect net and two points where baited traps wereinstalled. Two hundred fifty-four individuals belonging to twenty-two species

were collected.Eulaema cingulata (Fabricius) andEl. meriana (Olivier) were

the most common species. One hundred seventy-six (69%) of the total

individuals were collected with the nets and 78 (31%) collected through the

baited traps. As the sampling effort with baited traps was twice as big as that

with the insect nets, collecting with insect nets was four times more efficientthan those with baited traps. Benzyl acetate was the most attractive bait and

the activity peak of male orchid bees was reached between 09:30 and 10:00.

* Laboratrio de Sistemtica e Ecologia de Abelhas, Departamento de Zoologia, Universidade

Federal de Minas Gerais (ICB), Caixa Postal 486, Belo Horizonte MG, CEP: 30.123-970,

Brazil. E-mail: [email protected] ou [email protected].** Depto de Cincias da Natureza, Universidade Federal do Acre, Rio Branco - AC, 69915-

900, Brazil. E-mail: [email protected].

Rev. Tecnologia e Ambiente, Cricima, v. 10, n. 2, p. 71-80, jul./dez. 2004


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Keywords:Insecta, bee, Acre state, Amazon.Resumo

Machos de abelhas euglossinas atrados por sete iscas odorferas duranteoito meses foram coletados por meio de pu e armadilhas em diferentespontos amostrais na Reserva de Humait, Acre, sudoeste da Amazniabrasileira. Em cada ms, trs pontos amostrais foram selecionados em cadalocal: um no qual a coleta com pu era realizada e dois pontos ondearmadilhas eram instaladas. Duzentos e cinqenta e quatro indivduospertencendo a 22 espcies foram coletados.Eulaema cingulata (Fabricius) e

El. meriana (Olivier) foram as espcies mais comuns. Cento e setenta e seis(69%) dos 254 indivduos foram coletados com pu e os 78 restantes (31%),nas armadilhas. Como o esforo amostral com armadilhas foi duas vezesmaior que o esforo amostral com pu, a coleta com pu mostrou-se cercade quatro vezes mais eficiente. O acetato de benzila foi a isca mais atrativa eo pico de atividade deu-se entre as 09h30 e as 10 h.

Palavras-chave: insecta, abelha, Acre, Amaznia.

Introduction

Orchid bees are an important insect group and the only pollinators of hundredsof plant species in the Neotropics (revised by Dressler 1982). Until very recently,these bees were rare in entomological collections. Since aromatic compoundsattractive to euglossine bees were discovered in the 1960s (Dodson et al.1969) several inventories have been carried out in an attempt to characterizethe local faunas of these Neotropical bees.

Several of those faunistic surveys were carried out in the BrazilianAmazon (Powell & Powell 1987, Becker et al. 1991, Morato et al. 1992,Oliveira & Campos 1995), but all of them in the same region, ca. 90 kmnorth of Manaus. No other data concerning the orchid-bee fauna are availablefor the Brazilian Amazon. The euglossine bees of Acre state, southwesternBrazilian Amazon, is, thus, virtually unknown, both when sporadic and

systematic samplings are considered. From a biogeographic point of view,better sampling of this region is desirable for considerations of broader



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geographic patterns, critical to conceptual development and empirical

evaluation of hypotheses in ecology, as well as in conservation and

evolutionary biology (Lyons & Willig 2002).

The basic methodology used in orchid bee studies is to attract their

males to baits consisting of a piece of cotton or paper imbued in aromatic or

terpenoid compounds attractive to them. In some studies, bees were collected

with insect nets, while in others they were collected with baited traps. Morato

(1998) quoted these differences in methodology as detrimental to comparative

studies of euglossine faunas, and it has been observed that baited traps are

less efficient than collecting with insect nets, since some bees escape from the

traps or do not enter them (AN and EFM, pers. obs.). However, the difference

in efficiency between those methods was never quantified.

The aims of this study were: (i) to provide the first survey of Acrean

orchid-bee fauna, and (ii) to compare quantitatively the efficiency of insect

nets and baited traps in euglossine studies.

Material and methods

Study Area.This study was carried out in the Reserva Florestal de Humait(RFH), in the municipality of Rio Branco, Acre state, Brazil (943S - 948S;

6733W - 6748W; elevation = ca. 200 m above sea level). RFH is a 2,000

ha area covered, basically, by well preserved, pristine Tropical Humid Forest.

The Terra Firme forest occupies ca. 90% of the RFH (Souza, 1996), althoughit presents a conspicuously open canopy and high concentration of palm

trees (Arecaceae) and bamboos (Poaceae) (EFM, pers. obs.). The RFH is

surrounded by disturbed areas on its southern border and continuous foreston the north. The regional climate is tropical, hot and humid (transition from

Am to Aw, according to Kppen classification). The average temperature varies

from 23.4oC (July) to 26.6oC (October). The average relative humidity of the

air (1971-1994) was 83.5% (78%-87%) (Souza 1996).Sampling. Seven aromatic compounds were used to attract male

euglossine bees: 1,8- cineole, vanillin, eugenol, benzyl acetate, methyl

salicylate, skatole, and benzyl benzoate. The study was carried out from July1997 to November 1997, and in March, May, and July 1998. Each month, a

different sampling site was chosen, since Armbruster (1993)suggests that a

single site is not enough to sample the whole fauna of a given area. Once

sampled, a specific site was never sampled again. Each month, three sampling



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skatole and eugenol, and only one was attracted to benzyl benzoate (Table

3). Moreover, 40 bees were collected in flight, since they were attracted to the

sampling site but did not approach any specific bait.

The peak of activity of male orchid bees occurred between 09:30

and 10:00 h.Very few bees were collected after noon (Table 4).

Table 2. Number of specimens of each Euglossina species collected in baited

traps in Reserva de Humait, Acre, Brazil.

Table 1. Number of specimens of each Euglossina species collected in Reserva

de Humait, Acre, Brazil.



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de Humait, Acre, Brazil, with hand nets, according to the aromatic compound

(BA = benzyl acetate, BB = benzyl benzoate, C = cineole, E = eugenol, F =

in flight, MS = methyl salicylate, SK = skatole, T = total).


de Humait, Acre, Brazil, according to day time.



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Discussion

The abundance of orchid bees in this study is very low compared to other

studies of similar duration carried out in the Amazon Forest (e.g. Pearson &

Dressler 1985, Powell & Powell 1987, Morato et al. 1992, Oliveira & Campos

1995). On the other hand, the abundance verified in the study performed by

Becker et al. (1991) was similar to that observed here. Given the low

abundance obtained in the present study, however, the figure of 22 species

recorded is quite considerable, especially when compared to the 16 species

collected by Becker et al. (1991) among 290 individuals and the 27 species

collected by Morato et al. (1992), among 1,242 individuals.The high frequencies ofEulaema is outstanding, since expressive

numbers of individuals of this genus are generally characteristic of the highly

fragmented Atlantic Forest landscapes (e. g. Reblo & Garfalo 1991, 1997,

Bezerra & Martins 2001, Tonhasca Jr. et al. 2002, Nemsio 2003), contrarily

to what has been observed in most surveys in the Amazon (Pearson & Dressler

1985, Powell & Powell 1987, Morato et al. 1992, Oliveira & Campos 1995).

On the other hand, it is also remarkable that only one individual of the species

typically associated with open and/or disturbed areas, Eulaema nigrita

Lepeletier, was collected. The absence ofEuglossa stilbonota Dressler, the

most common species in Central Amazon (Powell & Powell 1987, Becker et

al. 1991, Morato et al. 1992, Oliveira & Campos 1995), is also noticeable.

This species is also absent from the Tambopata Reserve, in Peruvian Amazon,

and seems not to be present in westernmost Amazonia.

The considerable differences in efficiency between insect nets and

baited-trap collections suggest that the sole use of baited traps should be

restricted to situations in which the use of insect nets is impossible. The large

samples obtained in other studies (e.g. 2,422 bees in Central Amazon, Oliveira

& Campos 1995) should be considered with care. The study by Oliveira &

Campos (1995), for instance, was carried out during a whole year, with four

sets of traps. It may be hypothesized that where the large individuals of

Eulaema are abundant, as in Reserva Humait, individuals ofEuglossa are

more often disturbed byEulaema while trying to enter the trap. Aggressive

behavior of this nature has been observed in the field (AN, pers. obs.).

Moreover, males of at least some species ofEuglossa are extremely aggressive

while trying to approach the aromatic baits. One of us (AN) has seen severalsuch conflicts involving individuals ofEuglossa analis Westwood in Parque



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Estadual do Rio Doce, Minas Gerais state, southeastern Brazil (unpubl. data).

Eulaema versus Euglossa and also Euglossa versus Euglossa conflicts may

respond for the higher presence of individuals ofEulaema in traps than in

insect nets. The lower abundance of individuals in traps, however, may involve

other factors.Eulaema bees, generally, spend more time trying to collect the

compounds than do Euglossa (AN, pers obs.). That means that a single

individual may close an entrance to the trap for several minutes before

entering, whereas if it appeared in the presence of the researcher, the bee

would be removed quickly by means of an insect net. Moreover, individuals

ofEuglossa escape more frequently from the traps than doEulaema (AN and

EFM, pers. obs.), and this may be due to the relative small size ofEuglossa,

which allows them to escape through the entrance of the trap.

The observed high attractiveness of benzyl acetate in the present

study clearly seems to be due to the fact that this compound was by far the

most attractive to both of the dominant species. However, this substance has

not been much attractive in other studies in this region (e. g. Oliveira &

Campos 1996).

The peak of activity of male orchid bees agrees with the general figure

for this group of bees in Amazon (e. g. Oliveira 1999), and is different from

that observed in the Atlantic Forest of southeastern Brazil, in which most

bees are collected between 11:00 and 14:00 h (Reblo & Garfalo 1991,

1997, Nemsio, in prep.).

Acknowledgements

We thank Dr. David W. Roubik for comments and English review of the first

version of this manuscript. Dr. Gabriel A. R. Melo kindly helped with

identification of some specimens.

Literature cited

ARMBRUSTER, W. C. Within-habitat heterogeneity in baiting samples of

male euglossine bees: possible causes and implications.Biotropica, 25: 122-

128, 1993.



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BECKER, P.; J. S. MOURE, F. J. A. PERALTA. More about euglossine bees inAmazonian Forest fragments.Biotropica, 23: 586-591, 1991.

BEZERRA, C. P.; C. F. MARTINS. Diversidade de Euglossinae (Hymenoptera,Apidae) em dois fragmentos de Mata Atlntica localizados na regio urbanade Joo Pessoa, Paraba, Brasil.Revta Bras. Zool., 18: 823-835, 2001.

DODSON, C. H.; R. L. DRESSLER; H. G. HILLS; R. M. ADAMS; N. H.Williams. Biologically active compounds in orchid fragrances. Science, 164:1243-1249, 1969.

DRESSLER, R. L. Biology of the orchid bees (Euglossini). An. Rev. Ecol.Syst., 13: 373-394, 1982.

LYONS, S. K.; M. R. WILLIG. Species richness, latitude, and scale-sensitivity.Ecology, 83:47-58, 2002.MORATO, E. F.; L. A. O. CAMPOS; J. S. Moure. Abelhas Euglossini (Hyme-noptera, Apidae) coletadas na Amaznia Central.Revta Bras. Entomol., 36:767-771, 1992.

______. Estudos sobre comunidades de abelhas Euglossini.Anais do Encontrosobre Abelhas, 3: 135-143, 1998.

NEMSIO, A. Euglossina (Hymenoptera: Apidae: Apini) of Reserva Particulardo Patrimnio Natural Feliciano Miguel Abdala, Caratinga, Minas Gerais state,Brazil. Lundiana, in press, 2003.

OLIVEIRA, M. L. Sazonalidade e horrio de atividade de abelhas Euglossinae(Hymenoptera, Apidae) em florestas de terra firme na Amaznia Central.Revta Bras. Zool., 16:83-90, 1999._____; L. A. O. CAMPOS. Abundncia, riqueza e diversidade de abelhasEuglossinae (Hymenoptera, Apidae) em florestas contnuas de terra firme naAmaznica Central, Brasil.Revta Bras. Zool., 12:547-556, 1995.______; ______. Preferncias por estratos florestais e por substncias odorferasem abelhas Euglossinae (Hymenoptera, Apidae).Revta Bras. Zool. 13:1075-1085, 1996.



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PEARSON, D. L.; R. L. DRESSLER. Two-year study of male orchid bee(Hymenoptera: Apidae: Euglossini) attraction to chemical baits in lowlandsouth-eastern Per.J. Trop. Ecol., 1: 37-54, 1985.

POWELL, A. H.; G. V. N. POWELL. Population dynamics of male euglossinebees in Amazonian forest fragments.Biotropica, 19: 176-179, 1987.

REBLO, J. M. M.; C. A. GARFALO. Diversidade e sazonalidade de machosde Euglossini (Hymenoptera, Apidae) e preferncias por iscas-odores em umfragmento de floresta no sudeste do Brasil.Revta. Brasil. Biol., 51: 787-799,1991.

______; ______. Comunidades de machos de Euglossinae (Hymenoptera,Apidae) em matas semidecduas do nordeste do estado de So Paulo.An.Soc. Entomol. Brasil, 26: 787-799.

SOUZA, M. B. 1996. Anfbios Anuros da Reserva Florestal Humait, Estadodo Acre, Brasil. Dissertao de mestrado, Universidade Federal do Paran -UFPR. 156 p.

TONHASCA Jr., A.; J. L. BLACKMER G. S. ALBUQUERQUE. Abundanceand diversity of euglossine bees in the fragmented landscape of the BrazilianAtlantic Forest.Biotropica, 34: 416-422, 2002.


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Nemésio & Morato 2004