Ants Like Flower Nectar
1981; Wiley; Volume: 13; Issue: 3 Linguagem: Inglês
10.2307/2388126
ISSN1744-7429
AutoresWilliam A. Haber, Gordon W. Frankie, Herbert G. Baker, Irene Baker, Suzanne Koptur,
Tópico(s)Insect and Pesticide Research
ResumoJanzen (1977) speculated that ants generally do not feed on floral nectars in lowland tropical habitats because the nectars contain repugnant, indigestible, or toxic chemicals. We report numerous ant species taking floral nectar from 27 plant species in primarily a lowland dry forest habitat in Costa Rica. Floral nectar from 21 plants was readily accepted by ants in all but two cases. In these studies, some of the nectars were known to contain phenolic compounds and alkaloids. We find little evidence to support Janzen's speculation. JANZEN (1977) stated that ants generally do not feed on floral nectar in lowland tropical habitats. He used lack of observations of ants visiting flowers as a premise to propose the hypothesis that floral nectars in general contain chemicals that make them unpalatable to ants. Baker and Baker (1978) pointed out that ants may, in fact, not be uncommon flower visitors, but they also noted that floral nectars frequently contain non-nutritive, potentially toxic compounds such as alkaloids, phenolics, and non-protein amino acids that may deter unwanted flower visitors. Feinsinger and Swarm (1978) found that ants readily fed on floral nectars of three of four plant species tested in Trinidad. They also cited seven species of hummingbird-pollinated plants whose flowers were visited by ants. Guerrant and Fiedler (1981) offered floral nectar of 25 plant species to foraging ants in wet and dry forests in Costa Rica, and found in general that the nectars were palatable. They also suggested that chemical and morphological modifications of the floral parts may provide protection from thievery by chewing insects. During a 1976-1979 study of pollination systems in the lowland dry forest in northwestern Costa Rica (Frankie, Haber, Opler, and Bawa, in prep.) and elsewhere in Costa Rica, we frequently observed ants feeding on floral nectar. Thus, our experience is somewhat different from that of Janzen. We present information on flowers visited by ants for nectar; acceptability of various floral nectars to ants; and, responses of ants to potentially toxic compounds in nectar. FLOWERS VISITED BY ANTS.-Ants were observed feeding on nectar of 27 species of flowers (table 1). The list contains examples of most pollination systems in the area: large bee, small bee, butterfly, hummingbird, small moth, sphingid, bat, and generalist. Some flowers had hidden nectar and some had exposed nectar; 14 species had flowers with shallow corollas that expose nectar to unspecialized visitors, including ants; 13 species had tubular corollas or other structures that hide the nectar. Ants were observed feeding in flowers at night as well as during the day (figs. 1 and 2). TESTS OF NECTAR FED TO ANTS.-Because ants were not observed feeding on flowers of all species, palatability of nectars in these flowers was tested by either cutting the corolla of tubular flowers to allow ants access to nectar reservoirs, or removing nectar from flowers with micro-capillary tubes and placing droplets (about 2 /l in volume) on stems and branches of ant acacias where ants foraged. Nectars of 21 species were tested (table 2). In all but two species, ants consumed the nectar droplets in less than five minutes. Nectar of Caesalpinia pulcherrima, which ants rejected, was hidden at the base of an extremely narrow tube formed from the flag petal. In cutting the tube to remove nectar, contaminants from broken flower tissue probably mixed with nectar and may have influenced its acceptance. Nectar of Byrsonima crassifolia, also rejected by ants in these tests, was a thick secretion of the calyx lobes which is high in lipids, low in sugar (Baker 1978). This liquid also contained alkaloids and phenolics. Nevertheless, ants were observed feeding naturally on this secretion (table 1). Apart from B. crassifolia, nectars of the other four tested species with exposed floral nectars (table 2) were received favorably by ants. Yet it is these species that might be expected to have nectar with ant-repellant properties since structural defenses BIOTROPICA (13)3: 211-214 1981 211 This content downloaded from 157.55.39.78 on Wed, 22 Jun 2016 06:18:32 UTC All use subject to http://about.jstor.org/terms TABLE 1. Plant species visited by ants for nectar. Flowers have exposed (E) or hidden (H) nectar. (LDF = Lowland dry forest, Guanacaste Prov., elevation 100-200 m, MEF = Mid-elevation forest, Puntarenas Prov., elevation 14001600 m.) Flower Plant species Locality Pollinators type Ants taking nectar Asclepias curassavica L. (Asclepiadaceae) MEF butterfly H Monomorium floricola (Jerdon) Pheidole sp. Bauhinia ungulata L.a (Caesalpiniaceae) LDF bat E Camponotus sp. Bromelia pinguin L. (Bromeliaceae) LDF hummingbird H Ectatoma ruidum Roger Byrsonima crassifolia (L.) HBKa' b LDF bee E Crematogaster sp., and small red (Malpighiaceae) unidentified sp. Calycophyllum candidissimum (Vahl.)DC LDF generalist H not identified (Rubiaceae) Capparis indica (L.) Fawc. and Rendle LDF sphingid E not identified (Capparidaceae) C. odoratissima Jacq. LDF small moth, beetle E not identified Coccoloba caracasana Meisner LDF small bee E Camponotus sp. (Polygonaceae) C. venosa L. LDF small bee, wasp E Pseudomyrmex gracilis (Fabricius) Combretum farinosum HBK LDF hummingbird E P. gracilis, Camponotus sp. (Combretaceae) Crataeva tapia L. (Capparidaceae) LDF bat E Camponotus sp. Euphorbia pulcherrima Willd. butterfly E Brachymyrmex sp., (Euphorbiaceae) Myrmelachista sp. Godmania aesculifolia (HBK) Standl. LDF bee H Paratrechina longicornis (Latreille) (Bignoniaceae) Hasseltia floribunda HBK (Flacourtiaceae) MEF small bee E Myrmelachista sp. Helicteres guazumaefolia HBKb LDF hummingbird H 4 spp. including P. gracilis (Sterculiaceae) Hymenaea courbaril L,a' b (Caesalpiniaceae) LDF bat E Camponotus abdominalis (Fabricius), Crematogaster sp., Pheidole sp. Inga vera Willd. (Mimosaceae) LDF bat, sphingid H not identified Laetia thamnia L. (Flacourtiaceae) LDF bee E Monomorium sp. Luehea seemannii Tr. and P1. (Tiliaceae) LDF moth, bee H Cryptocerus sp. L. speciosa Willd. LDF sphingid H Crematogaster sp. Muntingia calabura (Sw.) DC LDF generalist E Camponotus sp. (Elaeocarpaceae) Passiflora adenopoda (Passifloraceae) MEF bee H not identified Perrottetia longistylis Rose (Celastraceae) MEF small bee? E Camponotus sp. Psychotria carthagenensis Jacq. bee, butterfly H not identified (Rubiaceae) Stachytarpheta jamaicensis (L.) Vahl. MEF butterfly, H Paratrechina longicornis (Verbenaceae) hummingbird Swietenia humilis Zucc. (Meliaceae) LDF moth, beetle H not identified aNectar contains alkaloids. bNectar contains phenolic compounds. TABLE 2. Plants whose floral nectar was tested for palatability to ants. All but Byrsonima crassifolia and Caesalpinia pulcherrima were accepted. Nectar is designated as exposed (H) or hidden (H). (LDF = Lowland dry forest, Guanacaste Prov., elevation 100-200 m, MEF = Mid-elevation forest, Puntarenas Prov., elevation 1400-1600 in.) Flower Plant species Locality Pollinators type Ants tested Anacardium excelsum (Bert. and Balb.) LDF bee H Monomorium floricola Skeels.a, b (Anacardiaceae) Bourreria quirosii, Standl. (Boraginaceae) LDF hummingbird H Pseudomyrmex belti (Emery) Byrsonima crassifolia (L.) HBKa b LDF bee E P. belti, P. ferruginea (Fredrick (Malpighiaceae) Smith) 212 Haber, Frankie, Baker, Baker, and Koptur This content downloaded from 157.55.39.78 on Wed, 22 Jun 2016 06:18:32 UTC All use subject to http://about.jstor.org/terms
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