Journal of Insect Science: Vol. 13 | Article 93 Campos

The aquatic communities inhabiting internodes of two sympatric in Argentinean subtropical forest

Raúl E. Campos1, 2

1Instituto de Limnología "Dr. Raúl A. Ringuelet", Universidad Nacional de La Plata – CONICET, CC 712 (1900) La Plata, Buenos Aires, 2Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)

Downloaded from Abstract In order to determine if phytotelmata in sympatric bamboos of the genus might be colonized by different types of arthropods and contain communities of different complexities, the http://jinsectscience.oxfordjournals.org/ following objectives were formulated: (1) to analyze the structure and species richness of the aquatic macroinvertebrate communities, (2) to comparatively analyze co-occurrences; and (3) to identify the main predators. Field studies were conducted in a subtropical forest in Argentina, where 80 water-filled internodes of Guadua chacoensis (Rojas Acosta) Londoño and Peterson (: ) and G. trinii (Nees) Nees and Rupr. were sampled. Morphological measurements indicated that G. chacoensis held more fluid than G. trinii. The communities differed between Guadua species, but many macroinvertebrate species used both bamboo species. The by guest on August 12, 2015 phytotelmata were mainly colonized by Diptera of the families Culicidae and Ceratopogonidae.

Abbreviations: C8, Hulbert’s coefficient of association; C.V, coefficient of variation; D, Durbin-Watson statistic; d, Berger-Parker index of dominance; de, depth; E, evenness; Gadj, G test; H’, Shannon-Wiener index of diversity; l, length; r2, Pearson’s coefficient of correlation; rs, Spearman’s coefficient of correlation; VIF, variance inflation factor. Keywords: community, Guadua chacoensis, Guadua trinii, insect association, mosquito, phytotelmata, predators Correspondence: [email protected] Received: 7 March 2012 Accepted: 21 August 2012 Published 30 September 2013 Copyright: This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed. ISSN: 1536-2442 | Vol. 13, Number 93

Cite this paper as: Campos RE. 2013. The aquatic communities inhabiting internodes of two sympatric bamboos in Argentinean subtropical forest. Journal of Insect Science 13:93. Available online: http://www.insectscience.org/13.93

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Journal of Insect Science: Vol. 13 | Article 93 Campos Introduction Studies of the effect of habitat size in treeholes Phytotelmata (gr. phyton = , telma = and bamboo stumps showed that the size of the pond) occur in a large number of terrestrial opening determines the rate of entry of leaf lit- that hold water in places such as stems, ter, which increases with phytotelm capacity sheathing leaves, and flowers (Frank and (Sota 1996). In turn, an increase in the capacity Lounibos 1983). Extensive lists of types of of the habitat should lead to increases in bio- phytotelmata have been presented by Fish mass and the number of metazoan inhabitants. (1983) and Machado-Allison et al. (1985), Furthermore, it was demonstrated that the sta- although only a few types have been exten- bility of phytotelmata has an additional effect sively studied. Bromeliads, pitcher plants, on community structure, due to the effect of treeholes, and bamboo internodes have been stability of the aquatic environment. Stability is among the most studied phytotelmata (e.g., influenced by hole depth (Sota et al. 1994), as

Kitching 1971; Istock et al. 1975; Louton et small deep holes are more stable than large Downloaded from al. 1996; Frank and Lounibos 2009) because shallow holes (Sota 1996). Therefore, the their fauna may include dipteran vectors of number of individuals and species composition diseases (Anosike et al. 2007), and because varies with the capacity of the treehole. Thus,

they are suitable for studies on ecological sys- mosquito species whose egg stages are not re- http://jinsectscience.oxfordjournals.org/ tems (e.g., Yee 2007). Treeholes and bamboo sistant to drought colonize more stable were termed as dendrotelmata (gr. déndron = treeholes than species with drought-resistant tree, telma = pond) due to characteristics that eggs (Bradshaw and Holzapfel 1983). The sta- differentiate them from other phytotelmata. bility of the aquatic micro-environment in The main feature that distinguishes them is bamboo internodes could be greater than the that the pool is formed in the trunk or woody stability in treeholes or bamboo stumps be- stem (Lozovei 1998), in contrast with the oth- cause the opening area where rainwater enters er plants that are herbaceous. Arguably, is generally small and lateral on internodes, as bamboos constitute the simplest phytotelmata opposed to stumps that have a larger opening by guest on August 12, 2015 from the viewpoint of their architecture. Each area facing up, like those of many treeholes. internode has the shape of a hollow cylinder, On the other hand, water-holding capacity of with smooth and vertical walls, and both ends internodes will not depend on their length, but are closed. The pool is formed when the inter- on the height where the side hole is. node is filled with rainwater (Kovac and Streit 1996) or the exudates of the bamboo (Lozovei Many studies have been conducted on bamboo 1998). Rainwater falls within the internodes phytotelmata, addressing different aspects of either when the top is cut, which may give rise the communities, mainly communities from to two types of bamboo-stump pools, open, or stumps. For example, the species richness in an semi-closed (Sunahara and Mogi 1997), or altitudinal gradient (Sota and Mogi 1996) was when the culm is injured by an insect borer studied, as well as the seasonal occurrence and such a chrysomelid (Macdonald 1962) or cur- distribution patterns of mosquitoes in bamboo culionid (Kovac and Azarae 1994) beetle. It groves (Sunahara and Mogi 1997) and the vari- must be emphasized that closed internodes ability of intra and interspecific competition of accumulate fluids but become phytotelmata mosquitoes in stumps (Sunahara and Mogi only when drilled or injured, allowing female 2002). The communities of aquatic macrofauna insects to enter and lay eggs (Lozovei 1998). of internodes were studied in a lowland tropical

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Journal of Insect Science: Vol. 13 | Article 93 Campos forest (Louton et al. 1996), but there are no herbaceous (Olyreae). Guadua Kunth, Mero- studies comparing the communities living in stachys Sprengel, and Chusquea Kunth are the internodes of sympatric bamboo species. From three genera of woody native bamboo observations made during a study on the diver- (Probambu 2011), but only Guadua and Mero- sity of Culicidae and Ceratopogonidae that stachys species, whose stems are hollow, inhabit phytotelmata in the subtropical region produce phytotelmata. In this study, Guadua of Argentina (Campos et al. 2011), it was (Rojas Acosta) Londoño and Peterson (Poales: found that two species of the bamboo genus Poaceae) and G. trinii (Nees) Nees and Rupr. Guadua had differences in morphology and were sampled, but Merostachys clausenii presumably are able to accommodate different Munro was not sampled, because at the end of detritus. Therefore, it was speculated that the 2006 this species bloomed (it occurs approxi- species richness and community structure of mately every 30 years, followed by a massive macroinvertebrates could be different. To sub- die-off, leaving large areas deforested). Both

stantiate this hypothesis, the following species of Guadua grow in the forest, mainly Downloaded from objectives were formulated: (1) to compare the in low places near streams. Guadua chacoen- structure and species richness of the aquatic sis is dominant and grows in clumps macroinvertebrate communities in two sym- occupying big areas, while G. trinii grows in

patric species of bamboo; (2) to compare the small clumps scattered in the forest. However, http://jinsectscience.oxfordjournals.org/ co-occurrence of aquatic macroinvertebrates both bamboos are often found together. between the two bamboos species, and (3) to identify the main predators in the aquatic Sampling communities of both bamboos. The preferred method for sampling internodes of bamboo is to cut the internode into sections Materials and Methods to remove all contents. However, in our study, a different method was used because the bam- Study area and bamboo species boos were in an area of biodiversity by guest on August 12, 2015 Field studies were conducted from 15–19 conservation. For this reason, only the aquatic March 2007 in Iguazú National Park (25º 39’ macroinvertebrates were considered in this re- S, 54º 18’ W), located in the northwest of search, and the terrestrial macroinvertebrates Misiones Province, Argentina, by the Iguazú that use the internodes as refuge were not con- River on the border of Brazil. The park is situ- sidered. ated in the Paranaense forest ecoregion (Dinerstein et al. 1995), which has a topogra- The study was carried out in early fall, after the phy and drainage pattern dominated by a summer rainfall. Thirty-nine water-filled bam- basaltic plateau, reaching altitudes of 700 m boo internodes of G. chacoensis and 41 of G. a.s.l. The dominant vegetation corresponds to trinii were sampled. Standing water containing the semi-deciduous forest, and the climate is macroinvertebrate inhabitants was extracted subtropical, characterized by dry winters and with a pooter (aspirator) attached to a lift wet summers, with an annual rainfall of 1,500– pump, and the volume of water was measured. 2,000 mm. The mean temperature varies from Because the diameters of the natural holes of 16–22º C (APN 2009). the internodes were in some cases smaller than the suction hose, new larger (2.5 cm) Iguazú National Park holds two kinds of bam- holes were made with a drill, just above the boo (Poaceae), woody (Bambuseae) and level of the original holes. Internodes were

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Journal of Insect Science: Vol. 13 | Article 93 Campos washed and re-extracted several successive Data analysis times with clean tap water until no macroin- Significant variation in the water volume, pH, vertebrates or sediments were observed in the and sediment among Guadua species was extracted water. No bamboo stumps were con- tested with Student (t) and Mann-Whitney sidered for this study. tests (U).

All macroinvertebrates were killed in the field Principal component analysis was used to and preserved in 80% commercial ethyl alco- study physical, chemical, and morphological hol, except some immature forms, which were variations of bamboo phytotelmata (Ter Braak carried alive to the laboratory in individual and Smilauer 1998). All data were standard- plastic tubes to be reared and identified. After ized previous to analysis (Ter Braak 1986). A removal of all macroinvertebrates, the fluid complementary non-parametric Mann- extracted (original siphoning plus washes) Whitney test was used to estimate differences

from the internodes was filtered, and the sed- and their significance between variables. Downloaded from iment was dried at 60º C for 48 hr, and weighed on a microbalance accurate to 0.01 To graph the frequency distribution of the size mg. of the holes in the bamboo internodes, they

were categorized into seven classes: 0–5, 5.1– http://jinsectscience.oxfordjournals.org/ The inner diameter; depth (de) (measured 10, 10.1–15, 15.1–20, 20.1–25, 25.1–30, and from bottom to level of the hole); wall thick- 30.1–35 mm. ness; height; and total length (l) of each bamboo internode and size of holes in the wall The diversity of macroinvertebrates from each were measured. The percentage of the length Guadua bamboo was measured by Shannon- of the internodes able to hold water was cal- Wiener index (H’) (Magurran 1988), and dif- culated as 100de / l. Capacity (c) of each ferences between H’ indexes calculated for internode was determined as πi2de / 4 (Sota each Guadua species were tested with Stu- and Mogi 1996). Water and air temperature dent’s t-test (Zar 1996). The evenness (E) of by guest on August 12, 2015 were measured before water extraction with a the numbers of taxa in each sample was esti- digital thermometer equipped with a probe, mated using Pielou’s index (Pielou 1975). The and pH was measured with a portable pH me- dominance of taxa in both Guadua species ter after extraction. was studied using the Berger-Parker index (Magurran 1988), which was calculated for Taxonomic resolution was attempted to spe- each internode. Differences in d indexes cies level, and for this reason some late instar among Guadua species were tested by Stu- larvae and pupae of insects recognized as dif- dent’s t-test (Zar 1996). ferent morphospecies were grown to adulthood. Culicidae were identified by the To examine interespecific associations among author using the keys of Darsie (1985), Cera- macroinvertebrates within each bamboo spe- topogonidae were identified by a specialist, cies, the C8 coefficient, which varies from +1 and the other taxa were identified to order or to -1 (Hulbert 1969), was used, and signifi- family using the keys of Stehr (1987, 1991). cance association was tested by χ2 corrected for continuity.

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Journal of Insect Science: Vol. 13 | Article 93 Campos Table 1. Mean + standard deviation of morphometric data from 81 internodes of two bamboo phytotelmata from subtropical forest, Misiones Province, Argentina.

Significant differences by Mann-Whitney test (U) are denoted by asterisk across rows (p < 0.001)

Multiple regression analyses were used to The proportion of both Guadua species con- Downloaded from

study the effect of abiotic parameters of each taining immatures of Toxorhynchites species bamboo phytotelmata on all macroinverte- in internodes with a hole entry less and greater

brates, and on mosquitoes in particular. than 10 mm of diameter was compared by

Height of the internodes, capacity, size of inlet Gadj. test. http://jinsectscience.oxfordjournals.org/

hole, water volume held, pH, and debris were considered as independent variables, and Results

number of individuals and number of taxa were the response variables. Dependent varia- Bamboo internodes as micro-habitats

bles were transformed as square root Eighty bamboo internodes were measured, 39 ( ), and independent variables as of which were from G. chacoensis and 41

log10, before analysis to accommodate as- from G. trinii (Table 1). The lengths of the sumptions of normality and homogeneity of internodes of both Guadua species were not by guest on August 12, 2015 variance (Zar 1996). Collinearity was tested significantly different (U = 1655; n = 39-42; p by the variance inflation factor (VIF), and cor- = 0.6). Internal diameter, wall thickness, ca-

relation between the residuals by the Durbin- pacity, water volume, sediment, and Watson statistic (D) (Santos and Luque 1996). proportion of internode length able to hold

Variables that showed collinearity were ex- water were significantly greater in G. cluded from analysis (Phillipi 1993). chacoensis than in G. trinii (U Diameter = 2414;

Complementary correlation coefficients of U Thickness = 2418; U Capacity = 2391; U Water = Spearman (rs) were calculated between num- 2380.5; U Sediment = 2130; U Proportion = 2044; n ber of mosquitoes per genera and pH for the = 39-42; p < 0.001). The pH was acid in both two bamboos. bamboos but not was significantly different (U = 1401.5; n = 34-38; p = 0.071). In both Significant variation in the abundances of ma- bamboos, the small holes dominated, as croinvertebrates inhabiting internodes among 61.5% of the internodes of G. trinii had holes holes of different sizes was tested with a one less than 5 mm, while 64.1% of G. chacoensis way-analysis of variance. If significant varia- had holes ranging from 5.1–10 mm. However, tion was detected, a posteriori comparisons the holes in G. chacoensis were located signif- were performed to identify significant differ- icantly higher than those in G. trinii (U Hole ences between groups. diameter = 1994.5; U Height of hole = 1990.5; n = 39-

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42; p < 0.001). Water temperature and differ- ence between air and water temperatures in

both Guadua species were not significantly different (t Water temperature = 0.0273; df = 79; p =

0.978; U Air/water temperature = 1385.5; n = 39-42; p = 0.044).

The first three axes of principal component

analysis explained 87.5% of the total variance. The first, second, and third axes explained

62.6%, 18.2%, and 6.7% respectively, and are associated with the variables shown in Table

2. The principal component analysis ordina-

tion diagram (Figure 1) shows two clusters Downloaded from

segregated along CC1. On negative axis 1, all except two G. trinii internodes are grouped, Figure 1. Relationship of physical, chemical, and morphologi- cal variables with the first two axes of principal component while on positive axis 1 the majority of G. analysis. Black circles represent Guadua chacoensis and the white

chacoensis internodes are found, showing that represent G. trinii. High quality figures are available online. http://jinsectscience.oxfordjournals.org/

they are bigger and hold more water and sed- iment than G. trinii internodes. All variables

are positively correlated with axis 1 except for Fauna communities water temperature and pH. The capacity and The number of individuals collected from G.

the volume of water held in the internodes are chacoensis and G. trinii was 1,752 and 1,073 the variables best correlated with axis 1 (r2 = respectively, distributed by taxonomic group

0.90 and 0.86 respectively). The pH of the wa- as shown in Table 3. The number of individu- ter retained in both bamboos was acidic als per internode was higher and significantly by guest on August 12, 2015 (Table 1), and the greater variability was ob- different (U = 1921; n = 39, 41; p < 0.001) in served in G. chacoensis (C.VG. chacoensis = G. chacoensis (Mean = 44.9; SD = 36.8) than

33.6%; C.V G. trinii = 22.3%). The principal in G. trinii (Mean = 26.2; SD = 32.1). component analysis diagram shows that the

pH of G. trinii is more likely to be more acid The total number of taxa identified was 18 than in G. chacoensis, however significant from G. chacoensis and 20 from G. trinii;

differences were not observed (Table 1). however, for analyses, 17 and 19 respectively

Table 2. Eigenvalues and correlation coefficients (r2) of parameters associated with the axes obtained in principal component analysis.

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Table 3. Taxonomic classification of the aquatic macro-invertebrates inhabiting two bamboos species from subtropical forest, Misiones Province, Argentina.

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by guest on August 12, 2015

1Includes Toxorhychites bambusicolus and T. guadeloupensis.

were considered because larvae of 2 species of higher in G. chacoensis (n = 9) than in G.

Toxorhynchites were indistinguishable (Table trinii (n = 5), while no difference was ob- 3). Mean number of taxa by individual inter- served between bamboos with respect to

node was 4.6 (± SD 1.4) and 4 (± SD 1.8) for Ceratopogonidae. Coleoptera were occasion- G. chacoensis and G. trinii respectively, but ally present in the communities, being

they were not statistically different (U = 1766; represented mainly by species of semi-aquatic n = 39, 41; p = 0.07). The maximum number habitats, such as scirtids and chelonariids.

of taxa found in an internode was 8 for both bamboo species. Eleven taxa were present in both species of

bamboo, and 6 were unique to G. chacoensis Taxa mainly were represented by immature and 8 to G. trinii (Table 3). Regarding the

insects. Diptera was the order best represented taxa unique to each bamboo, G. chacoensis in the bamboo communities, with Culicidae as hosted a greater number of species of Cu-

the dominant family, followed by Ceratopo- licidae while G. trinii hosted more species gonidae. Richness of Culicidae species was belonging to other dipterous families.

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Journal of Insect Science: Vol. 13 | Article 93 Campos topogonidae related to Wyeomyia sp. 1 and The 2 Guadua phytotelmata were significantly Runchomyia reversa (Lane and Cerqueira) different (t = -35.46; df = 48; p < 0.001) in were low and positive (C8 S. enigma-Wyomyia sp.1 terms of the diversity and evenness of ma- = 0.32, p < 0.01; C8 C. bambusicola-R. reversa = croinvertebrates occurring in them. The 0.43, p <0.05); in contrast, the association diversity was greater in G. trinii (H’ = 2.03; E between Dixidae and R. reversa was high = 0.69) than in G. chacoensis (H’ = 1.74; E = and negative (C8 = -1, p < 0.05). 0.61). The Berger–Parker index of dominance (d) was not significantly different (t = -1; df = Two C8 values were significant among taxa 78; p = 0.33) between G. trinii (d = 0.60 ± in G. trinii. Ceratopogonidae, Stilobezzia 0.20) and G. chacoensis (d = 0.56 ± 0.17). enigma Ronderos, Spinelli, and Borkent and Morisita-Horn index of similarity was high Forcipomyia sp. (C8 = 0.60, p < 0.001), and (CMH = 0.80) because the internodes of both Scatopsidae and Dolichopodidae (C8 = 0.50,

Guadua species shared most of the taxa. p < 0.01) showed significant positive asso- Downloaded from ciations. In G. trinii, no associations were Species association observed between species of Culicidae in Four values of the species association coef- contrast to G. chacoensis.

ficient (C8) for taxa inhabiting G. http://jinsectscience.oxfordjournals.org/ chacoensis were significant between species Abiotic parameters effects on aquatic of mosquitoes, and 5 between mosquitoes communities and other dipterans. Toxorhynchites spp. All morphological variables were used for the (Diptera: Culcidae) was negatively associat- analysis, as no collinearity was detected ed with Sabethes aurescens (Lutz) (C8 = -1, (VIFG. chacoensis < 1.86; VIFG. trinii < 1.96). Dur- p < 0.05) and Wyeomyia codiocampa Dyar bin-Watson test for independence of residuals and Knab (C8 = -0.43, p < 0.01), while S. detected no autocorrelation between variables aurescens and W. codiocampa showed max- for both bamboos (G. chacoensis: DNº indiv. = by guest on August 12, 2015 imum positive association (C8 = 1, p < 2.3; DNº Taxa = 2.2; G. trinii: DNº indiv. = 2.3; DNº 0.05). On the other hand, both species of Taxa = 1.9). The multiple regression model for Sabethes (S. identicus Dyar and Knab and S. G. chacoensis explained 42% of abundance aurescens) were not associated (C8 = 0, p variation of macroinvertebrates and was sig- <0.05). C8 significant values for associations nificant (F = 3.59; df = 6, 30; p < 0.01), but, between other dipterans and species of cu- the model was not significant for the number 2 licids were: Syrphidae showed a slight of taxa (r = 0.25; F = 1.67; df = 6, 30; p = positive association with Toxorhynchites 0.16). By contrast, for G. trinii, the number of spp. (C8 = 0.10, p < 0.05) but was not asso- individuals and the number of taxa were sig- ciated with Wyeomyia serrata (Lutz) (C8 = nificant (FNº indiv. = 3.62; df = 6, 34; p < 0.01; 0, p < 0.05). C8 values for species of Cera- FNº Taxa = 5.91; df = 6, 34; p < 0.001), and the

Table 4. Coefficient and Student’s t-test results (significant differences) from the multiple regression analysis from transformed data between macroinvertebrate individuals and number of taxa against abiotic variables of two bamboo phytotelmata.

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Table 5. Coefficient and Student’s t-test result (significant differences) from the multiple regression analysis from transformed data be- tween number of mosquitoes and number of species against abiotic variables of two bamboo phytotelmata.

model explained 39 and 51% respectively of lated to the pH of the standing water in bam-

the variation of these variables. boo internodes, the correlation coefficients were calculated for the number of mosquitoes

The number of individuals in the community per genera that made up the community of that lived in the internodes of G. chacoensis both species of Guadua phytotelmata. Alt-

was positively correlated with the volume of hough all species of mosquitoes were found in

water and the height of the internodes. For G. internodes with pH ranging from strongly Downloaded from

trinii, the volume of water and the detritus acidic to alkaline, no significant correlations correlated positively with both the number of were observed in any of them (G. chacoensis:

individuals and the number of taxa (Table 4). rs, Toxorhynchites spp. = 0.13, p = 0.15, n = 23; rs,

Wyeomyia spp. = -0.15, p = 0.44, n = 27; rs, R. reversa http://jinsectscience.oxfordjournals.org/

The independent variables regressed against = 0.17, p = 0.39, n = 26; rs, Sabethes spp. = -0.32, species of mosquitoes were not autocorrelated p = 0.75, n = 4; G. trinii: rs, Wyeomyia spp. = 0.13,

for either species of bamboo (G. chacoensis: p = 0.49, n = 31; rs, R. reversa = -0.10, p = 0.66, n DNº mosq. = 2.2; DNº species = 2; G. trinii: DNº mosq. = 22). All species were predominately in in-

= 1.8; DNº species = 1.8). The multiple regres- ternodes with an acidic pH. sion model for G. chacoensis was significant

(F = 2.90; df = 6, 30; p < 0.05) and explained Predators 37% of the variation of abundance and num- Seven predators were identified from both by guest on August 12, 2015 ber of species. For G. trinii, it explained 42% species of bamboo: Toxorhynchites bam- of the variation of the abundance of mosqui- busicolus (Lutz and Neiva), T.

toes and 26% of the variation of the number of guadeloupensis (Dyar and Knab), R. rever- species, but was only significant for abun- sa, S. aurescens, S. identicus, Culicoides dance (F Nº mosq. = 4.1; df = 6, 34; p < 0.01; FNº bambusicola (Lutz), and Corethrella sp. species = 2.90; df = 6, 34; p = 0.1). Species of Toxorhynchites are the biggest predators in the internodes, R. reversa, S. The abundance of mosquitoes and the number aurescens, S. identicus are medium and po- of species that inhabited internodes of G. tential facultative predators (as are other chacoensis was correlated with pH, while for species of Sabethes) (Lozovei and Luz 1976, abundance of mosquitoes in G. trinii the cor- Machado-Allison 1986), and C. bambusico- related variables were the water volume and la and the Corethrellidae are the smallest. the height of the internodes, and for the num- ber of species the water volume (Table 5). Because the species of Toxorhynchites are the largest predators in both G. chacoensis and G. As previous studies on bamboo internodes trinii, it was of interest to compare the occu- (e.g., Kurihara, 1959, 1983) showed that the pancy of the internodes with different size occurrence of the species of mosquitoes is re- entry holes in these species. Respectively, 59

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and 46.3% of internodes of G. chacoensis and

G. trinii were inhabited by larvae of Tox- orhynchites spp. All internodes contained 1

larva, except 1 G. chacoensis contained two. Most internodes with Toxorhynchites had en-

try holes of less than 10 mm. There were no larvae of Toxorhynchites in internodes with

entry holes of 20–30 mm, and only 1 larva was collected from internodes of G. chacoen- Figure 2. Number of internodes of Guadua chacoensis and G. sis with a hole greater than 30 mm (Figure 2). trinii inhabited by Toxorhynchites larvae segregated into hole size The smallest inlet size in an internode where a categories. High quality figures are available online.

Toxorhynchites larva was found was 3 mm in a G. trinii. However the proportion of inter-

nodes with entry holes less than 10 mm Downloaded from containing Toxorhynchites larvae was not sig-

nificantly different from internodes with entry holes greater than 10 mm for both G.

chacoensis (G adj. = 0.02, p > 0.50) and G. http://jinsectscience.oxfordjournals.org/

trinii (G adj. = 0.42, p > 0.50).

To determine whether prey abundance was

affected by the presence of the predator Figure 3. Guadua chacoensis: A- View of an entry hole to an Toxorhynchites in each internode of both internode, B- Cross-section showing the wall thickness of an internode and galleries (indicated by arrows) formed by a bamboo species, the numbers of individual boring beetle. Scaling = 1 cm. High quality figures are available prey collected from these two habitats were online.

compared. Mann-Whitney rank tests showed by guest on August 12, 2015 no significant differences between the num- beetle, as the wall of the stem was extremely

ber of prey in internodes with or without hard and thick (~ 3 cm). Moreover, internal

Toxorhynchites larvae (U G. chacoensis = 302, n galleries were observed when bamboos were

Min. = 16, n Max. = 23, p = 0.62; U G. trinii = cut (Figure 3b). The same circular inlet

421, n Min. = 19, n Max. = 22, p = 0.57). holes, but of smaller diameter, were ob-

served in G. trinii, although they were Discussion accompanied by grooves and irregular holes.

This heterogeneity of shapes and sizes could Bamboo internodes as micro-habitat be because the stem of G. trinii was much

Macroinvertebrates access internodes thinner (~ 5 mm) than the stem of G. through holes caused by the boring activities chacoensis, and can be attacked by several

of animals such as leaf beetles, long-horned species of arthropods. beetles, caterpillars, or woodpeckers in the

walls of culms (Kovac and Streit 1996), Factors with significant loading from prin- producing holes of different shapes and siz- cipal component analyses included internal

es. The inlet holes of G. chacoensis were diameter of internodes and the height of the smooth, circular drillings (Figure 3a), so entry hole, contributing to internode capaci-

they could have been caused by a boring ty to retain more water and detritus. The

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Journal of Insect Science: Vol. 13 | Article 93 Campos water retained in bamboo internodes comes pH of the water retained in the internodes of from the plant exudates (Louton et al. 1996) both species of Guadua was predominantly and from runoff during heavy rains (Kovac acidic (pH: minimum 2.7, mean: ~ 5), reach- and Streit 1996), leading to large variations ing strongly alkaline values (8.3) in G. in volume of water held by internodes. Lou- chacoensis and slightly alkaline (7.7) in G. ton et al. (1996) observed that the volume of trinii. water in G. weberbaueri had a range from 1–325 mL, and noted stains below the lat- Fauna communities eral opening which were attributed to The aquatic communities that inhabit bamboo frequent overflows, apparently, when inter- are mainly composed of immatures of several nodes are filled with water above the level dipterans (Louton et al. 1996), the Culicidae of the openings. Similar observations were being the most diverse and most studied fami- made in G. chacoensis and G. trinii, which ly. In the aquatic communities of South

showed differences not only in the volumes American bamboos, the mosquitoes are the Downloaded from of water from the internodes of both principal inhabitants, within which Sabethini Guadua, but also between the internodes of is the most diverse and dominant tribe. Ap- each species. proximately 40 species of Culicidae were

reported from bamboo phytotelmata, of which http://jinsectscience.oxfordjournals.org/ During the present study, spill stains were 14 and 12 identified and unidentified species, also noted, as observed by Louton et al. respectively, have been found in Guadua phy- (1996), although the volume of water never totelmata (Louton et al. 1996; Lozovei 1998, exceeded 60% of the capacity of the inter- 2001; Campos et al. 2011). In a recent study nodes. from subtropical Argentina, 9 identified spe- cies collected from Guadua were reported The origin of food resources in the inter- (Campos et al. 2011). In the present study, the nodes came from the runoff produced when same species were recorded, except Tri- heavy rainwater seeped through the bamboo, choprosopon pallidiventer (Lutz) and by guest on August 12, 2015 and from the faeces, exuviae, and corpses of Wyeomyia sabathea Lane and Cerqueira. macroinvertebrates that inhabit them (Per- From the species occurring in Guadua phy- sonal observation). Among the internodes of totelmata, only Tx. bambusicola and Tr. G. chacoensis, there was greater variation in pallidiventer have been recorded from con- the amount of debris retained than observed tainers other than bamboo phytotelmata for G. trinii. The higher variation in G. (Campos et al. 2011) in the study area. Other chacoensis could be related to higher entry species of mosquitoes (Table 3) can be con- holes (as shown in the principal component sidered as specialists of bamboo phytotelmata analysis diagram), allowing the entry of ter- because they were not found in other micro- restrial invertebrates that use the upper habitats. It is worth noting that no species of portion of the internodes as a refuge (Louton the genus Culex was found in the internodes et al. 1996). These invertebrates would con- of bamboos in the present study, as opposed to tribute to the debris from defecation and/or the abundance found by other authors (Louton food waste (Mogi and Suzuki 1983). et al. 1996; Lozovei 1998, 2001) who studied Lozovei (2001) mentioned that the water in the fauna inhabiting Guadua bamboo in Brazil live internodes is acidic (3.5) or neutral and Peru. Of the identified species of Cerato- (7.1). Unlike the results of that author, the pogonidae occurring in bamboo phytotelmata,

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Journal of Insect Science: Vol. 13 | Article 93 Campos C. bambusicola, (Ronderos and Spinelli 2000) of the perforation on the side of the internodes and S. enigma (Ronderos et al. 2012) are in- rather than to the volume of water or the habitants with no record from other habitats; height of the opening above ground, while the by contrast, Palpomyia guarani was collected number of taxa was not associated with any not only from bamboos, but also from tree- abiotic parameter of internodes (Louton et al. holes (Ronderos et al. 2004). 1996). The results showed that the volume of water and debris, and to a lesser extent the Other dipterans present in Neotropical phy- height of the opening above ground, are pa- totelmata are the Corethrellidae, with 19 rameters that strongly influence the aquatic species restricted to treeholes and bamboo in- community. The size of the entry hole to the ternodes (Borkent 2008). However, in the internodes could function as a mechanism for present study, only an unidentified species of selecting the size of the individuals rather than Corethella, which was the second most abun- their abundance. Louton et al. (1996) analyzed

dant Dipteran, was recorded in both species of the community of mosquitoes in particular, Downloaded from Guadua phytotelmata. and found that both the number of individuals and the number of species were significantly Species association correlated with the volume of water. Con-

In a study carried out in Perú, 2.7 taxa per in- versely, Lozovei (2001) noted that the number http://jinsectscience.oxfordjournals.org/ ternode of G. weberbaueri were recorded of mosquitoes depends on the volume of water (Louton et al. 1996). By contrast, the results retained within the internodes. The results of of the present study showed a mean of 4.6 and both Guadua studied here are ambiguous. The 4 taxa per internode of G. chacoensis and G. abundance and richness of species of mosqui- trinii, respectively. The present study showed toes that developed in the internodes of G. high species associations, both positive and trinii were correlated with the volume of wa- negative. Negative associations with predators ter, while the mosquitoes that developed in G. were possible due to asynchronies in occur- chacoensis were correlated to pH but not to rence with other macroinvertebrates in the the volume of water. by guest on August 12, 2015 internodes. While the observed positive asso- ciation occurred between predators and The succession of dipteran larvae in the syrphids, this would suggest that they may not bamboo is likely to occur as a result of suc- be a prey chosen by the predator, possibly due cessive changes in pH, and it is noted, for to their larger size or because the syrphids example, that the mosquito Aedes flavopic- possess some behavior for escaping from tus colonizes internodes when the pH is predators. The filter feeding Sabethes aure- acidic (pH ~ 6.2), while Armigeres subalba- scens and W. codiocampa were strongly tus colonizes them when the medium associated, suggesting that competition for becomes slightly alkaline (pH ~ 7.7) (Ku- resources is low. By contrast, both species of rihara 1983). No mosquito larvae were Sabethes (S. aurescens and S. identicus) were found when the pH was less than 5.5 (Ku- not associated. rihara 1959). The results found in the present study, unlike those of Kurihara Abiotic parameters effects on aquatic (1983, 1959), showed that the species of communities mosquitoes inhabiting the internodes of The abundance of macroinvertebrates in the Guadua bamboo (all Sabethini except Tox- water-filled Guadua was attributed to the size orhynchites spp.) were related preferably to

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Journal of Insect Science: Vol. 13 | Article 93 Campos acidic water, tolerating pH values well be- to its abundance, mainly in those internodes low 5.5 and being less frequent in alkaline that are not occupied by Toxorhynchites lar- water. Similar results were found by vae. Lozovei (2001) in a study on mosquitoes that inhabit Merostachys bamboo internodes It is known that larval feeding habits of New in Brazil. Word Sabethini are facultative predators or filter feeding (Judd 1996). For example, it was Predators observed in laboratory that the Isostomyia Immatures of Toxorhynchites, Corethrella sp., paranensis larvae (sister groups of Runchomy- and C. bambusicola were the main predators ia) prey on other larvae of mosquitoes, in the aquatic communities of both Guadua. grasping the body and sucking the soft tissues Other members of the community, as some without taking the skin (Campos and Zavort- genera of mosquitoes of the Sabethini tribe, ink 2010), and Runchomyia frontosa

are suspected to be predators, among them the occasionally preys on inhabitants of phytotel- Downloaded from species of Runchomyia and Sabethes. All the- mata (Zavortink 1986). Some species of se predators, except Toxorhynchites larvae, Sabethes are known as facultative predators, showed aggregated inter-bamboo distribution. preying on culicids, ceratopogonids and other

On the contrary, the predator Toxorhynchites, larvae of aquatic dipterans (Lozovei and Luz http://jinsectscience.oxfordjournals.org/ whose cannibalism has been widely docu- 1976; Machado-Allison 1976). Predation by mented (e.g., Lounibos et al. 1996; Campos R. reversa, S. aurescens, and S. identicus has and Lounibos 2000a, b), usually occurred not been documented. However, due to the alone in each internode. A similar observation fact that their mouthparts are similar to the was reported by Kovac and Streit (1996) from ones of other species of the same genus (Har- bamboo internodes in Malaysia. bach and Peyton 1993), they could be potential facultative predators in the aquatic Predation by Corethrellidae has been well- communities of Guadua. documented by Griswold and Lounibos by guest on August 12, 2015 (2006), who studied the effects of predation Conclusions by Corethrella appendiculata in treeholes. On the basis of the results of this article, it is These authors concluded that C. appendicula- concluded that: (1) G. chacoensis provided ta larvae change species composition by more aquatic habitats for the macroinvertebrate preferentially consuming a prey type, while community than G. trinii; (2) the entry hole Toxorhynchites larvae by reducing prey densi- determined directly (by limiting the size of de- ty, regardless of the species present in the bris) and indirectly (by limiting the size of community. In another study, carried out on visitors that provide faeces and corpses to the predatory habits of dipteran larvae inhabiting water) the resource availability; (3) the com- Nepenthes pitchers, it was observed that munities differed between Guadua species, but Corethrella calathicola larvae attack younger a large number of macroinvertebrates used culicids and immature ceratopogonids, and both phytotelmata; (4) the richness of species when prey are scarce they may develop a can- found in both species showed that these phy- nibalistic behavior (Mogi and Chan 1996). totelmata were mainly colonized by species of Predation by Corethrella was not examined Culicidae and Ceratopogonidae; and (5) the here, but due to the aforementioned studies, it largest predators, which tended to occur singly, is assumed it can be a significant predator due

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Journal of Insect Science: Vol. 13 | Article 93 Campos were mosquito larvae of the genus Toxorhyn- Borkent A. 2008. The frog-biting midges of chites. the World (Corethrellidae: Diptera). Zootaxa 1804: 1–456. Acknowledgements Campos RE, Lounibos LP. 2000a. Life tables I thank the National Park Administration, of Toxorhynchites rutilus (Diptera: Culicidae) Northeast Region, Centro de Investigaciones in nature in southern Florida. Journal of Med- Ecológicas Subtropicales (CIES) for logistical ical Entomology 37(3): 385–392. help and the license to collect. I thank Eduardo Lestani (Facultad de Ciencias Físicas, Exactas Campos RE, Lounibos LP. 2000b. Natural y Naturales, Universidad Nacional de Córdoba) prey and digestion times of Toxorhynchites for his help in field work, Gustavo Spinelli rutilus (Diptera: Culicidae) in southern Flori- (Facultad de Ciencias Naturales y Museo, Uni- da. Annals of the Entomological Society of

versidad Nacional de La Plata) for taxonomic America 93(6): 1280–1287. Downloaded from determination of Ceratopogonidae, and Monica Caviglia (ILPLA) for improvement of the Campos RE, Spinelli G, Mogi M. 2011. Cu- English. I thank Motoyoshi Mogi (Faculty of licidae and Ceratopogonidae (Diptera:

Medicine, Saga University, Japan) for his Nematocera) inhabiting phytotelmata in http://jinsectscience.oxfordjournals.org/ comments and suggestions on the preliminary Iguazú National Park, Misiones province, sub- manuscript and anonymous reviewers for their tropical Argentina. Revista de la Sociedad suggestions. This study was supported by Con- Entomológica Argentina 70(1–2): 111–118. sejo Nacional de Investigaciones Científicas y Técnicas (CONICET). This is a contribution of Campos RE, Zavortink TJ. 2010. Description the Instituto de Limnología: Journal Serie No. of the larva and pupa and redescription of the 908. adults of Isostomyia paranensis (Brèthes) (Diptera: Culicidae). Zootaxa 2689: 27–36. by guest on August 12, 2015 References Darsie, RF Jr. 1985. Mosquitoes of Argentina. Anosike JC, Nwoke BEB, Okere AN, Oku Part I. Keys for identification of adult females EE, Asor JE, Emmy-Egbe IO, Adimike D A. and fourth stage larvae in English and Spanish 2007. Epidemiology of tree-hole breeding (Diptera, Culicidae). Mosquito Systematics mosquitoes in the tropical rainforest of Imo 17: 153–253. state, South-East Nigeria. Annals of Agricul- tural and Environmental Medicine 14: 31–38. Dinerstein E, Olson DM, Graham DJ, Webster AL, Primm SA, Bookbinder MP, Fedec G. APN. 2009. Administración de Parques 1995. Una evaluación del estado de con- Nacionales. Available online: servación de las ecoregiones terrestres de www.parquesnacionales.gov.ar América Latina y el Caribe. WWF and World Bank. Bradshaw WE, Holzapfel CM. 1983. Predator- mediated, non-equilibrium coexistence of tree- Fish D. 1983. Phytotelmata: flora and fauna. In hole mosquitoes in southeastern North Ameri- Frank JH, Lounibos LP, Editors. Phytotelmata: ca. Oecologia 57: 239–256. terrestrial plants as hosts of aquatic insect communities. pp. 1–27. Plexus Inc.

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