Higher Ant Diversity in Native Vegetation Than in Stands of the Invasive Arundo,Arundo donax L.,Along the Rio Grande Basin in Texas,USA

Abstract

Our hypothesis was that there will be greater ant biodiversity in heterogeneous native vegetation compared with Arundo stands. Changes in ant biodiversity due to Arundo invasion may be one of the ecological changes in the landscape that facilitates the invasion of cattle fever ticks from Mexico where they are endemic. Ants collected in pitfall traps were identified and compared between native vegetation and stands of Arundo, Arundo donax L., monthly for a year at 10 locations. A total of 82 752 ants representing 28 genera and 76 species were collected. More ants were collected in the native vegetation which also had greater species richness and biological diversity than ants collected from Arundo stands. It is suggested that the greater heterogeneous nature of native vegetation provided greater and more predictable nourishment in the form of nectars and more abundant arthropod prey when compared with Arundo stands.

Keywords

Ant diversity extrafloral nectaries pitfall traps

Introduction

Incidence of cattle fever ticks, Rhipicephalus (=Boophilus) spp, breaching the US quarantine zone along the Rio Grande is on the increase motivating studies of ecological changes occurring concurrent to the establishment of the invasive Arundo donax L. (Poales: Poaceae). Arundo, also known as giant reed or carrizo cane, is native to the Mediterranean coasts of Europe and North Africa to south Asia. Arundo donax is an invasive weed of riparian habitats of the southwestern United States.^1–3 Classified as an invasive perennial species, it spread widely in riparian zones of Texas where it has altered wildlife habitats, created fire hazards, compromised water conservation efforts, affected flood control, and reduced visibility for law enforcement officers along the international border with Mexico. Arundo might also facilitate cattle fever tick, Rhipicephalus (=Boophilus) spp, invasion into the permanent quarantine zone along the Rio Grande between Del Rio and Brownsville, TX, by harboring known mammalian host such as white-tailed deer, Odocoileus verginianus (Zimmermann).^4–6

Ants were chosen as a survey taxon because they are known predators of ticks^7–10 and are often represented by multiple species demonstrating high diversity.^11,12 The diversity and abundance of ants in native vegetation and Arundo along the Rio Grande basin in Texas have not been previously studied. The objective of this study was to compare and contrast ant diversity between Arundo and native vegetation along the Rio Grande River at the Texas-Mexico border.

The hypothesis was that there will be greater ant biodiversity in heterogeneous native vegetation compared with Arundo stands. Native vegetation containing a variety of plant species provides for greater occurrences of various edges and niches increasing opportunities for various ant species to have survival advantages over competitors including predator avoidance and opportunities for specialized relationships with myrmecophytic plants when contrasted with a monoculture.¹¹ Changes in ant biodiversity due to Arundo invasion may be one of the ecological changes in the landscape that facilitates the invasion of cattle fever ticks from Mexico where they are endemic.¹³

Materials and Methods

Study sites

Ant samples were collected from 10 Texas research sites located just north of the Rio Grande along the Texas-Mexico border (Table 1, Figure 1).

Table 1.

Ant sample study site locations along the Rio Grande, TX, USA.

Location	County	Latitude, longitude
Los Indios	Cameron	26.05, −97.74
North American Butterfly Association (NABA)	Hidalgo	26.180243, −98.364973
Bentsen-Rio Grande State Park	Hidalgo	26.1731300, −98.3825200
San Ygnacio	Zapata	27.048175, −99.430788
Laredo Community College (LCC)	Webb	27.5084, −99.5214
La Bota Ranch	Webb	27.6161258, −99.5569872
Comanche Ranch	Maverick	28.643901, −100.444024
Rosita Ranch	Maverick	28.643901, −100.444024
Sycamore Creek	Kinney	29.4410659, −100.1228475
Del Rio	Val Verde	29.3709, −100.8959

Figure 1.

Study sites in the cattle fever tick quarantine zone along the Texas-Mexico border.

Ant sampling

Ants were sampled using pitfall traps (Figure 2). A trap comprised 470-mL polypropylene container (Ball, Fishers, IN, USA) 10.5 cm × 9.9 cm × 7.0 cm (height × top diameter × bottom diameter). A plywood shelter (30.5 cm × 30.5 cm) was supported ≈1.3 cm above the trap. Each trap contained a 50:50 mixture of propylene glycol and water. Trapping intervals were ≈30 d. Four traps were located 10 m apart within an Arundo stand, and 4 traps were similarly placed in native vegetation at each of the 10 locations.

Figure 2.

Standard pitfall trap.

Monthly pitfall trap collections were conducted during January to December 2014 at each site. Ant identification was conducted with a stereoscopic microscope using taxonomic ant keys.^14–19 A survey of plants and the presence of extrafloral nectaries was conducted at each study site.

Statistical analysis

Diversity profile estimations were calculated using Spade (Species Prediction and Diversity Estimation).²⁰ Continuous diversity profile including species richness, Shannon entropy, Simpson index, and Chao2 as well as their effective numbers of species based on incidence data were calculated using species richness prediction and diversity estimation. Shannon entropy provides expected mean which increases with a species richness and evenness. Simpson index values increase as diversity decreases, whereas the inverse Simpson index values increase as diversity increases providing a dominance index giving more weight to common or dominant species. Chao2 estimates true species diversity of a sample using incidence data. Value differences were considered significant when their confidence intervals did not overlap. The program iNEXT^21–23 was used to plot sample size–based rarefaction and extrapolation sampling curves where this curve plots the species richness estimates for a rarefied and extrapolated sample with respect to sample size following bootstrapping 100 times (Figure 4).²² iNEXT was used to calculate coverage-based rarefaction and extrapolation where species richness estimates for rarefied and extrapolated samples for sample coverage.²¹ Using incidence data, iNEXT was used to calculate sample completeness curve where this curve plots the sample completeness (as measured by sample coverage) with respect to sample size. The social nature of ants promotes clumping as members of a colony will recruit numerous nest mates to a particular location making analysis of incidence data (presence or absence) most appropriate.^24,25

Calculated Hill number unifies the reported biological diversity parameter such that the Hill numbers 0, near 1, and 2 provide the communities’ species richness, exponent of Shannon index, and inverse of Simpson index, respectively. More weight is give given to dominant species as the Hill number increases.²³ Coverage-based rarefaction and extrapolation sampling curve provide species richness estimates for rarefied sample and extrapolated sample with sample coverage up to double the reference sample size (Figure 4).

Results

After 12 months, a total of 82 752 ants representing 28 genera and 76 species were captured (Table 2). Only 7 species were captured from all 10 locations (see Table 2). Twenty species were captured at single locations (Table 2). Seven of the ant species were found only in the southern most test sites, Los Indios, North American Butterfly Association (NABA), or Bentsen R.G. In addition, 11 species were found only in the northernmost test sites, Comanche Ranch, Rosita Ranch, Sycamore Creek, or Del Rio. Pheidole was the most diverse genus represented by 21 species (Table 2).

Table 2.

Presence/absence of ants captured in pitfall traps in tick quarantine zone.

Species	Subfamily	LI	NABA	BRG	SY	LCC	LB	CR	RR	SC	DR
1. Aphaenogaster texana texana	Myrmicinae	+	+	0	0	0	0	0	0	0	0
2. Atta texana	Myrmicinae	0	0	+	+	0	0	0	+	+	0
3. Brachymyrmex depilis	Formicinae	0	0	0	0	+	+	0	0	0	+
4. Brachymyrmex patagonicus	Formicinae	+	+	+	+	+	+	+	+	+	+
5. Camponotus festinatus	Formicinae	0	+	0	0	0	+	+	0	+	0
6. Camponotus floridanus	Formicinae	+	+	+	+	0	0	0	0	0	0
7. Camponotus planatus	Formicinae	+	+	+	0	0	0	0	0	0	0
8. Camponotus sayi	Formicinae	+	+	0	0	0	0	0	0	+	0
9. Camponotus texanus	Formicinae	+	+	+	+	+	0	0	0	+	0
10. Cardiocondyla emeryi	Myrmicinae	0	0	0	0	+	0	0	0	0	0
11. Crematogaster crinosa	Myrmicinae	0	+	0	0	0	0	0	0	0	0
12. Crematogaster laeviuscula	Myrmicinae	+	+	+	+	+	+	+	+	+	+
13. Crematogaster lineolata	Myrmicinae	0	+	0	0	0	0	0	0	0	0
14. Crematogaster torosa	Myrmicinae	+	+	0	0	0	0	0	0	0	0
15. Cyphomyrmex rimosus	Myrmicinae	+	+	+	+	+	+	+	0	+	0
16. Dorymyrmex bicolor	Dolichoderinae	0	0	0	0	0	+	0	0	0	+
17. Dorymyrmex flavus	Dolichoderinae	+	+	+	0	+	+	+	+	+	+
18. Dorymyrmex insanus	Dolichoderinae	0	0	0	0	+	+	0	+	+	+
19. Forelius mccooki	Dolichoderinae	+	+	+	+	+	+	+	+	+	+
20. Forelius pruinosus	Dolichoderinae	+	+	0	0	+	+	0	+	+	+
21. Formica pallidefulva	Formicinae	0	0	0	0	0	+	0	0	+	0
22. Hypoponera opaciceps	Ponerinae	0	0	0	0	0	0	+	0	0	0
23. Hypoponera opacior	Ponerinae	0	+	0	0	0	+	+	+	+	0
24. Hypoponera punctatissima	Ponerinae	0	0	0	+	0	0	0	+	0	0
25. Labidus coecus	Dorylinae	+	+	+	+	+	0	0	+	+	+
26. Leptogenys elongata	Ponerinae	+	+	+	0	0	0	+	+	+	+
27. Monomorium minimum	Myrmicinae	+	0	0	+	0	0	+	+	+	0
28. Monomorium pharoanis	Myrmicinae	0	0	0	0	0	0	+	0	0	0
29. —	Mutillidae (Family)	+	+	+	+	+	+	+	+	+	+
30. Myrmecocystus mendax	Formicinae	0	0	0	0	0	0	0	0	+	0
31. Neivamyrmex nigrescens	Dorylinae	0	+	+	0	0	0	0	+	0	0
32. Neivamyrmex swainsonii	Dorylinae	0	+	+	+	0	+	+	+	0	+
33. Neivamyrmex texanus	Dorylinae	0	0	0	0	0	0	0	+	0	0
34. Odontomachus clarus	Ponerinae	0	0	0	0	0	0	0	+	+	+
35. Pachycondyla harpax	Ponerinae	0	0	0	+	0	+	0	+	0	0
36. Paratrechina terricola	Formicinae	+	+	+	0	+	+	+	+	+	+
37. Pheidole bicarinata	Myrmicinae	+	+	+	0	+	+	+	+	+	+
38. Pheidole cockerelli	Myrmicinae	0	0	+	0	+	0	0	0	0	0
39. Pheidole dentata	Myrmicinae	+	+	+	+	+	+	+	+	+	+
40. Pheidole flavens	Myrmicinae	0	0	0	0	0	0	0	0	+	0
41. Pheidole floridana constipata	Myrmicinae	+	+	+	+	+	+	+	+	+	+
42. Pheidole floridana floridana	Myrmicinae	+	+	0	0	+	+	0	0	+	+
43. Pheidole humeralis	Myrmicinae	0	0	0	0	0	+	0	0	0	0
44. Pheidole hyatti	Myrmicinae	0	0	0	0	0	0	0	+	+	0
45. Pheidole lamia	Myrmicinae	0	0	0	0	0	0	0	+	+	0
46. Pheidole mera	Myrmicinae	+	0	0	0	0	+	0	+	+	0
47. Pheidole metallescens	Myrmicinae	0	0	+	0	0	+	0	+	+	0
48. Pheidole moerens	Myrmicinae	0	0	0	0	0	0	0	0	+	0
49. Pheidole nuculiceps	Myrmicinae	0	0	0	0	0	+	0	0	0	0
50. Pheidole pelor	Myrmicinae	0	0	0	0	0	0	0	0	+	0
51. Pheidole porcula	Myrmicinae	+	0	+	+	+	+	0	+	+	+
52. Pheidole sciara	Myrmicinae	0	0	0	+	+	0	+	+	+	0
53. Pheidole spadonia	Myrmicinae	+	0	0	0	0	0	0	0	0	0
54. Pheidole tetra	Myrmicinae	0	0	+	0	+	+	+	0	+	+
55. Pheidole texana	Myrmicinae	0	0	0	0	0	0	0	+	0	0
56. Pheidole tysoni	Myrmicinae	0	0	0	0	0	0	0	0	0	+
57. Pheidole vallicola	Myrmicinae	0	0	0	0	0	0	+	+	0	0
58. Pogonomyrmex barbatus	Myrmicinae	+	0	0	0	0	+	0	0	0	+
59. Pogonomyrmex rugosus	Myrmicinae	0	0	0	0	0	+	0	0	0	0
60. Pseudomyrmex gracilis	Pseudomyrmecinae	0	+	+	0	0	0	0	0	0	0
61. Pseudomyrmex pallidus	Pseudomyrmecinae	0	+	0	0	0	0	0	0	0	0
62. Solenopsis aurea	Myrmicinae	0	+	0	0	0	0	0	+	0	0
63. Solenopsis geminata	Myrmicinae	0	0	+	0	+	+	+	+	0	0
64. Solenopsis invicta	Myrmicinae	+	+	+	+	+	+	+	+	+	+
65. Solenopsis molesta	Myrmicinae	+	+	0	+	0	0	0	0	+	0
66. Solenopsis texana	Myrmicinae	+	+	+	+	+	+	+	+	+	+
67. Strumigenys boneti	Myrmicinae	+	0	0	0	0	0	0	0	0	0
68. Strumigenys louisianae	Myrmicinae	0	+	0	0	+	+	0	+	+	+
69. Strumigenys membranifera	Myrmicinae	0	0	0	0	+	0	0	0	0	0
70. Tapinoma litorale	Dolichoderinae	0	0	+	0	0	0	0	0	0	0
71. Temnothorax subditivus	Myrmicinae	+	+	+	+	0	0	+	+	+	+
72. Temnothorax pergandei	Myrmicinae	+	0	0	0	+	0	+	+	+	0
73. Tetramorium bicarinatum	Myrmicinae	0	+	0	0	0	+	0	0	0	0
74. Tetramorium caldarium	Myrmicinae	0	0	0	0	0	+	+	0	0	0
75. Tetramorium lanuginosum	Myrmicinae	0	0	+	0	+	0	+	0	0	0
76. Tetramorium spinosum	Myrmicinae	+	0	+	+	+	+	+	0	+	0
77. Trachymyrmex turrifex	Myrmicinae	0	+	0	0	+	+	+	+	+	+

Abbreviations: BRG, Bentsen R.G.; CR, Comanche Ranch; DR, Del Rio; LB, La Bota; LCC, Laredo Community College; LI, Los Indios; NABA, North American Butterfly Association; RR, Rosita Ranch; SC, Sycamore Creek; SY, San Ygnacio.

Excluding the NABA site, 2-fold to 15.5-fold greater abundances of ants were captured, and more species were encountered, in the native vegetation than in Arundo at each test site (Table 3). Ant dominance (number of traps with ants × number of species captured at the respective locations) was higher in native vegetation (Table 3). With the exception of Bentsen R.G., all calculated estimates of biodiversity were greater in native vegetation than in Arundo (Table 4). Chao2 estimated that species richness was greater in at least 70% of the test sites. Diversity indicated by the exponential of Shannon index was greater in native vegetation compared with Arundo at 40% of the sites: Laredo Community College, Comanche Ranch, Sycamore Creek, and Del Rio (Table 4). Biodiversity as quantified using the inverse of the Simpson index was also greater in native vegetation than in Arundo at 40% of the sites. The number of estimated species shared between native vegetation and Arundo at each study site ranged from 40.9% to 23.7% (Table 3).

Table 3.

Enumeration of ants captured in pitfall traps at 10 sample sites along the Rio Grande in Texas January to December 2014.

	LI	NABA	BRG	SY	LCC	LB	CR	RR	SC	DR
Arundo
Total	573	1045	377	214	2059	1063	1089	4310	1737	1745
Ant dominance	137	168	83	62	150	117	84	154	103	81
No. of species	23	25	23	14	18	18	15	23	21	12
Native vegetation
Total	1607	1099	738	3317	11 461	5149	14 467	8583	11 884	9628
Ant dominance	248	276	111	173	238	149	257	224	287	197
No. of species	29	30	24	20	26	28	23	33	40	21

Ant dominance = traps with ants × species.

Table 4.

Ant biodiversity in Arundo stands and mixed native vegetation (±SE).

Location	No. of observed species	Chao2 estimated species richness	Exponential of Shannon index	Inverse of Simpson index	Chao2 estimated shared species (observed)
Los Indios					19.3 ± 0.9 (19)
Arundo	23	24.6 ± 2.1a	19.0 ± 1.5a	15.0 ± 1.7a
Native	29	33.1 ± 4.8b	19.7 ± 1.1a	14.8 ± 0.9a
NABA					28.3 ± 12.0 (19)
Arundo	25	29.4 ± 4.7a	14.8 ± 1.3a	9.5 ± 0.7a
Native	30	46.3 ± 14.5a	14.9 ± 1.1a	9.4 ± 0.5a
Bentsen R.G.					24.9 ± 8.1 (18)
Arundo	24	73.6 ± 59.1a	14.1 ± 2.2a	6.4 ± 1.1a
Native	24	27.5 ± 3.8a	19.2 ± 1.4a	15.1 ± 1.4b
San Ygnacio					12.0 ± 2.5 (11)
Arundo	14	16.2 ± 3.3a	11.4 ± 1.5a	8.1 ± 1.3a
Native	20	28.8 ± 10.0b	13.1 ± 0.9a	10.4 ± 0.6a
LCC					14.5 ± 1.4 (14)
Aroundo	18	20.6 ± 3.4a	11.1 ± 0.9a	8.2 ± 0.6a
Native	26	32.0 ± 6.0b	14.6 ± 0.8b	10.0 ± 0.5a
La Bota					18.3 ± 7.8 (11)
Arundo	20	51.8 ± 39.4a	10.7 ± 1.2a	6.6 ± 0.7a
Native	22	34.2 ± 10.5a	11.5 ± 1.0a	7.2 ± 0.6a
Comanche Ranch					10.5 ± 2.5 (9)
Arundo	15	24.5 ± 2.2b	8.3 ± 1.5a	4.7 ± 0.5a
Native	23	28.7 ± 1.1a	13.2 ± 0.6b	9.6 ± 0.5b
Rosita Ranch					27.3 ± 10.7 (18)
Arundo	31	54.5 ± 19.8a	17.9 ± 1.3a	11.2 ± 0.8a
Native	33	44.8 ± 9.5b	19.1 ± 1.5a	12.4 ± 0.8a
Sycamore Creek					32.4 ± 11.6 (19)
Arundo	23	36.2 ± 12.2a	14.4 ± 1.5a	8.2 ± 0.9a
Native	40	47.4 ± 5.85b	22.2 ± 1.2b	13.9 ± 0.8b
Del Rio					15.3 ± 11.8 (8)
Arundo	12	19.3 ± 8.0b	6.2 ± 1.1a	3.4 ± 0.4a
Native	21	26.1 ± 5.3a	11.7 ± 0.7b	8.0 ± 0.6b

Abbreviations: LCC, Laredo Community College; NABA, North American Butterfly Association.

Chao2 estimation of species richness is equivalent of diversity of order 0; exponential of Shannon index is equivalent of diversity of order 1; inverse of Simpson index is equivalent of diversity of order 2 (Chao et al., 2015). ^a,bMean values in a column from the same location pair followed by the same letter are not significantly different as indicated by overlap of 95% confidence intervals.

Total ants collected (mean ± SEM) were greater in native vegetation (6793.3 ± 1593.8) compared with Arundo (1421.2 ± 374.2: F = 10.768; df = 1, 19; P = .004). Ant dominance (mean ± SEM) was greater in native vegetation (216.0 ± 18.1) compared with Arundo (113.9 ± 11.6: F = 22.476; df = 1, 19; P < .001). Total species collected (mean ± SEM) was greater in native vegetation (27.4 ± 1.9) compared with Arundo (19.2 ± 1.4: F = 11.913; df = 1, 19; P = .003). Native vegetation has greater diversity than the Arundo with both the empirical and extrapolated calculations (Table 4, Figure 3). Greater species richness is found in natural vegetation than is found in Arundo indicated by nonoverlap of confidence limits (Table 4, Figure 4). More than 76% of the native vegetation possessed extrafloral nectaries (Table 5).

Figure 3.

Los Indios ant diversity index Hill number plots, native vegetation (left), and Arundo (right) (Chao et al., 2015).

Figure 4.

Los Indios ant species richness and diversity comparing Arundo and natural habitat. Chao2 (Chao and Jost, 2012) used as estimator of species richness and suggested estimator of sample coverage. (A) Sample size–based rarefaction and extrapolation sampling curve: species richness estimates for a rarefied and extrapolated sample with sample size up to double the reference sample size. (B) Sample completeness curve: sample completeness (as measured by sample coverage) with respect to sample size. This curve provides a bridge between sample size–based and coverage-based rarefaction and extrapolation. (C) Coverage-based rarefaction and extrapolation sampling curve: species richness estimates for rarefied sample and extrapolated sample with sample coverage up to double the reference sample size.

Table 5.

Presence/absence of plants and EFNs at 10 sample sites along the Rio Grande in Texas January to December 2014.

Species	EFN	Common Name	LI	NABA	BRG	SY	LCC	LB	CR	RR	SC	DR
Prosopis glandulosa	+	Mesquite	+	0	0	+	+	+	+	+	+	+
Celtis laevigata	0	Hackberry	0	+	+	0	0	+	+	+	+	0
Ulmus crassifolia	+	Cedar elm	+	+	+	+	+	+	+	+	+	+
Acacia spp	+	Acacia	0	+	+	0	0	+	+	0	+	0
Acacia rigidula	+	Blackbrush	+	+	+	+	+	+	+	+	+	+
Celtis pallida	+	spiny hackberry	+	0	+	+	0	+	+	+	0	0
Acacia smallii	+	Huisache	+	+	+	+	+	+	+	+	+	+
Mimosa pigra	0	Mimosa	0	0	+	+	0	+	+	+	+	0
Opuntia lindheimeri	+	Prickly pear cactus	+	+	+	+	+	+	+	+	+	+
Triadica sebifera	+	Chinese tallow	+	+	+	0	+	+	+	0	+	+
Ricinus communis	0	Castor bean		0	+	+	0	0	+	0	+	0
Cenchrus ciliaris	+	Buffel grass		+	+	+	+	+	+	+	+	+
Panicum maximum	+	Guinea grass		+	+	+	+	+	+	+	+	+
Triadica sebifera	+	Chinese tallow	+	+	+	0	+	+	+	0	+	+
Ricinus communis	0	Castor bean	0	+	+	0	0	+	0	+	0	0
Cenchrus ciliaris	+	Buffel grass	+	+	+	+	+	+	+	+	+	+
Panicum maximum	+	Guinea grass	+	+	+	+	+	+	+	+	+	+

Abbreviations: BRG, Bentsen R.G.; CR, Comanche Ranch; DR, Del Rio; EFNs, extrafloral nectaries; LB, La Bota; LCC, Laredo Community College; LI, Los Indios; NABA, North American Butterfly Association; RR, Rosita Ranch; SC, Sycamore Creek; SY, San Ygnacio.

Discussion

Pitfall trapping of ants has been recognized as an effective monitoring technique.^26,27 The magnitude and diversity of ant assemblages reflect the responses of individual species to environmental conditions of native vegetation and Arundo stands. Arundo stands represent a new environmental setting different from native vegetation where food resources for ants differ. Thus, species distribution appears driven by resources resulting in the observed ant species assemblages.²⁸

In the case of Los Indios, for example, the native vegetation has greater diversity than the Arundo with both the empirical and extrapolated calculations (Figure 3). Greater species richness in Los Indios natural vegetation is than found in Arundo indicated by nonoverlap of confidence limits (Figure 4). For Los Indios, the sample completeness curve indicates that the number of samples provided is adequate coverage of study area as indicated by the plateauing of the curve (Figure 4). The completeness curve provides a bridge between sample size–based and coverage-based rarefaction and extrapolation. Similar comparisons were conducted for all study sites as summarized in Table 4.

Presence of renewable and predictable food sources on vegetation will support greater populations of ants.^29–31 Composition of ant fauna differs between heterogeneous native vegetation and Arundo stands with the former supplying a heterogeneous supply of extrafloral nectaries and a greater reservoir of arthropods.^31–33 Many species of the native flora have extrafloral nectaries including trees and shrubs (Table 5). Reducing the dominance of Arundo and the subsequent re-establishment of native vegetation could increase the diversity and abundance of ant communities within the cattle fever tick permanent quarantine zone.

Extrafloral nectar is important for ant survival and growth and vitality of ant colonies. Ant richness and abundance will be higher where the availability of resources is greatest from water to extrafloral nectar to flower nectar being particularly important during dry periods.^34–36 Ants are obligated to search for other alternate sources of food and water including arthropod plant pests as prey where acquisition of resources by generalists with ant presence is influenced by availability of resources.^34,35

Arundo stands provide a simpler environment with less resources when compared with native vegetation which results in repressed ant communities with less biodiversity.

Footnotes

Acknowledgements

The authors thank reviewers for meaningful improvements of this manuscript.

Peer review:

Five peer reviewers contributed to the peer review report. Reviewers’ reports totaled 2484 words, excluding any confidential comments to the academic editor.

Funding:

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Declaration of conflicting interests:

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Author Contributions

All authors contributed equally.

References

DiTomaso

Healy

EA.

Aquatic and Riparian Weeds of the West (ANR Publication 3241). Berkeley, CA: University of California Press; 2003.

Yang

Goolsby

Everitt

JH.

Using QuickBird satellite imagery to estimate giant reed infestations in the Rio Grande Basin of Mexico. J Appl Remote Sens. 2009;3:033530.

Yang

Everitt

Goolsby

JA.

Using aerial photography for mapping giant reed infestations along the Texas-Mexico portion of the Rio Grande. Invas Plant Sci Mana. 2011;4:402–410.

Goolsby

Moran

Adamczyk

. Host range of the European, rhizome-stem feeding scale Rhizaspidiotus donacis (Hemiptera: Diaspididae), a candidate biological control agent for giant reed, Arundo donax (Poales: Poaceae) in North America. Biocontrol Sci Techn. 2010;19:899–918.

Moran

Goolsby

JA.

Biology of the armored scale Rhizaspidiotus donacis (Hemiptera: Diaspididae), a candidate agent for biological control of giant reed. Ann Entomol Soc Am. 2010;103:252–263.

Seawright

Rister

Lacewell

. Economic implications for the biological control of Arundo donax in the Rio Grande Basin. Southwest Entomol. 2010;34:377–394.

Butler

Camino

Perez

. Boophilus microplus and the fire ant Solenopsis geninata. In: Rodriguez

(ed.) Recent Advances in Acarology. New York: Academic Press; 1979: 469–475.

Robertson

Egg predation by ants as a partial explanation of the differences in performance of Cactoblastis cactorum on cactus weeds in South Africa and Australia. In: Proceedings of the 6th International Symposium Biological Control of Weeds (ed Delfosse

); August 19-25, 1984: 83–88; Vancouver, BC, Canada; 1985.

Showler

Reagan

TE.

Ecological interactions of the red imported fire ant in the southeastern United States. J Entomol Sci 1987;1:52–64.

10.

Velez-Bonner

Osbrink

WLA

Summy

. Mitigating predatory ants promotes establishment of biological control of Arundo by Arundo scale in the cattle fever tick quarantine zone. Subtropical Plant Sci. 2013;65:38–44.

11.

Longino

Colwell

RK.

Density compensation, species composition, and richness of ants on a neotropical elevational gradient. Ecosphere. 2011;2:1–20.

12.

Longino

Coddington

Colwell

RK.

The ant fauna of a tropical rain forest: estimating species richness three different ways. Ecol. 2002;83:289–702.

13.

Esteve-Gassent

Pérez

León

Romero-Salas

. Pathogenic landscape of transboundary zoonotic diseases in the Mexico-US border along the Rio Grande. Front Public Health. 2014;2:1–23.

14.

Bolton

Identification Guide to the Ant Genera of the World. Cambridge, MA: Harvard University Press; 1994.

15.

Cook

O’Keefe

Vinson

Drees

BM.

Texas Pest Ant Identification: An Illustrated Key to Common Pest Ants and Fire Ant Species. College Station, TX: Texas A&M AgriLife Extension Service, The Texas A&M University System; 2016.

16.

Creighton

The ants of North America. Bull Mus Comp Zool. 1950;104:1-585 + 57 plates.

17.

Holldobler

Wilson

. The Ants. Cambridge, MA: Belknap Press of Harvard University Press; 1990: 732.

18.

Mueller

UG.

Mueller Lab’s “ant identification key,” University of Texas at Austin. http://www.sbs.utexas.edu/muelleru/AntOutreach/. Published 2016.

19.

Vinson

O’Keefe

Cook

The Common Ant Genera of Texas: B-6138. College Station, TX: Texas A&M AgriLife Extension Service and Texas A&M AgriLife Research, The Texas A&M University System; 2003: 44. http://fireant.tamu.edu/files/2014/03/ENTO_001.pdf.

20.

Chao

Hsieh

Chiu

CH.

Online Program SpadeR (Species-richness Prediction and Diversity Estimation in R): Program and User’s Guide. http://chao.stat.nthu.edu.tw/wordpress/software_download/. Published 2015.

21.

Chao

Jost

Coverage-based rarefaction and extrapolation: standardizing samples by completeness rather than size. Ecology. 2012;93:2533–2547.

22.

Colwell

Chao

Gotelli

. Models and estimators linking individual-based and sample-based rarefaction, extrapolation and comparison of assemblages. J Plant Ecol. 2012;5:3–21.

23.

Chao

Gotelli

Hsieh

. Rarefaction and extrapolation with Hill numbers: a unified framework for sampling and estimation in biodiversity studies. Ecol Monogr. 2014;84:45–67.

24.

King

Porter

Evaluation of sampling methods and species richness estimators for ants in upland ecosystems in Florida. Environ Entomol. 2005;34:1566–1578.

25.

Morrison

Porter

Positive association between densities of the red imported fire ant, Solenopsis invicta (Hymenoptera: Formicidae), and generalized and arthropod diversity. Environ Entomol. 2003;32:548–554.

26.

Borgelt

New

Pitfall trapping for ants (Hymenoptera, Formicidae) in mesic Australia: the influence of trap diameter. J Insect Conserv. 2005;9:219–221.

27.

Pendola

New

Depth of pitfall traps—does it affects interpretation of ant (Hymenoptera, Formicidae) assemblages?

J Insect Conserv. 2007;11:199–201.

28.

Beier

Albuquerque

Evaluating β diversity as a surrogate for species representation at fine scale. PLoS ONE. 2016;11:e0151048.

29.

Showler

Knaus

Reagan

TE.

Foraging territoriality of the imported fire ant, Solenopsis invicta Buren, in sugarcane as determined by neutron activation analysis. Insect Soc. 1989;36:235–239.

30.

Showler

Reagan

TE.

Effects of sugarcane borer, weed, and nematode control strategies in Louisiana sugarcane. Environ Entomol. 1991;20:358–370.

31.

Belchior

Sendoya

del-Claro

Temporal variation in the abundance and richness of foliage-dwelling ants mediated by extrafloral nectar. PLoS ONE 2016;11:e0158283.

32.

Lach

Hobbs

Majer

Herbivory-induced extrafloral nectar increases native and invasive ant worker survival. Popul Ecol. 2009;51:237–243.

33.

Byk

Del-Claro

Ant-plant interaction in the Neotropical savanna: direct beneficial effects of extrafloral nectar on ant colony fitness. Popul Ecol. 2011;53:327–332.

34.

Ness

Morris

Bronstein

JL.

For ant protected plants, the best defense is a hungry offense. Ecol. 2009;90:2823–2831.

35.

Ruffner

Clark

WD.

Extrafloral nectar of Ferocactus acanthodes (Cactaceae): composition and its importance to ants. Am J Bot. 1986;73:185–189.

36.

Ness

Morris

Bronstein

JL.

For ant protected plants, the best defense is a hungry offense. Ecol. 2009;90:2823–2831.