Natal Nest Distribution and Pleometrosis in the Desert Leaf‐Cutter Ant Acromyrmex Versicolor (Pergande) (Hymenoptera: Formicidae)

Abstract

While most ant colonies are started by single queens, colony foundation by groups of queens, pleometrosis, also occurs (Wilson 1971, H6lldobler andWilson 1977). Several extensively studied, highly pleometrotic species are notably similar with respect to important aspects of colony ontogeny and population dynamics.Myrmecocystus mimicus, Solenopsis invicta and l/'eromessor pergandei queens found colonies mutualistically without respect to relatedness (Bartz and H6lldobler 1982, Tschinkel and Howard 1983, Pollock and Rissing 1985, Rissing and Pollock 1986. Further, while adult colonies of these species are highly territorial (Htilldobler 1976a(Htilldobler , 1981Wilson et al. 1971;Went et al. 1972, Wheeler andRissing 1975), natal colonies are clumped with brood raiding and subsequent worker defection from brood-raided colonies occurring (references cited above for M. mimicus and S. invicta, for F. pergandei: Rissing and Pollock, in press). Given such frequently deleterious natal colony interactions, adaptive value of b.abitat selection by founding queens resulting in clumping of natal nests is unclear. Natal nests of M. mimicus are generally clumped in areas devoid of adult nests (Bartz and H6lldobler 1982), yet still occur near such nests (B. H611dobler, pers. comm.) (Fig. 1). Although measurements were not taken, the same distribution of starting nests was observed at South Mountain Park. All queens examined for temperature tolerance survived exposure to temperature up to and including 40C for at least 2 hr; survivorship was 0, however, at Acromyrmex versicolor is highly pleometrotic; 82.5% of all queens excavated (N 160 queens from 64 nests) were from pleometrotic associations (Table 1). Relatedness appears unimportant in a queen's decision to enter a foundress association; five of the 8 "choice boxes" resulted in a single starting nest occupied by all 8 queens. The remaining 3 boxes had two starting nests each: of these 6 starting nests, 4 contained queens from both collection locales, contained 3 queens from one site only, and the last contained a solitary foundress. DISCUSSIONThe distinct habitat choice of A. versicolor queens (Fig. 1)

Nest-founding in Acromyrmex octospinosus (Hymenoptera, Formicidae, Attini): demography and putative prophylactic behaviors

“…Ninety-nine percent of 245 nests were founded by a single queen, and 3 nests (1 %) contained three queens. Other Acromyrmex species are haplometrotic (A. niger and A. balzani;Fowler, 1992), but A. versicolor is pleometrotic (Rissing et al, 1986). Monthly survivorship of A. octospinosus incipient nests was 52 % in the first month (n = 223), 60 % in the second month (n = 94), and 50 % after 2.7 months (n = 51), which is higher than survival rates for incipient nests of other Acromyrmex species (e. g., mortality rate in two-month old nests of A. niger was 88 %, and 83 % for A. balzani ;Fowler, 1992).…”

Patterns of colonization and incipient nest survival inAcromyrmex niger andAcromyrmex balzani (Hymenoptera: Formicidae)

“…No nest was ever found with more than one gyne; therefore, in the study area, we can rule out pleometrosis for these two species, in spite of the fact that A. balzani is closely related to the pleometrotic A. versicolor (Rissing et al, 1986).…”

“…For claustralcolony haplometrotic founding queens of Atta, patterns of spatial patterning and founding queen mortality have been shown to be directly related to the mature colony density (Fowler et al, 1984;Fowler, 1987). For Acromyrmex versicolor (Pergande), however, queens are not claustral, and found colonies through pleiometrosis (Rissing et al, 1986), as do some populations of Atta texana (Buckley) (Mintzer 1987(Mintzer , 1990. We have no information on other leaf-cutting ants (Atta and Acromyrmex) (Fowler et al, 1986).…”

Haplometrosis and pleometrosis in the antAcromyrmex striatus (Hymenoptera: Formicidae)

“…However, Atta texana colony foundation can be haplometrotic or pleometrotic (Mintzer, 1987), the same occurring in Acromyrmex versicolor (Rissing et al, 1986(Rissing et al, , 1989. Foundresses of Acromyrmex lundi (Weber, 1982) and Acromyrmex striatus (Diehl-Fleig and Lucchese, 1992) forage, which indicates semi-claustral foundation in these species.…”

“…While apparently in many ant species method of colony foundation is fixed and haplometrotic, in many other species method of colony foundation is populationspecific, e.g. haplometrotic and pleometrotic populations occur in Formica (Pamilo and Rosengren, 1984), Acromyrmex versicolor (Rissing et al, 1986(Rissing et al, , 1989Rissing, pers. commun.…”