A Latitudinal Gradient in Rates of Ant Predation

Abstract

Predation by ants on wasp larva baits was assessed at five latitudes from 43°N to 2°S. Rates of predation were significantly greater in the tropics; that is, a food item was exploited by ants in significantly less time in the tropics than in the temperate zone. It was also found that predation rates were higher in low second-growth vegetation than in forests and higher on the ground than on vegetation, and that these differences were more pronounced in the temperate zone than in the tropics. Rates of predation occurring on buildings were lower than in natural situations at every latitude. The number of ant species taken at the baits increased from 22 at the northernmost locality to 74 at the southernmost. In all localities but the northernmost the forest habitat produced a greater diversity of species than the field habitat. There was a greater degree of microhabitat specificity among ants in the tropics than in the temperate zone. The proportion of forest canopy specialists also increased toward the tropics. Overall predation rate and ant species richness were found to be positively correlated on a latitudinal scale, but this relationship broke down at the level of habitats and microhabitats.

Diversidade de formigas epigéicas (Hymenoptera: Formicidae) em capões do Pantanal Sul Matogrossense: relações entre riqueza de espécies e complexidade estrutural da área

“…Dessa forma, a maior representatividade de Pheidole em relação a Camponotus obtida no presente estudo parece ser resultado das coletas exclusivas no solo, e, provavelmente, devido à sazonalidade do clima no Pantanal Matogrossense. Essa pode ser também a razão para a baixa freqüência de Crematogaster (21%), gênero mais diversifi cado em áreas de mata e em coletas na vegetação (Jeanne 1979, Lopes & Leal 1991.…”

“…Muitos estudos têm observado relação positiva entre diversidade das comunidades de formigas e a complexidade do ambiente, mesmo quando comparando áreas com diferentes estágios sucessionais (Leal & Lopes 1992, Leal et al 1993, tipos de vegetação (Leal 2002), complexidade da vegetação (Hölldobler & Wilson 1990, Leal 2003b, densidade e riqueza vegetal (Leal 2003b), altitude (Jeanne 1979, Bieber et al 2006) e latitude (Benson & Harada 1988). Dessa forma, a complexidade da vegetação herbácea dos capões parece ser um fator importante para diminuição da sobreposição de nichos entre as espécies e, conseqüentemente, redução da competição entre elas.…”

Scent-Trail Diversion, a Novel Defense Against Ants by Tropical Social Wasps

“…The wasps' defences include "pecking" attacks with the mandibles accompanied by wing-fanning (West-Eberhard 1969), protective nest architecture (reviewed in Jeanne 1975), application of sticky and repellent substances to the nest support or pedicel (Jeanne 1975, Post & Jeanne 1981, rapid nest abandonment by swarms (Chadab 1979a), and nesting on trees inhabited by Azteca ants (known to afford protection against army ants -Chadab, 1979b). Chadab (1979b) noted that workers of Occipitalia sulcata scraped their mandibles on the nest envelope after incursions by Azteca ants, sometimes removing bits of carton and discarding them.…”

Morphology of the Sternal Glands of Polistes Fuscatus and P. Canadensis (Hymenoptera: Vespidae)

“…On the other hand, it is possible that the difference is taxonomic. We have found that the class 3 cells on the fifth sternite of females of Polybia (Polistinae: Polybiini) are globose and apparently not bounded by a membrane, even in histological sections (Jeanne and Post, in (Jeanne, 1979), one way P. canadensis, a tropical species, could counter this increased threat is by having more gland cells, producing greater amounts of ant repellent secretion.…”