Comparative analysis of mandible morphology in four ant species with different foraging and nesting habits

Abstract

Mandibles of ants can be considered as one of the most vital tools for the survival and success of their colonies since these are extensively utilised for defence, nest maintenance and foraging activities. We hypothesised that mandibular design is strongly dependent on the respective ecological niche and foraging habit of an ant species. In the present study, we compared the external morphology and zinc content in the mandibles of four species of ants by using scanning electron microscopy and energy dispersive X-ray spectroscopy. The ant mandible morphology varied significantly in accordance with their species-specific foraging and nesting strategies. The sickle-shaped mandibles of the strongly predaceous, Oecophylla smaragdina worker ants were characterised by a large number of pointed teeth which would be of immense utility for subduing the prey, while the shovel-shaped, highly sclerotized mandibles of Cataglyphis longipedem ants appear to be adaptations for the solitary scavenging habit and nest maintenance in arid habitats. The large-sized mandibles of Camponotus compressus ants and the stout mandibles of the predatory, Tetraponera rufonigra forager ants, have apparently evolved for collection of sugary secretions by the former and for the solitary foraging and arboreal nesting habit of the latter. The mandibular zinc content was highest in T. rufonigra ants and the lowest in the mandibles of the sugar-loving Cm. compressus ants. The diversity in the arrangement of bristles and the type of mandibular concavities, have also evolved accordingly. Thus, this study might prove to be instrumental in evaluating the various physical mechanisms involved in the evolution of insect mandibles for their defined function.

Mandible elemental composition and mechanical properties from distinct castes of the leafcutter ant Atta laevigata (Attini; Formicidae)

“…In ants, transition metals such as Zn were previously also detected in the mandible cutting edges [ 5 , 49 ], also in Atta relating to higher hard and stiffness values [ 47 , 48 , 50 , 52 ].…”

“…Additionally, there are indications for the involvement of biomineralization in the insect cuticle with alkaline earth metals such as calcium (Ca) and magnesium (Mg) [34,[42][43][44][45][46]. In previous studies on ants (also in leafcutter ants), Zn was detected in the cuticle of the mandible cutting edge [5,[47][48][49][50]. During ontogeny, Mn is first present in the cutting edges but is then replaced by Zn, the content of which increases more than 200-fold from a freshly emerged to a fully grown worker, making the region more than twice as hard [48].…”

“…[2]). This can be associated with morphological adaptations as muscle and mandible size and shape, leading to improved performance in their respective roles [2][3][4][5][6][7][8][9][10].…”

Foraging Behaviour and Population Dynamics of Asian Weaver Ants: Assessing its Potential as Biological Control Agent of the Invasive Bagworms <em>Metisa plana</em> (Lepidoptera: Psychidae) in Oil Palm Plantations

“…Asian weaver ants are reputable to be excessively pugnacious generalist predators preying on a wide range of insects [75] comprises of eight orders for twenty-six families with a total of more than one hundred pests [12]. Being by nature a highly predaceous ants, O. smaragdina exhibit extensive exploratory behaviour [31] with major workers having long, slender and serrated mandibles exhibiting elongated distal teeth, perfectly adapted to its hunting inner instinct [76]. Records show that in China, Oecophylla nests have been introduced in citrus orchards to control the pests since 300 A.D [77].…”