Meeting Abstract
In a savanna ecosystem, fire and herbivory are the two major disturbances that engineer structural complexity in vegetation. Vegetation complexity, in turn, affects insect diversity and morphology in some systems. Previous studies examining the effects of vegetation structure on insects have focused mainly on plant-feeders, whereas predatory insects like mantids have received little attention. In this study, we examined mantid diversity and morphometrics in three structurally distinctive, South African savanna habitats shaped by fire and herbivory: long bunchgrass, grazing lawns, and recently burned plots. Mantids were categorized into morphospecies based on body length and hind femur length – a trait related to maneuverability, which is important for both prey capture and predator escape. A greater number of morphospecies were identified in bunchgrass, the most complex vegetation. The largest individual mantid was also found in bunchgrass, although there was no significant difference in average body length across vegetation types. Mantids found in bunchgrass had significantly shorter hind femurs than those found in the other habitats – an effect that may be driven by limited maneuvering space, reduced predation risk, and the need to negotiate small spaces while searching for prey. Conversely, mantids in less complex vegetation rely more on mobility to escape from predators and capture prey, and most morphospecies in grazing lawns and recently burnt plots displayed proportionately longer hind limbs. The one exception to this pattern was Pyrgomantis rhodesica, which had shorter hind limbs but exceptionally long forelimbs; as a known ambush predator, this species likely relies on crypsis and its long reach to capture prey, even in relatively open habitats.
