Acanthoplus discoidalis is a species in the Hetrodinae, a subfamily of the katydid family (Tettigoniidae). Like its closest relatives, Acanthoplus discoidalis variously bears such as armoured katydid, armoured ground cricket, armoured bush cricket, corn cricket, setotojane and koringkriek. The species is native to parts of Angola, Namibia, Botswana, Zimbabwe and South Africa. Developing Integrated Pest Management Strategies for Control of the Armoured Bush Cricket, Acanthoplus Discoidalis (Orthoptera: Tettigoniidae). Poster 120 Mosupi, P. O. P., J. van den Berg, M. A. McGeoch & S. V. Green
Note that the common names are characteristically misleading; the species is not closely related to true crickets and "katydids" which originally belonged to the unrelated subfamily Pseudophyllinae.
Description
Diet
Especially when their diet is deficient in protein and salt, members of the species commonly become , so much so that when their populations peak in autumn and some of them stray across roads and are crushed by traffic, cannibalistic conspecifics congregate around the casualties and feed until they are killed in turn. During that season their remains may form large patches on roads.
Defense
When attacked from the side, both males and females will attempt to bite the attacker and males will stridulate (females have no functional stridulatory mechanism). In about half the attacks from the side, either gender may autohaemorrhage, squirting between 5 mg and 80 mg of possibly toxic haemolymph at the attacker at ranges of up to 3 cm.
When attacked from above, and therefore not in a good position to bite the attacker, either gender will autohaemorrhage more than when attacked from the side.
Experiments have shown that the haemolymph is distasteful to at least two reptile species, but the repellent components have not been determined. It has been hypothesised that they may be found in plants that the insects eat and that they then sequester those substances to use as defensive compounds themselves.
After autohaemorrhaging the insects clean themselves meticulously. This is thought to reduce the probability that other members of the species will attack them cannibalistically. Research on the species suggests that autohaemorrhage is a precisely regulated defence response rather than an accidental consequence of being attacked. Another defensive response is to regurgitate their stomach contents when attacked, which happens most often when the insect has already been attacked repeatedly.
Reproduction
A female must mate before laying her first clutch of eggs. Thereafter she may mate and lay eggs again in any arbitrary order, as she can store sperm. Accordingly, it is advantageous for males to mate with , as a higher proportion of the offspring of a virgin female will be their own. Virgins are lighter than non-virgins, which offers males a basis for distinguishing them when copulating. Males accordingly complete more matings with virgins than non-virgins and they transfer their spermatophore more quickly.
Control
External links
|
|
