The effects of season of collection, feeding, maturation and gender on the potency of funnel-web spider (Atrax infensus) venom.

Assays of the venom of adult male and female as well as immature funnel-web spiders (Atrax infensus) were performed both at the end of the winter hibernation period and during the active summer months. For both sexes an increase in venom potency appeared to have occurred with the approach of summer, the venom of adult males then being clearly more potent than that of adult females. However, it was also found that, at least for adult females, forced abstinence from feeding was associated with an increase in venom potency, while feeding (at least on one insect species that A. infensus is known to accept as prey) seemed to lead to a lowered potency. From these observations it was concluded that the neurotoxin in the venom of female (and presumably also male) A. infensus spiders is probably synthesized in the venom glands rather than being extracted from the prey on which A. infensus normally feeds.