Research done by ARC-PPRI has shown that a variety of spiders are predators of the harvester termite, Hodotermes mossambicus (Hagen 1858) in Southern Africa. Harvester termites forage in sporadic bursts of activity on the soil surface from their subterranean nests. When present in high numbers they can cause severe damage to grassland, especially during long periods of drought. One of the most important predators are members of the family Ammoxenidae of the genus Ammoxenus.

The ammoxenid spiders are free-living soil-dwellers, also known as sand divers due to their ability to dive headfirst into sand when disturbed. They are only known only from southern Africa, with six described species occurring throughout the region. They are commonly found in high numbers in areas infested with harvester termites. Ammoxenus species are regarded as specialist predators of the harvester termites.

They are invariably found in the soft soil mounds left after excavation by the termites in close proximity to the nest entrance. They are able to detect termite foraging activity either through soil vibration or chemical cues. The spiders use tactile cues to select suitable prey items after initially handling of the prey. During prey capture, the termite is grabbed and bitten between the head capsule and the cephalothorax. The dead termite is pulled below the soil surface by the spider before feeding commences. Prey is sucked out and not chewed. They spend inactive periods in sac-like retreats made in the soft soil humps, left by the termites during excavations of their subterranean nests. Along with the retreat sacs, other soft silk sacs containing dead harvester termites (4-8 termites per sac) were collected from the soil mounds. It appears that these termites might serve as a food reserve for the spiders during the long periods when the termites are inactive. Harvester termites display erratic bursts of activity. The ammoxenids are able to detect these busts whether they occur nocturnally or diurnally. The termites are thus available sporadically for short periods, above ground for the spiders to catch. The termite workers are either killed, pulled immediately below the soil surface and fed upon or they are paralyzed and stored in silk sacs just below the soil surface for feeding at a later stage.

Further reading:

Dippenaar, A.S. & M.K.P. Meyer. 1980. On the species of the African genus Ammoxenus (Araneae: Ammoxenidae), with descriptions of two new species. Journal of the Entomological Society of Southern Africa 43:41-49.

Dippenaar-Schoeman, A.S., M. de Jager & A. van den Berg. 1996a. Behaviour and biology of two species of termite-eating spiders, Ammoxenus amphalodes and A. pentheri (Araneae: Ammoxenidae), in South Africa. African Plant Protection 2:15-17.

Dippenaar-Schoeman, A.S., M. de Jager & A. van den Berg. 1996b. Ammoxenus species (Araneae: Ammoxenidae) - specialist predators of harvester termites in South Africa. African Plant Protection 2:103-109.

Dippenaar-Schoeman, A.S. & Harris, R. 2005. Food storage by a wandering ground spider (Araneae, Ammoxenidae, Ammoxenus). Journal of Arachnology 33: 850-852.

Van den Berg, A. & A.S. Dippenaar-Schoeman. 1991. Ground-living spiders from an area where the harvester termite Hodotermes mossambicus occurs in South Africa. Phytophylactica 23:247-253.

Research on other species

Haddad, C.R. & Dippenaar-Schoeman, A.S. 2006. Spiders (Araneae) inhabiting abandoned mounds of the snouted harvester termite Trinervitermes trinervoides (Sjöstedt) (Isoptera: Termitidae: Nasutitermitinae) in the Free State, South Africa, with notes on their biology. Navorsinge van die Nasionale Museum, Bloemfontein22: 1-15.

Ammoxenus sp. feeding on termite

Ammoxenus sp. also known as sand divers

Egg sacs

Spiders in Agro-Ecosystems

Spiders in cotton orchards

Spiders in macadamia orchards

Spiders in citrus orchards

Spiders in pistachio orchards

Spiders in avocado orchards

Spiders in strawberry fields

Spiders on grapes

Spiders as predators of mites