Prey Specifity and Prey Recognition in the Digger Wasp Liris Niger Fabr.: The Importance of Close Range Chemical Cues

Summary

Females of the digger wasp Liris niger Fabr. hunt crickets as food-supply for their offspring. Prey specifity: All intact females of L. niger accepted the following cricket species as prey: (i) Acheta domesticus, A. canariensis, Nemobius sylvestris, (ii) Only 30 to 40% of females accepted: Gryllus campestris, Teleogryllus commodus and Scapsipedus spec, (iii) All females rejected: the cricket species Gryllus bimaculatus, the bush cricket Tettigonia spec, and the locust Locusta migratoria.

G. bimaculatus was even rejected by adult wasps which were experimentally raised on this species. From this result a learning process during postembryonal development can be excluded. Instead a genetically determined prey specifity can be inferred.

Prey recognition: L. niger females in “hunting mood” reacted attentively to all moving optical stimuli within a range of about 15 cm; hunting behavior ceased completely after the compound eyes were blinded. However, the actual decision whether a cricket is accepted as prey is made only after antennal contact. The releaser is a chemical substance on the prey which is soluble in polar solvents. The specific reaction of Liris females failed completely after ablation of both antennal flagella: G. bimaculatus was then accepted, paralyzed and the egg was deposited as in Acheta, even grasshoppers were attacked and bush crickets were paralyzed. Similar effects were found (i) if at least the 7 distal segments of both flagella were ablated or (ii) if the dorsal half of the antennal flagella was covered with beeswax. These results are concurrent with our findings on the topography and fine structure of the sensilla basiconica on the antennal flagella.