Differential Predation of Forage Seed.

In recent field experiments we observed that the main invertebrate seed predators of overseeded tall fescue (Festuca arundinacea Schreb.) or Italian ryegrass (Lolium multiflorum Lam.) seed in unimproved pastures were harvester ants (Pogonomyrmex sp.) and common field crickets (Gryllus sp.) To determine if there is differential predation of tall fescue, 'Jesup', and Italian ryegrass, 'Marshall', a laboratory study was conducted using the common cricket (Acheta domesticus L.) as a model predator.  Crickets were obtained commercially. After preconditioning to controlled environment conditions (24 °C, and 13-h photoperiod) for 3 days, the crickets were fasted for 24 h before the feeding trials. Each trial consisted of three treatments (tall fescue-, tall fescue+, and ryegrass) with five replications.  Crickets were blocked across replications by weight.  Separate crickets were placed in a container (10 cm high; 7 cm dia.) with 25 seed of tall fescue or ryegrass and replaced in the chamber for 24 h.  At the end of 24 h, the seed were counted and categorized as damaged, undamaged, or missing.  The trials were repeated in time and the data combined for analysis.   Over the 24-period, predation (damaged plus missing) was significantly greater for the tall fescue (40%) than for Italian ryegrass, in which only 18% of the seed were damaged and missing.  There was a slightly greater predation of the tall fescue without endophyte (44%) then when the endophyte was present (36%), but there was no significant difference between the two treatments.