AN ASSOCIATION BETWEEN PASYALUM DILATATUM AND BLACK BEETLE IN PASTURE

Abstract

Field monitoring of black beetle, Heteronychus arutor (F.), populations in Waikato pasture showed a strong association between black beetle numbers and the presence of Paspalum dilatatum Poir. Increasing paspalum gave higher adult numbers in spring resulting from increased overwintering survival, and in some seasons, reduced autumn dispersal. Numbers of larvae damaging pasture in February were directly related to adult numbers in September. Black beetle preferentially select paspalum plants in mixed pasture. This can place paspalum at a competitive disadvantage relative to other pasture species, but also permits the retention of higher adult black beetle numbers, even at low paspalum levels.