Effects of Amdro Fire Ant Insecticide Mound Treatments on Southern California Ants, 1982

Abstract

Acceptability of Amdro fire ant insecticide to 12 species of ants was determined in Sep at 3 elevations by mound applications. All Myrmicine species accepted bait to a greater or lesser degree and rate of colony kill was inversely related to speed of bait acceptance. Foragers from nests of P. californicus located at 3 different elevations did not accept bait as readily at the highest elevation as at the lower 2. Acceptance of bait appeared to be mitigated by the degree of satiation of the colonies. At 300 M elevation seeds of annuals and perennials were very scarce and bait was entirely removed into the nests within 1 h of application. At 900 M, P. californicus nested in an open sandy area adjacent to a stream course in a woodland canyon where L. occidentale was nesting in Torested sites. Seed availability at this elevation was poor at the time of treatment. At 1500 ‘R seed supplies were abundant and some bait particles remained on P. californicus nest discs after 1 wk. Nests of V. pergandei were located at ca 300 M elevation in uncultivated sandy areas and foragers avidly collected bait. Nests of S. maniosa treated were located at the same elevation, but in or adjacent to urban lawns and bait acceptance was considerably slower. Nests of F. pruinosum and T. sessile were also encounted in this habitat and foragers of these species shunned the bait entirely. Nests of P. rugosus were encountered at ca 600 M elevation in uncultivated foothill grassland and were large perennial colonies known to be 3 or more years of age at the time of treatment. The remaining 2 Myrmicine species V. andrei and V. chamberlini were found at 1500 M elevation in grassland areas also densely inhabited by P. californicus, C. bicolor, and C. insana. V. andrei was slow to accept bait but none remained on the nest mound after 2 wk. The rare species, V. chamberlini, readily accepted bait and even foraged bait which had been applied to P. californicus nests several meters away.