Field Crops News
Native Predators Reduce Armyworm Damage to Corn
Naturally occurring predatory insects and spiders may be important in reducing armyworm
damage in corn. Laboratory studies showed that individuals of several ground beetle species, a
rove beetle and a wolf spider consumed 5-10 second or fourth instar armyworm larvae in a 24
hour period. A field study used pitfall traps to reduce the density of ground dwelling generalist
predators in corn. Based on densities removed and known feeding habits, the most important
predators in the field study included ground beetles, rove beetles, wolf spiders and possibly ants.
Percentage of damaged plants was increased from 10% to almost 40% where predators were
reduced with pitfall traps.
Clark, M.S., J.M. Luna, N.D. Stone, and R.R. Youngman. 1994. Generalist predator consumption of
armyworm (Lepidoptera: Noctuidae) and effect of predator removal on damage in no-till corn. Environ. Entomol.
Convergent Lady Beetle Partially Tolerant of Permethrin
When female convergent lady beetles were exposed to permethrin (Ambush, Pounce) residues on
alfalfa, 95.6% experienced initial knockdown symptoms (difficulty in movement, paralysis)
within 12 hours. However, 61% of females recovered when removed from exposure. Those
recovering showed no reduction in longevity, number of eggs laid or length of egg laying period
compared to those not exposed to permethrin. These data indicate that if covergent lady beetles
survive field exposure to permethrin there are no long term effects on life span or egg laying.
Peckman & Wilde. 1993. Sublethal effects of permethrin on fecundity and longevity of Hippodamia
convergens. J. Kansas Entomol. Soc. 66:361-364.
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