R. F. L. Mau and L. R. Gusukuma-Minuto
University of Hawaii
Dept. of Entomology
3050 Maile Way, Rm. 310
Honolulu, HI 96822
Phone: (808) 956-7063


HEAD CABBAGE: Brassica oleracea L. 'C-G Cross'

Diamondback moth (DBM); Plutella xylostella (Linnaeus)


Treatments were evaluated using the leaf dip method. Head cabbage was seeded in community pots. Each pot contained approximately 10 cabbage plants. Potted head cabbage in the 5-7 true leaf seedling stage was dipped in each respective solution for complete coverage and allowed to air dry. Leaves from treated plants were detached and placed in a ventilated plastic petri dish. DBM larvae from a laboratory colony that originated from individuals collected from a cabbage field at Kula, Hawaii and Kamuela, Hawaii were used. Ten third instar larvae were placed on each leaf. Each treatment was replicated 10 times. The number of dead larvae was counted at 24-hour intervals. Larvae were recorded as dead when there was no movement when probed.

Fipronil provided rapid kill at all test rates. Many of the larvae in the 0.025 and 0.05 lb. ai/A treatments were dead or moribund within 5 hours after placement on the treated leaves. At that time some of the larvae in the 0.0125 lb. ai/A treatment were exhibiting insecticide poisoning symptoms. There were several shot-hole damage observed in the fipronil treatments. This suggested that the larvae initially fed but the rapid action of the insecticide prevented extensive feeding damage. There were small differences in larval mortality at the 24-hour post treatment census but the differences were not statistically significant. Complete kill was observed at 48 hour post treatment. Xentari provided slower larval mortality. Comparable mortality with fipronil was observed 72-hours post treatment. Warrior did not provide favorable mortality. Surviving larvae on leaves treated with Warrior remained active throughout the test.


                                                                      % Mortality (DAT)  
Treatment     Concentration
(amt/100 gal)
    1   2   3
fipronil 80 WDG     0.0125 lb. (AI)     93.7+3.11a   100.0+0.00a   100.0+0.00a
fipronil 80 WDG     0.025 lb. (AI)     99.0+1.00a   100.0+0.00a   100.0+0.00a
fipronil 80 WDG     0.05 lb. (AI)     95.9+1.68a   100.0+0.00a   100.0+0.00a
Warrior II 1 EC     3.84 oz.     3.1+1.58c   6.2+2.16c   11.5+3.35b
Xentari     1.0 lb.     44.3+5.89b   79.5+2.60b   95.8+2.37a
Untreated check     ---     0.0+0.00c   2.1+1.40a   2.2+2.20c

Numbers in the same column followed by a different letter are significantly different (P<0.0001 Tukey's studentized range test SAS Institute version, 6.08). Data was subjected to arcsine transformation prior to analysis. Untransformed number are presented.




Trade Composition\Common name     Formulation         name     Source
fipronil     WDG         fipronil     Rhone-Polenc
Warrior     EC         lambdacyhalothrin     Zeneca
Xentari     ME         B. thuringiensis     Abbott