LABORATORY EVALUATIONS OF BIOINSECTICIDES AGAINST DBM LARVAE, 1994:

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) 956-6737
FAX: (808) 956-2428
 
R. S. Shimabuku
Cooperative Extension
Service
310 Kaahumanu Ave.
Kahului, HI 96732

 

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 true leaf seedling stage were 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 were used. Ten newly hatched larvae were placed on each leaf. Fresh leaves from the original treated plant were added every two days. The number of dead larvae was counted at 24 or 48 hour intervals. Larvae were recorded as dead when there was no movement when probed.

Three tests were completed each with different treatment rates and treatment combinations. In each tests, the Align + B. thuringiensis combination and B. thuringiensis treatments were most effective. Larvae in Align treatments did not die immediately. Instead, Align appeared to affect larval growth and molting to the pupal stage. Larvae in the Align treatment were smaller in size when compared to the corresponding larval instar in the untreated check. Align treated larvae continued to feed through the end of the trial, but at a lower feeding rates than in the untreated check. All of the Align affected larvae that survived to the fourth instar did not pupate. In contrast, all of the fourth instar in the untreated check pupated.

                                                        __% Mortality (DAT)__
Treatment     Rate/Acre     1     2     3  
Align     21 oz     1.3b     9.1c     66.0b  
Xentari     0.5 lb     28.0a     48.2b     82.0a  
Align + Xentari     21 oz + 0.5 lb     45.8a     82.1a     97.0a  
Untreated Check     ---     0.0b     0.0c     1.9c  
Numbers in the same column followed by a different letter are significantly different (P<0.0001 Tukey's
studentized range test SAS Institute version, 6.04). Data was subjected to arcsine transformation prior
to analysis. Untransformed number are presented.

 

                                                        ________% Mortality (DAT)________
Treatment     Rate/Acre     1     2     3     4     6
Align     11 oz     0.0a     1.7b     21.5b     34.0b     65.5b
MVP     3 qt     1.9a     62.5a     86.0a     94.3a     100.0a
Align + MVP     11 oz + 1.5 qt     0.0a     57.1a     79.0a     84.9a     100.0a
Untreated check     ---     0.0a     2.7b     3.7b     3.7c     3.7c
Numbers in the same column followed by a different letter are significantly different (P<0.0001 Tukey's
studentized range test SAS Institute version, 6.04). Data was subjected to arcsine transformation prior
to analysis. Untransformed number are presented.

 

 

                                                        ________% Mortality (DAT)________
Treatment     Rate/Acre     1     2     3     4     6
Align     16 oz     0.0a     0.0c     23.0b     38.7b     65.7b
MVP     3 qt     0.0a     49.0a     85.6a     89.0a     95.9a
Align + MVP     16 oz + 1.5 qt     1.3a     29.2b     75.6a     85.2a     100.0a
Untreated check     ---     1.4a     3.8c     3.8c     5.0c     8.7c
Numbers in the same column followed by a different letter are significantly different (P<0.0001 Tukey's
studentized range test SAS Institute version, 6.04). Data was subjected to arcsine transformation prior
to analysis. Untransformed number are presented.

 

Trade Composition\Common name     Formulation         name     Source
Align     EC         azadiractin     AgriDyne
Xentari     ME         B. thuringiensis     Abbott
MVP     ME         B. thuringiensis     Mycogen