April 19145 E-647
U~nited-St,-.tes. Department of Agriculture 'Agricul'tural Research Administraion B ~ueai of, 1xtomology and: Pliant Quarantinb<
DDT F'OR C 01TM0L 0' TEE SUJGARCANE~ BOQRER,
THE- IGM ST I14-UG, MD A GRASS WMW0BM.
3Y y JT1 Wo ngam'. i.' XC Bynum, W X T .l ey,. and L. J. Charpentier,
D fivi'sion of' Oereal and Forage Insebt Investigations.
Although-exprments conducted at Eouina' La., in-l9143 indicated
~h!that DDT (l1-trichloo-2,2-bis(p-chloro~henyl)ethane) was less effective
than f-yoAite in controlling the sugarcane borer, (Diatraea saccharalis
(i.) )-',t was further> tested in 1944 agains-t firs-t-and. secondgeneration borers,
Two experiments.comparing 10 percent fDT-pyrophyllite dust with
cryolite4 and flunosilicates were conducted du: ing April and May against
the first geeain wnit-acre plots wrearra2i_&ed in aLai
square. In one experiment 6 by,6-plots of C.J. 29/19 cane and in the other' 5 by 5-plots of C.?. 2-9/103 -cane were used. Each treatment was applied four times at weekly intervals atthe rate of ap,-)roximately 8 rounds of the dust per acre-application, Control was determined from
countvs-of, the surviving borers in-treated and untreated plots (table 1).
On th~e C.?. 28/19 cane synthetic cryolite gave a control'of 95 percent, natu.fal cryolite 63 percent, and DDT-pyophyllite only 11 percent. Inh
the tests on variety C.P. 29/103 cane synthetic. cryolite gave a control
itf 8J1 percent, natural cryoli~te 90 percent, and-)DT-pyrohyllite only 314
TIable 1.-Survival of first-generation- sugarcane borers in two varieties
of dan'e fcdliowing treatment v,*ith IT., crylite, or'fluosilicate.
Average number of borers
Treatmen~t per plot
~C0P. 29/19 C.P. 29/103
synheic cryojte-sodiuifluosilia4 -(w:O 6.7
Synthetic .eryoite 7~ .(11:22
Potassium fluosilicate-/-pyrophyllt-e (75:25) 15 ,_7
Natural cryolite 75 *l1,4
DDT pyrophJllite .(=YT 10%) 417. 3.14
Check, no'treatment., 47?0- 59.0
Difference recjuired .for, significance:
Odds 19:1 164-12.0
Odds 99:1 22.14 18.1
1/ Na2Sir6 and IC25iF6 each 97%.. 2/ Last 3 applications only*
*1/Ingram,, J. W, Tests of DDT dust against the sugarcane borer, the
yellow sugarc ane, anhid, and the Argentine ant. (Scientific Note) Jour.
Boon. Ent- 37:1414-1445. 191414.
2IThe synthetic and natural-cryolite used in the tests reported in
this paper were analyzed by the Dlivision of Insecticide Investigations APR-I sndfound to contain 90.1 and 9.7 percent of NlajAl2B6, respectively.
In June and July a similar experiment was conducted for the control of second-generation borers. A 6 by 6 Latin-square arrangement was used on C.P. 36/191 cane. Four weekly applications were made at the rate of approximately 10 pounds of the dust per acre-application. Based on percentages of joints bored in the treated plots as compared with the checks (table 2), synthetic cryolite applied on regular schedule gave a control of 61 percent and natural cryolite'50 percent. In the plots dusted with DDT 1 ~percent more of the joints were bored than in the undusted check plots. This difference was rot'significant, but the DDTtreated plots showed significantly heavier borer injury than the plots treated with any of the other insecticides.
Table 2.--Comparison of DDT with various cryolite schedules for control
of second-generation borers in sugarcane variety C.P. 36/191
Treatment Application Average joints bored
Synthetic cryolite Regular 6.2 14.1
Delayed 1 week 4,0 11,2
Regular plus one application 5,6 12,5
Natural cryolite Regular 8,O 15,9
DDT-pyrophyllite (10%) Regular 19.0 25.4
Check, no treatment -- 16.1 23,1
Difference required for significance:
Odds of 19:1 3.5
Odds of 99:1 4.7
In September and October a 10 percent DDT-pyrophyllite dust was
compared with synthetic cryolite in two replicated experiments, one at Houma and the other at Raceland, La., of six plots per treatment on sugarcane planted the previous August. This cane was similar in size and growth to that prevailing in the spring at the time of dusting for the control of first-generation borers. Four weekly applications were made at the rate of approximately 9 pounds per acre-application. From the number of live borers surviving (table 3) on variety 0.P. 34/120, synthetic cryolite gave a control of 8S percent, and almost three times as many borers were found in the DDT plots as in the untreated plots; on variety C.P. 28./19 synthetic cryolite gave 95 percent and DDT 9 percent control. The increase in borers in the IDT plots in the first experiment may have been due to its effect on Trichogramma and other natural enemies of the borer under conditions of a heavy infestation, when Trichogramma is usually more abundant.
Table 3.--Survival of sugarcane borers on two varieties of summerplanted cane, following treatment with DT and cryolite.
Average number of borers per plot
Treatmet 0-.P. 34/12C0 0.P. 28/19
Synthetic cryolite 1, 0.5
DDT-pyrophyllite (I0 DDT) -1.3 8.g
Check, no treatment 15,2 9,7
Differences required for significance:
Odds of 19:1 10.7 5.3
Odds of 99:1 14.6 7.2
In September and October DDT spray was compared with synthetic
cryolite dust in a replicated experiment on variety C.P. 29/120 sugarcane planted in August. As in the previous experiment, this cane was similar in size and growth to that prevailing in the spring. The DDT spray, which was made up of 20 pounds of.1 O percent of DDT-pyrophyllite and 7 ounces of a sticker-spreader per 100 gallons of water,. was applied at the rate of 50 gallons per acre. The synthetic cryolite dust was applied at the rate of S pounds per adre#. Each material was applied four times at weekly intervals on four 1/20-acre plots. Cn untreated check plots an average of 63 borers survived. On the plots dusted with synthetic cryolite an average of 9.5 borers survived as compared with 45 on the pl6ts sprayed with DT.. Control with cryolite was thus 95 percent but with DDT spray only 29 pec enit.
In the experiment cohdicted in 1943 the number of leaves infested with. the yellow sugarcane aphid (Sipha flava (Forbes)) was six times as great in plots treated with DDT as in untreated check plots ~d over twice as great as in plots treated with synthetic cryolite. In the first-'generation experiments with DXT in 1944 thdre was very little yellow aphid injury, but in the second-generation experiments the aphid infestation was noticeably greater in DDT-treated plots than in plots receiving any other treatments
4 DT-pyrophyllite dust was tested-in aI cage. experiment on the rice stinkbug (Solubea pugnax (F.)) in 1944. On September 23 six screen-wire cages about 3 by 3 by 3 feet in size were each stocked with 10-adult stinkbugs and a bunch of ?aspalum urvillei panicles. The rapalum stems'. were inserted in a jar of water through a small hole in a paper cover. Three of the stocked cages were carried into the open and.dusted with 10 percent DDT-pyrophyllite at 'about the rate used in making a 10-poundper-acre ,application on sugarcane. All the cages were then placed, on antproof benches in a screened insectary.
4 -_IIRSTYOFFL A
"'I/itI/IIIIII I~ lB lllll 111I
3 1262 09238 7090
The results shown in table 4 indicate that BDT dust may have considerable promise for use in the control of the rice stinkbug. This dust gave an 8S.5 percent control of adults 2 days after dusting,and g2.4 percent after )4 days. The lateness of the season prevented additional experiments with this bug.
Table 4.-Results of cage tests of DDT-pyrophyllite dust on the rice
Perentage mortality after --- Nymphs
1 day 2-days 3 daysF4 days 10 days' found
n usted cages
1 70 70 90 90 100 None
2 0 l10o 10 10 100 None
3 90 100 100 100 100 4 dead
Average 93 90 97 97
110 10 10 10 100 15 live
2 0 10 10 10 100 10 live
3 10 20 30 30 100 15 live
Average 7 13 17 17
A grass webworm (Pachyzancla phaeopteralis Guen,) defeliated many
lawns and pastures in southern Louisiana in September and October. On a lawn near Houma a strip about 50 feet wide and 3C00 feet long was dusted with synthetic cryolite while the dew was on the grass at the approximate rate of'10 pounds per acre. A similar strip was dusted with 10 percent DDT-pyrophyllite, applied at the rate of about 10 pounds per acre while the dew was on the grass, and a third strip was sprayed with ordinary kerosene emulsion at the approximate rate of 1 gallon to each square yard of surface after the dew had dried. The emulsion waz made by dissolving
1 pound of laundry soap in 1 gallon of water and adding 1/2 gallon of kerosene while stirring vigorously; 1 part-of this emulsion was then mixed with 50 parts of water by volume for application to the lawn.
These treatments were all applied on September 29. Two days later many live larvae and no dead ones were found in the untreated and the cryolite-treated areas, many dead-.ones and ne live ones in the DDTtreated strip, and about 30 percent of the larvae were dead in the strip treated with rcerosene emulsion. Nine days after the application the untreated areas and the areas treated with synthetic cryolite or kerosene emulsion were brown from defoliation ikile the DDT-treated area was of a normal green color. This difference was still apparent the last of November.
On October 3 parts of another webworm-infested lawn were treated with a 10 percent EDT-pyrophyllite dust at the rate of about 10 pounds per acre. Over 90 percent of the larvae were killed by the ZDT treatment in areas examined, and only live larvae were found in untreated areas. Carpetgrass (Axonopus compressus (Swartz) Beauv*) was the main lawn grass in both this and the preceding location.