ant Cop.3 DC BRANCH Evaluation of Malathion, Diazinon, A Silica Aerogel, and a Diatomaceous Earth As Protectants on Wheat Against Lesser Grain Borer Attack ...in Small Bins Marketing Research Report No. 860 Agricultural Research Service UNITED STATES DEPARTMENT OF AGRICULTURE Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. This publication reports research involving pesticides. It does not contain recommendations for their use, nor does it imply that the uses discussed here have been registered. All uses of pesticides must be registered by appropriate State and/or Federal agencies before they can be recommended. CAUTION: Pesticides can be injurious to humans, domestic animals, desirable plants, and fish or other wildlife—if they are not handled or applied properly. Use all pesticides selectively and carefully. Follow recommended practices for the disposal of surplus pesticides and pesticide containers. Use Pesticides Sofely FOLLOW THE LABEL U.S. DEPARTMENT OF AGRICULTURE PREFACE This report presents results of a small-bin, intermediate-type experiment with wheat treated with the standard malathion protectant application, a candidate chemically active insecticidal material (diazinon), a silica aerogel (Cab-O-Sil), and a diatomaceous earth (Kenite 2-I) for protection against the lesser grain borer. Materials and dosages treated were selected on the basis of previous laboratory and small-bin studies. The two experimental protectant materials—diazinon and Cab-O-Sil—have not been registered with the Pesti- cides Regulation Division, Agricultural Research Service, as grain storage treatments, and residue tolerances have not been established by the Food and Drug Administration for Cab-O-Sil or diazinon. All diatomaceous earth prod- ucts containing more than 80 percent silicon dioxide are exempt from the requirements of a tolerance for use on certain stored grains including wheat. Trade names or proprietary names are used in this publication solely to provide specific information. Mention of a trade name or testing of a material does not constitute a guarantee or warranty of the product by the U.S. Depart- ment of Agriculture and does not imply either a recommendation for its use or an endorsement over comparable products. The entomological phases of the studies were conducted at the Mid-West Grain Insects Investigations Laboratory at Manhattan, Kans. Edwin Dicke, J. L. Wilson, Ralph L. Ernst, and Leon H. Hendricks assisted in the entomo- logical phases. Residue determinations were made by A. G. Quintana, R. S. Cail, and M. Cooper of the Chemical Unit at the Stored-Product Insects Research and Development Laboratory, Savannah, Ga. Both laboratories are field stations of the Stored-Product Insects Research Branch, Market Quality Research Division, Agricultural Research Service, U.S. Department of Agriculture. Itt CONTENTS Gram temperatire and moisture. 2. <2 2552222225 ee ee Malathion tesidues 2.21 ones sews ond See be e e eee Insect: populations we sete te wees ied eee eae ee Tomicity studiess. S202: 2245 0en fo, SE as Fe eee Insect iemersonee. 2 oon. cose ckc a Gaceeeo ee eee oe eee TWSOCb eMare ro I ee Progeny (amae@s 23 2b a oto tas eos oe eee Comisercial orade@so2 2-5 a ee ent a eee es Sees Conclusions: (7 odie ees kiss senses ee hiterature Cited ss ce oh cost Joe ees ee ee Washington, D.C. cr iJ ODORDAanmMtAHARWwWNH BB eel tl ow NY KF eK Issued April, 1970 IV Evaluation of Malathion, Diazinon, a Silica Aerogel, and a Diatomaceous Earth as Protectants on Wheat Against Lesser Grain Borer Attack ...in Small Bins By De~tmMon W. LA HuveE, Entomologist Market Quality Research Division, Agricultural Research Service SUMMARY Malathion, diazinon, and two inert dusts, a silica aerogel and a diatomaceous earth, were compared as protectants of wheat against the lesser grain borer in 5-cubic-foot bins for 12 months. The mala- thion residues degraded from 7.5 p.p.m. to 2.7 p-p.m. during this time. Damaging infestations of lesser grain borers readily developed in all bins of the untreated check wheat from insects released in the storage room. Later in the storage period, although neither rice weevils nor flat grain beetles had been introduced by the experimenters, infestations of both these in- sects became established in the untreated wheat. The silica aerogel Cab-O-Sil at 60 pounds per 1,000 bushels of wheat afforded nearly complete protection from insect damage for 12 months. The 1-pint dosage of malathion (0.63-pound active in- gredient) and the 210-pound application of the diatomaceous earth Kenite 2-I were only slightly less effective. Diazinon at a rate of 0.5 pint (0.25- pound active ingredient) per 1,000 bushels, pro- tected the wheat from extensive damage for 6 months but its effectiveness diminished gradually thereafter. BACKGROUND AND OBJECTIVES Three phases of testing are required to develop a protective treatment for grain: First, a prelimi- nary laboratory study to determine the toxicity and repellency of a test material to stored-product insects; second, an intermediate evaluation in small bins to compare promising materials at selected dosages with an accepted or standard insecticidal application and with untreated grain; and third, field-scale bin, warehouse, and elevator tests. Only those materials most promising in the pre- liminary laboratory studies are further tested to evaluate dosage rates and effectiveness of residual protection. Five-cubic-foot cylindrical bins have been successfully used in extensive intermediate- type protectant studies with corn (7),' farmers stock peanuts (9), wheat (6, 10), and sorghum (8). Successful grain protectants are easy to apply, relatively safe to humans, effective in initial and residual action, and relatively low in cost. Only a very few materials that meet all of these criteria have been approved for use, but the search for new and promising residual protectant materials continues. * Italic numbers in parentheses refer to items in “Litera- ture Cited,’ p. 11. Resistance of stored-product insects to insecti- cides and fumigants has been reported for many years from widespread areas, emphasizing the need for other acceptable insecticidal materials. Brown (1) reported that more than 150 cases of acquired insect resistance or tolerance to insecticides were known. However, relatively few of these were stored-product insects. Parkin and Forster (14) found that red flour beetles (Z7ribolium castaneum (Herbst) ) from a field-collected culture were far more difficult to kill with malathion than was a laboratory strain. Parker and Forster (73) and McDougall (17) reported that certain field-col- lected cultures of the rice weevil (Sitophilus oryzae (L.)) were more difficult to kill with lindane than laboratory-reared cultures. Numerous similar re- ports have been made. The probability of such field-acquired resistance or tolerance is of major importance. Laboratory-induced tolerance ratios do not indicate conditions in farm and commercial storages but do indicate what may happen under certain insecticidal selection pressures. The review of reports of resistance by Parkin (72) indicates the need to continue the search for new insecticides. Strong et al. (18) stated that diazinon was more effective than malathion applied at equal dosages in acetone solutions to wheat against lesser grain 1 2 MARKETING RESEARCH REPORT NO. 860, U.S. DEPARTMENT OF AGRICULTURE borers (Rhyzopertha dominica (F.)), rice weevils, red flour beetles, confused flour beetles (7ribolium confusion Jacquelin duVal), Angoumois grain moths (Sitotroga cerealella (Olivier) ), corn wee- vils (Sitophilus zeamais (Motschulsky)) and certain other stored-product insect pests. Mala- thion was more effective against saw-toothed grain beetles (Oryzaephilus surinamensis (.)), mer- chant grain beetles (O. mercator (Fauvel)) and granary weevils (Sttophilus granarius (U.)). Previous studies by Strong and Sbur (76, 17) had shown that diazinon was effective as a residual grain protectant. Unpublished results from extensive laboratory studies by La Hue with four species of insects ex- posed to Hard Red Winter Wheat treated with diazinon as a water emulsion indicated that this chemical showed enough promise to warrant further investigation. Although diazinon is about 10 times more toxic to mammals than malathion, it seemed advisable to include it in a small-bin study to test protection of wheat against the lesser grain borer at a dosage less than that found effec- tive by Strong. Milling and baking tests and flavor evaluations had indicated that the application of 8 parts per million (p.p.m.) of diazinon to com- mon white wheats had no untoward effects on quality (79). Two types of inert dust materials, namely, silica aerogels and diatomaceous earths, have shown some promise as grain protectants. Some work has been done with silica aerogels, and there has been considerable study of the diatomaceous earths. Cot- ton and Frankenfeld (2) reported that a silica aerogel was effective against stored-grain pests in wheat. King et al. (5) obtained satisfactory con- trol of the rice weevil in grain sorghum with the silica aerogel SG-68. In studies by Strong and Sbur (75), wheat seed treated with the diatomaceous earth Dicalite IG 3 showed no evidence of insect injury in comparison with the heavily damaged untreated check lots. Applications of 4, 6, and 8 pounds per ton ap- peared to be equally effective during the first 6 months after treatment. Only the 8-pound-per-ton application appeared to be effective against the lesser grain borer for longer than 9 months. One pint of 57-percent malathion emulsifiable concentrate and 210 pounds of Kenite 2-I per 1,000 bushels of wheat were about equally toxic to rice weevils and lesser grain borers exposed to samples periodically collected during a 15-month small-bin storage study (0). In the same study, 45 pounds of Cab-O-Sil per 1,000 bushels did not give satis- factory protection, although the results indicated that a higher dosage might be satisfactory. Flour- yielding capacity and bread-baking properties of wheat were not changed by the addition of Cab-O- Sil or Kenite 2-T dusts. In another study, Cab-O- Sil was one of the five most promising dusts tested to prevent insect infestation (4) by direct applica- tion to dried fish. The primary objective of this experiment was to compare the relative effectiveness of selected dos- ages of two basic types of chemically inert dusts and a candidate residual chemical to the standard malathion application, when applied to Hard Red Winter Wheat to prevent establishment of infesta- tions after periodic introductions of active popu- lations of the lesser grain borer. On the basis of promise shown in previous experiments, diazinon, Cab-O-Sil, and Kenite 2-T were selected for com- parison with malathion in this intermediate-type, small-bin study. The 1-year study started in 1966, and the first samplings were taken in February. MATERIALS AND METHODS Hard Red Winter Wheat was purchased locally at harvest and stored in bulk in a metal bin for 6 months. Immediately before treatment, the wheat was passed through a small shaker and fan-type seed cleaner to improve uniformity. A malathion emulsion spray was prepared from premium-grade 57-percent malathion emulsifiable concentrate (5 pounds technical malathion per gal- lon) and neutral distilled water. It was applied at a dosage of 1 pint concentrate (0.63 pound ac- tive ingredient) per 1,000 bushels. This is the standard treatment for grain protection; it was included as a check for the other treatments. A diazinon emulsion spray was formulated from a 48-percent diazinon emulsifiable concentrate (4 pounds technical diazinon per gallon) and neutral distilled water. The application rate was 0.5 pint of emulsifiable concentrate (0.25 pound active in- gredient) per 1,000 bushels. Both emulsions were applied at the rate of 5 gallons of finished spray per 1,000 bushels with a DeVilbiss HM-521 compressed air spray gun through an aperture in the lid of a rotating barrel fig. 1). Fo silica aerogel Cab-O-Sil was applied at a rate of 60 pounds per 1,000 bushels and the diato- maceous earth Kenite 2-I at a 210-pound rate. All insecticidal materials were applied to 2-bushel lots of wheat in the barrel, which rotated on its side at 16 revolutions per minute (r.p.m.) on an electric barrel roller for 5 minutes to mix the insecticide thoroughly with the wheat. Immediately after treatment of two lots, the 4 bushels of treated wheat were placed in a 5-cubic-foot bin (fig. 2). Five bins of untreated wheat were included as checks. The grain surfaces were leveled to provide EVALUATION OF PROTECTANTS ON WHEAT AGAINST LESSER GRAIN BORER 3 BN—32123 FicurE 1.—Application of liquid insecticide to 2 bushels of grain through an aperture in the lid of a rotating barrel. equal exposure areas in all bins. Each bin repre- sented a treatment replicate, and all treatments were replicated 5 times in a 5 by 5 block selective randomized arrangement. The 25 bins were placed in rows in a 18- by 18- foot room. A humidistat-controlled water-evapo- rating cooling unit maintained a minimum relative humidity of about 50 percent. Conditions favored insect development throughout the storage period. Major releases, each of about 5,000 vigorous lesser grain borer adults, were made in the storage room 10, 21, 42, 62, 126, and 198 days after the experiment was started. No flat grain beetles (Cryptolestes pusillus (Schénherr) ) or rice wee- BN-—31488 FiGcurE 2.—Cardboard drum, holding 4 bushels of grain, used as a small bin in testing insecticides as protectants of grain against insect attack. vils were released in the room, but populations of both developed in the infestation room during the last 7 months of storage. SAMPLING Samples of grain were taken from the bins with a nonpartitioned grain trier 24 hours and 1, 3, 6, 9, and 12 months after treatment. The probe was 1n- serted twice near the center of the bin and once about 2 inches from the bin wall in each of the four major directions. Soon after the samples were probed, they were shaken for 1 minute on a Roto- matic sifter to remove the insects. All fine dusts from the samples with the inert dust treatments were immediately separated from the screenings with a fine-mesh sieve and were returned to the parent sample for a 15-minute mixing period on a 33-r.p.m. wheel mixer. The live and dead insects were counted for an estimation of the populations in the various bins. The samples were sealed in 1-gallon glass jars until used for the periodic studies. Replicated 200-gram subsamples from the probe samples were placed in 1-pint glass mason jars cov- ered with a 40-mesh screen for the bioassay or tox- icity tests. Adult lesser grain borers were exposed to the grain for 21 days at about 80° F. and 60 percent relative humidity. After the toxicity tests were completed with mortality and progeny counts, all subsamples were retained for a later assessment of visible progeny damage. The test weight, moisture content, and percent of damaged kernels were determined for each treatment. Samples from the malathion treatment were submitted for residue determination. Immediately after treatment and again after 12 months’ storage, commercial grades were deter- mined. Information on the grading of grain con- taining foreign substances (3) is included in the appendix. As each bin was emptied at the end of the 12- month storage period, duplicate 1-gallon samples were progressively collected from top to bottom. 4 MARKETING RESEARCH REPORT NO. 860, U.S. DEPARTMENT OF AGRICULTURE These samples were sifted over a 10-mesh screen to remove the insects, kernel bits, dusts, and insect frass. The screenings were sifted over a 20-mesh sieve to separate the insect frass and other dusts from the insects and kernel bits. The frass and other dusts were weighed for an estimation of the amount of insect damage. The sifted wheat was retained in covered jars for 60 days for a record of insect emergence. Before treatment and after 3, 6, 9, and 12 months’ storage, 1,000-kernel sam sles were exam- ined from each bin to determine the percentage of kernels damaged by insects. A calculation of the kernel weight loss due to insect feeding during the 12-month storage was made by comparing the weights of damaged and undamaged kernels. RESULTS Grain Temperature and Moisture Temperatures were taken with mercury ther- mometers from near the center of the grain mass in each bin at weekly intervals after treatment. Higher temperatures in the bins of untreated check wheat were first noted during the fifth month of storage and continued through the rest of the 12 months (table 1). During the last 8 months, the temperatures in the untreated bins were about 30° higher than in the bins containing treated wheat. Higher temperatures were noted in some of the bins containing diazinon-treated wheat 9 months after treatment; however, some bins with the diazinon treatment did not have higher tempera- tures caused by insects even after 12 months’ stor- age. No higher temperatures due to insect activity were recorded in the bins with the malathion, Cab-O-Sil, or Kenite 2-I treatments. Changes in the moisture content of the grain paralleled the changes in grain temperature. They increased slightly during the warm spring months; thereafter a gradual decline was noted in all bins except the untreated checks (table 2). Malathion Residues Data from the residue analyses (table 3) are expressed in parts per million (p.p.m.) of the in- secticide, based on the actual weight of the wheat. The residues recovered immediately after treat- ment ranged from 6.2 to 8.4 p.p.m. and averaged 7.5 p.p.m. In samples taken 1 month later, an aver- age of 9.1 p.p.m. malathion was recorded. In sub- TABLE 1.—Average grain mass temperatures during 12 months’ storage Insecticide eae dosage per 1,000 Months of storage 4 5 6 7 8 9 10 11 12 bushels 1 2 3 a oR oR Malathion, 1 pint_._________________ 64.6 70.1 73.6 Diazinon, 0.5 pint__________________ 64.3 70.1 73.6 Cab-O-Sil, 60 pounds_______________ 64.6 70.6 73.8 Kenite 2-I, 210 pounds____________- 64.5 70.4 73.7 Untreated check__________________- 64.7 70.2 73.7 oF. oF. oR: oes ial 3 or. ia vr. ae 76.8 84.0 81.1 765 71.9 69.0 66.0 66.6 66.8 76.6 84.0 80.7 76.3 72.4 69.7 67.1 68.5 72.7 76.7 84.0 81.1 76.4 72.2 69.0 65.9 66.9 67.1 77.0 841 81.0 76.7 72.6 69.4 66.4 66.9 67.5 77.2 91.0 97.9 85.2 81.8 83.9 983 99.3 100.5 TABLE 2.—Moisture content of Hard Red Winter Wheat at given intervals after insecticide treatment Insecticide and dosage per 1,000 bushels Before Immediately treatment after treatment Sprays . Percent Percent Malathion, 1 pint____________ 11. 79 11. 84 Diazinon; 0:5: pint....c..c.s.2 11. 72 11. 83 Dusts: Cab-O-Sil, 60 pounds_______._ 11. 69 11. 53 Kenite 2-I, 210 pounds_-_-___-_- 195:79 11. 63 Untreated check. 2220252. 25 552528 11. 74 11. 73 Moisture content ! After After After After After 1 3 6 9 12 month months months months months Percent Percent Percent Percent Percent 11. 70 12. 16 11. 89 11. 30 11. 28 11. 70 12. 20 11. 86 11. 19 11. 14 11. 46 11. 84 11. 58 10. 88 10. 83 11. 54 11. 95 11. 58 10. 89 10. 86 11. 68 12. 16 11. 28 11. 69 12. 06 ! Determined on a RC 512 Steinlite Moisture Tester. EVALUATION OF PROTECTANTS ON WHEAT AGAINST LESSER GRAIN BORER 5 TABLE 3.—Malathion residues on Hard Red Winter Wheat at given intervals during storage ' Replication Immediately After nuinber after 1 treatment month P.p.m. P.p.m Wee ce eet eases 8.3 ike DE Ae SE la cence ene 8.0 9. Fel ences oar ae a 8. 4 8. BT eee 6. 2 8. Oi Ss sesbsteceaad 6. 6 11. Average-__- 1.5 9. After After After After 3 6 9 12 months months months months P.p.m. P.p.m. P.p.m. P.p.m 7.6 2.8 2.7 2. 4 5. 4 4.1 3.9 2.8 8. 7 4. 0 2.8 3. 0 3. 8 3. 0 2. 5 2. 8 5. 9 3. 7 3. 4 2.7 6.3 3.5 oul 2. 7 1 Values are expressed in parts per million of the insecticide based on actual weight of the wheat. sequent determinations, the malathion residues gradually decreased. Analyses were not made to determine the diazinon residues. Insect Populations The numbers of live adult insects recovered from probe samples taken from all bins in the infestation room at intervals indicated the populations within the bins (tables 4 and 5). After 1 month of storage, small infestations of lesser grain borers were al- ready established in the untreated check wheat. The progeny developing in probings from these bins produced a considerable amount of damage to the grain (table 11). After 3 months, lesser grain borer populations in the untreated grain had in- creased nearly sixfold, and after 6 months, tre- mendous numbers of lesser grain borers were found. Although all of the treatments of the wheat showed excellent control of these insects at 6 months, fewer insects were found in bins treated with Cab-O-Sil and Kenite 2-I than in bins treated with either malathion or diazinon. Progeny damage tests (table 11) showed that only mala- thion protected the wheat for 6 months from be- coming infested; however, very little progeny damage occurred in wheat treated with Kenite 2-I and Cab-O-Sil. After 9 months’ storage, it was evident that the effectiveness of the diazinon was diminishing. Comparatively few lesser grain borers were found at that time in the wheat treated with either dust, and slightly larger populations in the wheat treated with malathion. Only malathion, however, effectively prevented damage by progeny (table 11). Similar results were recorded during the 12 months’ examinations. Very little differences were found between the results of the malathion, Cab-O- Sil, and Kenite 2-I treatments. The inert dust treatments protected the wheat from nonintroduced “wild” insects for 12 months. Malathion and diazionon failed to protect against the rice weevil at 9 and 12 months. By the end of 6 months, an infestation of flat grain beetles had become established in the untreated check bins. This infestation increased to damaging propor- tions by the end of 12 months. A considerable in- festation of other insects was present in the same bins. Very few rice weevils were present in the untreated grain. TaBLeE 4.—Lesser grain borer adults in probe samples taken during 12 months’ storage Insecticide and dosage per 1,000 bushels Insects in samples taken after— 1month 38months 6 months 9 months 12 months Sprays: Number Number Number Number Number Malathion, 1 pint_______ 3 18 105 79 130 Diazinon, 0.5 pint_______ 7 90 114 913 1, 653 Dusts: Cab-O-Sil, 60 pounds____ 3 12 2 25 15 Kenite 2-I, 210 pounds___ 4 38 31 36 4 Untreated check___________ 100 574 9, 060 15, 247 18, 604 6 MARKETING RESEARCH REPORT NO. 860, U.S. DEPARTMENT OF AGRICULTURE Toxicity Studies Bioassay tests were conducted with lesser grain borers exposed in replicate to subsamples of wheat from the different treatments. Malathion was effective against the lesser grain borer in toxicity tests conducted during the first 3 months of storage; but thereafter, its efficiency against adult borers gradually diminished and progeny damage was quite evident (tables 6 and 12). Diazinon was less effective than malathion. Cab-O-Sil and Kenite 2-I both suppressed progeny development of the lesser grain borer throughout the entire storage period but at no time completely controlled the adults nor prevented progeny damage. Insect Emergence The emergence of insects from the 1-gallon sam- ples of wheat taken progressively as the bins were emptied at the end of the test indicated the extent of the selft-contained infestations that had become established in the wheat. Fewer insects emerged from the untreated wheat than might have been expected from its heavily damaged condition. Cab- O-Sil prevented the establishment of rice weevil, flour beetle, or flat grain beetle infestations, but a few lesser grain borers did emerge (table (i ). No flour beetles or flat grain beetles emerged from wheat treated with malathion, but rice weevil infestations were firmly established. Fewer lesser grain borers emerged from malathion-treated wheat than from any other treatment. Relatively large numbers of lesser grain borers emerged from the Kenite 2-I treated wheat. Both rice weevils and lesser grain borers infested the diazinon- treated wheat. Insect Damage Insects may inflict a certain amount of damage before they are killed by insecticide residues. Dam- age to the inside of kernels results in weight losses. eavily damaged kernels may break into frag- ments during handling. Insect damage to the wheat can be expressed i in percent of kernels damaged by insects, kernel weight losses, losses in pounds per bushel, amount of insect frass, and ratings of visi- ble damage by insect progeny. Very little weight loss was due to damage by the several species of insects present during the 12 months in wheat treated with Kenite 2-I or Cab-O-Sil (table 8). Wheat treated with mala- thion and diazinon lost 0.8 and 1.6 pounds per bushel, respectively. Untreated wheat lost about 14.7 pounds per bushel, or 24 percent of its orig- inal weight, to insects duri ing 12 months of storage. The percent of insect- damaged kernels was de- termined from 1,000-kernel samples from each bin, and weight losses were calculated from this figure. TasiE 5.—Miscellaneous live adult insects in probe samples taken during 12 months’ storage Insects in samples taken after— 6 months 9 months 12 months 3 months Insecticide and dosage per Flat grain beetles 1,000 bushels Rice weevils Flat grain beetles Rice weevils Flat Rice weevils Flat Rice weevils Others Others Others grain beetles Others grain beetles Number Number Number Number Number Number Number Number mod Number Number Number Number Diazinon, 0:5 pint.=--2-=.+ Malathion, 1 pint.___----- Dusts: Sprays: ooo Kenite 2-I, 210 pounds-_ -_-_- Cab-O-Sil, 60 pounds- -- --- Untreated check_________----- EVALUATION OF PROTECTANTS ON WHEAT AGAINST LESSER GRAIN BORER “‘suOT}eol[dar G JO OBVIOAY 1 Tvl Z6L G’8 0 ST br6 vy ET G‘¢ 966 (tens ice loi ee ar cei yooyo pozyvorquy 0 “EZ 0€ 9 'F8 GGG GZ 9 °S6 o'TL 801 Osy 0 ee e spunod (IZ ‘J-Z 9}ua sy 8 0S Or $16 Zz 69 6 & °S6 1 vg ve ot ~e spunod 09 ‘TIS-O-4%) :sysnq 6°S CLE @ ‘8ST 6 “ZI o8 G&S 1% L9 Que os ae ft quid GQ ‘uoulzeId v 61 L9 L°g G GG 67 6 ‘TG 67 8 SER Pea quid T “UOIyyeye yA 7U90Lad LaQUenny quarLad quadlag LaqQUunny quarlagd quaasagy Laquunny quae :sABIdg peed THIOL peed 1830, peod THIOL ATCO TN Aqyeyoyyy = —— AyTeYIOYL Aud301g Auds01g AUNB01g - sjeysngq Q00‘T 10d asvsop pute oplorjoosuy sqquow Z] SsyyUuOU § syjyuou 9 ponuyuog—jBeyM Jo WOT}eYSoJUT PUB YUSTAZVOI} UIOMJOd POMOg LZ GPP ‘TT 6% VT PEL SG € T L&G8 i ( iia ae pata e ee Sia Gate Siete rea ayeue poyeor}uly) ¢ ‘0S 1? v $6 9 “6P UG 0 “86 8 ES O€ S700. met ne la ee spunod Q1Z 1-6 Oreo 0°19 1G G ‘06 6 E9 L € G6 b 19 L OG ase spunod 99 ‘TIS-O-4%) Se :Sysnq 0 OF S OGG ee 0 v '86 a! z O6G.- Jose eee quid g*9 ‘uoulzerd are 0 8 °L6 ee 0 ‘O0T Sey HO 9 “66 Sperone Str eraser = AU OME OTIN quadad LaqUunn Wada quaolad LaqUnn Waa Wasa LaQuUenny quad :sABidg peed TeyO.L peed Te}O.L peod Te10.L AYTBILO PT -— AyyeWopy = — AY TVILOYAT Auds01g Audsolg Auds01g speysnq goo‘T 19d osvsop puv oplorpoosuy syyuoul ¢ qyuour J SINOY FZ {Roy JO UOT}VISOJUT PUY JUOTA}VIIY USOMYOq PONOg , uoynjsafur af shop gy huabosd 'y y} fo souabsawma yuanbasqns pub woayn pazvaij-aproyoasur o7 aunsodxa shvp 1g iafo hyyowopy :synpp 1as0g Usb sassxT— 9 ATAV I, 8 MARKETING RESEARCH REPORT NO. 860, U.S. DEPARTMENT OF AGRICULTURE About 1.40 percent of the kernels showed insect damage before treatment. Only a 0.19-percent loss in kernel weight was calculated for wheat from the Cab-O-Sil treatment during 12 months’ storage (table 9). Kernel weight losses of 0.60 and 1.13 percent were calculated for wheat treated with Kenite 2-I and malathion, respectively. The in- crease from 1.38 to 11.72 percent of kernels dam- aged by insects in wheat treated with diazinon resulted in a kernel weight loss calculated at only 2.38 percent. The calculated kernel weight loss in the untreated wheat was 34.07 percent, with 73.84 percent of the kernels damaged after 12 months’ storage. The calculated kernel weight losses of 0.19, 0.60, and 1.13 percent for Cab-O-Sil, Kenite 2-I, and malathion treatments, respectively, confirm the small recorded losses in test weight due to insect damage. Weights of fine dust, primarily insect frass, sifted from samples taken as the bins were emptied during the termination of the test, indicated the damage from insect feeding during storage. The small amounts of dust recovered from the bins treated with Cab-O-Sil and malathion reflected the slight amount of damage to the wheat with these treatments (table 10). The amounts of dust recovered from the Kenite 2-I treatment were larger than expected, although part of this was undoubtedly dust originally applied. The large amount of dust recovered from the untreated grain reflected the great amount of insect damage. Progeny Damage Remnant samples from the periodic probings and test subsamples were held for 4 or 5 months to observe the extent of the damage by progeny of established infestations. A study of the damage in samples from the peri- odic probings indicates that malathion gave the best overall protection during the first 9 months (table 11). Damage to wheat treated with Cab-O- Sil and Kenite 2-I was not great, but infestations in the wheat treated with diazinon had caused con- siderable damage after 3 months’ storage. Damage to the samples from toxicity tests in- dicated that lesser grain borers, although some- TABLE 7.—Emergence of insects from 1-gallon samples of wheat taken at end of the experiment Insecticide and dosage Rice Flour Flat Lesser per 1,000 weevils beetles grain grain Others Total bushels beetles borers Sprays: Number Number Number Number Number Number Malathion, 1 pint.-_______--_- 233 0 0 18 0 251 Diazinon, 0.5 pint_____-__--- 400 1 1 606 0 1, 008 usts: Cab-O-Sil, 60 pounds________- 0 0 0 33 0 33 Kenite 2-I, 210 pounds____-_-_- 0 0 0 845 0 845 Untreated check___________-__-_- 2 46 168 1, 869 0 2, 085 TABLE 8.—Weight loss per bushel of insecticide-treated Hard Red Winter Wheat at given intervals during storage Weight per bushel— Insecticide and dosage per a may 1,000 bushels Immediately After 1 After 3 After 6 After9 After 12 after month months months months months Loss treatment Sprays: Pounds Pounds Pounds Pounds Pounds Pounds Pounds Malathion, 1 pint____________- 60. 2 60. 5 60. 5 60. 4 59. 9 59. 4 0.8 Diazinon, 0.5 pint_____________ 60. 4 60. 5 60. 6 60. 6 59. 8 58. 7 Led Dusts: Cab-O-Sil, 60 pounds_________- 54.5 54. 6 54. 5 54.3 54. 6 54. 4 1 Kenite 2-I, 210 pounds_-_______ 55. 3 55. 3 55. 2 55. 0 55. 2 55. 0 3 Untreated check___._____________- 60. 3 60. 5 6U. 2 52:7 46. 4 45. 6 14.7 EVALUATION OF PROTECTANTS ON WHEAT AGAINST LESSER GRAIN BORER 9 TaBLE 9.—Kernel damage by insects in insecticide-treated Hard Red Winter Wheat during 12 months’ storage Kernels damaged in sample— Insecticide and dosage per 1,000 Calculated bushels Before After After After After weight treatment 3 6 9 12 loss months months months months Sprays: Percent Percent Percent Percent Percent Percent Malathion, 1 pint.__.____------- i 1. 48 1. 70 3. 60 4. 1.13 Diazinon, 0.5 pint___----------- 1. 38 1. 58 1. 86 5. 74 11, 72 2. 38 usts: Cab-O-Sil, 60 pounds_-_-__-------- 1. 62 1. 44 1.52 2. 32 2. 40 .19 Kenite 2-1, 210 pounds_____-_--- 1. 36 1. 34 1. 48 1. 92 3. 86 . 60 Untreated check_______------------ 1. 30 21. 52 41. 78 67. 76 73. 84 34. 07 what suppressed, could become established in wheat protected by Cab-O-Sil and Kenite 2-I (ta- TABLE 10.—Weight of fine dust and insect frass from insecticide-treated wheat samples collected as the bins were emptied Insecticide and dosage per Dust and frass weight ! 1,000 bushels ee - Average ? Range Sprays: Grams Grams Malathion, 1 pint__-________ 1. 84 12- 17 Diazinon, 0.5 pint____----___- 5. 45 1.9- 10.1 Dusts: Cab-O-Sil, 60 pounds- ---____-_ 1. 48 .8- 3.8 Kenite 2-I, 210 pounds-__---_-_ Untreated check______________ 4.18 3.3- 6.3 383.13 318. 0-503. 5 ! Per 1-gallon sample. 22 samples per bin; 5 bins of each treatment. ble 12). Malathion protected completely during the first part of the storage, but after 6 months in- festations established during toxicity tests did some damage. Commercial Grade At the beginning of the experiment, a composite taken from all grain being used for the different treatments, and composites from each treatment were submitted for official grade determinations. After 1 year’s storage, treatment composites were again graded and compared with untreated wheat (table 13). The source untreated wheat graded No. 1 Hard Winter. Treatment with Kenite 2-I reduced the test weight 4.3 pounds per bushel and with Cab-O- Sil 5.5 pounds. After 12 months’ storage, the test weights of wheat from these two treatments had not materially changed. Lowered test weight was TaBLE 11.—Visible damage by insect progeny in composited bin samples taken during 12 months’ storage Damage observed 150 days after sampling following storage periods of !— Insecticide and dosage per 1,000 bushels 24 hours 1 month 3 months 6 months 9 months 12 months Sprays: Rating Rating Rating Rating Rating Rating Malathion, 1 pint___.__________ 0 0 0 0 0. 2 3. 0 Diazinon, 0.5 pint_____________- 0 0 3. 2 4.0 4.0 4.0 Dusts: Cab-O-Sil, 60 pounds___________ 0 0 2 .6 1.0 .6 Kenite 2-I, 210 pounds_________ 0 0 0 .6 1,0 2.0 Untreated check___________________ 0 2.8 5.0 5. 0 4.2 4.8 1 Damage ratings code: 0=no visible infestation; 1= slight damage as evidenced by a few insects and a small amount of insect frass; 2, 3, and 4=ascending numbers of insects and corresponding amount of insect frass; 5=large infestation with great amounts of insect frass and spoilage of grain. 10 MARKETING RESEARCH REPORT NO. 860, U.S. DEPARTMENT OF AGRICULTURE the predominant factor responsible for the low numerical grade of wheat treated with these dusts. Wheat treated with diazinon and Cab-O-Sil was graded DLQ (distinctly low quality) because of the presence of an unknown substance.” ° See “Grading of Grain Containing Foreign Substances” in the appendix. Total defects in wheat treated with malathion and with Cab-O-Sil increased slightly from 1.3 to 1.8 and from 0.7 to 1.2 percent, respectively, during the 12-month storage. Defects in the wheat treated with Kenite 2-I increased from 1.1 to 2.8 percent. Total defects in diazinon-treated wheat increased from 1.5 to 5.7 percent, but the increase was from 1.6 to 61.2 percent in the untreated wheat. TABLE 12.—Visible damage by lesser grain borer progeny in composited samples from the toxicity tests Insecticide and dosage per 1,000 bushels Damage observed 120 days after sampling following storage periods of 1— 24 hours 1 month 3 months 6 months 9months? 12 months 2 Sprays: Rating Rating Rating Rating Rating Rating Malathion,. 1 pint2 .22222s-42s< 0 0 0 1.2 1,2 12-2 Diazinon; 0:5, pint. o2....<2s2