Corncob Grits Research Articles

Control of European Corn Borer on Whorl Stage Corn in West Central Nebraska, 1992

Abstract Various pesticides were applied to whorl stage (stage 2) field corn on 26 Jun. Treatments were applied over the whorl of the plant with insecticide boxes mounted on a tool bar. Each treatment was applied to 3 × 10 m plots and was replicated 4 times in a split plot design. Insecticide treatments were designated as whole plot treatments, infestation method (artificial and natural) was designated as the split plot treatments. A total of =40 first instar ECB larvae were applied to 4 randomly selected plants within each plot. These larvae were applied on corn cob grit to the whorl of the plant 1 day prior to pesticide application. To evaluate control of ECB larvae, 4 artificially ECB infested and 4 randomly selected corn plants were collected from each plot 4 wk post application. Each stalk was split from root to tassel and the number of ECB larval cavities were counted. In addition to this evaluation method, 25 consecutive plants within 1 row of each plot were evaluated for the presence of ECB feeding damage. Finally, 4 randomly selected plants were marked and evaluated at 10, 17, 24, 32 and 46 DAT for the presence of spider mites and arthropod predators.

Control of European Corn Borer and Twospotted Spider Mite in West Central Nebraska, 1991

Abstract Various pesticides were applied to field corn in two fields in west central Nebraska. Pesticides were applied to field 1, near North Platte, to blister stage, (R6 stage) ‘Pioneer 3475’ hybrid field corn on 4 Aug. Treatments were applied with a CO2-charged backpack sprayer through 8001 flat fan nozzles at 206,786 Pa (30 PSI), in a total volume of 196,405 ml/ha (21 gal/acre). Each treatment was applied to 3 by 10 m plots, replicated 3 times in a randomized complete block design. A total of about 40 first instar European corn borer (ECB) larvae was applied to 4 randomly selected plants within each plot, in corn cob grit, to the collars of the ear leaf and the leaf below, 1 day prior to pesticide application. Twospotted spider mites (TSM) were applied 3 days prior to treatment by tying 2 mite infested leaves to each of 2 plants within each plot. Since mite infestations were made close to the time of application no pre-treatment counts were conducted. Size of mite colonies were rated on the underside of three leaves below the ear, the ear leaf and two leaves above the ear at 7 and 14 DAT. Ratings were made on a 0-6 scale where 0 = no mites, 1 = individual mites, 2 = small colonies, 3 = large, individual colonies, 4 = large connected colonies but not covering the underside of the leaf, 5 = colonies completely covering the underside of the leaf, 6 = leaf dead due to spider mite damage. In addition to the spider mite colonies, spider mite predators were also counted. To evaluate the effectiveness of treatments in control of ECB larvae 4 artificially ECB infested and four randomly selected corn plants were collected from each plot four weeks post application. Each stalk was then split from root to tassel and the number of ECB larval cavities were counted. In a second field, near Hershey, Nebraska, insecticides were applied by center pivot injection on 13 Aug to soft dough stage (R7 stage) ‘Jacques 7710’ and ‘Jacques 7770’ hybrid field corn. Treatments were applied with a Pulsa diaphragm injector pump in a total volume of 9,353 ml/ha (1 gal/acre). One treatment also required the addition of 2,338 ml/ha (1 qt/ha) Veg-oil emulsified crop oil. These mixtures were sequentially injected, at a rate of 520 ml/min (18 oz/min), into a Zimmatic irrigation system, equipped with Rainbird impact sprinklers, making a 0.64 cm (0.25 inch) water application. Two replications of each treatment were applied to 8 acre pie shaped plots arranged in a randomized complete block design. Negotiation with the cooperator necessitated 2 slightly smaller check plots. Within each plot 4 randomly selected plants were artificially infested with a total of ca 40 first instar ECB larvae. These larvae were applied in corn cob grit to the collars of the ear leaf and the leaf 1 below the ear 3 days prior to pesticide application. Four weeks post application 4 artificially ECB infested and 5 randomly selected plants were collected from each plot. Each stalk was then split from root to tassel and the number of ECB larval cavities were counted.

Pushcart Mounted Rotary Applicator for Infesting Plants with the Larvae of Spodoptera frugiperda (Lepidoptera: Noctuidae)

A pushcart mounted rotary applicator for dispensing newly eclosed fall armyworm, Spodoptera frogiperda (J. E. Smith), larvae mixed in corncob grits was designed, developed, and evaluated. The efficiency of the device to establish fall armyworm in the whorls of field Corn, Zea mays L., was Compared with that of a standard, hand-held bazooka applicator. Output of grits from the rotary applicator was independent of hopper load when the hopper was operated at a frequency of 60 rpm and normal walking velocities. In field trials of larval applicators there were no significant differences between application methods in the number of larvae recovered per plant when 2.2 or 8.8 larvae were applied per plant. However, the bazooka applicator was more efficient than the rotary applicator when 35 fall armyworm larvae were applied per plant. A mean of 83% ± 7.8 (SE) of the plants became infested when 8.8 larvae per plant were applied with the rotary applicator, and 72% of these plants had more than one larva. The rotary applicator system has proven to be an effective method of establishing larvae of the fall armyworm in whorl-stage Corn (≤68 cm in height) and is likely adaptable for use with other lepidopterous pests and other crops.

Tractor-mounted Rotary Dispenser for Artificially Infesting Whorl-Stage Corn with Larvae of Spodoptera frugiperda (Lepidoptera: Noctuidae)

A rotating dispenser system for artificially infesting whorl-stage corn (Zea Mays L.) with larvae of the fall armyworm, Spodoptera frugiperda (J. E. Smith), was designed, developed, and evaluated. The system uniformly dispenses larvae up to a density averaging 76 larvae per g of corncob grits, while rotating at 75 rpm. The mortality of larvae tumbled in the hopper with grits was higher than the mortality of those not tumbled, but mortality did not differ significantly among larvae tumbled for 5, 10, or 20 min. Following application, the mean number of larvae recovered per plant, the mean percentage of plants infested, the mean percentage of plants infested with multiple larvae, and the mean percentage of damaged plants increased progressively and significantly as the density of dispensed fall armyworm larvae was increased from 1 to 16 per plant. The application system probably can be used to convey the larvae of numerous lepidopterous species on a variety of row crops and also may be adaptable for use in the augmentation of biological control agents.

Storage of Diapausing Tobacco Budworm Pupae (Lepidoptera: Noctuidae)

Diapausing tobacco budworm, Heltothis virescens F., pupae were stored underground in one of three different containers: 30-ml plastic cups (housed in 10.0-liter carboy) containing either sand, corncob grit, or 2% agar; 1.0-liter plastic containers containing sand; or 10.0-liter carboys containing 2% agar and corncob grit. Control pupae were stored in plastic Petri dishes in an environmental chamber at 1°C. Pupae were exhumed after 110 d. Samples from each treatment were placed in a diapause termination environment (27°C and constant light). Ninety percent of the control pupae emerged as adults. Of the pupae stored underground, those stored in 30-ml plastic cups containing either sand or agar had the highest percent emergence (68%).

Control Test, 1987

Abstract In Experiment 1, treatments of Lorsban 4 EC, Lorsban 15 G, and Asana 1.9 EC were tested on plowed pineapple fields on Lanai Island, Hawaii, for efficacy against ants with pineapple foliage and mulch removed. Pretreatment ant populations were monitored by using 6 wooden tongue depressors coated with a 50:50 mixture of peanut butter and soybean oil placed near the center of each plot. Treatments were applied to 0.5-acre plots when the ant populations had stabilized after the plowing stress. Each treatment was replicated 3 times. Ant counts were indexed, and 0, 1, 2, 3, and 4 represented 0, 1-10, 11-25, 26-75, and >75 ants, respectively. In Experiment 2, two corn cob grit baits were tested for efficacy against bigheaded ants on 4-acre plots of ratoon pineapple. Ant densities were monitored using 6 redwood stakes placed near each plot center baited with a 50:50 mixture of peanut butter and soybean oil. Ant counts were indexed, and 0, 1, 2, 3, 4, and 5 represented 0, 1-25, 26-100, 101-300, 301-500, and >500 ants/stake respectively.

Thrips Control; Effect on Plant Growth, 1986

Abstract This test was conducted to compare insecticides applied in furrow for thrips control and to determine the effects on plant growth characteristics. The plots were 4 rows × 20 ft long with 4 replicates in a randomized complete block design. The soil type was Austin clay. Treatments were Temik 15G at 0.25 and 0.5 lb (AI)/acre, Counter 15G at 1.0 and 2.0 lb (AI)/acre, and Furadan 10G on corn cob grit (CCG) at 0.5 and 1.0 lb (AI)/acre. These treatments were applied in furrow at planting with a John Deere Flex 71 planter on 13 May. Plants from the outside rows were pulled and beaten on hardware screen over a white pan and thrips adults and nymphs counted. Twelve consecutive plants from each outside row were collected and thrips were counted on 27 May, 6 Jun, and 10 Jun. Ten consecutive 28-day-old plants from the center 2 rows were pulled on 19 and 20 May, and plant growth data were determined by dissecting the tap root at the cotyledon leaf node and leaves at the petiole. Leaves, stems, and roots were then weighed separately. The number of plants that were squaring was determined. Later in the season, earliness was measured by counting the number of bolls on 0.02-acre subplots in each center row. Total yield was obtained by stripping the center 2 rows with a brush stripper on 18 Sep.

Meridic Diet for Rearing Tomato Pinworm Larvae (Lepidoptera: Gelechiidae)

An artificial diet was developed for rearing larvae of the tomato pin worm (TPW), Keiferia lycopersicella (Walsingham). The diet contained (in grams): tomato juice, 200.0; baby-food carrots, 40.0; wheat germ, 50.0; wheat germ oil, 2.0; soy oil, 1.0; torula yeast, 20.0; casein, 10.0; lactalbumin, 10.0; corncob grits, 40.0; no. 2 salt mixture, 4.0; sucrose, 12.0; fructose, 4.0; ascorbic acid, 2.0; cabbage looper vitamin mixture, 6.0; methylparaben, 2.4; sorbic acid, 0.8; aureomycin, 0.7; water, 600.0; agar, 30.0; and KOH (to adjust the pH to 6.5). Diet-reared insects compared favorably with those reared on tomato foliage in terms of eggs per female, egg hatch, days to pupation, pupation, pupal weight, pupal days, and emergence. The only indication of suboptimal nutritional quality was the increase in number of days required for pupation from 12.0 on foliage to 17.7 on diet. However, this problem might have resulted from diet presentation. TPW has been reared on this diet for more than five generations.

Field Evaluation of Affirm, Amdro, and Logic Baits for Control of Red Imported Fire Ants, 1984

Abstract Field tests were conducted on non-agricultural land located on 3 different airport properties. Treatment blocks averaging 95 acres in size were aerially treated September 18-25. Prior to treatment and on 3 occasions following treatment, all fire ant colonies within 10 randomly located 0.25-acre circular subplots in each treatment block were enumerated and categorized on a 1 to 25 rating scale. Population indices were calculated and % colony mortality was determined from the raw data by the method described elsewhere (Lofgren and Williams; 1982. J. Econ. Ent. 75:798-803). All baits were formulated with the AI dissolved in once-refined soybean oil and impregnated on pregelled defatted corn grits at 30% by weight except for one Logic formulation which contained 25% soybean oil impregnated on expanded corn cob grits.

Mechanical Insect Dispenser for Infesting Plants with Greenbugs (Homoptera: Aphididae)

Greenbugs, Schizaphis graminum (Rondani), mixed in corncob grits were effectively transferred to wheat, sorghum, and pearl millet plants in both field and greenhouse by a mechanical insect dispenser (inoculator or bazooka). Numbers of greenbugs released were determined by the ratio of greenbugs: grit. Over 90% of greenbugs survived in grits for 2, 6, 12, and 24 h at 35, 25, 15, and 5°C, respectively. Infestations produced by greenbug releases from the inoculator were more uniform than those obtained by mass infestation methods. Preliminary observations suggest that the technique also may be useful to infest plant with other aphid species and some Hemiptera.

Effectiveness of EL-468, and Ac 217,300 for Control of Imported Fire Ants, 1980

Abstract Field tests were initiated in Hamilton Co, FL with EL-468 (Eli Lilly and Company), and AC 217,300 (American Cyanamid Company) formulated as bait toxicants for control of natural infestations of the red imported fire ant (RIFA). Baits were formulated in 30% soybean oil and 70% pregel defatted corn grits (PDCG). The AC 217,300 was formulated in a 25% soybean oil and 75% expanded corncob grit bait (ECG). The EL-468 baits formulation also contained 0.25% Calico oil blue dye in the soybean oil so that worker ants could be collected and examined for uptake of the bait. All applications were made using a tractor-mounted auger applicator. Fifty 1-acre plots were established in an improved pasture of bermuda grass Cynodon dactylon (L.) and each plot contained a 0.5-acre circular subplot for evaluation. The population index method (Harlan et al; 1981. Southwestern Entomol. 6: 150-157) was used for evaluation. Five 1-acre untreated plots were used as checks. Twenty-four hours following treatment with the EL-468 baits, 25 colonies in each treated plot were sampled to determine the percentage of ants that fed on the bait. Post-treatment evaluations were made at 6 and 30 wk. The reason that evaluations were not made at 12 and 18 wk post treatment was due to severe drought conditions occurring between the 6 and 30 wk post treatment periods. Under these conditions evaluations are not possible since the ants move deep underground, and thus, are not available for observation.

Evaluation of Field Releases of Laboratory-Reared Larval and Adult Bactra verutana (Lepidoptera: Tortricidae) for Control of Purple Nutsedge 1

The native tortricid moth, Bactra verutana Zeller, was evaluated for efficacy in large-scale releases for the biological control of purple nutsedge, Cyperus rotundus L., and yellow nutsedge, C. esculentus L. Adults, first-stage larvae, and fourth-stage, 13-day-old larvae were released. When 4,800 to 8,200 adults (1:1 sex ratio) were released at one point, 50% of the plants were attacked at all six sites out to 5 m from the points of release and at one site out to 10 m. Moths flew only when disturbed during the hours of light but flew freely after dark. They mated at night or at dawn. Although all of fourth-stage larvae attacked dense nutsedge populations averaging 83 shoots per 9.29 dm 2 , only 30% attacked sparse populations averaging 8 shoots per 9.29 dm 2 With sparse growth averaging 1.4 or 7.0 shoots per m of row, first-stage larvae on corncob grits, released in a narrow band, attacked 57 and 46%, respectively, of the shoots up to 5 cm away. When the corncob grits were broadcast, first-stage larvae increased infestation by 30 to 87% over untreated areas. Regardless of the stage of B. verutana upon release, the degree of control depended on the age and condition of the plants. Rates of infestation were high only when the majority of the shoots were in a vigorous growing condition 10 to 21 days old.

Aerial Applications of Ac-217,300 (American Cyanamid Company) Baits for Control of Red Imported Fire Ants, 1979

Abstract Aerial applications of baits containing AC-217,300 against natural infestations of the red imported fire ant were conducted in GA and FL during Aug. The treatments were made alone the shoulders and median strips of 2 highways. The chemical was formulated in soybean oil and applied on 4 carriers; pre-gel defatted corn grits, pre-gel degermed corn grits, puffed (extruded) corn and corncob grits (12/30 mesh). The concentration of AC-217,300 was 0.75% on all the carriers except corncob grits (0.375%). Corncob grits contaned 15% soybean oil and all other carriers 30%. The applications were made using a gravity flow hopper and tube system mounted on a Bell 47 helicopter flying at 75 ft altitude and 75 mph with a swath width of 70 ft. The pre-gel defatted and degermed corn grit carriers were applied at 3 rates; 0.75, 1.5, and 2.25 lb/acre. The puffed corn was applied at 0.75 lb/acre while the corncob grits were applied at 2.5 lb/acre.

A Larval Dispenser-Capper Machine for Mass Rearing the Southwestern Corn Borer12

A food-packaging machine was modified for mass rearing Diatraea grandiosella (Dyar). It semi-automatically infests diet-filled cups with a predetermined number of larvae mixed in corn cob grits, caps the cups, and moves them onto a loading tray in a continuous process. The modification of the commercial machine is simple and inexpensive. Preparation of the larvae-grit mixture and operation of the machine are discussed.

Field Performance of a New Formulation of the Screwworm Adult Suppression System12

A new pelletized formulation of the Screwworm Adult Suppression System (SWASS) was evaluated in Jeff Davis Co., TX, for effectiveness under field conditions. In 2 separate field evaluations, SWASS pellets prepared from 30.5% sugar, 30.5% dried blood, 7.5% corn cob grits, 2% dichlorvos, and 29.5% of a hardened wax preparation of swormlure-2 (82% swormlure-2, 18% wax) were applied aerially twice weekly at the rate of 1 kg/5.7 km2. In the 1st test, the SWASS pellets reduced populations of native screwwonn, Cochliomyia hominivorax (Coquerel) ca. 84% and populations of secondary screwworm C. macellaria (F.), ca. 90%. In a 2nd test, the SWASS pellets reduced the native screwworm population ca. 72–95%. The new formulation of SWASS is compact and appears amenable to mass production.

Consumption and Utilization of Soyflour-Wheat Germ Diets by Heliothis Spp1, 2, 3

Larvae of Heliothis zea (Boddie) (Noctuidae) consumed significantly more of a soybean flour-wheat germ diet than did larvae of H. virescens (F.) or backcross larvae of male H. virescens × Fn female progeny from a cross between male H. virescens and female H. subflexa (Guenee). H. zea larvae also gained significantly more weight. Differences in food consumption or weight gain between H. virescens and backcross larvae were not significant. When corn cob grits were added to the soybean flour-wheat germ diet, and the soybean flour content was nearly doubled, the 2 species and the backcross used food more efficiently and gained more weight. Heliothis spp. reared on a soybean flour-wheat germ diet containing corn cob grits prepared with either high or low amounts of agar had similar growth and development parameters, but larval survival was lower with the lesser agar.

Imported fire ants: 10-5, an alternate formulation of mirex bait.

The formulation of mirex bait was modified so the soybean oil was applied to the corncob grits at 2 times; mirex was included in only the 2nd application. The bait (called 10–5) contained only ⅓ (0.1%) as much toxicant as the standard 4× bait (0.3%). The procedure concentrated the toxicant on or near the surface of the grits, which made the mirex more available to Solenopsis invicta Buren and S. richteri Forel. In 3 field tests against natural infestations of S. invicta with 10–5, the control obtained was comparable to that obtained with the standard.

Substitutes for Agar in a Wheat Germ Diet Used to Rear the Corn Earworm and the Sugarcane Borer1,2,3,4

In rearing Heliothis zea (Boddie) over 5 successive generations, soyflour-wheat germ diets that contained cottonwood sawdust or corncob grits instead of the normal amount of agar were superior to diet containing oak sawdust in all criteria evaluated: larval development and mortality, pupation, pupal development and mortality, and adult emergence. In rearing Diatraea saccharalis (F.) over 5 successive generations, similar diets containing cottonwood sawdust or corncob grits were superior to diet containing oak sawdust and were about equal in performance, except for pupal development. The ♀ pupae produced from diet containing corncob grits were larger than those from diet containing cottonwood sawdust, and pupal development for both sexes were longer.

Granular Materials Used in Implanting Boll Weevil Eggs on Artificial Diet123

Granular materials were used to cover the artificial diet and the eggs of Anthonomus grandis Boheman after the eggs were sprayed on the diet surface as a substitute for the usual diet scarifyiug and drying operation, The number of adult weevils produced from the petri dishes when the diet and eggs were covered with mortar sand. Vermiculite, fine mineral granules, and corncob grit was as great as or greater than that produced from the regular egg implanting method. By use of the granular material covering, the scarifying and drying operations of the regular egg planting method can be eliminated.

Low-cost Larval Diets for Mass Production of the Olive Fruit Fly1

Low-cost larval diets for mass production of Dacus oleae (Gmelin) were developed and compared. Diets SFC and MNC containing inexpensive celluloses and diets CCG and CCM containing corn cob were found satisfactory. Two brands of brewer’s yeast (differing in cost) tested with these diets gave similar yields. Diet CCG with corn cob grits was the most economical and reduced the cost of pupal production up to 4 times compared with the control diets. It also improved significantly pupal yield.