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Leaf-feeding ratings (infestations with ca. 450 European corn borers [ECB], Ostrinia nubilalis (Hübner), eggs per plant) were made during midwhorl stage of plant development, and DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) contents of midwhorl leaf tissue were determined for four inbred lines of dent maize, Zea mays L., grown under field and greenhouse conditions. CI31A, B75, and B85 (grown in the field) were almost immune to leaf feeding by first-generation ECB larvae, but were susceptible when grown in a greenhouse. WF9 was susceptible under both field and greenhouse conditions, but the leaf-feeding damage was more intense in the greenhouse. In general, DIM BOA concentrations in leaf tissue were the same or were higher for the four inbred lines grown under greenhouse conditions compared with the lines grown under field conditions. Thus, high DIMBOA content in resistant inbred lines grown in a greenhouse did not prevent severe leaf-feeding damage by ECB larvae.

To determine if destruction of woodland ground vegetation affects abundance of questing adult deer ticks, Ixodes dammini, four plots were burned and one plot was mowed at a tick-infested site in Cape Cod, Mass. Burning or mowing, followed by tick sampling by dragging, was undertaken during spring or fall when adult ticks were most active. Abundance of questing adult deer ticks was reduced by as much as 88% and persisted for as long as 12 months following burning, but this effect disappeared thereafter. Mowing produced similar results. Vegetation modification is an effective method of reducing local abundance of questing adult I. dammini.

A technique for collecting eggs of the sunflower moth, Homoeosoma electellum (Hulst), for artificially infesting sunflower, Helianthus annuus L., is described. Eggs laid on blue-green velour pads (0.95 by 0.95 cm) and stored in the refrigerator (4.4°C) for up to 7 days are used to infest plants with the desired number of larvae.

A method is described of screening corn, Zea mays L., for resistance to the European corn borer, Ostrinia nubilalis (Hübner), in the laboratory by adding lyophilized plant material to the insect diet. Measurement of larva length at 10 days is sufficient to show differences in growth response to feeding on the resistant or susceptible plant material.

Throughout a 9-mo period, chlorpyrifos-methyl was much more effective than malathion in controlling insects on 14.6% moisture red winter wheat stored in plywood bins. However, chlorpyrifos-methyl persisted longer on the wheat than malathion did.

The U.S. National Germplasm System’s active collection of popcorn, Zea mays L., is maintained at the North Central Regional Plant Introduction Station at Ames, IA. From 1983 to 1989 and from 1982 to 1990, 299 accessions of this collection were evaluated for sources of resistance to com earworm, Helicoverpa zea (Boddie), and European com borer, Ostrinia nubilalis (Hübner), respectively. During 1990, 32 accessions previously rated as resistant to com earworm, and in 1991, 39 accessions previously rated as resistant to leaf feeding by first-generation European com borer were retested for resistance. Com earworm larval weights, when grown on silks from 21 of the 32 accessions retested for resistance, were not significantly different from the weights of larvae grown on the resistant control but were significantly smaller than larvae grown on the susceptible control. Fourteen of the 39 accessions retested for first-generation feeding resistance to European com borer retained their resistance. Genetic studies will be necessary to determine if these new sources of resistance are governed by genes different from those in previously identified sources.

Partial control of the European com borer, Ostrinia nuhilalis (Hübner), in maize, Zea mays L., has been achieved through germplasm resistant to leaf feeding that was incorporated into breeding populations. Leaf-feeding resistance to European com borer in maize had generally been attributed to presence of the chemical 2,4-dihydroxy-7-methoxy-l,4-benzoxazin-3-one (DIMBOA). New sources of resistance, other than that mediated by DIMBOA, are desirable for developing new resistant cultivars. From 1990 to 1992, 1,601 accessions of Peruvian maize maintained in the U.S. National Plant Germ plasm System were evaluated for leaf-feeding resistance to European com borer. Eleven resistant accessions were identified, all of which originated from Peru's north coast. The 11 resistant accessions were then analyzed for 6-methoxybenzoxazolinone (MBOA), the degradation product of DIMBOA and an indicator of DIMBOA levels present in the plant. All 11 resistant accessions contained low MBOA concentrations, equivalent to that found in the susceptible inbred WF9, indicating that DIMBOA is not the basis of this resistance. The factor(s) underlying this source of host plant resistance remains to be determined. Six morphologically diverse Peruvian maize races were evaluated in the greenhouse for ovipositional nonpreference by the European com borer. Some differences were noted, but morphological factors could not be confirmed as causing the differences.

Cultivars of proso millet, Panicum miliaceum L., were tested for oviposition and feeding response to 5 insect pests of grains in Oklahoma. ‘Big Red’ showed good tolerance to light infestations of chinch bugs, Blissus leucopterus leucopterus (Say) while foxtail millet, Setaria italica (L.) Beauv., survived a heavy attack. Corn earworms, Heliothis zea (Boddie), and fall armyworms, Spodoptera frugiperda (J. E. Smith), oviposited readily on millet entries, but southwestern corn borers, Diatraea grandiosella (Dyar), did not. Corn earworm larvae preferred the cultivar ‘Dawn’, but fall armyworm showed no preference. Weight differentials were significant when fall armyworms were reared on the millets. Reaction to feeding by the yellow sugarcane aphid, Sipha flava (Forbes), showed that some entries had intermediate resistance.

Field plots of corn, pearl millet, and sorghum were hand infested with egg masses of Diatraea grandiosella (Dyar) to study the effects of infestation time and planting date. Host plants reacted similarly, but corn had the greatest amount of damage, millet had the least, and sorghum had an intermediate amount. Plants infested 2 weeks after anthesis had the least stalk tunnelling, but the earliest infestation time had fewer ears of corn tunnelled. Late plantings of corn and male fertile sorghum had more damage than earlier plantings. The intermediate planting of millet had the least tunnelling. Late-planted corn yielded the least. Conversely, millet and sorghum had heavier losses when planted earlier. Male sterile sorghum (no pollen) had a higher percentage of tunnelled plants and slightly longer tunnels, but fewer heads tunnelled when compared with male fertile sorghum.

Discovery that popcorn (Zea mays L.) PI 340856 was resistant to corn earworm (Heliothis zea (Boddie)) led us to evaluate 34 additional lines developed by J. C. Eldredge for resistance to corn earworm, European corn borer (Ostrinta nubtlalis (Hübner)), and fall armyworm (Spodoptera frugiperda J. E. Smith). The 35 lines were evaluated for corn earworm resistance in the field with artificial infestation at Ames, Iowa, and Tifton, Ga., and with natural infestation at Hermiston, Oreg. None of the lines was better than the resistant check, ‘Zapalote Chico’ (PI 217413), at any of the three locations. Several lines had significantly better damage ratings than the susceptible checks. A bioassay of these materials for corn earworm resistance was run in the laboratory at Ames and Tifton by adding dried maize silks to laboratory diets and monitoring insect growth and development. Six lines were evaluated as resistant at both locations. In the field at Ames, two of these six lines were rated resistant to European corn borer. Fall armyworm field resistance ratings at Tifton indicated that one line was resistant after 7 d, but it was intermediate after 14 d. The J. C. Eldredge collection of popcorns provides sources of antibiosis to corn earworm and European corn borer and is available for use by plant breeders. Corn earworm resistance may be enhanced by breeding for husk protection, which may provide an environment that will capitalize on the antibiotic factors found in the maize silks.

Strains of cotton, Gossypium hirsutum L., that ranged from glabrous to densely pubescent, and also differed in other characteristics, were evaluated in field cages and in the field for relative damage caused by Pectinophora gossypiella (Saunders). Damage was lower in TM-1 (H2), a densly pubescent strain carrying the pilose allele H2, than in most other strains tested, but levels of pubescence below that of TM-1 (H2) did not insure resistance. A glabrous strain in ‘Stoneville 7A’ background, carrying the Sm2 allele, had less pink bollworm damage than its normally pubescent counterpart. Two other strains that had no more damage than TM-1 (H2) in 1975 were 1 × 6–56 and AET-5 × (108 × Br-2)-7-69, The former was significantly earlier than the other strains tested and thus probably escaped some damage. The latter, however, is a promising strain because it had a significantly lower amount of damage than the controls ‘Deltapine 16’ and Stoneville 7A but was only moderately pubescent and slightly earlier and seemed to possess the high yielding capacity of the cultivars.

New sources of com ear worm, Helicoverpa zea (Baddie), silk feeding resistance art' needed to protect the maize, Zea mays L., crop without increasing the use of pesticides. Previous evaluation of popcorn germ plasm with red peri carp color showed a high incidence of resistance. Within the National Plant Germ plasm System, there are 15 maize accessions with pure red peri carp color. These 15 accessions were grown in the field at Ames, lA, and Tifton, GA. Fresh silks were collected, dried, and incorporated into a standard pinto bean diet for rearing corn ear worms. Diets were infested with neonates, and the larvae were weighed after 8 d. Results of the diet testing identified four plant introduction accessions that produced 8-d larval weights equal to the resistant control, ‘Zapalote Chico’. The 15 accessions were analyzed for the presence of maysin, three of its analogues, and chlorogenic acid. One accession, PI 245138, had low levels of maysin but was resistant. In addition, eight maize accessions acquired by the National Plant Germ plasm System from 1948 to 1951 were evaluated for corn ear worm silk feeding resistance at Ames and Tifton. One accession, PI 172.328, was rated resistant at both locations.

An advanced breeding stock of upland cotton, Gossypium hirsutum L., consistently showed less seed damage from Pectinophora gossypiella (Saunders) than commercial cultivars in Arizona and Puerto Rico. This stock, designated AET-5 × (45-108 × Br-2-10)-7-69, and 2 other related stocks that also showed reduced seed damage have a complex pedigree that includes Triple Hybrid material, (G. arboretum L. X G. thurberi Tod.) X G. hirsutum. These stocks approach commercial cultivars in agronomic and fiber properties but suffer some deficiencies, particularly in fiber length and yield potential. Their level of resistance is probably not high enough to eliminate insecticide use. Therefore, the AET stocks can best be used as sources of resistance to combine with other sources in the development of improved cultivars.

When an x-ray method of examining the damage done by Pectinophora gossypiella (Saunders) to cottonseed was compared with an examination of green bolls for numbers of insects, the data obtained by both methods were significantly correlated. The main advantages of the x-ray method are that it provides a direct measure of plant (seed) damage and we can examine damage to single plants in segregating progenies that would not provide enough green bolls for weekly examination. Disadvantages include possible mutagenic effects, and unsuitability for monitoring seasonal fluctuations in insect populations. However, mutagenic effects probably will be negligible since the dose of irradiation is small. Also, it may be possible to estimate seasonal fluctuations in percentage seed damage, an indirect measure of insect populations, by altering the sampling technique.

Movements of 1st-instars of pectinophora gossypiella (Saunders) on 6 varieties of cotton with leaves and petioles differing in amount of pubescence were observed, timed, and traced with a camera lucida. The 2 most pubescent varieties, SA-166 and TM-1(H2), appeared to confuse larvae and greatly impeded their movements. We conclude that high plant hair density in cotton is a promising mechanism for host plant resistance to the pink bollworm. Larvae paused regularly to head swing and to sample the substrate with their mandibles while moving on leaves and petioles. When leaf neclaries were encountered by larvae, feeding usually occurred.

Grain amaranth, Amaranthus cruentus L., is a potential, alternative crop for Midwestern farmers. The tarnished plant bug, Lygus lineolaris (Paisot de Beauvois), is a potentially serious pest of amaranth, feeding on grain amaranth and causing developing seed to shrivel and discolor. Field tests were conducted during 1987 and 1988, at Ames, Iowa, to determine the effect of L. lineolaris on amaranth seed weight. The treatments included artificially (by hand) infesting heads with selected numbers of tarnished plant bugs and determining the effect of tarnished plant bug density, the effect of a naturally occurring tarnished plant bug population, and the effect of tarnished plant bug feeding duration. In 1987, when 50 tarnished plant bugs were caged on developing heads for 8 wk, seed weight decreased by 82%. When 10 bugs were caged on developing heads, there was no significant decrease in seed weight. In 1988, when 12 bugs were caged on developing heads for 8 wk, seed weight decreased by 80%. In 1987. when tarnished plant bugs were caged on developing heads for 2, 4. 6. or 8 wk, seed weight significantly decreased by 39.5% between the second and fourth week of feeding. In 1988, tarnished plant bugs feeding on the developing heads for 5 wk reduced seed weight by 57.6%. During 1987. naturally occurring tarnished plant bugs feeding continuously on the terminal heads significantly reduced seed weight by 28.2% between the third and fifth week of feeding.

Two nectariless strains of cotton, Gossypium hirsutum L., that were field tested for resistance to Pectinophora gossypiella (Saunders) supported significantly fewer insects and sustained less seed damage than their nectaried counterparts. A glabrous strain also had fewer insects and less seed damage than a hirsute cultivar. The nectariless and glabrous characters combined in a single strain reduced seed damage cumulatively.

Silks of popcorn, Zea mays L., in the Eldredge collection were evaluated for effects on growth of larvae of the corn earworm, Helicoverpa zea (Boddie), and assayed for content of maysin, chlorogenic acid, apimaysin, and 3’-methoxymaysin. The weights of 9-d-old larvae ranged from 8 mg on ‘PI340856’ to 952 mg on ‘PI340855’. Silks from about one-third of the popcorn collection produced corn earworm larvae equal to or smaller than larvae that fed on silks of the resistant standard, ‘Zapalote Chico’. Content of maysin, a luteolin-C-glycoside, ranged from zero for eighteen PIs to 1.128% for ‘PI340856’. Significant negative correlations were found between contents of all four allelochemicals assayed and larval weights. Silks of ‘PI340853’ had no detectable levels of any of the allelochemicals assayed, yet they produced larvae with an average weight of only 37 mg. Silks of several introductions had higher concentrations of chlorogenic acid, apimaysin, and 3’-methoxymaysin than silks of ‘Zapalote Chico’.

Fresh and lyophilized silks of a susceptible corn, Zea mays (L.), ‘Stowell’s Evergreen’ (SEG), and a resistant line, ‘Zapalote Chico 2451# (PC3)’ (ZC), were incorporated as base-plant materials into standard and substandard corn/soy/milk solids(CSM) and pinto bean (PB) diets and used to measure corn earworm (CEW), Heliothis zea (Boddie), larval growth and development. Eighty grams of fresh ZC silks had to be mixed into 300 ml of the standard CSM diet to reduce CEW larval weights as much as on those reared on fresh ZC silks. When added to the CSM diet, ZC silks held in the laboratory or left on the ear in the field for 5 days did not have the resistance that was shown by silks blended immediately or refrigerated or frozen for 5 days. Significant weight differences were detected between larvae fed on lyophilized SEG and those fed on ZC silk powder mixed in 300 ml of diet. All concentration levels (2, 4, 8, and 16 g per diet) of ZC silk powder added to PB diets produced significantly smaller larvae than did the SEG silk powder added to those diets. Results from the CSM diets were more variable, but ZC resistance was shown at higher concentration levels. Weights of larvae fed for 10 days and longer indicated that the resistance factor was more effective in the PB diets than in the CSM diets.

The North Central Plant Introduction Station collection of proso millets, Panicum milliaceum L., was evaluated for resistance to fall armyworm, Spodoptera frugiperda (J. E. Smith). Of the 153 lines evaluated, 8 were selected as resistant and 2 were selected as susceptible and retested. P.I. 176653 consistently was more resistant than the other seven lines when larval feeding weights, pupal weights, and larval development times on these lines were compared with those on the susceptible checks.

Four lines of common oats, Avena sativa L., were tested in the greenhouse to determine their type of resistance to 2 biotypes of Schizaphis graminum (Rondani). PI 186270 showed antibiosis, nonpreference, and tolerance to biotype C, the biotype predominant in the Great Plains. CI 4888 showed antibiosis, nonpreference, and tolerance to biotype B. CI 1579 and 1580 showed antibiosis to biotypes B and C and non preference to biotype C.

Corn breeders have previously obtained silk-feeding resistance to larval feeding by Heliothis zea (Boddie) predominantly from one main source: a corn originally collected in Mexico named ‘Zapalote Chico’ (PI 217413). Herein is reported a search for other sources of resistance from plant introduction corn maintained at the North Central Regional Plant Introduction Station, Ames, Iowa. From 1981 to 1984, 325 lines were evaluated in the laboratory for H. zea silk-feeding resistance. Twenty-four lines were selected from the 325 lines and retested in 1985. Three lines (PI 213705, PI 340856, and PI 369361) produced 6-d larval weights that did not differ significantly from those from the resistant check, ‘Zapalote Chico.’ These lines may provide new sources of resistance for corn breeders to use in development of resistant cultivars.

Mutants of ‘American Pima’ cotton, Gossypium barbadense L., were field-tested in 1974–76 for resistance to pink bollworm, Pectinophora gossypiella (Saunders), and in 1974–75 for resistance to cotton leaf perforator, Bucculatrix thurberiella Busck. Damage to seeds by pink bollworm was significantly reduced all 3 years in the mutant Pima glandless; also in 1975, 2 monomeric (reduced glandedness) mutants had significantly less seed damage than did the cultivar, Pima S-5. None of the mutants were effective in reducing cotton leafperforators in either year, but Pima pilose and ‘Young’s dwarf’ mutant had smaller populations in 1975 despite generally heavy infestations. ‘Pima Red’ had more seed damage from pink bollworms and higher populations of cotton leaf perforators than did the check cultivars both years it was tested.

Over 2000 plant introductions of Zea mays were given an initial screening under natural infestations of Diabrotica spp. from 1962 to 1969. On the basis of the data obtained from the original screening, 441 varieties were selected for retesting at Dayton, Iowa, in 1970. Comparison of the field data for specific seed types disclosed that flour and dent varieties had the lowest average root damage ratings, the highest average number of secondary roots present, the greatest average height, and were, on an average, later manning. Dent seed types had the largest average root-size, and flour corn was significantly lower in average percent lodging. Rootworm resistance as expressed and measured in the field was believed to be mainly tolerance. The introductions that responded best to corn rootworm infestations were P.I. 177606, P.I. 239099, P.I. 214288, P.I. 177645, P.I. 303923, and P.I. 257625.

Four types of oils typifying naphthenic Vs. paraffinic composition at comparable and different viscosity and distillation ranges were prepared as pairs, one refined by solvent extraction to 92 U.R. and the other given an additional treatment of mild hydrogenation. Each oil was used with each of 2 emulsifiers in laboratory dosage-mortality spray trials against eggs of citrus red mite, Panonychus citri (McGregor), and adult female California red scale, Aonidiella aurantii (Maskell). The LD95 values were calculated by a computer using the maximum likelihood solution of probit analysis. Efficiencies of the oils treated with extraction plus mild hydrogenation are as good as those of the comparable oils refined by solvent extraction alone. The efficiency of the oils formulated with the oil-soluble emulsifier was distinctly better against citrus red mite eggs than that of the same oils applied with blood albumin spreader, and the data indicate that the emulsifier may have a role in the performance of spray oils against California red scale.

A field technique was developed for more rapid determination of oil deposit on citrus leaves and fruit. An automatic, constant-volume, portable pipette was used to strip the dyed oil in the field. Oil deposit was determined through colorimetric analysis with a spectrophotometer. Leaf area measurements were expedited with a leaf-outline chart. The method was validated by comparison with the planimeter method. Du Pont's Oil Red A dye worked very satisfactorily at 0.18% by weight of the oil. Oil Red O dye was not so stable with time in preliminary comparisons of the 2 dyes. Precautions and suggestions are given for those who may use the technique or may adapt certain phases in other procedures.

Aerial applications of low-volume concentrate sprays of malathion when applied at the rate of 2 and 4 ounces per acre, gave excellent control of Glyptotendipes paripes Edwards adults. At the 4-ounce dosage rate, control was achieved within 3 hours and the residual effect of the spray gave control for 4 days. At the 2-ounce dosage rate, it took almost 6 hours to achieve a satisfactory kill, and the residual effect usually lasted 3 days. It appears that there is no difference in the initial kill when 1, 2, or 3 swaths are laid down. However, there are indications that the residual action is slightly less with 1 swath. At malathion concentration of 0.5 and 1.6 ppm, there was complete mortality of mosquito larvae and good control of midge larvae, but no mortality of the mosquito pupae. In the field, after spraying there was mortality of Hippelates eye gnats, muscid flies, small beetles, and wasps.

Seven compounds were evaluated for control of some spider mites on 3 ornamental plants in Louisiana. These were: Acaralate® (isopropyl 4,4’-dichlorobenzilate), GS-19851 (isopropyl 4,4’-dibromobenzilate), GS-13005 (O, O- dimethyl phosphorodithioate S-ester with 4-(mercaptomethvl)-2-methoxy-&incrmnt;2-1,3,4-thiadiazolin-5-one), Galecron® (N’- (4-chloro-o-tolyl)-N, N-dimethylformamidine), Nissol® (2-f1uoro, N-methyl-N-I-naphthylacetamide) (may apply only to 25% EC), chlorobenzilate, and tetradifon. GS 13005 and GS-198.51 were most effective in controlling the southern red mite, Oligonychus ilicis (McGregor), on holly and azaleas and the two-spotted spider mite, Tetranychus urticae Koch, on roses. GS-13005 was most effective in controlling a green mite, Eotetranychus clitus (Pritchard & Baker), and GS-19851 ill controlling the privet mite, Brevipalpus obovatus Donnadieu, on azaleas. Other compounds gave a significant degree of control, but none were so effective as GS-13005 and G5-19851.

The food habits of Solenopsis saevissima richteri Forel in pasture and young loblolly pine stands in southeastern Louisiana were studied in 1967. Foraging material was collected by exposing foraging trails and capturing each ant transporting a particle to the mound entrance. Material obtained in the pine areas totaled 3969 items or an average of 47.80 items an hour. Termites constituted the largest foraging item and composed 16.32% of the foraging material. A total of 3732 items was taken in pasture areas for an average of 56.54 items per hour. Collembola made up 12.90% of the collected material in pasture sites.

Lactating dairy cows stanchioned in controlled environment chambers were exposed to 650-1600 Stomoxys calcitrans (L.) per cow for periods of 5-8 days. Although the cows were noticeably bothered by the flies, milk production significantly decreased in only one trial. In another trial, the flies appeared to slightly increase milk production. It is concluded, however, that the tested populations of stable flies did not have an adverse effect on the milk-production response of stanchioned dairy cows with free access to a high-energy ration.

Field studies were conducted in southeastern Louisiana in 1966 and 1967 to determine the effect of imported fire ant, Solenopsis saevissima richteri Fore!, predation on larval and pupal populations of the Nantucket pine tip moth, Rhyacionia frustrana (Comstock). Results indicate that predation by the imported fire ant reduced larval and pupal populations of the pine tip moth very little. Counts of both larvae and pupae indicated about equal populations in both heptachlor-treated and untreated plots from early June through October. Spider counts also suggest that spiders influence larval and pupal tip moth populations only slightly during the summer season.