Showing papers in "Journal of Economic Entomology in 1975"

Resistance to organophosphates and carbamates in Anopheles albimanus Based on reduced sensitivity of acetylcholinesterase.

Abstract: A high degree of insensitivity of acetylcholinesterase to inhibition by paraoxon and propoxur was demonstrated in 2 strains of Anopheles albimanus Wiedemann highly resistant to parathion and propoxur. The strains remained susceptible to fenthion and their acetylcholinesterase was of nearly normal sensitivity to fenoxon.

Mating, Oviposition Patterns, Fecundity and Longevity of the Western Corn Rootworm

Abstract: Field-collected mating pairs of Diabrotica virgifera LeConte were maintained under controlled laboratory conditions. Females lived an average of 78.2 days, had a mean preoviposition period of 12.2 days, and a mean fecundity of 1087 eggs laid in 13.5 clutches over a reproductive period of 76.4 days. Intervals between clutches averaged 5.0 days through the 8th clutch or to 75% oviposition. Females reared from field-collected soil and mated in the laboratory laid fewer eggs. Males lived an average of 102.4 days. Females copulated only once; males will mate with several females. Egg-laying started at a high level with the 3rd clutch averaging largest and, for each female observed, one of her 1st 4 clutches was the largest. On a seasonal basis, 24% of the potential egg population were laid by Aug. 25, and 57% by Sept. 10, 83% by Sept. 30, and 90% by Oct. 10. Mating apparently speeds ovarian development. Ovaries of active gravid females fluctuate between ratings 4 to 3 to 4 etc., and this fact should be considered in interpretations of field populations examined for ovarian development.

Formula for Describing Effect of Insect and Host Tree Factors on Resistance to Western Pine Beetle Attack

Abstract: A descriptive formula for the effect of insect and host tree factors on resistance to Dendroctonus brevicomis LeConte attack was developed. Research results suggest this formula: Resistance = f [(resin quantity, resin quality) ÷ (beetle attack density, beetle quality)], in which resin quality is measured by xylem monoterpene composition.

Lepidopteran Pests of Soybeans: Consumption of Soybean Foliage and Pods and Development Time

Abstract: The foliage consumption potential by 6 lepidopteran larvae and the pod consumption potential by larvae of Heliothis zea (Boddie) were determined in laboratory feeding tests to be: Trichoplusia ni (Hubner)—119 cm2 of leaf/larva, Pseudoplusia includens (Walker)—114 cm2 Spodoptera exigua (Hubner)—52 cm, H. virescens (F.)—155 cm2 H. zea —336 cm2, and Anticarsia gemmatalis Hubner—84 cm2. For each species, ca. 90% of the feeding occurred during the final 2 larval stages. Larvae of T. ni held at 25°C consumed 23% more leaf area than those held at 20°C and 32% more area than those held at 30°C. Development of H. zea from the 4th through the 6th instar inclusive resulted in damage amounting to 8.2 pods and 7.1 seeds/larva.

Apple Maggot Control by Sticky Red Spheres

Abstract: The 469 sticky-coated red spheres, 7.5-cm-diam, hung in the 81 fruiting, unsprayed apple trees in my orchard in 1974 captured 9689 apple maggot flies, Rhagoletis pomonella (Walsh). The percentage of apples infested by apple maggot larvae was only 1.1–2.7, compared with 97.2–98.2 in 3 nearby unsprayed, untrapped check orchards, and more than 80% in each of these 4 orchards in 1972.

An Alfalfa Weevil Larval Resistance Mechanism Detected in Medicago

Abstract: Twenty-five entries representing 21 species of Medicago were evaluated for larval resistance of Hypera postica (Gyllenhal) by using M. sativa L. (Variety ‘Vernal’) as a control. Mortality rates for larval, prepupal, and pupal stages were determined as well as the rate of larval and prepupal-pupal development. Adult male and female weights also were determined. Larval mortality of 100% occurred on M. scutellata Mill. and M. disciformis DC. High larval mortality also occurred on M. marina L., M. laciniata Mill., and M. tornata Mill. Delayed larval development occurred on M. echinus DC., M. intertexta (L.), and M. minima (L.), while delayed prepupal-pupal development was observed on M. echinus . Male and female adult dry weights were low on M. praecox DC. and adult male weights were low on M. minima . The exudate from secretory trichomes on M. disciformis caused alfalfa weevil larval antibiosis. The larvae do not survive when placed on the plant, nor do they survive when the exudate is applied to 1st instars topically. At low concentrations of exudate, larvae showed a reduced rate of development and a reduced rate of feeding.

Mechanisms of resistance to organophosphorus insecticides in Culex tarsalis.

Abstract: A 55.6-fold level of resistance to parathion in larvae of a multiresistant strain of Culex tarsalis Coquillett was shown to be due to slower penetration and increased metabolism of the toxicant. After 4 h exposure, 1.9× more water-soluble metabolites and 0.4× less intact parathion were recovered from the resistant strain relative to the susceptible. Comparable amounts of paraoxon were isolated from both strains. During the same period, larvae of the susceptible strain absorbed 1.3× as much parathion as resistant larvae. In vivo tests revealed strong synergism of organophosphorus compounds in the resistant strain by DEF (S, S, S-tributyl phosphorotrithioate) but antagonism or no effect by piperonyl butoxide. In vitro assays indicated that resistance was not due to acetylcholinesterase insensitivity to inhibition by organophosphates.

Organophosphorus Multiresistance in Culex pipiens quinquefasciatus in California

Abstract: A broad spectrum of resistance to organophosphorus insecticides has evolved in Culex pipiens quinquefasciatus (= fatigans) Say in California’s San Joaquin Valley. Resistance levels determined on F1 larvae following control failures by chlorpyrifos, involve Abate® ( O, O′ -(thiodi- p -phenylene) O, O, O′O′ -tetramethyl phosphorothioate) at a level of 116.7 times the normal LC50, chlorpyrifos 52.2×, fenthion 48.9×, methyl parathion 24×, malathion 16.4×, and parathion 12.9×. Such multiresistance had appeareel earlier in 2 other major species, Aedes nigromaculis (Ludlow) and Culex tarsalis Coquillett, and is related to the multitude of chemicals employed in mosquito control and agriculture. Resistance in larvae is almost entirely overcome by the synergist DEF ( S, S, S -tributyl phosphorotrithioate) but is unaffected by piperonyl butoxide. Thus, hydrolytic esterases and not mixed function oxidases are implicated as primary resistance mechanisms. Certain synthetic pyrethroids, derivatized carbamates, insect growth regulators, and a biodegradable DDT analogue have demonstrated high activity against the resistant population.

Influence of Twospotted Spider Mite Populations on Photosynthesis of Apple Leaves

Abstract: Populations of Tetranychus urticae Koch were studied to determine their influence on photosynthesis of leaves of potted ‘Franklin’ and ‘Red Delicious’ apple trees. Nine days after treatment, 15, 30, and 60 mites/leaf had reduced net photosynthesis values 26, 30, and 43% below check Franklin leaves. Significant negative correlations were found between photosynthesis and leaf color values. On Red Delicious leaves, initial population levels of 15 and 30 mites/leaf reduced photosynthesis as early as 7 days after treatment. Significant negative correlations were found among photosynthesis, mite populations, and color values. Observers could not detect visible yellowing of leaves even when there were reductions in net photosynthesis.

Determination of Spraying Dates for Adoxophyes orana by Sex Pheromone Traps and Temperature Recordings

Abstract: Successful spraying against Adoxophyes orana (Fischer von Roslerstamm), the main leafroller pest in Dutch orchards, depends on correct timing. Sprays are most effective against newly hatched larvae before they reach young leaves where they spin their webs. Prediction of hatching of larvae is based on sex pheromone trap observations of the preceding moth flight and temperature recordings during embryonic development of the eggs. A model has been designed for quick calculation of stage of egg development as a percentage of total development. As soon as the cumulative percentages exceed 100, hatching can be expected.

Boll Weevils: Chemosterilization of Both Sexes with Busulfan plus Thompson-Hayward TH-6040

Abstract: Female Anthonomus grandis Boheman fed diets containing 0.1% busulfan are incompletely sterilized. Fertility is significantly decreased when insects fed busulfan are dipped in 0.1% TH-6040 in acetone. The combined treatment should be valuable for sterilization of boll weevils in control programs which utilize sterile males.

Activity of Insect Growth Regulators, Hydroprene and Methoprene, on Wheat and Corn Against Several Stored-Grain Insects

Abstract: Two insect growth regulators (IGR), hydroprene and methoprene, when applied to wheat and corn kernels at concentrations ranging from 2 to 10 ppm, prevented the metamorphosis of the Indian meal moth, Plodia interpunctella (Hubner), and effectively reduced the F1 populations of the lesser grain borer, Rhyzopertha dominica (F.), the confused flour beetle, Tribolium confusum Jacquelin duVal, and the sawtoothed grain beetle, Oryzaephilus surinamensis (L.). However, they were not as effective against the rice weevil, Sitophilus oryzae (L.), since substantial numbers of progeny developed in wheat kernels treated at a rate of 10 ppm with either of the compounds.

Greenbug Resistance to Organophosphorous Insecticides on the Texas High Plains

Abstract: Resistance to disulfoton in populations of Schizaphis graminum (Rondani) was suspected following failure to obtain adequate control in grain sorghum grown in the Texas High Plains. Laboratory tests confirmed the finding of resistance to disulfoton and demonstrated a decrease in susceptibility of ca. 30-fold. For a greenbug population from Lubbock an LC50 of 0.24 and LC90 of 0.50 ppm at 48 h was determined. For greenbugs from the Edmonson area these values were LC50 = 8.16 and LC90 = 13.88 ppm at 48 h. The organophosphate-resistant green-bugs are designated as Biotype D.

Suppression of Heliothis spp. with Cottons Containing Combinations of Resistant Characters

Abstract: The use of nectariless, glabrous, and high-gossypol cottons and cottons with combinations of the 3 characters were evaluated against Heliothis species in replicated large field cages and in field plots. In cage tests, insect populations increased only 1.1 times (a maintenance population) between the 1st and 2nd generations on a cotton combining all 3 characters. Populations on glabrous plus high-gossypol cottons or on glabrous plus nectariless cottons increased 2-fold between the 1st and generations. Normal commercial types of cotton with none of the 3 characters had a 10–12-fold increase between generations. In the 1974 field tests, the glabrous plus high gossypol line yielded 700 lb/acre more seed cotton than the commercial check; and a high gossypol cotton (not glabrous) yielded 950 lb/acre more seed cotton. In field tests, glabrous plus high-gossypol cottons reduced populations of the bollworm, Heliothis zea (Boddie), and tobacco budworm, H. virescens (F.). A glabrous line suppressed larval populations by 68%, and 4 lines with a combination of both characters suppressed populations 60–88%. The nectariless character did not reduce insect populations because of the small size of the plots.

Aflatoxin production and Lepidopteran insect injury on corn in Georgia

Abstract: Bagging ears of a dent corn hybrid in the field was effective in reducing damage by naturally occurring populations of Lepidoptera, but was not effective in reducing the production of aflatoxin on the ear. Insects produced conditions in the infested ear that were conducive to aflatoxin production and insect species differed in their relationship to increased aflatoxin production. Ears infested with European corn borer, Ostrinia nubilalis (Hubner), had the highest concentrations of aflatoxin B1.

TH 6040: Laboratory and Field Trials for Control of Gypsy Moths

Abstract: TH 6040, 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea, affected 3rd-stadial larvae of Porthetria dispar (L.) at an EC50 of 0.013 ppm of artificial diet. On apple trees infested with gypsy moth, mistblower rates from 0.125 to 0.00139 lb AI/10 gal water protected foliage equally well and as well as 0.75 lb AI carbaryl/10 gal water. The parasitoid, Apanteles melanoscelus (Ratzeburg), was affected within the gypsy moth host by the TH 6040 treatments.

Dimilin Toxicity to the Gypsy Moth Larval Parasitoid, Apanteles melanoscelus

Abstract: Larvae of Apanteles melanoscelus (Ratzeburg) were exposed to Dimilin® (1-(4-chlorophenyl)-3-(2,6-difluoroben-zoyl)-urea) by feeding treated artificial diet to parasitized gypsy moth hosts. The EC50 and EC95 for the parasitoid were 0.0059 and 0.026 ppm, respectively. The EC50 of A. melanoscelus was similar to that of the host. Dimilintreated leaves fed to hosts produced effects on parasitoids during their 2nd–3rd larval molt and later in development. The toxicity is a direct effect of the chemical and not due to host morbidity. Dimilin does not affect progeny production when fed to adult female parasitoids. These experiments suggest that Dimilin may be used in an integrated program compatibly with A. melanoscelus .

Diel Activity and Vertical Flight Distribution of Adult Western Corn Rootworms in Iowa Cornfields

Abstract: Vertical yellow sticky traps, 3.048 m long and 10.160 cm diam, were utilized at 5 locations during 1973 and 1974 to ascertain the diel periodicity and vertical flight distribution of Diabrotica virgifera LeConte in cornfields ( Zea mays L.). Western corn rootworm flight activity is bimodal with flight activity peaks occurring in the 2–3 h periods after sunrise and before sunset. Flight activity peaks were further characterized by a temperature range of 22.2 to 27.0°C. Statistical differences (0.05 level) in height of flight activity between the sexes were not observed below 182.88 cm where the majority of the insects was captured. Significantly more (0.05 level) females than males were captured between 182.88 and 304.80 cm. The 2 sexes fly at the same time and height of flight showed no relationship with time of day.

Variation in Brassica oleracea Resistance to Cabbage Looper and Imported Cabbage Worm in the Greenhouse and Field

Abstract: In the field, cauliflower PI 234599 was resistant to the cabbage looper, Trichoplusia ni (Hubner), and the imported cabbageworm, Pieris rapae (L.), but much less so in the greenhouse. Degree of maturity and environment influenced these resistance factors which apparently were associated with antibiosis. Red cabbages were less preferred (in both field and greenhouse) for P. rapae oviposition than other types tested. It appears feasible to transfer the resistance characteristics from PI 234599 into desirable cabbage and cauliflower lines.

Population Increase of Phytoseiulus persimilis on Different Insectary Feeding Programs

Abstract: Experiments were conducted to determine the optimum amount and stage of Tetranychus pacificus McGregor (prey) needed for production of the predator, Phytoseiulus persimilis Athias-Henriot, under insectary conditions. A diet which started with 2 mg of prey eggs/10 ♀ predators, fed 3 times a week and doubling the amount of food each week, produced an average of 9.7 active stages of predators per mg of prey after 35 days. A 50% reduction in the amount of prey resulted in less than ½ the number of predators being produced and fewer predators per mg of prey eggs. A diet of all stages of prey (with 50% eggs) produced somewhat fewer predators compared to prey eggs as food, and adult stages of prey were unsatisfactory for rearing the predator. A method is described for mass-rearing P. persimilis

A practical evaluation of TH6040 as a mosquito control agent in California.

Abstract: TH6040 (1-[4 chlorophenyl]-3-[2, 6 difluorobenzoyl]-urea) successfully controlled mixed species populations of Aedes nigromaculis (Ludlow) and A. melanimon Dyar when 0.025 lb AI/acre was applied by aircraft. This dosage was operationally effective against organophosphorus-resistant strains of these species in both the Sacramento and San Joaquin Valleys. TH6040 also provides a means of controlling organophosphorus-resistant strains of Culex tarsalis Coquillett, a vector of St. Louis and Western equine encephalitis in California.

Toxicity of Citrus Pesticides to Some Predaceous Phytoseiid Mites

Abstract: The relative toxicity of pesticides to adult predaceous phytoseiid mites in relation to plant feeding mites was evaluated by the slide dip technique. The toxicity ratios of Typhlodromus occidentalis Nesbitt, Amblyseius hibisci (Chant), A. stipulatus Athias-Henriot, Iphiseius degenerans (Berlese), and Phytoseiulus persimilis Athias-Henriot were compared to Panonychus citri (McGregor) or Tetranychus pacificus McGregor. T. occidentalis was more resistant to many of the pesticides than the plant feeding mites; the other 4 species of predators were generally more susceptible to the pesticides than P. citri or T. pacificus . Azinphosmethyl and Vendex® (hexakis (beta, beta-dimethylphenethyl)-distannoxane) had similar order of toxicity to the 4 predaceous species as the plant feeding mites, and tricyclohexylhydroxytin was less toxic to all 5 predaceous mites than to P. citri or T. pacificus . A. hibisci eggs were exposed to concentrations of citrus pesticides by utilizing the Potter Tower sprayer. A wide range of susceptibility of both eggs and immatures was shown to exist to the various pesticides evaluated. The egg stage was relatively tolerant to a number of the pesticides evaluated. Propargite and Vendex residues were the least toxic to the immature mites.

Artificial Dissemination and Epizootic Initiation of Nomuraea rileyi, an Entomogenous Fungus of Lepidopterous Pests of Soybeans

Abstract: Nomuraea rileyi (Farlow) Samson was distributed in in the form of pieces of dead, infected larvae of the tobacco budworm, Heliothis virescens (F.), among soybeans, Glycine max (L.), in North Carolina. One application of the fungus was made in each of 3 tests. In the 1st test, treatment significantly lowered populations of the larave of the green cloverworm, Plathypena scabra (F.), and corn earworm, H. zea (Boddie). There also were significantly more fungus-killed larvae and less pod damage to the soybeans in plots treated with N. rileyi . Results of the 2nd test, begun 14 days after the 1st, were generally similar to those of the first. However, significant differences were found on only a few of the subsequent sampling dates. Lower population levels of corn earworm larvae in the treated plot resulted in significantly less pod feeding damage. The 3rd test was initiated when a natural epizootic was developing. As a result, there were few differences between treated and untreated plots in the host of pathogen population levels. Results demonstrated that an epizootic can be initiated artificially by applying N. rileyi prior to the time when natural epizootics normally occur.

Field populations of cereal aphids in South Dakota spring grains.

Abstract: Studies of field populations of cereal aphids in spring small grains in South Dakota (1963–72) showed that Schizaphis graminum (Rondani), Macrosiphum avenae (F.), and Rhopalosiphum padi (L.) commonly colonized wheat, barley, and oats; R. maidis (Fitch) was found only in barley and only while the developing leaf blades were still furled. S. graminum often was present during a greater proportion of the season than the other species. Populations of all species were predominantly nymphal throughout the season with substantial numbers of alatae (migrant) only present as founders of colonies early in spring. S. graminum was distributed nearly randomly within fields, but M. avenae and R. padi were distinctly aggregated.

Insecticide resistance in selections of the greenbug.

Abstract: Satisfactory control of Schizaphis graminum (Rondani) had been obtained with single application of insecticides until the summer of 1974, when difficulties were experienced on grain sorghum in some areas. Field collected greenbugs in 1974 from Texas, Oklahoma, and South Dakota were not satisfactorily controlled in greenhouse tests by some of the organophosphates even at the 1 lb/A rate. Results suggest that an insecticide resistant biotype of the greenbug has developed, and control failures with some insecticides might be expected to be more frequent than in previous years. However, other insecticides showed little or no loss of effectiveness in the greenhouse tests.

Reflective Mulches and Foliar Sprays for Suppression of Aphid-borne Viruses in Lettuce

Abstract: Field tests indicated that reflective mulches repelled alate aphids and reduced incidence of cucumber mosaic virus (CMV) in late-planted lettuce but did not adequately suppress wingless aphids. Acephate, pirimicarb, demeton, and to a lesser extent, parathion, controlled apterous aphids but did not significantly reduce virus transmission. Oil sprays (2.5%) did not reduce CMV incidence or suppress aphid populations. Yellow pan water traps showed that peak aphid flights occurred in August and Myzus persicae (Sulzer) was the predominating vector on the lettuce. CMV and trace amounts of broad bean wilt virus and lettuce mosaic virus were detected in infected lettuce by using either differential symptoms produced on the host range indicator, visualization of virus particles in an electron microscope, or serology.

Aerial Applications of a Nucleopolyhedrosis Virus and Bacillus thuringiensis Against the Douglas Fir Tussock Moth

Abstract: Efficacy of applications of a nucleopolyhedrosis virus (NPV) and Dipel ( Bacillus thuringiensis Berliner) against Orgyia pseudotsugata (McDunnough) was determined on replicated field plots of 20 acres in size. Population reductions exceeded 95% at 35 days on plots treated with NPV dosages of 100×109 and at 100×1010 polyhedra/acre in 2 gal/acre of a 25% molasses formulation. Application of Dipel at 1 lb/acre in 25% molasses was as effective as the NPV. These treatments also provided excellent foliage protection, with estimated defoliation levels below 25%. In contrast, Dipel formulated in BioFilm® failed to reduce larval densities to a satisfactory level or to prevent severe defoliation.

Leaf-feeding Resistance to the European Corn Borer in Genotypes of Tropical (Low-DIMBOA) and U.S. Inbred (High-DIMBOA) Maize

Abstract: Leaf-feeding and survival of 1st instar Ostrinia nubilalis Hubner) were studied using 5 genotypes of maize, Zea mays L. Plant factors other than DIMBOA mediated resistance during a 60 h post-caging observation period on the tropical genotypes I.D.R.N. Cornell 6008 (Puerto Rico-1 × Antigua-2) and I.D.R.N. Cornell 6006 (San Juan-3 × Antigua-8D). In addition to any DIMBOA induced mortality on the inbreds (B49 and B68), feeding deterrency may be important in natural resistance as well. Rate of feeding was greatly suppressed on B49 and 6006, while feeding on 6008 and B68 was moderately reduced compared to a susceptible control WF9, in no-choice and 2-choice regimes using 2 caging techniques.

Boll Weevils: Field Populations Controlled by Sterilizing Emerging Overwintered Females with a TH-6040 Sprayable Bait

Abstract: A spray able invert sugar bait containing Thompson-Hayward TH-6040 ( N- (4-chlorophenyl)-N′-(2,6-difluorobenzoyl)urea) was applied in the field (as a coarse spray with maximum droplet size in the 3- to 4-mm-diam range) to sterilize female Anthonomus grandis Boheman. Weevil infestations were determined 3 times weekly from June 14 to July 10. Adult emergence from all infested squares was reduced 98%. This experiment demonstrated that the field population of boll weevils was drastically suppressed by sterilizing the females so as to prevent the development of the F1 generation.

Population Studies on Cadra cautella in a Citrus Pulp Warehouse with Particular Reference to Diapause

Abstract: The maximum increases in almond moth population density observed in a citrus pulp warehouse were 25- to 50-fold, and subsequently the growth rates were reduced by a pathogen, parasite, and 2 egg predators, Generation time was 6–8 wk. Throughout the storage period, last-instar larvae entered diapause in increasing numbers. Diapausing larvae remained active after nondiapausing larvae of the same generation pupated. The spatial distribution of diapausing and nondiapausing last-instar larvae was the same and changed systematically during the storage period.