Insecticide Deposits Research Articles

Laboratory assessment of several insecticides against the potato tuber mothPhthorimaea operculellaZeller (Lepidoptera, Gelechiidae)

Abstract Insecticides azinphos ethyl, endosulfan, acephate, methamidophos, and ENT 27041 were tested in the laboratory against various stadia of Phthorimaea operculella. Azinphos ethyl was superior as an ovicide and larvicide but was a poor adulticide. Endosulfan and acephate were good adulticides. All were effective against larvae inside foliage mines. Insecticide deposits on leaves had repellant activity against ovipositing females, greatest activity being shown by ENT 27041. No apparent resistance to the commonly used insecticides azinphos ethyl and endosulfan was detected in the field population. A comparison of azinphos ethyl and azinphos methyl showed azinphos ethyl to be slightly superior. Acephate and methamidophos exhibited strong systemic activity when applied to the soil but were systemically ineffective when applied to the foliage. Desirable properties of an insecticide for use against potato tuber moth include strong ovicidal and larvicidal activity and reasonable longevity. These criteria were best satisfied hy azinphos ethyl.

Deposition and Dissipation of Azinphosmethyl-Oil Combination Sprays in a Plum Orchard

Addition of petroleum oil to certain azinphosmethyl sprays slightly increased initial insecticide deposits on wood and leaves of plum trees. However, subsequent dissipation of residues was not greatly affected by the oil. Loss of azinphosmethyl from tree branches was slower than disappearance from foliage. Azinphosmethyl-oil combination sprays did not appear to alter the insecticide’s control of the plum curculio, Conotrachelus nenuphar (Herbst).

Reduction of Pesticide Deposits on Pear Following Overtree Irrigation1

Abstract Overtree irrigation of pear trees following application of pesticides by speedsprayer resulted in lowering most insecticide deposits by 30-90%. Addition of a spreader sticker to pesticide sprays did not reduce pesticide loss.

Insecticidal and Residual Properties of EC and Encapsulated Formulations of Methyl Parathion Sprayed on Alfalfa1

Encapsulated (Pencap M(R)) and standard BC formulations of methyl parathion gave excellent, and equal control of alfalfa weevil, Hypera postica (Gyllenhal), larvae when applied as foliage sprays. There were no differences in levels of insecticide deposits or in dissipation rates of methyl parathion from alfalfa treated with these two formulations.

Natural Surfaces in a Gulf Port Warehouse: Influence on the Toxicity of Malathion and Gardona to Confused Flour Beetles13

Malathion and Gardona® (2-chloro-1-(2,4,5-trichlorophenyl) vinyl dimethyl phosphate), were applied at 2 dosage levels to sections of concrete floor, fiberboard, and wooden pallets in a port warehouse on the Gulf Coast. The insecticidal effectiveness of the treatments was measured at weekly intervals for 6 weeks with Triboium confusum Jacquelin duVal. High temperatures, high relative humidity, and slightly alkaline concrete surfaces may have made conditions unfavorable for the insecticidal deposits. In spite of these conditions, the low dosage of malathion (1260 mg per m2) was over 90% effective for 2 weeks, and the high dosage (2520 mg/m2) was over 95% effective for 5 weeks. The 2 dosages of Gardona (1140 and 2280 mg/m2) were about equal in biological effectiveness. On concrete surfaces, both Gardona treatments were superior to the low malathion treatment and slightly inferior to the high malathion treatment.

Drift of methyl parathion aerially applied low volume and ultra low volume.

An emulsifiable concentrate formulation of methyl parathion (4 Ib/gal) was applied ultra low volume (ULV) and low volume (LV) with a Piper PA-18-A airplane. Insecticidal deposits were sampled in the swath and downwind of the swath at various intervals down to ½ mile with Whatman no. I filter paper sheets and with oil-sensitive cards. Aerial drift was studied in air samples taken at several locations downwind of the swath with cascade impactors. The ULV methyl parathion spread over a wider swath and was deposited on the ground sample sheets in higher concentrations downwind of the swath than the LV applications. A greater portion of the airborne material from ULV aerial sprays than from the LV sprays remained at the 5-ft height sampled downwind by the cascade impactors.

Contribution of Hair-Shedding to the Loss of Insecticidal Deposits from Cattle

Contribution of Hair-Shedding to the Loss of Insecticidal Deposits from Cattle

Possible control of the melolonthid (Costelytra zealandica(White)) using transient insecticides against the adult

Abstract To investigate the possible control of grass grub (Costelytra zealandica (White)) by applying insecticides at the time of adult emergence, the pattern of development of pupae and adults and of the appearance of eggs was determined on four sites in four successive years by soil sampling. Data on primary emergence of beetles were obtained on three of the sites and related to presence of eggs in the soil. Light-trap records showed that beetles were not generally trapped until quite old, and the appearance of numbers of beetles in the traps was too late in relation to primary emergence to be of value in timing insecticide treatments. Seventeen insecticides of low residue hazard were examined for contact activity against C. zealandica adults. The best of these were “Dursban”, Bayer 77488, and diazinon. Three field trials were conducted using these insecticides, two with ultra-low-volume and one with dilute spraying, each applied to plots within areas of infested pasture. DDT was also included in the high-volume spray trial. Up to four applications, each with rates of use up to 1 lb per acre, were made. Results, based on ensuing numbers of eggs and larvae in the plots, were all negative. It is suggested that the failure of treatments to exert any effect is associated with the behaviour of adult beetles, especially females, resulting in very limited contact with an insecticide deposit on the pasture surface. Unless ways of increasing this contact can be devised (e.g. by the use of attractants), it is concluded that this approach to control is not likely to be effective.

The effect of different methods of application and spray diluents on contact toxicity of insecticide deposits

ZusammenfassungDie Methoden der Toxizitätsprüfung zu standardisieren, ist eines der wich‐tigsten Anliegen der Insektizidprüfung. Als Beitrag hierzu wurde die Kon‐takt‐Toxizität von Malathion (57%), DDT (100%) und Sevin (85%) auf die Adulten von Tribolium confusum (Duv.) geprlift.Die Ergebnisse zeigten, daß der trockene Belag des Insektizids auf Glas‐oberflächen stärker toxisch als auf Filterpapier wirkt. In den meisten Fällen war das direkte Besprühen der Versuchstiere durch das „Potter tower”‐Gerät weit wirksamer als trockene Insektizidbeläge, die mit Hilfe verschiedener Methoden aufgebracht waren.Zusätzlich wurde die Toxizität der Aceton‐Lösungen von Malathion E.K. 57%, Dipterex E.K. 50% und DDT E.K. 25% (E. K. = emulgierbares Konzentrat) mit der Toxizität der wäßrigen Lösungen derselben Insektizide bei gleicher Konzentration verglichen. Hierbei sollte die Wirkung des Ver‐dünnungsmittels untersucht werden. Die Adulten wurden durch das „Potter tower”‐Gerät besprüht. Die Ergebnisse zeigten, daß die wäßrigen Emul‐sionen der Insektizide effektiver als die Aceton‐Lösungen waren. Möglicher‐weise begünstigen die wäßrigen Emulsionen die hohe Oberflächentätigkeit der Emulgatoren und der anderen Hilfsstoffe und erhöhen dadurch die Toxizität.

Residual activity of benzene hexachloride formulations on the bovine coat.

A bioassay method, a modification of the WHO test for assessing resistance in mosquitoes, was used in a study of the residual activity of an emulsifiable concentrate and a wettable powder of benzene hexachloride on cattle. In 3 experiments, conducted during June-October 1965 with both formulations, there was a sharp decrease of gamma isomer activity in the first 72 hours post treatment. On the 4th to the 8th days post treatment some residual activity could still be detected, becoming negligible afterward. No appreciable difference could be noted between the emulsifiable-concentrate and wettable-powder formulations in residual activity and actual insecticide deposits on the coat of the animals; the wettable-powder preparation proved to be somewhat more persistent. Individual variations within the experimental groups were sometimes considerable and deserve further study. This method may be used in the study of pesticides applied to livestock under both laboratory and field conditions.

The Relative Efficiency of Aerial Application of Ultra-Low-Volume and Emulsifiable Concentrate Formulations of Insecticides1

Tests were conducted in 1966 to compare efficiency of applying insecticides as ultra low volume (ULV) and emulsifiable concentrates (EG). The ULV formulations were applied in volumes of from 1 pint to ½ gallon and the EG formulations were diluted with water to a volume of 1½ gallons. The ULV was applied with the ULV boom using the necessary numbers of 80015 tips and with a rotary atomizer. The EG was applied with a conventional boom. Flight heights of 20 and 5 feet were compared with both formulations. Efficiency of application was evaluated by droplet counts across the target area and for 1200 feet downwind, and chemical analyses of insecticide deposit in the 100-foot target area. Application to a precise target area was less efficient at a 20-foot than a 5-foot height of flight. The droplet count was much lower when insecticides were applied from the 20-foot height for about 100 feet downwind. Applications from the 5-foot height of flight were more efficient in control of deposit in the target area. There was no evidence of more droplets deposited from 300 to 1200 feet downwind with either formulation. More droplets per square inch were recovered in the target area with EC than with ULV concentrates. However, more insecticide was recovered from ULV applications than from EC. The larger droplet sizes (avg 150 µ) of ULV (with fewer droplets per square inch) resulted in from 2- to 4-fold more insecticide being recovered in the target area. ULV formulations applied in droplet sizes ranging from 100 to 200 µ drifted less than EC water diluted formulations. Results of these tests offer an explanation of the frequent reports that ULV formulations are more effective than EC. It may be that with ULV treatments, more insecticide reaches the desired area and less is lost to drift.

Influence of repellency on the efficacy of blatticides. II. Laboratory experiments with German cockroaches.

The efficacy of insecticides under simulated field conditions in which German cockroaches, Blattella germanica (L.), had the opportunity to avoid the insecticide deposits (choice boxes or mock-up wall voids) was approximately inversely proportional to their contact activity when the insects were continuously confined with the deposits (petri-dish tests). The addition of attractants to insecticides or to areas in which they were applied did not appreciably counteract their repellency, which was the principal factor affecting their efficacy. An 8-fold increase in the quantity of insecticide dust of a given concentration of toxicant, when applied to the dark compartment of a choice box, generally did not significantly increase the kill of German cockroaches, but doubling the concentration of toxicant greatly increased it. Simulated field treatment against German cockroaches was adversely affected by physiological resistance or reduced concentration of toxicant, but only because the insects could take advantage of the slower insecticidal activity to begin evasive action before their initial exploratory Contacts with the toxicant became fatal. When deposits of boric acid formulations in open petri dishes were exposed to air of moderate humidity for 3 months, their insecticidal efficacy did not decrease, but when they remained in water-saturated air for 3 months and were then dried, the powders were not so fluffy and were not picked up as readily by the cockroaches. The addition of certain adjuvants had the effect of preventing agglomeration of boric acid particles and decreasing the adverse effects of prolonged high humidity. Storage of boric acid formulations in moisture-proof containers is recommended. In treated choice boxes and mock-up closets the rate of cockroach mortality increased with increased light intensity, since the area of acceptable insecticide-free harborage was decreased by the light. Increased environmental complexity decreased the effect of light on mortality. In an untreated choice box or closet, the closer the food and water were placed to the preferred harborage sites, the lower the rate of mortality. Cockroaches having approximately a 1-second contact with dust deposits carried away with them a lethal dose of insecticide, whereas a 5-minute contact with deposits from dilute solutions of insecticides that kill by cholinesterase inhibition did not result in the death of the insects in 48 hours. Organochlorine insecticides had a more potent latent effect than organophosphorus and carbamate insecticides. In wall-void tests, the efficacy of 5 insecticide dusts 30 days after treatment was in the order boric acid>2% diazinon>Drione = sodium fluoride>2% Baygon. Deposits from an aqueous solution of boric acid + detergent gave a 50% kill of cockroaches continuously confined to them in approximately 6 days on asphalt, red-clay tile, or glass, and 12.3 days on concrete. They gave a 63.5% net kill in 2 weeks in a mock-up kitchen. the floor of which was mopped once with the solution.

Influence of repellency on the efficacy of blatticides. I. Learned modification of behavior of the German cockroach.

Devices were developed for determining the behavior of the German cockroach, Blattella germanica (L.), when it is given the ‘choice’ of entering or avoiding areas that would normally be attractive, such as dark voids, but which have been contaminated by residues of liquid insecticides or by deposits of insecticide dusts, dust diluents, or other powders. Using such devices, repellency was found to be the most important factor affecting the insecticidal efficiency of blatticides. When using ‘choice boxes’ or other similar devices, it is important that observations be made only when the cockroaches are not in a condition of stress, otherwise the ratings given to potential blatticides may not be in accord with what is found to be their comparative value under conditions of normal behavior. The German cockroach was able to learn to avoid the repellent types of insecticide deposits applied in dark areas, thereby resisting its strong impulse to enter such areas. The period required to learn and the effectiveness of the learning process were indicated by the time-mortality curves, which were characteristically hyperbolic rather than sigmoid. The effectiveness and duration of the modified behavior pattern were increased by the ease with which the insects could habituate themselves to a light (and insecticide-free) environment. The complete insecticide-avoidance behavior pattern involved associative learning augmented and extended by a more elementary type of learning known as ‘habituation.’ Boric acid powder possessed so little repellency that German cockroaches repeatedly entered dusted areas until they succumbed to its relatively feeble contact toxic action. In both the ‘choice boxes’ and ‘wall-void devices,’ a given number of cockroaches were exterminated more rapidly with boric acid powder than with deposits of various currently used toxicants or dust desiccants, which were far more insecticidal than it, when the insects were confined continuously upon the deposits. The addition of flour or powdered sugar to boric acid, as possible attractants, was of no value; both were more repellent than boric acid to German cockroaches. In addition, sugar decreases ‘pick-up’ by the cockroaches. It becomes increasingly detrimental with passing time. An important characteristic of a boric acid deposit is that it is readily picked up by insects after it has become damp and subsequently dry. (This characteristic is not possessed by borax and many other powders.) In addition, the deposit left by an aqueous solution of boric acid is insecticidal.

A simulated-field method of testing residual insecticide deposits against cockroaches.

A method of testing residual deposits of insecticides under simulated household conditions in which the insect has a choice of contacting a treated or nontreated surface for harborage is described. Opportunity for exposure is continuous but the amount of treated surface can be varied from complete coverage to any degree desired, and the effectiveness of a compound is reported on the basis of length of time required for specific levels of mortality.

The toxicity of insecticides to larvae of the codling moth, Cydia pomonella (L.). II. Maintenance of a toxic deposit in the field.

The persistence, as assessed by biological and chemical methods, of field deposits on apples from two spray programmes, each of DDT, carbaryl or azinphos-methyl, was compared throughout eight weeks following the first application in an orchard in south-eastern England. Newly emerged larvae of the codling moth, Cydia pomonella (L.), were used to assess, in the laboratory, the biological activity of the deposits. The spray programmes studied were (1) two applications of conventional concentrations (i.e., 0·1 per cent, for DDT and for carbaryl, 0·04 per cent, for azinphos-methyl) three weeks apart and (2) three applications of half these concentrations at two-weekly intervals. DDT wettable powder, carbaryl and azinphos-methyl were compared in 1961, DDT emulsion, DDT wettable powder and carbaryl in 1963. Results of biological and chemical assessment of the deposits are presented graphically. Over-all, the performance of the three-application programmes was as satisfactory as that of the two-application programmes, although a smaller amount of chemical was used. The serious reduction in deposit caused by heavy rain shortly after the first application of DDT wettable powder and of carbaryl in 1961 is noted. In the absence of heavy rain, carbaryl was biologically the most persistent, but the best performances of the other chemicals were almost as good as that of carbaryl.LD50 values of fresh deposits obtained by field spraying were shown to be similar to those obtained by laboratory dipping.Comparison of the toxicity of fresh and weathered field deposits of similar magnitude indicated that the biologically available proportion of a DDT deposit from either formulation decreases as a result of weathering. This phenomenon was not found to occur with carbaryl and either not at all or to a much lesser extent with azinphos-methyl.The deposits obtained in the comparison of the spray programmes were separated into their fresh and aged components, so that differences in the contribution to the final deposit provided by each application could be seen. With the very persistent DDT emulsion, only about half of the six-week deposits was composed of chemical from the final application, but, with the much less persistent carbaryl and azinphos methyl, the six-week deposits were almost entirely derived from the final application. By substitution in an equation to obtain the rates of decay of the deposits from the three-application programmes of all chemicals, it is shown that deposits from the second and third applications were, in all cases, more persistent than those from the first. Possible reasons for this difference are discussed.The significance, in terms of field control, of the results for the larvicidal activity of the deposits from the different spray programmes is indicated. It is concluded that data on the LD90 of insecticidal deposits on apples, together with measurement of their persistence in the field, can be used to assess the probable field performance of codling-moth insecticides and to determine the most efficient means of employing them, although the deposit level that ensures 90 per cent, larval mortality in the field is higher than the LD90 determined in the laboratory.

Evaluation of Insecticides as Protectants Against Pests of Stored Grain and Seeds. II.1

Results are presented from a series of tests with varying dosages of each of 46 insecticides in acetone solution sprayed on wheat for protection against adults of the rice weevil, Sitophilus oryzae (L.), granary weevil, Sitophilus granarins (L.), and confused flour beetle, Tribolium confusum Jacquelin duVal. Mortality of adult insects recorded after an exposure of 14 days was the only criterion used to assess the effectiveness of insecticide deposits. Malathion was used as the standard insecticide in making comparisons. Fenthion was the most effective compound tested. American Cyanamid 12008 (O,O-diethyl S-isopropylthiomethyl phosphorodithioate), and Bayer 41831 (O,O-dimethyl O- (4-nitro-m-tolyl) phosphorothioate) were less effective than fenthion but more effective than malathion as indicated by dosages resulting in 100% mortality of all 3 species of test insects. Bayer 25141 (O,O-diethyl O-p- (methylsulfinyl) phenyl phosphorothioate), Bayer 25198 (O-O-dimethyl O-p- (methylsulfinyl) phenyl phosphorothioate), and GC 3707 (dimethyl 3- (dimethoxyphosphinyloxy) glutaconate) were equally as effective as malathion under the conditions of the study.

Protective Sprays Against Internal Infestations of Grain Beetles in Wheat1

Results are given from laboratory tests made in a study to assess the effectiveness of American Cyanamid 12009 (O,O- diethyl S-n-propylthiomethyl phosphorodithioate), dichlorvos (DDVP), diazinon, Guthion® [O,O-dimethyl S-(4-oxo-1,2,3- benzotriazin-3(4H)-ylmethy) phosphorodithioate], malathion methyl parathion, mevinphos, naled, parathion, phorate, and ronnel against internal infestations in wheat of 3 species of grain beetles: Sitophilus granaries (L.), Sitophilus oryzae (L.), and Rhyzopertha dominica (F.). Extremely hazardous Materials were chosen deliberately for comparison with compounds that have some chance of being used on grain and seeds and around storage facilities. Secondary consideration was given to the effectiveness of insecticides in killing adult insects completing development and emerging from treated grain. What samples sprayed with acetone solutions of insecticide to give deposits of 10 ppm and 20 ppm contained all stages of development of the test insects normally found inside grain. Dichlorvos was the most effective compound tested in reducing the total number of insects emerging from infested wheat, which is the criterion used to assess the effectiveness of treatments against internal infestations. Malathion and diazinon had little value against internal infestations, but adult insects were killed when they came in contact with insecticide deposits after emerging from treated grain. The potential use of dichlorvos in a grain protectant program appears to be primarily on grain infested prior to treatment, ann possibly under special conditions where a protectant with a short residual life is needed. The results indicate that including dichlorvos with a residual grain protect ant offers intriguing possibilities in a grain protect ant program where infestations may originate in the field and storage facilities are unsuitable for fumigation.

A field test of a lindane/dieldrin smoke for control of the death-watch beetle, Xestobium rufovillosum (Deg.) (Coleoptera, Anobiidae)

In view of the promising results obtained with insecticidal smokes against the common furniture beetle, Anobium punctatum (Deg.), a field trial was conducted to study the effect of deposits from lindane/dieldrin smoke on adults of the death-watch beetle, Xestobium rufovillosum (Deg.), emerging from infested roof timbers of a college chapel in Cambridge, England, in 1963. Quantitative determination of the insecticidal deposits was made and methods were devised for studying the effect of the treatment on the numbers of beetles emerging subsequently in order to assess the long-term value of annual treatments for reducing the population. Beetles collected from an untreated building were used for comparison.Fewer males were found than in preceding years and it is postulated that some may have been prevented by the insecticides from emerging. The normal sequence of beetles dropping from roofing timbers—males predominating first, then females—did not occur. Both sexes dropped nearly uniformly, a fact suggesting, particularly in the case of the females, that the insecticides had caused them to drop before their normal time. Mating was considerably reduced. Examination of females showed no signs of their having laid eggs, this being attributed to the action of the insecticide deposits. Beetles obtained from an untreated building and placed on wood surfaces which had been exposed to the smoke treatment were affected but laid some eggs, of which a small proportion hatched; larval boring into such surfaces was, however, completely prevented.From these results it was inferred that the deposits from the treatment with lindane/dieldrin smoke prevented emerging adults from causing reinfestation of the roofing timbers and it is argued that, provided that this can be achieved annually by a succession of treatments, the beetle population should ultimately be eliminated or, at least, greatly reduced. Other possible effects which might result from annual smoke treatments are accumulation of the insecticide deposits with a consequent increase in toxicity of the timber surfaces and sorption of the deposits by the timber to a point where they might exert a toxic effect on larvae or pupae beneath the surface.

An assessment by bioassay of the comparative toxicity and persistence of dieldrin and isobenzan deposits on riverine vegetation in the Northern Guinea Savannah zone of Nigeria in relation to the control of Glossina palpalis (R.-D.)

The toxicity and persistence under natural field conditions of deposits of dieldrin and isobenzan, derived from dilutions of emulsion concentrates, on the leaves of riverine vegetation in the Northern Guinea Savannah vegetation zone of Nigeria were studied by a bioassay method, using teneral females of Glossina palpalis (R.-D.) as test insects. Although deposits of both insecticides were extremely toxic when first sprayed, neither product was found to have a long residual action, and isobenzan was found to be approximately half as efficient as dieldrin. It is suggested that because of its poor residual action isobenzan will be little used in tsetse control campaigns in areas similar to that in which the investigations were performed.

Laboratory assessment of the toxicity of field-weathered deposits of insecticides to larvae of the codling moth, Cydia pomonella (L.)

The toxicity of naturally weathered deposits of 21 chemicals to larvae of the codling moth, Cydia pomonella (L.), was assessed by spraying apple trees in the orchard and testing samples of the fruit picked at various intervals after treatment. Each apple was placed in a separate glass container with one first-instar larva from a laboratory culture, and larval mortality and damage to the fruit (defined as removal of a portion of the skin) were recorded after three days in a constant environment.The site of entry of the larvae was shown to vary with fruit size, calyx entries decreasing and side entries increasing with increase in the surface area of the fruit.The relationship between larvicidal activity and age of the spray deposit for periods up to ten weeks after spraying is illustrated graphically; data are presented for fruit damage caused by larvae applied one and three weeks after spraying.On the basis of larval mortality and fruit damage recorded in tests on deposits up to three weeks after application, a spray containing 0·1 per cent, carbaryl was the most effective, followed by 0·05 per cent, fenthion, while Bayer 5024, Zectran, DDT, DDD (all at 0·l per cent.) and 0·04 per cent, azinphos (as the methyl or ethyl homologue) were only slightly less effective. Deposits from 0·1 per cent. Kepone, 0·02 per cent, diazinon, 0·11 per cent, malathion, 0·01 per cent, parathion and 0·05 per cent, carbophenothion, dimethoate and ethion also caused 90–100 per cent, mortality when fresh, but were less persistent. Fresh deposits from 0·1 per cent, endosulfan, 0·04 per cent, dioxathion, 0·05 per cent, phenkapton, 0·02 per cent, phosphamidon, 0·2 per cent, lead arsenate and 0·6 per cent, ryania only killed 50–88 per cent, of the larvae, and their residual toxicity was proportionately low.Heavy rain soon after spraying caused a large reduction in deposits from wettable powders but the accompanying reduction in larvicidal activity was shown to be greater in the case of carbaryl than for DDT or DDD.