Chemical Insecticide Treatments Research Articles

Comparative Evaluation and Economic Potential of Ecorational Versus Chemical Insecticides for Crucifer Flea Beetle (Coleoptera: Chrysomelidae) Management in Canola

From 2001 to 2004, field studies were conducted to evaluate the effect of the ecorational insecticides SpinTor (spinosad), BotaniGard (Beauveria bassiana), Neemix (azadirachtin), and Surround (kaolin) against crucifer flea beetle on canola, Brassica napus L., at the cotyledon stage. The ecorational treatments were compared with a standard foliar chemical insecticide, Capture (bifenthrin), and the chemical seed treatment insecticide Helix XTra (thiamethoxam). This study indicated that flea beetle injury was lower for Helix XTra, Capture, and the ecorational insecticide SpinTor. SpinTor was less effective when flea beetle populations were relatively high (200-300 per trap-week). Yields for chemical insecticide treatments were always greater than SpinTor, with differences being the smallest (68-374 kg/ha) at low levels of flea beetle feeding injury. Differences were greatest when canola seedling injury was high (775-1,364 kg/ha). Yield differences between the conventional insecticides and BotaniGard, Neemix, and Surround were 119-439 and 61-2,248 kg/ha at low and high flea beetle feeding injury, respectively. Although yield differences between SpinTor and chemical insecticides were relatively small at lower levels of flea beetle injury, net losses ranged from $47 to $151/ha when SpinTor was used as an alternative to a standard chemical seed treatment, Helix XTra. This suggests that SpinTor would not be a viable alternative to the chemical insecticide. Net losses ranged from $30 to $266/ha when BotaniGard, Neemix, and Surround were used as alternatives to the seed treatment.

Efficacy of optical brightener formulations of Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) as a biological insecticide in greenhouses in southern Spain

Abstract The efficacy of optical brightener formulations of a native Spanish isolate of Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) was determined for control of S. exigua on greenhouse grown sweet pepper (Capsicum annuum) in Almeria, Spain. In laboratory bioassays involving diet surface contamination, the 50% lethal concentration in fourth instars was reduced 25-fold and 5731-fold, compared to SeMNPV occlusion bodies (OBs) alone, or in mixtures with 0.1% and 1% of the stilbene-derived optical brightener leucophor AP, respectively. The efficacy of spray applications of 1 × 1012 OBs/Ha SeMNPV alone, or in mixtures with 0.1% leucophor AP, was tested in a greenhouse planted with sweet pepper. The prevalence of virus infection in larvae collected at intervals post-application and reared on artificial diet in the laboratory was very high (62–97% mortality). Compared to the treatment involving SeMNPV OBs alone, OBs applied in mixtures with leucophor AP resulted in a significant increase in the prevalence of infection in larvae collected at 2 days post-application, but not in insects collected subsequently. In contrast, a chemical insecticide treatment, lufenuron, performed poorly (

Impact of Bt maize pollen (MON810) on lepidopteran larvae living on accompanying weeds

Environmental risks of Bt maize, particularly pollen drift from Bt maize, were assessed for nontarget lepidopteran larvae in maize field margins. In our experimental approach, we carried out 3-year field trials on 6 ha total. Three treatments were used in a randomized block design with eight replications resulting in 24 plots: (i) near-isogenic control variety without insecticide (control), (ii) near-isogenic control variety with chemical insecticide (Baytroid) and (iii) Bt maize expressing the recombinant toxin. We established a weed strip (20 x 1 m) in every plot consisting of a Chenopodium album (goosefoot)/Sinapis alba (mustard) mixture. In these strips we measured diversity and abundance of lepidopteran larvae during maize bloom and pollen shed. C. album hosted five species but all in very low densities; therefore data were not suitable for statistical analysis. S. alba hosted nine species in total. Most abundant were Plutella xylostella and Pieris rapae. For these species no differences were detected between the Bt treatment and the control, but the chemical insecticide treatment reduced larval abundance significantly. Conclusions regarding experimental methodology and results are discussed in regard to environmental risk assessment and monitoring of genetically modified organisms.

Steinernema carpocapsae (Rhabditida: Steinernematidae) as a biological control agent against the fungus Gnat Bradysia agrestis (Diptera: Sciaridae) in propagation houses

A recently introduced fungus gnat, Bradysia agrestis, has caused serious problems in Korean propagation houses where vegetable seedlings are produced for transplant into the fields. Although chemical insecticides are available against this pest, alternate control measures are needed. A Korean isolate of the entomopathogenic nematode, Steinernema carpocapsae Pocheon strain, was tested against this insect in the laboratory and propagation house. In the laboratory, S. carpocapsae affected oviposition, with the untreated females laying an average of 121±25 eggs, whereas the treated females averaged 7±2 eggs. The infectivity of S. carpocapsae to the fungus gnat was affected by the developmental stage and temperature, with highest mortality observed with the third and fourth instars and pupal stage. Nematode mortality in the second instar fungus gnat ranged between 23 and 35%, but showed no significant differences among the temperatures tested. The egg and first instar were not infected by the nematode. In nematode dispersal studies, adult female fungus gnats alone dispersed S. carpocapsae from the nematode-treated area to the control area at a higher rate than male and female gnats or male gnats alone. In the propagation house experiments with watermelon seedlings, no significant difference was observed in fungus gnat larval reduction at S. carpocapsae concentrations of 5, 10, or 20 infective juveniles (IJs)/g of soil at 7, 14, and 21 days after treatment. In comparison with the control, the S. carpocapsae treatments significantly reduced B. agrestis larval numbers. When the watermelon seed was treated with S. carpocapsae at sowing, the larval density of B. agrestis was significantly reduced, that is, the number of B. agrestis larvae ranged from four to eight and from five to eight in the nematode-treated plots compared with 26 and 30 in the control plots on the 17th and 34th day post-treatment, respectively. In the chemical insecticide treatments, diflubenzuron and chlorpyrifos were significantly more effective than S. carpocapsae and diazinon in reducing larval populations of the fungus gnat. Our data show that, although some of the chemical insecticides were more effective than S. carpocapsae Pocheon strain, the nematode was still an effective tool for management of the fungus gnat larvae and in protecting seedlings from damage in propagation houses.

A field trial of the entomogenous fungus Metarhizium anisopliae for control of onion thrips, Thrips tabaci

In Kenya, Thrips tabaci Lind., is an important constraint to onion production. The current strategy to use synthetic pesticides is inadequate and unsustainable. An isolate of Metarhizium anisopliae (Metsch.) Sorok. with high pathogenicity to legume thrips, Megalurothrips sjostedti, and western flower thrips, Frankliniella occidentalis, was tested in field trials as a potential alternative for control of onion thrips. Weekly and bi-weekly applications of the fungus M. anisopliae and bi-weekly spray of the chemical insecticide dimethoate (Rogor ® 50) were compared for 3 seasons. M. anisopliae was applied at the rate of 1×10 11 conidia ha −1 and dimethoate was applied at the recommended rate of 17.5 g a.i. ha −1. In all the trials, thrips density and damage were significantly lower in the fungal and chemical insecticide treatments compared with the untreated control. Onion bulb yield did not differ significantly among the treatments during the first season trial. However, in the second season trial, dimethoate-treated plots provided the greatest bulb yield (17 metric tons ha −1) and in the third season trial, M. anisopliae applied weekly recorded the highest yield (24 metric tons ha −1). With the exception of spiders, densities of nontarget organisms were higher in plots treated with M. anisopliae than in dimethoate-treated plots. The results indicate the potential of using M. anisopliae for the control of T. tabaci while protecting biodiversity in the onion agroecosystem.

Effect of biological and chemical insecticides on Spodoptera species (Lep., Noctuidae) and marketable yields of tomatoes

Various biological and chemical insecticide treatments were evaluated against beet armyworm Spodoptera exigua (Hübner), yellowstriped armyworm Spodoptera ornithogalli (Guenée) and southern armyworm Spodoptera eridania (Cramer) to determine their effects on Spodoptera species, fruit quality and marketable yields of tomatoes Lycopersicon esculentum Mill. Biological insecticides included several Bacillus thuringiensis (Berliner) products including Condor® OF, Dipel® 2X, Javelin® WG, Bactec® III, Biobit® FC, Cutlass® WP and Lepinox® G. Other biological treatments included a baculovirus, SeNPV isolated from S. exigma, and an entomophagous nematode, Steinernema carpocapsae Weiser. Chemical treatments consisted of several insecticides from various classes including a carbamate (methomyl), pyrethroid (fenpropathrin) and an organophosphate (chlorpyrifos). A natural extract from the neem tree azadirachtin and an untreated control were also included in the evaluation studies. Population densities of S. exigua were below the economic threshold level in control plots and there were no significant differences for small, medium and large larvae. Densities of S. ornithogalli and S. eridania larvae exceeded the threshold level and significant treatment differences were observed in their populations. Fruit injuries were significantly higher in nonefficacious treatments that included S. carpocapsae, SeNPVs and untreated controls. Average weight per fruit was not significantly affected by treatment rates of applications, but total marketable yields were significantly higher in efficacious biological, chemical and combination treatments compared with the control.

Early-Season Insect Control in Alfalfa, 1997

Abstract Eleven chemical insecticide treatments were evaluated for efficacy in controlling AW larvae and BAA infesting the first crop of a 3rd-year stand of ‘Cimarron VR’ alfalfa at the Agronomy Research Station, Stillwater, OK. Pretreatment samples indicated a population of 2.2 AW larvae/stem and 19.0 B AA/stem. Insecticides were applied on 11 Mar using flooding nozzles (Spraying System Co., TK SS-5) calibrated to deliver 20 gpa at 24 psi when traveling at 3 mph. Treatments were arranged in a RCB design on plots 5 X 10 m in size, repli-cated 4 times. Sampling was conducted at 2, 6, 13, 20, and 27 DAT by pulling 25 stems/plot and placing them in standard Berlese funnels to extract in-sects for counting. Subsamples of aphids were identified on each date to determine if species other than BAA were present. Dry matter yields were esti-mated for first harvest on 5 May by removing forage from a 1 X 5 m area in each plot using a flail-type harvester. Subsamples were dried for determination of moisture content and yields were calculated on a dry weight/acre basis.

Bacillus thuringiensis Alone and in Mixtures with Chemical Insecticides against Heliothines and Effects on Predator Densities in Cotton

Tests were conducted in a cotton field in 1994 and 1995 to evaluate the efficacy of Bacillus thuringiensis var. kurstaki Berliner alone and in mixtures with thiodicarb and cyhalothrin against heliothines and to evaluate the survival of predators on cotton. The heliothine population treated in both years was almost entirely Helicoverpa zea (Boddie) (>97%). In both years, B. thuringiensis alone failed to reduce larval populations over the control plots (P > 0.05). Larval densities were similarly reduced in thiodicarb and thiodicarb-B. thuringiensis treatments. Treatments that contained cyhalothrin and/or profenofos provided the best control. Bacillus thuringiensis treatment of plots did not have any delayed effects on H. zea such as reductions in developmental rates or delayed mortality beyond 3 days after application. In addition, heliothine egg mortality in the 1994 collection 3 days after application did not differ significantly among treatments. Predator density in the B. thuringiensis alone treatment was similar to the untreated control. All treatments that contained conventional chemical insecticides, including thiodicarb at the ovicidal rate, reduced predator densities to low numbers. These data indicate that B. thuringiensis did not provide control of H. zea in cotton fields and did not improve control of H. zea when used in mixtures with an ovicide or larvacide. Therefore, caution should be urged in recommending B. thuringiensis when the heliothine species composition is skewed toward H. zea. Furthermore, when B. thuringiensis was used in mixtures with chemical insecticides, there was no conservation of arthropod predators relative to use of traditional chemical insecticide treatments.

Production and field evaluation of a Granulosis Virus for control of Sesamia cretica Led. (Lep., Noctuidae) in maize fields in Egypt

AbstractPilot field trials were conducted against Sesamia cretica Led. using a Granulosis Virus recently isolated from the corn borer infesting maize at Kafr El‐Sheikh Governorate. The efficacy of spray application of ScGV was compared with the currently recommended chemical insecticides (Methomyl and Monocrotophos) as two different control strategies against S. cretica larvae on maize. The viral insecticide is a highly purified suspension of granules in water plus 10% molasses as a sticker as well as a feeding stimulant additive. The spray containing 0.1 g of granules/1 (i.e. 1.48 × 1010I.B./ml) was applied twice at the rate of 1.25 and 2.5 1/0.01 feddan (1 feddan = 4200 m2) at 2 week intervals, starting 3 weeks after sowing. For the chemical insecticides, the methomyl was applied at the same time as the ScGV suspension against S. cretica larvae, and the monocrotophos was applice twice, 2 months after sowing, and 2 weeks later, against Ostrinia nubilalis and Chilo agamemnon larvae. All treatments were made using a portable knapsack sprayer. Additional plots were left as control. Results revealed that both tested treatments (microbial and chemical insecticides) noticeably reduced the numbers of S. cretica larvae. Regarding yield, the mean weight of seeds was higher for the plots which were treated with either virus or insecticide than untreated ones. However, the chemical insecticide treatment was more effective than the formulated virus treatment. The corrected yield in ardab (1 ardab = 145 kg)/feddan were 20.11, 16.04 and 12.79, for chemical insecticide, viral insecticide and control treatments, respectively. It is concluded that ScGV seems to be pathogenic to the field population of S. cretica and may be considered a promising biocontrol agent to support the Integrated Pest Management Programme of such an important corn borer.

Early Season Insect Control in Alfalfa, 1996

Abstract Eight chemical insecticide treatments were evaluated for efficacy in controlling AW larvae and aphids infesting the first crop of a fourth year stand of TCI 630’ alfalfa at the Southcentral Research Station, Chickasha, OK. Pretreatment samples indicated a population of 30 larvae/25 stems and 68.7 aphids/stem. Insecticides were applied on 8 Apr using spraying system TK SS-5 flooding nozzles calibrated to deliver 20 gpa at 24 psi when traveling at 3 mph. Treatments were arranged in a RCB design on plots 5 X 10 m in size, replicated 4 times. Sampling was conducted 3, 8, and 13 DAT by pulling samples of 25 stems per plot and placing them in standard Berlese funnels to extract insects for counting. Subsamples of aphids were identified on each date to determine the proportions of species present. Dry matter yields were estimated for 1 st harvest on 16 May by removing forage from 1 X 5 m area in each plot using a flail-type harvester. Subsamples were dried for determination of moisture content and yields were calculated on a dry weight/acre basis.

Control of Insect Pests in The First Alfalfa Crop, 1995

Abstract Seven chemical insecticide treatments were evaluated for control of AW larvae and aphids in the first crop of a second year stand of ‘Cimarron VR’ alfalfa on the Agronomy Experiment Station, Stillwater, OK. Pretreatment samples indicated a population of 3.1 AW larvae and 20.5 aphids per stem. Insecticides were applied on 1 Apr using flooding nozzles (Spraying Systems Co., TK SS-5) calibrated to deliver 20 gpa at 24 psi when traveling 3 mph. A RCB design was used with 5 X 10 m plots replicated 4 times. Sampling was conducted at 3, 6, 13, and 18 DAT by pulling 25 stems per plot and placing them in standard Berlese funnels to extract insects for counting. Subsamples of aphids were identified on each date to determine the proportions of species present. Dry matter yields were estimated from samples of forage taken from a 1 X 5 m area in each plot. Subsamples were dried for determination of moisture content and yields were calculated on a dry weight/acre basis.

Aerial Insecticide Applications for Control of First-Generation European Corn Borer Larvae in South Dakota, 1994

Abstract A corn field near Beresford, SD, was chosen to evaluate aerially-applied chemical and biological insecticide treatments for control of first-generation ECB larvae. Pretreatment counts indicated a light, but uniform infestation of ECB larvae in 42% of plants sampled. Stadial composition consisted of 13, 32, 38, and 17% 1st-, 2nd-, 3rd-, and 4th-instar larvae, respectively. A strip-plot experimental design was used. Each strip contained 4 replicates. Individual treatment plots were 40 m (41 rows) by 122 m. Insecticides were applied on 29 Jun at whorl (ca. 10 d prior to tasseling) stage. All insecticide treatments were applied at 8.0 lb formulated product/acre in 20-m swaths using a Cessna Ag Truck aircraft. A Duke metering system mounted on the aircraft was used for insecticide calibration and application procedures. Approximately 1 month following treatment (28 Jul), 40 plants in each plot were randomly selected, split vertically and examined for cavity (tunnelling) damage. The number and length of cavities were recorded and analyzed using SAS’s General Linear Models (GLM) procedure with means being compared by DMRT.

First Generation European Corn Borer Control Using Insecticide Rescue Treatments, 1994

Abstract A cornfield near Parkston, SD, was chosen to evaluate 35 chemical and biological insecticide treatments for control of first-generation ECB larvae. Preapplication counts indicated a uniform infestation of ECB larvae in 71.0% of plants sampled. Stadial composition consisted of 20, 35, 35, and 10% 1st-, 2nd-, 3rd-, and 4th-instar, respectively. Treatments were applied on 7 Jul at whorl (approximately 1 wk prior to tasseling) stage of physiological development. Three untreated control plots were used to compare 10 granular insecticides and 25 liquids for efficacy in preventing ECB tunnelling. Treatments included multiple rates of some compounds. Insecticides were applied to single row plots (16.4 cm by 30.5 m) in a RCBD with 4 replicates. Granules were directed into corn plant whorls using a pneumatic applicator powered by a 3.5 horsepower engine mounted on a Highboy. Noble metering units attached to a modified chain-driven apparatus regulated the amount of granules released into the pneumatic applicator. Liquid treatments were applied to corn plant whorls using a single-nozzle 3-gal, CO2-propeIled backpack sprayer system. Approximately I month following insecticide applications (12 Aug), 20 corn stalks were randomly chosen from each plot. Each plant was split vertically and examined for tunnelling damage. The number and length of cavities were analyzed using SAS’s General Linear Models procedure with means being compared by DMRT.

Early Season Insect Control in Alfalfa, 1994

Abstract Nine chemical insecticide treatments were evaluated for efficacy in controlling AW larvae and aphids infesting the first crop of a third yr stand of ‘Cimarron’ alfalfa located at the Agronomy Research Station, Stillwater, OK. Pretreatment samples indicated a population of 0.8 AW larvae and 27.5 aphids/stem. Insecticides were applied on 1 Apr using a tractor-mounted boom sprayer equipped with flooding nozzles (Spraying Systems Co., TK SS-5) calibrated to deliver 20 gpa at 24 psi when traveling at 3 mph. Treatments were arranged in a RCB design on plots 5 × 10 m in size, replicated 4 times. Efficacy of treatments was determined for both AW and aphids at 3, 7, 13, and 20 DAT by pulling samples of 25 stems from each plot and placing them in standard Berlese funnels to extract insects for counting. At 18 DAT, an additional sample was collected by clipping 10 stems/plot and rinsing aphids into alcohol for counting. Subsamples of aphids were identified on each date to determine proportions of species present. Dry matter yields were estimated by removing forage from a 1 × 5 m area in each plot using a flail-type harvester. Subsamples were dried for determination of moisture content and yields were calculated on a dry weight/acre basis.

Control of Insect Pests in the First Alfalfa Crop, 1993

Abstract Nine chemical insecticide treatments were evaluated for efficacy in controlling AW larvae and aphids on a second year stand of ‘Cimarron’ alfalfa located at the Agronomy Research Station, Stillwater, OK. Pretreatment samples indicated a population of 3.3 AW larvae/stem, while aphid numbers averaged 45 per 25 stems. Sprays were applied on 9 Apr using a tractormounted boom sprayer equipped with flooding nozzles (Spraying Systems Co., TK SS-5) calibrated to deliver 20 gpa at 24 psi while traveling at 3.0 mph. Plot size was 5 × 8 m, arranged in a randomized complete block design with 4 replications. Efficacy of treatments was determined from samples of 25 stems pulled from each plot at 2, 7, 14, and 21 DAT. Standard Berlese funnels were used to extract AW larvae and aphids from the stem samples for counting. Subsamples of aphids were examined on each date for species determination. Dry matter yield estimates were made by harvesting two 0.5 m quadrates from each plot on 14 May and drying forage before weighing and calculating yield on a per acre basis.

Current Status of Bacillus thuringiensis for Spruce Budworm Control

Research and development over many years have now established that Bacillus thuringiensis Berliner (B.t.) can be a safe and effective biological insecticide for spruce budworm. B.t. must be ingested before it can kill the insect and good results are thus obtained when the B.t. spray is applied at the correct time and covers the foliage so that most larvae consume a lethal dose of B.t. within 1 or 2 days of application. Under these conditions, B.t. treatments can save as much foliage as chemical insecticide treatments. However, the cost of materials and application for a B.t. treatment is higher than for a chemical treatment. In recent years emphasis in B.t. research has thus been to reduce cost by obtaining better distribution of the material on foliage, by reducing the volume of liquid carrier, and by looking for strains and fermentations of B.t. that provide an even more potent product against spruce budworm.

Codling Moth Granulosis Virus: Its Efficiency in the Field in Comparison with Organophosphorus Insecticides123

A granulosis virus for control of Laspeyresia pomonella (L.) was tested during 2 successive years in a commercial apple orchard in comparison with organophosphorus insecticides. The efficiency of the virus was influenced by the soil management used in the orchard. In all but the chemically treated plots, codling moth infestation over green covered soil was significantly lower than over clean cultivated soil. Four virus sprays at a concentration of ca. 1011 capsules/liter gave equal or even better protection against codling moth damage over green cover than the same number of chemical insecticide treatments. Reduction of the population, estimated by sampling diapausing larvae in corrugated paper bands, was much betler by the virus than by the insecticides, reaching 100% in the 2nd year. No virus persisting from the previous season could be found.

Field Effectiveness of the Granulosis Virus of the Green Cloverworm as Compared with Bacillus thuringiensis and Selected Chemical Insecticides on Soybean12

On Aug. 16, 1972, a granulosis virus was field-tested at 1 × 1011 capsules/acre against Plathypena scabra (F.) larval populations in a soybean field near Cambridge, Iowa. Bacillus thuringiensis Berliner and selected chemical insecticides were applied to small plots in a complete randomized-block design for comparison. No significant differences existed between the check and virus-treated plots for the first 4 days after application, whereas all plots treated with chemical insecticides R. thuringiensis were significantly different from the check. Larval numbers in virus-treated plots differed significantly from those of the check, beginning with the 6th day after treatment, with no significant differences between virus, B. thuringiensis , and 5 out of 6 chemical insecticide treatments on that date.