Aerial Insecticide Research Articles

Improved Chemical Control for the Mexican Rice Borer (Lepidoptera: Crambidae) in Sugarcane: Larval Exposure, a Novel Scouting Method, and Efficacy of a Single Aerial Insecticide Application

A three-treatment aerial application insecticide experiment was conducted in five commercial sugarcane, Saccharum spp., fields in south Texas to evaluate the use of pheromone traps for improving chemical control of the Mexican rice borer, Eoreuma loftini (Dyar), in 2009 and 2010. A threshold of 20 moths/trap/wk was used to initiate monitoring for larval infestations. The percentage of stalks with larvae on plant surfaces was directly related to the number of moths trapped. Reductions in borer injury and adult emergence were detected when a threshold of >5% of stalks with larvae present on plant surfaces was used to trigger insecticide applications. Novaluron provided superior control compared with beta-cyfluthrin; novaluron treated plots were associated with a 14% increase in sugar production. A greenhouse experiment investigating establishment and behavior of E. loftini larvae on two phenological stages of stalkborer resistant, HoCP 85-845, and susceptible, HoCP 00-950, sugarcane cultivars determined that more than half of larvae on HoCP 00-950 and > 25% on HoCP 85-845 tunneled inside leaf mid-ribs within 1 d of eclosion, protected therein from biological and chemical control tactics. Exposure time of larvae averaged < 1 wk for all treatments and was shortest on immature HoCP 00-950 and longest on mature HoCP 85-845. This study shows a short window of vulnerability of E. loftini larvae to insecticide applications, and demonstrates the potential utility of pheromone traps for improving insecticide intervention timing such that a single properly timed application may be all that is required.

Field assessment of novaluron for sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), management in Louisiana sugarcane

On-farm field experiments were conducted in 2004 and 2007 to assess the suitability of novaluron, a chitin synthesis inhibitor, for sugarcane borer, Diatraea saccharalis (F.), management in Louisiana sugarcane ( Saccharum spp. hybrids). Aerial insecticide applications reproducing commercial production practices were made when D. saccharalis infestation levels exceeded a recommended action threshold. In addition to decreased D. saccharalis infestations, 6.3 – 14.5-fold reductions in end of season injury, expressed as the percentage of bored sugarcane internodes, were observed in plots treated with novaluron. D. saccharalis control in novaluron plots was equivalent to ( P > 0.05) or better ( P < 0.05) than that achieved with tebufenozide, an ecdysone agonist that has been extensively used for over a decade on sugarcane. With a numerical trend of a 3.1-fold decrease in percent bored internodes, the pyrethroid gamma-cyhalothrin seemed less effective than the biorational insecticides in protecting sugarcane against D. saccharalis. Using continuous pitfall trap sampling, no measurable ( P > 0.05) decreases in predaceous and non-predaceous soil-dwelling non-target arthropods were associated with insecticides. However, numerical trends for decreases in immature crickets associated with novaluron and gamma-cyhalothrin were recorded in 2007. Our data suggest that novaluron will fit well in Louisiana sugarcane integrated pest management.

Impact of Aerial Spraying of Pyrethrin Insecticide on &lt;I&gt;Culex pipiens&lt;/I&gt; and &lt;I&gt;Culex tarsalis&lt;/I&gt; (Diptera: Culicidae) Abundance and West Nile Virus Infection Rates in an Urban/Suburban Area of Sacramento County, California

In response to an epidemic amplification of West Nile virus (family Flaviviridae, genus Flavivirus, WNV), the Sacramento and Yolo Mosquito and Vector Control District (SYMVCD) sprayed ultralow-volume (ULV) formulations of pyrethrin insecticide (Evergreen EC 60-6: 6% pyrethrin insecticide, 60% piperonylbutoxide; MGK, Minneapolis, MN, applied as 0.003 kg/ha [0.0025 lb/acre] ) over 218 km2 in north Sacramento and 243.5 km2 in south Sacramento on three consecutive evenings in August 2005. We evaluated the impact of this intervention in north Sacramento on the abundance and WNV infection rates of Culex pipiens L. and Culex tarsalis Coquillett. Mortality rates of caged Cx. tarsalis sentinels ranged from 0% under dense canopy to 100% in open fields. A comparison of weekly geometric mean mosquito abundance in CO2-baited traps in sprayed and unsprayed areas before and after treatment indicated a 75.0 and 48.7% reduction in the abundance of Cx. pipiens and Cx. tarsalis, respectively. This reduction was statistically significant for Cx. pipiens, the primary vector of WNV, with highest abundance in this urban area, but not for Cx. tarsalis, which is more associated with rural areas. The infection rates of WNV in Cx. pipiens and Cx. tarsalis collected from the spray zone were 8.2 and 4.3 per 1,000 female mosquitoes in the 2 wk before and the 2 wk after applications of insecticide, respectively. In comparison, WNV infection rates in Cx. pipiens and Cx. tarsalis collected at same time interval in the unsprayed zone were 2.0 and 8.7 per 1,000, respectively. Based on the reduction in vector abundance and its effects on number of infective bites received by human population, we concluded that the aerial application ofpyrethrin insecticide reduced the transmission intensity of WNV and decreased the risk of human infection.

Environmental concentrations, fate, and risk assessment of pyrethrins and piperonyl butoxide after aerial ultralow‐volume applications for adult mosquito management

One of the most effective ways of managing adult mosquitoes that vector human and animals diseases is the use of ultralow-volume insecticides. Because of concerns about the safety of the insecticides used for the management of adult mosquitoes, we conducted an environmental fate and efficacy study in Princeton and Colusa (both CA, USA) after aerial applications of pyrethrins and piperonyl butoxide (PBO). One hour before application, PBO concentrations in water were 0.008 and 0.2175 microg/L for Princeton and Colusa, respectively. One hour after the spray event in Princeton, the average PBO concentrations were 0.0125 microg/cm2 on ground-deposition pads and 0.1723 microg/L in water samples, with concentrations decreasing significantly over time. One hour after the spray event in Colusa, the average PBO concentrations were 0.0199 microg/cm2 on deposition pads and 1.274 microg/L in water samples, with concentrations decreasing significantly over time. A significant time and location effect for both deposition pads and water samples in Princeton and Colusa was observed (p<0.001 and p=0.014, respectively). Pyrethrins were not detected in nearly all ground and water samples. One hour after application, mortality of Culex tarsalis and Culex pipiens in sentinel cages was significantly higher than at the control site for both locations (p<0.001). Risk quotients for aquatic surrogate species in Princeton and Colusa were 0.002 or less at 1 h after application, which did not exceed the U.S. Environmental Protection Agency risk quotient level of concern for endangered aquatic organisms of 0.05. Our results suggest that the amounts of pyrethrins and PBO deposited on the ground and in water after aerial ULV insecticide applications are lower than those estimated by previous exposure and risk assessments.

Effect of aerial insecticide spraying on pine wilt disease in central Japan

SummaryTo clarify the effect of aerial insecticide spraying on pine wilt disease, pine wilt disease impacts was surveyed in pine stands and the damage evaluated using a logistic model. Eleven quadrats were established randomly in stands with or without aerial spraying. Aerial spraying alone did not entirely prevent the disease. Average annual mortality was lower in stands with aerial spraying than in stands without aerial spraying. Aerial spraying slowed the progress of pine wilt disease, as measured by the disease progress index. The biomass of live pine trees decreased with increased damage in stands without aerial spraying, whereas biomass was maintained in stands with aerial spraying. However, the relative basal area showed that succession of pine forests to forests dominated by other species was accelerated even in stands with aerial insecticide spraying.

Change of Abundance of Arthropods in Pine Forests Caused by Aerial Insecticide Spray

As pine wilt disease (PWD) spread rapidly throughout the Republic of Korea, pine stands were subjected to insecticide spraying that was gradually increased, which raised concerns regarding the negative impact of insecticides sprayed on nontarget organisms of pine forests. This study aims to estimate the changes in the abundance of arthropods caused by long-term insecticide spraying common in PWD-infected forests. Four pine stands were selected as sprayed and unsprayed sites in two locations in the southern regions of Busan and Gyongnam-do, showing the peaks of PWD epidemics. Beatings, sweepings, and pitfall trappings were used for collecting arthropods at the crown, undergrowth, and ground for 4 years, starting in May 2001. Long-term effects caused by yearly repeated insecticide treatments were not found to be related to changes in the abundance of arthropods, but short-term impacts within a year showed different influences according to habitats and functional groups.

Dead wood dynamics in declining balsam fir and spruce stands in New Brunswick, Canada

Forest management prescriptions increasingly incorporate snag and downed dead wood (DDW) guidelines. This study utilizes permanent inventory plots to determine dead wood dynamics in 33 balsam fir ( Abies balsamea (L.) Mill.) – spruce ( Picea spp.) (BFSP) and 17 spruce – balsam fir (SPBF) stands in New Brunswick, Canada. Stands were declining, unmanaged, and had a history of recurrent spruce budworm ( Choristoneura fumiferana (Clem.)) outbreaks and aerial insecticide spraying. Fixed-area sampling matched remnants of 1165 dead trees and 864 corresponding pieces of DDW to plot trees that died over the last 15–18 years with known year and cause of death. Declining BFSP stands had the highest accumulation of dead wood (196 m3/ha) compared with SPBF and nondeclining BFSP (122 m3/ha and 77 m3/ha, respectively). Dead wood dynamics were influenced by cause of death, as a function of differences in tree height at death affecting snag decay, fragmentation, and fall. One-half of all dead trees never made a significant contribution to the snag population (25% uprooted and 25% stem breakage), and attrition resulted in only 50% of snags standing with a mean height of 6 m 15–20 years after death. This study will be of direct value to those managing or modeling dead wood dynamics in similar forests.

Effects of Gypsy Moth Defoliation on Softwood and Hardwood Growth and Mortality in New Brunswick, Canada

Abstract The first major European gypsy moth (Lymantria dispar L.) outbreak occurred in central New Brunswick, Canada, on over 3,000 ha of forestland, from 2001ߝ2003. The outbreak was severe enough to result in considerable landowner concern and a privately funded aerial insecticide spray program to protect trees. Defoliation was unexpectedly severe on several tree species thought to be resistant or immune, as indicated from studies in the northeastern United States. Fifty plots (564 trees) were established and measured for standard mensurational characteristics, defoliation, and annual tree mortality, and after the cessation of defoliation, 44 trees were destructively stem analyzed to determine growth patterns. Balsam fir (Abies balsamea [L.] Mill.) with defoliation of more than 75% sustained specific volume increment reduction averaging 55% and 25% mortality after 2 years of severe defoliation. Red oak (Quercus rubra L.) sustained about 40% growth reduction, similar to results of previous studies. However, white birch (Betula papyrifera Marsh.) and trembling aspen (Populus tremuloides Michx.), with more than 75% defoliation for 2 years, sustained 43ߝ48% growth reduction, higher than in previous studies, and 4ߝ12% mortality. The gypsy moth range in Canada appears to be gradually expanding beyond previous climatic (cold winter temperature) limitations, and these results will help to predict future impacts.

Managing cabbage seedpod weevil in canola using a trap crop—A commercial field scale study in western Canada

Cabbage seedpod weevil is a relatively new pest of canola (oilseed rape) in the Prairie Ecozone of western Canada. In some years, in southern Alberta, farmers have had to resort to costly aerial insecticide applications to protect their canola crops. In this study, we evaluated perimeter trap cropping as a strategy to manage weevils in large commercial fields of canola. A total of 11 experimental fields (with perimeter trap crops) and nine conventional fields without trap crops were studied from 2000 to 2003. Field perimeters of Brassica rapa planted at the same time as the main crop of B. napus flowered ∼1 week earlier and effectively concentrated weevil populations that were sprayed with insecticide. The perimeter trap crop kept weevil populations below threshold levels in the main crops when fields were large and square (1600m×1600m). However, further research is required to develop management tools that augment the efficacy of trap crops in situations where fields are small or narrow (<400m wide), especially when populations are several times the economic threshold. Pod damage was less than 12% in the main crops of experimental fields where only the trap crops were sprayed which was comparable to that of conventionally managed fields. The savings in chemical insecticides, labor and time, as well as possible integration with other IPM strategies such as biocontrol, make perimeter trap cropping an important tool for cabbage seedpod weevil management.

A simple empirical model to predict forest insecticide ground-level deposition from a compendium of field data

Deposit data from 205 aerial forest insecticide applications conducted in field trials by the Canadian Forest Service, Great Lakes Forestry Centre over a 15-year period are summarized. Deposit measurements were taken under “worst case” scenarios in the sense that direct applications were made over water bodies, and ground samplers were intentionally placed in open or cleared areas of forest. The median % deposit on shoreline collectors (32 separate applications) was 5.7%, on mid-stream collectors (44 separate applications) was 6.2%, and on forest floor collectors (129 separate applications) was 4.9%. Forest floor deposit was most closely associated with application rate and droplet size (r = 0.624, p < 0.001 and r = 0.662, p = 0.011, respectively) but these variables combined only explained 44% of the variation in deposit. Data from all three collector types were grouped by 10% deposit increments and combined to provide a data set from all deposition scenarios. A negative exponential model was fitted to the proportion of these combined sites regressed on % deposit in 10% increments and plotted as a deposit probability distribution curve (p < 0.001, r2 = 0.992). The probability distribution curve indicated that 5–10% deposit would be expected about 57–91% of the time, whereas 50% deposit or greater would be expected about 2% of the time or less. In a probabilistic risk assessment for aerially applied insecticides in a conifer-dominated forest environment, the probability distribution curve based on empirical data presented here can be used to refine the characterization of exposure scenarios from which effects estimates can be derived.

Effects of aerial insecticide sprays on ant communities to control pine wilt disease in Korean pine forests

Pine wilt disease is one of the most serious diseases in the pine forests of Korea. Since the first report of the disease in Busan, Korea, in 1988, the disease has been gradually spreading into neighboring regions and now occurs in many regions of the southern part of the Korean Peninsula. The control of the disease is focused on the killing of the sawyer, Monochamus alternatus, an insect vector, by aerial insecticide spraying for adult control and by fumigation or burning infected trees for larval control. This study was conducted to evaluate the effects of aerial insecticide application on pine forest fauna by comparing ant communities in insecticide-sprayed and unsprayed areas. Samples were collected from five regions using three different sampling methods (pitfall trap, sweeping net, and shaking net). The results showed that community indices such as abundance, species richness and species diversity were not significantly different between insecticide-sprayed sites and unsprayed sites. According to a cluster analysis and a correspondence analysis, ant communities were generally grouped based on the location of the sampling sites with a slight variation of insecticide application, but not grouped by insecticide application, showing that ant community structures were not significantly different between the insecticide-sprayed sites and the unsprayed sites. Our results, overall, support the theory that the impact of the aerial insecticide application on pine forest fauna may be less severe than expected.

Guillain-Barre Syndrome in a Rural Farming District in South Africa: A Possible Relationship to Environmental Organophosphate Exposure

Although organophosphate (OP) insecticides have been recognized as having neuropathic potential, a relationship with Guillain-Barre syndrome (GBS) has not been previously confirmed. A cluster of 7 cases of GBS was noted over an 11-yr period in an isolated farming region in the Northern Cape Province of South Africa, an area subject to intensive aerial application of OP insecticides. Observed cases were more than 4 times higher than expected based on a Poisson probability distribution. Four cases were clustered in an area where the topography showed a marked hollow, and where spray drift of aerial OP insecticides was anticipated. The rate of GBS in this subcluster was more than 14 times higher than expected. The authors explored the hypothesis that aerial OP insecticide application was related to the raised incidence of GBS in this area and made suggestions for future research.

Factors Influencing Aerial Insecticide Application to Forests

A successful aerial insecticide application is one that provides the desired degree of pest control at an economic cost, with little environmental impact. This paper discusses a broad range of factors that affect treatment efficacy and environmental impact from aerial insecticide application to forests. Efficacy is affected by parameters such as the choice of active ingredient and its application rate, the volume application rate, tank mix characteristics, the spray droplet size spectrum, and the timing of, and meteorological conditions during an application. Environmental impact is influenced by aspects such as active ingredient specificity, meteorological conditions during the application, avionics use and buffer zone width. Key differences between insecticide applications in forestry and agriculture are pointed out.

Impact of Spray Volume and Wetting Agent on Efficacy of Aerial Insecticide Applications to Man-Age First-Generation European Corn Borer Larvae in South Dakota, 1997

Abstract Field plots were established in central South Dakota near Letcher to evaluate aerially applied insecticide treatments for control of first-generation ECB larvae. The field was planted on 11 May at a rate of 20,400 kernels per acre. The study was carried out to determine the impact of Silwet™ wetting agent and spray volume on the effectiveness of Warrior 1 EC insecticide. Pre-treatment counts revealed an average of 2 ECB larvae (ca. 50% each of 2nd- and 3rd-instars) existed per plant. A strip-plot ex-perimental design was used, and each strip contained 4 replicates. Sampling was conducted within a 32-row subplot (30.5 m by 100 m) for each treatment area. Insecticides were applied on 13 Jul at whorl (ca. 2 d before tasseling) stage in 15.2-m swaths at a speed of 110 mph using a Piper Brave aircraft. A Crop Hawk system was mounted on the aircraft to monitor and regulate spray flow through CP™ nozzles at 25 psi. Treatments consisted of Warrior 1 EC at 0.025 lb (AI)/acre in a spray volume of 2 or 5 gpa. Additionally, each of these spray volumes was evaluated with or without Silwet™ (wetting agent), and all were compared with an untreated control. Approximately one month after insecticide applications (8 Aug), 40 plants in each plot were randomly selected, split vertically and examined for ECB cavity (tunneling) damage. The number and length of ECB cavities were recorded and analyzed using the ANOVA procedure and means were compared by LSD.

Correlation between Overall Pesticide Effects Monitored by Shrimp Mortality Test and Change in Macrobenthic Fauna in a River

The relationship between change in benthic fauna in the Suna River and shrimp mortality in the river water samples (test was conducted two times per week from May to September) was investigated to assess the insecticide impact on the benthic community. The river was selected because pesticide application had been restricted for a long time in the upper reaches, while aerial insecticide spraying had been done four times on paddy fields in the lower reaches in summer. Species richness and density of benthos were high at the stations in the upper reaches. High shrimp mortality was measured in the water samples collected from a downstream station during the pesticide spraying period, from late July to late August. Species richness and density of benthos markedly decreased at the stations in the lower reaches in that period. However, several species of chironomids,Cheumatopsyche(Trichoptera), which demonstrated tremendous insecticide resistance, andBaetis sahoensis(Ephemeroptera), which has a high recovery potential, were not affected, even in the insecticide spraying period. The benthic fauna in the lower reaches tended to recover from autumn to spring, although not sufficiently. It is considered that the temporal recovery of the benthic community was brought about through recruitment from the benthic community in the 5-km upper reaches. A close correlation was found between the high mortality of shrimp in the water samples and the deterioration in the benthic fauna in this river which was contaminated with insecticides during the summer.

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.

Spray deposits from aerial insecticide spray simulant applications to a coniferous plantation in low and high wind speeds

Aerial insecticide applications were made on a jack pine plantation in low and high wind speeds, using a fixed-wing aircraft equipped with rotary atomizers. A 16 ha area with an average canopy height of 6.5 m was sprayed with a suspension of fluorescent particles in tripropylene glycol monomethyl ether at 0.42 l ha −1, using a 65 m swath width. The spray was released from 18 m above ground and had a volume median diameter of 41 μm. Wind speeds at release height were 1.2 and 4.5 m s −1 in trials 1 and 2, and the air layers between canopy top and spray release height were stable and unstable respectively. Average drop counts per conifer needle from trials 1 and 2 were significantly different at 0.91 and 1.92, and foliar deposits at 4 and 6 m were significantly greater in the high wind trial. Drop counts per needle increased with height and the count ratios at 2, 4, and 6 m were 1:2:4 and 1:3:10 in trials 1 and 2. Drop count distributions on needles from different heights showed significant differences and a larger proportion of needles received drops in the high wind trial, implying the potential for improved insecticide efficacy. Drop densities (cm −2) on Kromekote ground cards from trials 1 and 2 were significantly different at 3.26 and 1.85, implying substantially reduced contamination of the understorey in high winds. Drop sizes were similar, with average volume and number median diameters of 71 and 45 μm. Drop sizes on Kromekote combs placed in the canopy were also similar in both trials, with average volume and number median diameters of 49 and 21 μm. The results indicate an excellent opportunity for improving on-target spray deposits and efficacy while reducing understorey contamination from silvicultural insecticide applications, as well as their cost and temporal constraints.

Compatibility of Imidacloprid with Fungicides as a Seed-Treatment Control of Russian Wheat Aphid (Homoptera: Aphididae) and Effect on Germination, Growth, and Yield of Wheat and Barley

Imidacloprid insecticide, applied as a seed treatment, singly or in combination with fungicides (carboxin-thiram, triadimenol-captan, and tebuconazole-thiram), protected growing plants of wheat and barley from developing infestations of Russian wheat aphid, Diuraphis noxia (Mordvilko) for 27-85 d after planting based on four greenhouse and four field trials. There were no compatibility problems in insecticide performance by combining imidacloprid with fungicides on the seed. Imidacloprid significantly reduced plant damage by D. noxia in all trials and increased yields in three of three field trials where plots were entirely infested. As a seed treatment, imidacloprid offers an environmentally safer approach to the control of D. noxia than is possible with wide-spectrum aerial or in-furrow granular insecticide treatments.

Life History of Oracella acuta (Homoptera: Pseudococcidae) in Loblolly Pine Seed Orchards in Georgia

A loblolly pine mealybug, Oracella acuta (Lobdell), had four to five generations per year in loblolly pine ( Pinus taeda L.) seed orchards in southern Georgia. Crawlers overwintered between the needles in the fascicles or under old resin cells made by females of previous generations. Males of the overwintering generation were usually apterous, whereas males of subsequent generations were alate. Population densities did not usually differ significantly between crown levels. Populations in orchards fluctuated; these cycles were apparently caused in part by the adverse effects of aerial insecticide applications on natural enemies, a major factor in mealybug population declines. The two most abundant parasitoids were an encyrtid, Acerophagus coccois E. Smith, and a platygastrid, Allotropa sp.

Aerial Insecticide Control Against Mexican Rice Borer on Sugarcane, 1989

Abstract Foliar spray concentrates were applied aerially to a field of sugarcane in Hidalgo Co., near Monto Alto, TX. The field was divided into plots consisting of 34 rows (60-inch centers) × 1027 ft, with the center 26 rows treated. Insecticide treatments were randomly assigned to plots in a complete block design with 4 replications. Each spray was applied to the crop canopy with two 55-ft swath widths at a rate of 5-gal finished formulation (material + water)/acre. All treatments included Val Buff (1 qt/100 gal) and Triton CS-7 (1 pt/100 gal). Treatments were applied during evening (6:00-7:45 pm CDT) on 27 May, 28 Jun, 16 Jul, and during morning (6:45-7:30 am CDT) 11 Aug, after leaf sheath infestations exceeded 10% (action threshold). Postspray counts of bored internodes (30 stalks/plot) were taken on 22 Sep to evaluate injury levels.