Fipronil Treatment Research Articles

Soil efficacy of fipronil to early stage pests of sugarcane, and its effect on development on Chilo infuscatellus Snellen (Crambidae: Lepidoptera)

Fipronil soil applications of 75 and 90 g a.i./ha at pre- and post-germination stages of sugarcane improved plant germination and cane yield without affecting juice quality. Fipronil was highly toxic against the stem boring moth C. infuscatellus, and termites (Odontotermes spp.). Pre- and post-germination application of fipronil 75 days after planting (DAP), resulted in 65 and 31% reductions in dead-hearts and termite incidence, respectively. Fipronil-treated cane shoots fed to C. infuscatellus larvae resulted in 64.6–73.6% and 39–54.1% mortality at 15 and 30 days post-insecticide treatment, respectively. Fipronil treatment resulted in reduced larval and pupal weight, as well as an increase in pupal duration time. Fipronil at 90 g a.i./ha applied at 0 or 45 DAP did not reduce C. infuscatellus between-season population carry-over in stubbles.

Effect of fipronil on the reproduction, feeding, and relative fitness of brown planthopper, Nilaparvata lugens

Applications of fipronil (1.25×10−2 μg) and fipronil (7.50×10−3 μg) significantly stimulated the fecundity of Nilaparvata lugens compared with the control. The stimulating effect of fipronil on fecundity was dose-dependent. Fifteen and 30 days after treatment, the quantity of honeydew significantly increased in 1.25×10−2 μg fipronil treatment. Fifteen days after treatment, the effect of fipronil on the quantity of honeydew was dose-dependent. The results revealed that the fipronil treatment group had developmental advantages. Selection with 25 mg/l fipronil led to a continuous increase in the resistance ratio (from 1.0 to 30.05) in eight generations. The life table indicated that the resistant strain had obvious disadvantages, including decreasing the survival rate from 3rd to 5th instar in G8 generation and decreasing fecundity in G5 generation. Compared with the susceptible strain, resistant insects had a relative fitness of only 0.577 and 0.750. The lower fitness includes a lower larval survival rate from 3rd to 5th instar (in G8 generation), lower adult emergence rate (in G8 generation), lower copulation rate (in G8 generation), lower fecundity (in G5 generation) and fewer offspring. It was concluded that the brown planthopper had the potential to develop high resistance to fipronil but that the lower fitness of resistant hoppers could result in quick recovery of sensitivity when the population did not come into contact with fipronil. This means that a reasonable resistance management program with less fipronil use may efficiently delay or even stop resistance development.

Fipronil-induced disruption of thyroid function in rats is mediated by increased total and free thyroxine clearances concomitantly to increased activity of hepatic enzymes

Fipronil is a widely used phytosanitary product and insecticide for pets. In the rat, fipronil can disrupt thyroid function by decreasing plasma concentrations of total thyroxine (T4) likely through increased T4 clearance. However, the mechanism of fipronil action on thyroid function remains unclear. The goals of the present study were to evaluate the effects of fipronil on thyroid hormone (TH) concentrations and elimination in the rat under well characterized plasma exposure to fipronil and its main metabolite fipronil sulfone. In thyroid-intact female rats, fipronil treatment (3 mg/(kg day) per os for 14 days) decreased both total and free TH plasma concentrations concomitantly to increased thyroid stimulating hormone plasma concentrations. A T4-free euthyroid-like model consisting of thyroidectomized rats treated with tri-iodothyronine (12 μg/(kg day), sc) was developed to evaluate both total and free T4 clearances. In this model, fipronil treatment induced a twofold increase in total and free T4 clearances. The same fipronil treatment increased antipyrine clearance in thyroid-intact rats suggesting an increase in the activity of cytochrome P450 enzymes. Finally, this treatment was also associated with an increase in hepatic microsomal 4-nitrophenol UDP-glucuronosyltransferase activity involved in T4 glucuronidation. Thus, fipronil-induced thyroid disruption results from an increased rate of T4 elimination likely mediated by increased hepatic enzyme activity. Plasma concentrations of fipronil sulfone were at least 20-fold higher than those of fipronil. This highlights the need to further investigate the contribution of fipronil sulfone to the fipronil-induced thyroid disruption.

Field Evaluation of Potential Control Strategies Against the Invasive Eastern Subterranean Termite (Isoptera: Rhinotermitidae) in Chile

Four different termite control strategies consisting of two soil treatments with cypermethrin and fipronil and two bait treatments with hexaflumuron and sulfluramid were evaluated for their efficacy and potential for controlling the invasive eastern subterranean termite, Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), in Quillota and Valparaíso, Chile. Monitoring stations were installed at all sites to measure the overall termite activity next to and at distances up to 30 m away from infested structures, most being 3–5 m. Foraging activity was extremely seasonal with the maximum consumption rates occurring from January to April. Termite foraging activity was low from July to September. After treatments in January 2003, there was a significant decrease in wood consumption, percentage of active stations, and numbers of termites in traps for the first 6 mo with hexaflumuron baits. No significant change in R. flavipes foraging activity was observed on wood consumption and percentage of active stations for sulfluramid bait or cypermethrin and fipronil soils treatments. The seasonal pattern of foraging activity remained unchanged for all treatments in 2004 and 2005, except structures baited with hexaflumuron. Feeding activity at the monitors in the area surrounding the hexaflumuron baits declined to 0 after January 2004. Alate flights occurred in ≈38% of the structures treated with cypermethrin and sulfluramid bait in 2003 and in ≈40% of the structures treated with cypermethrin, fipronil, and sulfluramid bait in 2004. Sulfluramid baits and cypermethrin soil treatments did not have any impact within a 15-m radius of the structures. Soils treatments of fipronil and cypermethrin prevented termites access in 75% of the homes. The number of active monitoring stations only declined within 2 m of the fipronil-treated zone. Hexaflumuron exhibited a reduction in activity for at least a 15-m radius.

Influence of Portland cement amendment on soil pH and residual soil termiticide performance

Soil adjacent to new brick veneer work is likely to have a higher pH owing to the mixture of cement with the soil. In the Gainesville, FL, area, soil samples taken from such locations had a range of pH values from 9.0 to 10.1; similar soils used in bioassays had a pH of 5.6 before the addition of cement. Addition of 15 mg of Portland cement to 33 g of soil increased the pH to 6, and addition of 291 mg of Portland cement increased the pH to 9. The pH of soil amended with cement was stable for the first 5 months. After 10 months, soil pH values decreased from alkaline to near neutral in all cases. Eastern subterranean termite workers, Reticulitermes flavipes (Kollar), were exposed to the treated soil at pH 6-9 for 24 h, and percentage mortality was recorded at 5 days, 5 months and 10 months. Termite mortality significantly decreased at higher soil pHs for bifenthrin, chlorpyrifos, fipronil and imidacloprid treatments at 5 months and similarly for bifenthrin, permethrin, chlorpyrifos, fipronil and imidacloprid treatments at 10 months. There was an inverse linear relationship between soil pH and mortality. Increased soil pH diminished residual activity of termiticide in the following order: imidacloprid > fipronil > chlorpyrifos = bifenthrin > permethrin > cypermethrin.

P.1.c.020 Regulation of cytochrome P-450 activity by the brain dopaminergic system

The goal of the present study was to evaluate fipronil effects on the activities of drug metabolizing enzymes in rat liver microsomes. Rats were orally treated with fipronil at doses of 1, 5, 10 and 15 mg/kg bw/day for 6 days. Determinations of cytochrome P450 (CYP) enzyme activities were carried out in hepatic microsomes isolated from treated rats. The activities of some members of CYP2E, CYP1A, CYP2A, CYP2B and CYP3A subfamilies significantly increased after fipronil treatment in a dose-dependent manner as compared to control. The major effects were observed in the O-deethylation of ethoxyresorufin and O-demethylation of methoxyresorufin (reflecting CYP1A1/2 activities), in the O-depenthylation of pentoxyresorufin and 16β-hydroxylation of testosterone (reflecting CYP2B1/2 activities), and in the N-demethylation of erythromycin and 6β-hydroxylation of testosterone (reflecting CYP3A1/2 activities). Immunoblot studies revealed that fipronil increased the apoprotein levels of CYP1A1. Our results suggest that fipronil is an inducer of hepatic phase I CYP enzymes, causing an increased potential to interact with a wide range of xenobiotics or endogenous chemicals that are substrates of the CYP1A, CYP2B and CYP3A subfamilies. Further investigations are required to in vivo evaluate the potential of the metabolite fipronil sulfone as an inducer of phase I CYP enzymes.

Transient alterations in neuronal and behavioral activity following bensultap and fipronil treatment in rats

In the present multilevel study, neuromodulatory effect of two insecticides, bensultap and fipronil were investigated in rats. Although the new generation of insecticides shows greater affinity to invertebrate as compared to mammalian receptors, toxic effect of these compounds in vertebrates cannot be excluded. The aim of the study was to follow the course of neuronal changes in rats for 1 week after a high-dose insecticide exposure. Alterations in synaptic excitability, in sleep–wake pattern and in behavior were analyzed using conventional in vitro brain slice method, long-lasting EEG recordings, and open-field tests. The two chemicals examined in this study induced only weak and transient effects. Bensultap, acting on nicotinic acetylcholine receptors, caused a transient decrease in neuronal excitability. Sleep and behavioral changes demonstrated a similar time course. Fipronil, on the other hand, increased excitability and its effect lasted slightly longer. All effects were greatest on the first day following ‘poisoning’, and measured variables usually returned to normal within a week. These results suggest that the studied compounds do have some effects on the mammalian nervous system, but this effect is usually mild and temporary.

Efficacy of fipronil/( S)-methoprene combination spot-on for dogs against shed eggs, emerging and existing adult cat fleas ( Ctenocephalides felis, Bouché)

The inhibitory activities of fipronil (10% (w/v) solution), ( S)-methoprene (9% (w/v) solution), and fipronil/( S)-methoprene (10 and 9% (w/v) solution, respectively) combination against eggs and emerging adult cat fleas ( Ctenocephalides felis) and adulticidal activity were tested on experimentally infested dogs. Thirty-two Beagle dogs were selected for this study and eight replicates of four animals were formed based on body weight within sex. One dog in each replicate was randomly allocated to treatment with: (1) untreated control; (2) fipronil 10% (w/v) solution, (3) ( S)-methoprene 9% (w/v) solution, and (4) fipronil 10% (w/v) and ( S)-methoprene 9% (w/v) combination solution. Treatments were applied once topically on Day 0 at the rate of 0.067 ml/kg. On Days −12, −1, 21, and weekly to Day 84 each dog was infested with ∼200 fleas and comb counted ∼24 h later, or 2 days (our 48 h) after in the case of Day −1 infestation. On Days −11, 1, 22, and weekly to Day 85 each dog was again infested with ∼200 fleas. Flea eggs were collected over ∼24 h beginning 3 days after infestation. Fleas were combed off of the dogs and counted at the end of the egg collection period (∼96 h count). One aliquot of up to about 100 eggs, if available, from each animal at each infestation time was incubated for ∼72 h to determine larval hatch and the other for 35 days to determine the number of adults that developed. The 10% (w/v) fipronil spot-on provided excellent control (>95%) of adult fleas on dogs for 5 weeks. Similarly, the combination spot-on of 10% (w/v) fipronil and 9% (w/v) ( S)-methoprene provided excellent control of adult fleas, i.e., >95% for 5 weeks. From week 6 post-treatment onward, the relatively low inhibition of adult flea emergence substantiated the lack of significant ovicidal/larvicidal activity in the fipronil (10%, w/v) treatment group. However, the combination product provided excellent (>90%) ovicidal activity for 8 weeks and high (91.4%) inhibition of adult flea emergence for 12 weeks. In addition, a synergistic effect of the two compounds in combination was demonstrated with fipronil enhancing the ovicidal and inhibition of adult flea emergence activity of ( S)-methoprene against cat flea eggs. When all stages of the life cycle of the cat flea are considered, the combination spot-on product provided a high level of total flea control yielding a curative effect against adult fleas and inhibition of flea development stages with little to no potential reinfestation pressure on the animal or in the environment for 12 weeks.

The effects of the contemporary-use insecticide (fipronil) in an estuarine mesocosm

To examine the effects of environmentally realistic fipronil concentrations on estuarine ecosystems, replicated mesocosms containing intact marsh plots and seawater were exposed to three treatments of fipronil (150, 355, and 5000 ng/L) and a Control. Juvenile fish ( Cyprinidon variegatus), juvenile clams ( Mercenaria mercenaria), oysters ( Crassostrea virginica), and grass shrimp ( Palaemonetes pugio) were added prior to fipronil in an effort to quantify survival, growth, and the persistence of toxicity during the planned 28-day exposure. Results indicated that there were no fipronil-associated effects on the clams, oysters, or fish. Shrimp were sensitive to the highest two concentrations (40% survival at 355 ng/L and 0% survival at 5000 ng/L). Additionally, the highest fipronil treatment (5000 ng/L) was toxic to shrimp for 6 weeks post dose. These results suggest that fipronil may impact shrimp populations at low concentrations and further use in coastal areas should be carefully assessed.

Fipronil effects on estuarine copepod (Amphiascus tenuiremis) development, fertility, and reproduction: a rapid life-cycle assay in 96-well microplate format.

Fipronil is a novel gamma-aminobutyric acid receptor-specific phenylpyrazole insecticide commonly used near estuarine environments for rice production, turf-grass management, and residential insect control. In this study, we evaluated the acute, developmental, and reproductive toxicity of fipronil to the estuarine harpacticoid copepod Amphiascus tenuiremis. Fipronil was highly toxic to A. tenuiremis (adult 96-h median lethal concentration [LC50] = 6.8 microg/L) and was more toxic to male copepods (96-h LC50 = 3.5 microg/L) than to nongravid female copepods (96-h LC50 = 13.0 microg/L). By using a newly developed 96-well microplate-based life-cycle toxicity test, we successfully reared single individuals of A. tenuiremis to adulthood in 200-microl microwells and concurrently assessed developmental and reproductive effects (after paired virginal matings) of environmentally relevant aqueous fipronil concentrations (0.16, 0.22, and 0.42 microg/L measured). Throughout the entire life cycle, copepod survival in all treatments was >90%. However, fipronil at 0.22 microg/L and higher significantly delayed male and female development from stage 1 copepodite to adult by approximately 2 d. More importantly, fipronil significantly halted female egg extrusion by 71% in the 0.22-microg/L fipronil treatment, and nearly eliminated reproduction (94% failure) in the 0.42-microg/L fipronil treatment. A three-generation Leslie matrix-based population growth model of fipronil reproductive and life-cycle impacts predicted a 62% decline in population size of A. tenuiremis relative to controls at only 0.16 microg/L.

Lethal and sublethal effects of insecticide residues on Orius insidiosus (Hemiptera: Anthocoridae) and Geocoris punctipes (Hemiptera: Lygaeidae).

Laboratory-reared predators, the insidious flower bug, Orius insidiosus (Say), and big-eyed bug Geocoris punctipes (Say), were exposed to 10 insecticides, including three newer insecticides with novel modes of action, using a residual insecticide bioassay. These species are important predators of several economic pests of cotton. Insecticides tested were: azinphos-methyl, imidacloprid, spinosad, tebufenozide, fipronil, endosulfan, chlorfenapyr, cyfluthrin, profenofos, and malathion. There was considerable variation in response between both species tested to the insecticides. Tebufenozide and cyfluthrin were significantly less toxic to male O. insidiosus than malathion. Tebufenozide was also significantly less toxic to female O. insidiosus than malathion. Imidacloprid, tebufenozide, and spinosad were significantly less toxic to male G. punctipes than chlorfenapyr, endosulfan, and fipronil. Spinosad, tebufenozide, and azinphos-methyl were significantly less toxic to female G. punctipes than fipronil and endosulfan. Fecundity of O. insidiosus was significantly greater in the spinosad treatment compared with other treatments including the control. Consumption of bollworm, Helicoverpa zea (Boddie), eggs by O. insidiosus was significantly lower in the fipronil, profenofos, and cyfluthrin treatments compared with other treatments including the control. Consumption of H. zea eggs by G. punctipes was significantly lower in the malathion, profenofos, endosulfan, fipronil, azinphos-methyl, and imidacloprid treatments compared with the control. Egg consumption by G. punctipes was not significantly different in the tebufenozide treatment compared with the control. The lower toxicity of spinosad to G. punctipes is consistent with other reports. Based on these results, the following insecticides are not compatible with integrated pest management of cotton pests: malathion, endosulfan, profenofos, fipronil, and cyfluthrin; while imidacloprid, tebufenozide, azinphos-methyl, and spinosad should provide pest control while sparing beneficial species.

Resistance to dieldrin + fipronil assorts with chromosome inversion 2La in the malaria vector Anopheles gambiae.

Cyclodiene insecticide resistance in malaria vector mosquitoes of the Anopheles gambiae species complex (Diptera: Culicidae) has been reported previously from several parts of Africa. We report resistance to dieldrin, a cyclodiene, in two laboratory strains of An. gambiae Giles sensu stricto code-named Ian P20 from Nigeria (1979) and CIG from Cote d'Ivoire (1997). Dieldrin resistance levels were high in adult female mosquitoes (40-75% survived exposure to 4% dieldrin for 1 h) and was closely linked with chromosomal paracentric inversion 2La. This inversion did not occur in Hardy-Weinberg proportions, but showed an excess of heterozygotes in both strains, which may account for the high levels of resistance. This linkage also suggests that dieldrin resistance in Ian P20 is dominant. After subsamples of strain Ian P20 were exposed for 1 h to dieldrin 4% or fipronil 2% (discriminating concentrations), the resultant mortality-rates (61% and 65%) were not significantly different. Most survivors after fipronil treatment also survived subsequent exposure to dieldrin (46/50=92%). This apparent cross-resistance between insecticides of two classes (cyclodiene and phenyl pyrazole) has implications for the management of insecticide resistance in wild populations of the An. gambiae complex.

A comparison between preventative and curative soil treatments for control of fungus gnats

Preventative and curative insecticide treatments were assessed for efficacy against fungus gnats (Bradesia paupera) in potting soil. Insecticide solutions (20 ml per 250 ml of growing medium per 100 mm diameter pot) were either mixed into the potting medium before planting tobacco seedlings (preventative treatment) or watered into the pots immediately after planting into medium infested with fungus gnat larvae (curative treatment). Preventative treatments of fipronil (0.1, 0.2 or 0.4 g/litre) and diflubenzuron (0.25 g/litre) were equally effective over 4 weeks at preventing plant loss, maintaining plant vigour (measured by the length of the longest leaf) and keeping fungus gnat larval numbers low (<1 per 25 ml medium versus 18 per 25 ml from watertreated medium). In the curative trial, 70% of the water-treated plants died, compared to 60% of the diflubenzuron and <7% of the fiproniltreated plants. Vigour of the surviving plants was similarly affected, but larval numbers had declined in all treatments from day 0 to14 days after treatment. Measuring the effect of treatments on a susceptible test plant and on larvae in the growing medium were both important for determining the efficacy of treatments for fungus gnat control.

Evaluation of a Pour-on Formulation of Fipronil Against Boophilus Annulatus (Acari: Ixodidae) Under Natural South Texas Field Conditions

A long-term field study (60 consecutive weeks) was conducted to determine whether a Boophilus annulatus (Say) population could be eradicated through repeated applications of a 1% pour-on formulation of fipronil on cattle held in an infested pasture. Animals treated repeatedly over time (seven applications) were infested with significantly fewer (p < 0.05) female ticks (5 mm in size) than untreated animals in all except one of the 57 weekly tick counts conducted after the first treatment was applied. As the number of treatments increased over time, there was a progressive decrease in the number of instances in which engorging females were observed on the treated cattle. Tick numbers obtained from sentinel cattle placed in pasture with untreated and treated cattle at various intervals throughout the study indicated that a single fipronil treatment had no observable adverse effect on the field tick population. However, after two treatments had been applied, there were always dramatically fewer ticks obtained from sentinel animals placed with treated cattle than were observed on sentinel animals placed with untreated cattle. Furthermore, tick numbers obtained from sentinel cattle placed with treated cattle over time indicated that the tick population in the pasture declined by stages. While a single treatment had no effect on the tick population, the application of two to four fipronil treatments at various intervals dramatically reduced the tick population, even though substantial numbers of females were still present on the sentinel animals. Ultimately, the application of five to seven fipronil treatments resulted in an extremely low tick population in the pasture, although total eradication of the population was not achieved during the study. The mean weight gain of treated animals was significantly higher (p < 0.05) than untreated animals during the study, indicating that the fipronil treatments had a highly beneficial impact on weight gain production.

Fipronil seed treatments for the control of chironomid larvae (Diptera: Chironomidae) in aerially-sown rice crops

The phenyl pyrazole insecticide fipronil was bioassayed against final instar larvae of Chironomus tepperi Skuse, and found to be highly toxic (LC 50 0.43 μg l −1, LC 90 1.05 μg l −1) relative to conventional organophosphorus insecticides. A comparison of fipronil and malathion (the standard bloodworm seed treatment in use in New South Wales) under glasshouse conditions using model soil/water systems showed that fipronil at 0.005 mg l −1 gave superior residual control to malathion at concentrations of up to 0.6 mg l −1. In small plot trials fipronil applied to pregerminated seed provided control of Chironominae at 12.5 and 25 g active ha −1 at least equivalent to that provided by the standard 300 g active ha −1 malathion treatment. The 12.5 g active ha −1 rate provided between 9 and 14 days residual control of Chironominae, whilst raising the application rate to 50 or 100 g active ha −1 increased residual control to between 14 and 19 days and provided significantly better control than malathion. Other chironomids (predominantly Tanypodinae) were strongly suppressed by all rates of fipronil for all or most of the 34-day trial period. Plant establishment and shoot length were significantly greater in all fipronil treatments relative to both the malathion standard and the untreated control. There was also evidence of stronger root system development in the fipronil treated plants. At an initial application rate of 12.5 g active ha −1, fipronil levels in the water column declined from 2.1 μg l −1 1 day after sowing to 0.01 μg l −1 14 days after sowing (DAS). At 22 DAS the parent compound was below detection limits (0.005 μg l −1). Four unreplicated commercial scale trials of fipronil were conducted in which three treatments or treatment combinations were evaluated. In general, fipronil (12.5–15.75 g active ha −1) either alone or followed by a post-sowing chlorpyrifos treatment (75 g active ha −1 10–15 DAS) provided a level of control equivalent to paired chlorpyrifos applications (75 g active ha −1 at 2–5 and 10–17 DAS), but at one site fipronil alone was inadequate without a post-sowing chlorpyrifos treatment. Our results indicate that fipronil applied to seed at 12.5 g active ha −1 is a more efficacious seed treatment than malathion at 300 g active ha −1 and provides protection against chironomids for 9–14 DAS. An additional post-sowing insecticide application may still be required in some seasons, but should only be applied in response to high larval populations and evidence of crop damage.

Impacts on nontarget insects of a new insecticide compound used against the desert locust [Schistocerca gregaria (Forskål 1775)

In 1994, the effects of fipronil, a new insecticide compound of the phenyl-pyrazol chemical group, was tested against desert locusts during a field experiment in Mauritania. The impacts of these spray treatments on nontarget Coleoptera and Hymenoptera were also studied. In relation to organophosphorous insecticides usually used against grasshoppers and locusts, fipronil appeared more effective and persistent. Similar results were obtained for nontarget Carabidae and Tenebrionidae which were almost totally eliminated from the treated plot. The effects on Hymenoptera varied according the family; Scelionidae and Sphecidae seemed to be more affected than Apoidea. Positive and negative aspects of fipronil treatments are discussed. Appearing as one of the most convenient insecticides to successfully prevent locust outbreaks, at a very early stage of invasion under Saharan conditions, fipronil simultaneously induces heavy mortality in some nontarget insect groups.

Evaluation of Soil Treatments on Control of Onion Thrips on Onions, 1996

Abstract A trial was conducted at the Horticulture Field Research Center, Ft. Collins, CO, to evaluate the effects of soil treatments on control of onion thrips. Onions (cv. Vega) were transplanted 14 May by placing them in shallow furrows and covering. Prior to covering, Admire and Fipronil treatments were applied; Vydate applications were made 22 May as a drench that was subsequently irrigated. Individual plots were 15 row-ft, arranged in a randomized complete block with five replications. Plots were evaluated by counting thrips on ten plants/plot.

Comparison of Various Soil Insecticides and Application Methods to Control Soil Insects in Sweet-Potatoes, 1996

Abstract Sweetpotatoes were transplanted on 20 Jun at the Eastern Shore Agricultural Research and Extension Center, Painter, VA. Each plot consisted of 3 rows 20 ft long with 3-ft between-row spacing. An untreated guard row separated each plot from its neighbor. Treatments were replicated 6 times in a RCB. Mocap treatments were applied preplanting and incorporated on 7 Jun. The Lorsban and Fipronil treatments were applied immediately before planting and incorporated on 20 Jun. The application method (15 inch band v. broadcast) for each treatment is indicated in the table. A backpack sprayer equipped with a 6 plant fan nozzle boom/3 rows was used to apply the broadcast treatments, and a single flat fan nozzle boom was used to apply the band treatments. In order to control the summer generations of the soil insects after the main treatment had broken down, the plots (except for the check) were sprayed with Sevin XLR at 1.00 lb (AI)/acre alternating weekly with Thiodan 3EC at 0.56 lb (AI)/acre on 22 and 30 Jul and 5 and 15 Aug. The same sprayer was used for the foliar treatments as was used for the broadcast treatments, both of which were applied in 21 gal water/acre at 40 psi.

Control of Rice Water Weevil with Fipronil, 1996B

Abstract The experiment was a non-replicated experimental use permit with 4 treatments. Whole plot size was 2.5 acres for the fipronil treatments and 1.7 acres for the Furadan and untreated plots. Whole plots of fipronil treatments were divided into 6 subplots 60 ft X 310 ft. The untreated area was divided into 3 subplots 75 ft X 310 ft. The Furadan area was divided into 4 subplots 75 ft X 310 ft. Each subplot was bound by levees. EXP 60720A was tank-mixed with water and applied preplant on 22 May by a tractor-mounted sprayer delivering 13 gpa. The plot was then cultivated at a 2-3 inch depth. Rice was drill-seeded in very dry Crowley silt loam at 90 lb/acre on 22 May and emerged on 5 Jun. Subplots were temporarily flooded (flushed) on 25-26 May and again on 4 Jun to initiate germination and to facilitate emergence, respectively. Propanil at 4 lb (AI)/acre was applied for weed control on 16 Jun. Nitrogen was applied in a three-way split of 90 lb N/acre as urea on 24 Jun and 30 lb N/acre on 15 and 22 Jul. Permanent flood was established on 25-26 Jun. Furadan 3G was applied by aircraft on 7 Jul 9 d after permanent flood. On 17 Jul and 1 Aug 4X4 inch (diam by depth) soil cores with an average of 7 plants/core were removed from subplots. Soil was washed from the plant roots into a40-mesh screen. The screen was immersed in salt water and RWW immatures were removed. Whole subplots were harvested with a combine on 4, 7 and 9 Oct. Reported yields were adjusted to 12% moisture. Yields and insect counts were not statistically analyzed.

Control of Rice Water Weevil with Fipronil, 1996A

Abstract The experimental design was a RCB with 11 treatments and 4 replications. Plot size was 9 rows (7 inch spacing) by 25 ft. Adjacent plots were separated by a 2 ft alley. Rice was drill-seeded in Crowley silt loam at 90 lb/acre on 16 May and emerged on 22 May. Propanil and Bolero at 3 and 2 lb (AI)/acre, respectively, were applied for weed control on 11 Jun. Nitrogen was applied in a 3-way split of 90 lb N/acre as urea on 18 Jun and 30 lb N/acre on 13 and 22 Jul. Preplant treatments of fipronil were made with a CO2-pressurized back-pack sprayer at 18 gpa. and incorporated to a 2 inch depth with a tractor-mounted rotary tiller. Seed treated with fipronil was supplied by Rhone Poulenc Ag. Chemical Company. Permanent flood was established on 18 Jun. Furadan 3G was applied 14 d after permanent flood with a hand-shaker. On 11 and 12 Jul and on 25 and 26 Jul, five 4 X 4 inch (diam by depth) soil cores with an average of 9 plants/core were removed from plots. Soil was washed from the plant roots into a 40-mesh screen. The screen was immersed in salt water and RWW immatures were removed. Plots were harvested with a small combine on 25 Sep. Reported yields were adjusted to 12% moisture. Data were analyzed with ANOVA and LSD.