Ultra-low Volume Formulation Research Articles

Benefits of ULV Application to Control Locusts in Caucasus and Central Asia

This paper discusses the state-of-the-art of Ultra-Low Volume (ULV) spray application with rotary atomisers in the Caucasus and Central Asian (CCA) region to control locusts. The technology is widely used around the world for locust control and promoted by the UN Food and Agriculture Organisation (FAO) as an effective and efficient control intervention that meets the scale and challenge posed by large area locust outbreaks. The technology utilises precisely controlled spray droplets in the range 50–100um using ready-to-use oil-based ULV formulations to target locusts more efficiently. Volume rates as low as 0.5–1.0 l/ha are utilised which greatly improves productivity of ground and aerial spray applications, timeliness, and reduces cost and waste of pesticide and water. ULV has become more widely adopted in CCA during recent years to control major economic pests such as Moroccan, Italian, and Asian migratory locusts. Its further adoption is hampered by the lack of available ULV formulations in the region and need for investment and training in the technology. ULV technology is highly appropriate for use of biological products to reduce risks to operators and the environment and efforts to increase regional cooperation and the registration of safer pesticides across the region present opportunities for its wider adoption.

Field Evaluation of Fyfanon Ew Against Aedes Aegypti: A Low Odor Ultra-Low Volume Formulation of Malathion.

A low odor formulation of ultra-low volume (ULV) malathion (Fyfanon EW®) mosquito adulticide was evaluated in the field for its efficacy using caged female Aedes aegypti. Cages were placed in three rows, 30 m apart at 30, 60, and 90 m from the spray line. The product was applied at the manufacturer's suggested operational rate of 0.28 liter/min (9.5 fl oz/min) and at the maximum label rate of 0.37 liter/min (12.6 fl oz/min) with a Guardian 190ES truck mounted ULV sprayer. At 1 h post-treatment for the manufacturer's suggested operational rate, adult mortality ranged from 85% at 30 m to 46% at 90 m (overall average 65.5%). At 24 h post-treatment, mortality was significantly greater at each distance with complete control of caged mosquitoes at 30 m and >95% at 90 m. Overall, 24-h average mortality at this rate was 96.8%. At the maximum label rate, mosquito mortality at 1 h was considerably greater at all distances and ranged from about 89% to 75% with an overall average of 84.3%. At 24 h post-treatment, complete mortality was recorded at all transect distances at this higher rate. In conclusion, our results showed that at 24 h, Fyfanon EW® was considered very effective when applied by ULV truck mounted ground equipment for area-wide control of mosquitoes.

Optimization of aviation adjuvants based on wettability analysis for insecticide application on maize using UAV

Adjuvants can increase the control efficacy of diseases and insect pests by changing the physico-chemical properties of pesticides. Most of the aviation spray adjuvants are versions of ground adjuvants. Maize insecticide sprays with unmanned aerial vehicles (UAV), have problems such as relatively low droplet deposition rate and poor wettability. Hence, wettability research and optimization tests for aviation spray adjuvants are needed. The present study screened 12 spray adjuvants using physico-chemical property experiments. The adjuvants were applied to improve the droplet deposition and control efficacy in maize borers controlling by UAV. The selected spray adjuvants were Po2 (a hyperbranched polymer adjuvant) and VO3 (a vegetable oil adjuvant). Results showed that, (1) When Po2 was added in water-dispersible granules (WGs) at volume rate of 12 L/hm2, the dynamic surface tension (DST) of WGs was decreased by 37.41%, and the maize leaves were covered by droplets 100%, the droplet deposition was increased by 104% and maize borer control was increased by 46%; (2) VO3 decreased the surface tension of ultra-low-volume (ULV) formulation by 12.02% and the maize leaves were covered by droplets 100%. The effect of VO3 on improving the droplet deposition and control efficacy at 12 L/hm2 with ULV was not significant. Thus, the addition of aviation spray adjuvant to improve the wettability of WGs significantly improved the droplet deposition and control efficacy but it had no significant effect on the ULV formulation. Keywords: unmanned aerial vehicles, spray adjuvants, wettability, maize insecticide application DOI: 10.25165/j.ijabe.20211405.6605 Citation: Zang Y, Zhou Z Y, Zang Y, Luo X Y, Liao J, Ming R, et al. Optimization of aviation adjuvants based on wettability analysis for insecticide application on maize using UAV. Int J Agric & Biol Eng, 2021; 14(5): 11–18.

Modelling the Impacts of Early Intervention on Desert Locust Outbreak Prevention

To preserve crop production losses, monitoring of desert locust attacks is a significant feature of agriculture. In this paper, a mathematical model was formulated and analyzed to protect crops against desert locust attack via early intervention tactics. We consider a triple intervention approach, namely, proaction, reaction, and outbreak prevention. The model integrates a stage-structured locust population, logistics-based crop biomass, and blended early intervention via pesticide spray. We assume that the amount of pesticide spray is proportional to the density of the locust population in the infested area. Conventional short residual pesticides within ultralow volume formulation and equipment control operations are considered. The trivial and locust-free equilibrium of the model is unstable, whereas the interior equilibrium is asymptotically stable. Numerical simulations validate the theoretical results of the model. In the absence of intervention measures, desert locust losses are approximately 71% of expected crop production. The model projection shows that effective proactive early intervention on hopper stage locust contained locust infestation and subdued public health and environmental hazards. Relevant and up-to-date combined early interventions control desert locust aggression and crop production losses.

Comparative effects of pesticides, fenitrothion and fipronil, applied as ultra-low volume formulations for locust control, on non-target invertebrate assemblages in Mitchell grass plains of south-west Queensland, Australia

The effect of an aerial application of two broad-spectrum insecticides, the organophosphorus compound, fenitrothion, and the phenyl pyrazole pesticide, fipronil, on non-target invertebrates was investigated during Australian plague locust (Chortoicetes terminifera, (Walker, 1870)) control operations on a Mitchell grass (Astrebla spp.) plain in south-western Queensland, Australia, between 2002 and 2004. The invertebrate assemblages were monitored using yellow pan and Malaise traps to target flying invertebrates and pitfall traps to target ground-dwelling invertebrates, sampled immediately before spraying and then at 3, 7, 39, 79, 189 and 414 days after spraying. Both pesticides caused significant changes to invertebrate community composition immediately after spraying, largely due to changes in the abundance of Orthoptera, Collembola and Formicidae. The richness and abundance of invertebrates in Malaise and yellow pan traps did not differ significantly with pesticide application although significant changes in assemblage composition persisted for up to 79 days. Although not statistically significant, the richness and abundance of invertebrates in pitfall traps declined at sprayed sites after treatment, relative to controls. Assemblage composition in pitfall traps at sprayed sites was significantly different from that in the control sites and these differences persisted for up to 189 days post-spray. Prolonged drought across the study site is likely to have affected the recovery of invertebrate populations and a return to pre-spray abundances did not occur until after heavy rain fell approximately one year after the commencement of the study. The controlling influence of climatic conditions on recovery of non-target arthropod populations after exposure to pesticides therefore has implications for risk assessments for the use of pesticides in arid environments.

Fenitrothion, an organophosphorous insecticide, impairs locomotory function and alters body temperatures in Sminthopsis macroura (Gould 1845) without reducing metabolic rates during running endurance and thermogenic performance tests.

Endemic Australian mammal species are exposed to pesticides used for locust control as they occupy the same habitat as the target insect. The authors examined the impact of an ultra-low volume formulation of the organophosphorous insecticide fenitrothion (O,O-dimethyl-O-[3-methyl-4-nitrophenol]-phosphorothioate) on a suite of physiological measures that affect the ability of animals to survive in free-living conditions: locomotory and thermogenic functions, metabolic performance, body mass, and hematocrit and hemoglobin levels. Plasma and brain cholinesterase activity in relation to time since exposure to pesticide were also determined. An orally applied dose of 90 mg kg(-1) fenitrothion reduced running endurance in the stripe-faced dunnart, Sminthopsis macroura, by 80% the day after exposure concomitantly with a reduction of approximately 50% in plasma and 45% in brain acetylcholinesterase activity. These adverse effects disappeared by 10 d postexposure. Maximal metabolic rates reached during running were unaffected by pesticide, as were body mass and hemoglobin and hematocrit levels. Maximal cold-induced metabolic rate (measured as peak 2 min metabolic rate attained during cold exposure), time taken to reach peak metabolic rate on cold exposure, cumulative total oxygen consumed during shivering thermogenesis, and body temperature before and after cold exposure were unaffected by fenitrothion. Dunnart rectal temperatures showed a reduction of up to 5 °C after exposure to fenitrothion but returned to pre-exposure levels by 10 d postdose. Such physiological compromises in otherwise asymptomatic animals demonstrate the importance of considering performance-based measures in pesticide risk assessments.

The efficacy of a combined larvicide–adulticide in ultralow volume and fumigant canister formulations in controlling the dengue vector Aedes aegypti (Diptera: Culicidae) in Northwest of Argentina

The efficacy of an ultralow volume formulation (ULV) and fumigant canister, containing both permethrin and pyriproxyfen, was compared with that of standard permethrin applications in a field assay conducted in Banda del Río Salí, Tucumán (north-western Argentina). Five treatment areas were established: first area was sprayed with a ULV formulation of 10% permethrin, a second area was treated using a fumigant canister containing 10% permethrin and 3% pyriproxyfen, the third area was sprayed with a ULV formulation of 10% permethrin and 3% pyriproxyfen, the fourth area with ULV formulation of 10% permethrin using a portable aerosol generator and the fifth area was a left untreated area. Immature and adult Aedes aegypti individuals placed in containers and sentinel cages were positioned within the treated and control areas. The effects of treatment and time on larval, pupal and adult survival were tested. We also investigated the effects of treatment and time on the numbers of larval and pupal deaths, on the proportion of larvae that metamorphosed into pupae and adults, and on the proportion of dead adults. Larval A. aegypti survivorship in 250mL containers revealed a significant treatment effect and significant treatment × time interaction 2 and 24h after the application of the ULV treatment with 10% permethrin using the portable aerosol generator. The number of dead larvae in 20L containers differed significantly by treatment and by time. ULV treatment with 10% permethrin and 10% permethrin plus 3% pyriproxyfen using the cold fogger truck mount ULV resulted in the greatest numbers of dead larvae; most larvae died 2weeks after application. Adult A. aegypti mortality in all treatments did not differ significantly 2 and 24h after application. In addition, we found no significant differences in adult mortality between cages exposed at 3m and those at 6m from the ULV application line. However, there was a significant difference in adult mortality between the 10% permethrin treatment applied with cold fogger truck mount ULV and that applied using the portable aerosol generator (P < 0.001). The larval index known as Breteau index (BI) was higher before treatment than after treatment in different areas. After the treatments, the lowest value of BI was observed in the area treated with the fumigant canister formulation, and a long-lasting effect was observed with the formulation of 10% permethrin and 3% pyriproxyfen.

Efficacy of a new combined larvicidal–adulticidal ultralow volume formulation against Aedes aegypti (Diptera: Culicidae), vector of dengue

A new ultralow volume formulation (ULV) containing permethrin as an adulticidal active ingredient and the insect growth regulator (IGR) pyriproxyfen as a larvicide was developed and its efficacy evaluated in a field trial in Wanda, Misiones (Argentina). Two separate study areas were sprayed: one with a ULV formulation of permethrin 15% plus pyriproxyfen 3% and the other with permethrin 15% only. A third untreated area was kept as a control. Sentinel cages containing adult mosquitoes and jars containing Aedes aegypti larvae III/IV were placed in treated and control areas. The residual activity of the formulations was tested using 20 L water containers. The adulticide effect of permethrin 15% + pyriproxyfen 3% formulation was similar to the permethrin 15% formulation, however, the inhibition of adult emergence in the treatment with permethrin 15% never exceeded 20%, whereas the inhibition of adult emergence in the treatment with permethrin 15% plus pyriproxyfen 3% showed initial values of 96% maintaining this high level of inhibition up to 35 days after ULV spraying. Larval indexes (House and Breteau indexes) showed that a greater, long-lasting effect was obtained with the permethrin 15% plus pyriproxyfen 3% formulation.

Laboratory and scaled up evaluation of cis-permethrin applied as a new ultra low volume formulation against Aedes aegypti (Diptera: Culicidae)

Ultra low volume (ULV) aerial spraying is a common methodology for spatial treatments for Aedes aegypti (L.) control. Previous studies from our laboratory indicated that the cis isomer of permethrin has an excellent efficacy for vector control, in particular for Triatoma infestans. It was of interest to determine the efficacy of this pure isomer in a ULV water-based formulation for adult A. aegypti control, since both vectors usually are found together in South America. A method is presented to make a quick measure at laboratory level of the knock down effect (KT 50) of a new EC water-based formulation of cis-permethrin, in a small Peet Grady chamber of 0.34 m 3, with a specially designed glass sprayer. A deltamethrin standard ULV formulation “CISLIN” was used for comparison. cis-Permethrin showed a significantly lower KT 50 value than deltamethrin (7.50 and 9.65 min, respectively). When the mosquitoes were introduced into the chamber 10 min after spraying KT 50 values were almost equal (15.59 and 15.88 min, respectively). In scaled up bioassays the ULV formulation of cis-permethrin showed 100% mortality of A. aegypti adult mosquitoes at the beginning of the treatment ( t = 0) and some mortality at 1 h post treatment of freshly introduced mosquitoes. It was concluded that cis-permethrin could be an excellent tool for control of A. aegypti and other vectors of medical importance, with fewer side effects and better cost-effectiveness than with the cyanopyrethroids.

Studies on very-low volume (VLV) water-based sprays for the control of cotton pests

We evaluated, water-based very-low volume (VLV) sprays of various pyrethroids at different dosage levels, comparing these with ultra-low volume (ULV) sprays for the control of cotton pests in the Nampula province of Mozambique. The results showed that karate (lambda-cyhalothrin) 2.5% SG at a dosage level of 15 g a.i./ha applied as VLV gave a significantly higher yield than karate 0.8% ULV (28 g a.i./ha). Also, karate 3.75% WG (12 and 15 g a.i./ha) gave a similar yield to that of karate 0.8% ULV (28 g a.i./ha). Karate 5% EC (15 and 20 g a.i./ha) gave a yield similar to Karate 0.8% ULV (28 g a.i./ha). Baythroid (cyfluthrin) 5% EC at 15, 22.5 and 30 g a.i./ha gave a yield similar to baythroid 1.2% ULV (36 g a.i./ha). Bulldock (beta-cyfluthrin) 12.5% SC at dosage levels of 6, 9 and 12 g a.i./ha gave a similar yield to that using baythroid 1.2% ULV (36 g a.i./ha). In all four trials, water-based VLV sprays gave a yield of cotton and degree of pest-control similar to those obtained with the ULV formulations at comparatively lower dosage levels. Integrated with other pest management practices, these could play an important role in the cost effective management of insect pests of cotton on small-scale farms in many countries.

Barrier treatment with fipronil to control desert locust Schistocerca gregaria (Forskal, 1775) hopper bands infesting a large area in Mauritania

Fipronil, a compound belonging to a new chemical family, the phenylpyrazols, was tested as a barrier treatment in Mauritania against bands of hoppers of the desert locust (Schistocerca gregaria, Forskal1775). An ultra-low volume formulation (ADONIS 12.5UL) was applied at 15.7 and 16.6/km. The doses were 1.96 and 1.04 g ai/ protected ha. Two sites of approximately 2800 and 7200 ha were sprayed from a helicopter flying at 20m. There were 12 track spacings, ranging from 330m to 2600m. The effects of fipronil on hopper bands were determined by comparison with the initial locust populations at the two sites. Several hopper bands were monitored in two untreated areas. The hopper bands were controlled within two days in the area up to 500m from the flight path, within 7 days in the area between 1000 and 2000m, and within 12 days in the area between 2000 and 2600m. The speed of mortality was related to the upwind distance from the flight path. When ADONIS 12.5UL (12.5g ai/l of fipronil) is applied at 16 l/km, at 20m height, with track spacings up to 1000m, the efficacy was similar to that obtained with a blanket treatment (11 g ai/ha) performed the previous year in Mauritania.

Potential of the entomopathogenic fungus, Metarhizium anisopliae (Metsch.) Sorokin for control of the legume flower thrips, Megalurothrips sjostedti (Trybom) on cowpea in Kenya

Field experiments were conducted at Mbita, western Kenya for two seasons to evaluate the potential of the entomopathogenic fungus, Metarhizium anisopliae (Metsh.) Sorokin, for biological control of the legume flower thrips, Megalurothrips sjostedti (Trybom), on cowpea. An ultra-low-volume (ULV) oil/aqueous formulation and a high-volume (HV) aqueous formulation of conidia were applied three times each at two concentrations of 1 × 10 11 and 1 × 10 13 conidia ha −1. Compared with the untreated controls, both formulations significantly reduced thrips populations and plant damage in both seasons. Adult insects collected from fungal-treated plots and reared in the laboratory showed a high mortality due to mycosis. Flower and pod production was significantly higher in treated plots compared to the control plots. HV formulation was superior to ULV formulation in reducing thrips population and plant damage, and in increasing flower and pod production. During the first season, plots treated with HV formulation at 1 × 10 13 conidia ha −1 produced yields that were significantly higher than other treatments. No significant difference in grain yield was found between the fungal-treated plots and the synthetic insecticidal treatment during the second season. The results of these experiments suggest that M. anisopliae is a potential candidate for the management of M. sjostedti on cowpea.

Effects of the Sunscreen Oxybenzone on Field Efficacy and Persistence of Metarhizium flavoviride Conidia Against Kraussella amabile (Orthoptera: Acrididae) in Mali, West Africa

A field trial was performed at Mourdiah, northwest Mali, to evaluate whether the performance of Metarhizium flavoviride conidia would improve if 2% oxybenzone, an oil-soluble ultraviolet light protectant, was used. Conidia were applied in an ultra-low volume formulation against nymphs of the grasshopper Kraussella amabile . Mortality was assessed by collecting grasshoppers directly from field plots (sweep net samples) or by exposing untreated nymphs to sprayed vegetation for 48 h (field cage samples). For sweep net samples, the mortalities in M. flavoviride treatments varied between 94.5 and 99.9% up to 7 days after treatment, while control mortalities were significantly lower (20.7-55.0%). There were no significant differences between M. flavoviride treatments with or without oxybenzone. The average survival times were found to be significantly lower for fungal treatments (4.9 days) compared with the control treatment (11.8 days). W ith field cage samples, the mortality in M. flavoviride treatments declined from > 95.0% for nymphs exposed just after application to < 30.0% for nymphs exposed to treated vegetation on the 10th day after application. The control mortalities varied between 5.1 and 37.2%, and were significantly lower than fungal treatments for samples placed just after application and 10 days after application. The overall average survival times were 10.9 and 10.7 days for M. flavoviride with and without oxybenzone respectively, and 13.9 days with the control treatment. An exponential regression was fitted using cage mortality data which indicated that the half-life for conidial infectivity was 4.3 days on treated vegetation.

Control of Spodoptera spp. using ULV formulations of the acylurea insect growth regulator, flufenoxuron: Field studies with Spodoptera exempta and effect of toxicant concentration on contact activity

AbstractField trials in Kenya showed that an ultra‐low‐volume (ULV) application of flufenoxuron (25 g a.i. litre−1; 1–0 litre ha−1) gave consistently good control of late‐instar larvae (L4‐L6) of the armyworm, Spodoptera exempta Walk. Flufenoxuron gave equivalent or greater control of S. exempta than did cypermethrin (24 g a.i. litre−1; 1–0 litre ha−1) from 96 h after ULV application. While initial (24–48 h) levels of larval mortality were greater with cypermethrin, many larvae treated with flufenoxuron showed signs of incomplete moulting after 48–72 h and would have been unable to feed normally. Laboratory spray bioassays with L3 Spodoptera littoralis suggested that the ULV formulation of flufenoxuron was most active at 25 g a.i. litre−1 when compared with higher (50 g) or lower (6.25 and 12.5 g a.i. litre−1) rates. Topical application studies with ULV formulations containing [14C]flufenoxuron showed that the accumulation of pesticide by L3 S. exempta over 1–4 h was consistently greater in larvae treated with 25 g than with 12.5 g flufenoxuron litre−1 and while initially lower, accumulation of pesticide appeared to be greater in larvae treated with 25 g than with 50 g flufenoxuron litre−1 after 2–4 h. The potential of ULV formulations of flufenoxuron for control of S. exempta is discussed.

Influence of formulation and spray droplet size upon the persistence of permethrin deposits on brussels sprouts leaves

The persistence of two permethrin formulations, i.e. ultra-low-volume (ULV) and emulsifiable concentrate (EC), sprayed at two droplet sizes on brussels sprouts leaves was evaluated biologically using the larvae of Plutella xylostella. The bioassay was carried out on the treated leaves collected at various time intervals after treatment. The loss of biological efficacy of permethrin deposits was greater with the EC formulation than the ULV formulation. The persistence of permethrin deposits was also influenced by the interaction between formulation and spray droplet size. On the basis of mortality, the persistence of the permethrin ULV formulation sprayed at 80 μm was significantly better than that of spray deposits of the ULV formulation sprayed at 157 μm, the EC formulation at 154 μm and the EC formulation at 83 μm.

Liquid Chromatographic Method for Determination of Technical Deltamethrin and Deltamethrin in Pesticide Formulations: CIPAC Collaborative Study

Abstract A liquid chromatographic method for determination of deltamethrin In 6 different technical and formulated products was collaboratively studied In 14 laboratories. Each sample Is dissolved In lsooctane-1,4-dloxane (80 + 20), separated by LC on a silica gel column (cyano column for ultra low volume formulation), and detected at 254 nm (230 nm for ≤0.5% powder formulations). Quantitation Is done by peak area measurements. Relative standard deviations for repeatability and reproducibility ranged from 0.56 to 1.00% and from 0.76 to 2.90%, respectively. The method has been approved Interim official first action by AOAC as a CIPAC-AOAC method.

The rainfastness of permethrin deposits of emulsifiable concentrate (EC) and ultra‐low‐volume (ULV) formulation on brussels sprout leaves

Abstract The permethrin deposits on brussels sprout leaves from an emulsifiable concentrate (EC) and ultra‐low‐volume (ULV) formulation applied as monosized droplets were evaluated by bioassay before and after simulated rainfall using Plutella xylostella larvae. No significant reduction of permethrin deposits from ULV formulation applied with 80 μm droplets was observed after 30 and 60 min of continuous rainfall (50 mm/h). However, the rain significantly reduced the deposits from the EC formulation. Using both formulations, similar results were observed at 135 μm droplets after 30 min of rain. The results indicated that the rainfastness of permethrin could be improved by using the ULV formulation.

Controlling desert locust nymphs with bendiocarb applied by a vehicle-mounted spinning-disc sprayer

The requirements of ultra-low volume (ULV) spray trials against bands of locust nymphs are outlined. Trials of a ULV formulation of bendiocarb applied with a vehicle-mounted spinning-disc sprayer are described. Very rapid and effective control was consistently achieved at dosages of about 100 g a.i./ha. The sprayer proved to be robust, and both safe and easy to operate, and produced a desirably narrow range of small droplets.

Gas Chromatographic Method for Determination of Cypermethrin in Pesticide Formulations: Collaborative Study

Abstract A gas chromatographic method for determination of total cypermethrin in technical and formulated products has been developed and subjected to a collaborative study involving IS participating laboratories. Each sample was dissolved in methyl isobutyl ketone containing di(2-ethylhexyl) phthalate as internal standard and analyzed by gas chromatography on a glass column with 3% OV-101 on Chromosorb W-HP. Each collaborator was furnished with reference stdard and 4 samples of technical material, 3 emulsifiable concentrates, one wettable powder, and one ultralow volume formulation for analysis. The coefficients of variation of the results obtained ranged from 0.955 to 1.7462%. The method has been adopted as official first action by AOAC.

A study of population changes in adult Culex quinquefasciatus Say (Diptera: Culicidae) during a mosquito control programme in Dubai, United Arab Emirates.

The effectiveness of insecticidal control measures on adult Culex quinquefasciatus Say in Dubai, United Arab Emirates, was examined. Direct treatment of the study site with cypermethrin applied as a fog caused a temporary reduction both in total numbers (males and females) and in the proportion of older females. When cypermethrin was applied as an ultra low volume formulation at dusk and dawn numbers of males were greatly reduced, but numbers of females were not affected. It appears that the adulticiding operations had little overall effect on the total numbers or survival rate of females, or breeding success. The oviposition cycle duration was estimated to be two days, with the survival rate per oviposition cycle calculated as 30%. With these values it is thought unlikely that filariasis would be transmitted in Dubai.