Characterization of the inheritance of field-evolved resistance to diamides in the fall armyworm (Spodoptera frugiperda) (Lepidoptera: Noctuidae) population from Puerto Rico.

The fall armyworm (Spodoptera frugiperda) is one of the most destructive pests of corn. New infestations have been reported in the East Hemisphere, reaching India, China, Malaysia, and Australia, causing severe destruction to corn and other crops. In Puerto Rico, practical resistance to different mode of action compounds has been reported in cornfields. In this study, we characterized the inheritance of resistance to chlorantraniliprole and flubendiamide and identified the possible cross-resistance to cyantraniliprole and cyclaniliprole. The Puerto Rican (PR) strain showed high levels of resistance to flubendiamide (RR50 = 2,762-fold) and chlorantraniliprole (RR50 = 96-fold). The inheritance of resistance showed an autosomal inheritance for chlorantraniliprole and an X-linked inheritance for flubendiamide. The trend of the dominance of resistance demonstrated an incompletely recessive trait for H1 (♂ SUS × â™€ PR) × and an incompletely dominant trait for H2 (♀ SUS × â™‚ PR) × for flubendiamide and chlorantraniliprole. The PR strain showed no significant presence of detoxification enzymes (using synergists: PBO, DEF, DEM, and VER) to chlorantraniliprole; however, for flubendiamide the SR = 2.7 (DEM), SR = 3.2 (DEF) and SR = 7.6 (VER) indicated the role of esterases, glutathione S- transferases and ABC transporters in the metabolism of flubendiamide. The PR strain showed high and low cross-resistance to cyantraniliprole (74-fold) and cyclaniliprole (11-fold), respectively. Incomplete recessiveness might lead to the survival of heterozygous individuals when the decay of diamide residue occurs in plant tissues. These results highlight the importance of adopting diverse pest management strategies, including insecticide rotating to manage FAW populations in Puerto Rico and other continents.

Trunk injection to control Xylosandrus germanus (Coleoptera: Curculionidae) in topworked apple trees.

Xylosandrus germanus (Blandford) is an invasive species of ambrosia beetle known to attack apple trees in North America. Xylosandrus germanus are attracted to ethanol produced by stressed and injured trees and can be a serious problem when grafting a new cultivar onto established fruit trees (topworking). The objective of this study was to evaluate the efficacy of 2 insecticides (emamectin benzoate and azadirachtin) and injection timing (fall and spring) on their ability to control X. germanus colonization in apple trees with simulated topworking. Our study shows evidence that both emamectin benzoate and azadirachtin injections can reduce X. germanus infestations; however, our results were inconsistent. The timing of injections influenced X. germanus, with spring injected azadirachtin being more effective than fall injections. Residue analyses of emamectin benzoate and azadirachtin showed the presence of residues in woody tissue comparable to those found in leaves.

Trunk injection delivery of dsRNA for RNAi-based pest control in apple trees.

BACKGROUND: RNA interference (RNAi) is a promising new approach for controlling insect pests without the use of synthetic pesticides. Trunk injection is a delivery system for woody plants that harnesses the vascular system of the tree to transport materials to the tree canopy. Full size apple trees were injected with double-stranded RNA (dsRNA), and season-long leaf samples were taken to measure the vascular mobility and temporal persistence of dsRNA, using quantitative reverse transcription polymerase chain reaction (qRT-PCR). RESULTS: The qRT-PCR results revealed that the quantities of dsRNA in the apple leaves of treated trees were significantly greater than those in the leaves of untreated trees for both 2019 and 2020 studies. The peak dsRNA concentration in 2019 was 242 pg/30 mg of leaf tissue, and in 2020 was 16.4 pg/30 mg. The persistence of dsRNA in the apple tree canopy in 2019 was at least 84 days, and in 2020 was at least 141 days. CONCLUSIONS: The highest mean measurement of dsRNA on a single date in 2019 was 242 pg, which is approximately equivalent to 8 ng/1 g leaf tissue. The projection using the highest replicate concentration from the same date is approximately equivalent to 27 ng/1 g leaf tissue, which may be sufficient to be considered biologically active. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Resistance Affects the Field Performance of Insecticides Used for Control of Choristoneura rosaceana in Michigan Apples and Cherries.

Field-based residual bioassays and residue analysis were conducted to assess the field performance and toxicity longevity of different insecticides that had previously been associated with resistance of Choristoneura rosaceana populations collected from apple and cherry orchards. In this study, 12-24 h-old larvae of apple and cherry populations were exposed to apple and cherry leaf samples, respectively, at post-application intervals and a susceptible population served as a reference of each. In the apple and cherry trials, the order of residual longevity of insecticides that effectively controlled the tested populations was as follows: bifenthrin and spinetoram (apple: 14, cherry 21-day post-application), phosmet (apple: 7, cherry 14-day post-application), chlorantraniliprole (apple: 7-day post-application), and indoxacarb and emamectin benzoate (apple: 1, cherry 7-day post-application). Compared to the susceptible population, the resistant populations resulted in a measurable loss of field performance, or "practical resistance", for the insecticides emamectin benzoate (at 7-day post-application), chlorantraniliprole (at 21-day post-application), and indoxacarb (at all post-application intervals) in the apple trials, while in cherry trial just indoxacarb at 7-day post-application showed a reduced efficacy. In terms of long-lasting residues, only chlorantraniliprole and indoxacarb maintained measurable leaf residues over all post-application intervals while the leaf residues of the other compounds had largely degraded within the first 7 days. These findings can help fruit growers make adjustments to their spray/re-application intervals and optimally utilize important chemical tools in their integrated pest management programs.

Efficacy of intermittent exposure to bright light for treating maladaptation to night work on a counterclockwise shift work rotation.

OBJECTIVES: Rotating shift work is associated with adverse outcomes due to circadian misalignment, sleep curtailment, work-family conflicts, and other factors. We tested a bright light countermeasure to enhance circadian adaptation on a counterclockwise rotation schedule. METHODS: Twenty-nine adults (aged 20-40 years; 15 women) participated in a 4-week laboratory simulation with weekly counterclockwise transitions from day, to night, to evening, to day shifts. Each week consisted of five 8-hour workdays including psychomotor vigilance tests, two days off, designated 8-hour sleep episodes every day, and an assessment of circadian melatonin secretion. Participants were randomized to a treatment group (N=14), receiving intermittent bright light during work designed to facilitate circadian adaptation, or a control group (N=15) working in indoor light. Adaptation was measured by how much of the melatonin secretion episode overlapped with scheduled sleep timing. RESULTS: On the last night shift, there was a greater overlap between melatonin secretion and scheduled sleep time in the treatment group [mean 4.90, standard deviation (SD) 2.8 hours] compared to the control group (2.62, SD 2.8 hours; P=0.002), with night shift adaptation strongly influenced by baseline melatonin timing (r2=-0.71, P=0.01). While the control group exhibited cognitive deficits on the last night shift, the treatment group's cognitive deficits on the last night and evening shifts were minimized. CONCLUSIONS: In this laboratory setting, intermittent bright light during work hours enhanced adaptation to night work and subsequent readaptation to evening and day work. Light regimens scheduled to shift circadian timing should be tested in actual shift workers on counterclockwise schedules as a workplace intervention.

Organic Control of Pear Psylla in Pear with Trunk Injection.

Organic production of pears is challenging in part because OMRI (Organic Materials Review Institute) approved biopesticides are short lived when applied as foliar sprays. Trunk injection is an alternative method of insecticide delivery that may enhance the performance of biopesticides for control of pear psylla. The objective of this study is to compare the efficacy of azadirachtin and abamectin in the control of pear psylla using two different application methods, airblast sprayer and trunk injection. Trunk injections of azadirachtin and abamectin were compared to airblast applications of equal labeled rates on 33-year-old Bartlett Pear trees (Pyrus communis L., var "Bartlett"). The azadirachtin and abamectin trunk injected treatments performed equally or better than the two airblast applications in the control of the pear psylla. The trunk injected trees from the first season provided a moderate level of control into the second season, one year after the injections. This study suggests that trunk injection is a superior delivery system for biopesticides used in organic pear production.

Curative Activity of Insecticides Used to Control Spotted-Wing Drosophila (Diptera: Drosophilidae) in Tart Cherry Productions.

Spotted-wing drosophila (Drosophila suzukii Matsumura) is a major pest of soft-skinned fruit and due to the low infestation tolerance for marketable fruit, growers take preventive actions to hinder spotted-wing drosophila damages. Insecticides application is one of the measures taken by growers. Although intensive spraying programs have been used to manage spotted-wing drosophila, its early infestation, rapid reproduction, and vast range of host have caused damage to still occur in fruit, including tart cherries, Prunus ceraus (Linnaeus). Therefore, there is a merit for information on insecticide's curative activity to understand whether sprays manage spotted-wing drosophila individuals within infested fruit. Tart cherry fruit were exposed to spotted-wing drosophila adults for 3 d. After this infestation period, insecticides were applied 1 and 3 d later. Small larvae, large larvae, and pupae were counted 9 d after initial infestation. A parallel set of insecticide-treated tart cherries were subjected to residue analysis. Phosmet and spinetoram were able to reduced live spotted-wing drosophila counts compared with the control at all life stages and insecticide application times, whereas zeta-cypermethrin, acetamiprid, and cyantraniliprole were less consistent in reducing spotted-wing drosophila numbers. Chromobacterium subtsugae demonstrated no curative action. Residue analysis demonstrated that zeta-cypermethrin residues mostly remained on fruit surface. Small portions of phosmet, spinetoram, and cyantraniliprole were able to penetrate fruit surfaces and move into subsurface tissues. Acetamiprid was the only compound which >47% penetrated into the fruit subsurface consistently across both years. Curative activity demonstrated in this study can provide additional tactics for spotted-wing drosophila management in tart cherry Integrated Pest Management (IPM) programs.

Metabolic mechanisms of indoxacarb resistance in field populations of Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae).

Synergism and metabolic studies were conducted to identify the resistance mechanism against indoxacarb in two Choristoneura rosaceana (Harris) field populations compared to a susceptible population. The synergism study was carried out using diet incorporation bioassay for indoxacarb and the three synergists PBO, DEM, and DEF. The metabolic study consists of indoxacarb in vitro reaction with fifth instar larvae 12,000 g midgut supernatant or with pre-inhibited (in vivo by the esterases inhibitor DEF) fifth instar larvae 12,000 g midgut supernatant at different incubation times. In both susceptible and cherry populations, only DEF significantly synergized indoxacarb with a synergism ratio (SR) of 6.5 and 22.6-fold respectively indicating an involvement of esterases in the both populations. In the apple population, all synergists PBO, DEM, and DEF significantly synergized indoxacarb with SR of 9.6, 7.7, and 285.6-fold respectively indicating a complex resistance case with the possible involvement of all three metabolic resistance mechanisms with the central role of esterase enzymes. In vitro, the indoxacarb (DPX-JW062) was very rapidly metabolized within 5 min into small molecules in the lower portion of the metabolic pathway when it reacted with the midgut supernatant of each population. None of the metabolites in the upper portion of the metabolic pathway were detected at any incubation time including the potent sodium channel blocker DCJW metabolite. The two field populations showed significantly higher rates of metabolism of DPX-JW062 compared to the susceptible population at five min of incubation and that may explain the presence of indoxacarb resistance. In the second part of the in vitro study, the bio-transformation of DPX-JW062 was remarkably decreased when it reacted with the pre-inhibited (by DEF) midgut supernatant of each population. Additionally, the degradation of metabolites in the upper portion of the metabolic pathway remarkably decreased, which resulted in accumulation of DCJW and MP819 metabolites. The accumulation of DCJW metabolite under the pre-inhibited midgut supernatants treatment provided a persuasive explanation of the synergistic impact of esterase inhibitor DEF on indoxacarb in C. rosaceana.

Rainfastness of Insecticides Used to Control Spotted-Wing Drosophila in Tart Cherry Production.

Tart cherry production is challenged by precipitation events that may reduce crop protection against spotted-wing drosophila (Drosophila suzukii) (SWD). Due to SWD's devastating impacts on yield, growers are often faced with the option of insecticide reapplication. Semi-field bioassays were used to assess simulated rainfall effects towards adult mortality, immature survival, and residue wash-off from different plant tissues for several compounds. Tart cherry shoots were treated with 0, 12.7 or 25.4 mm of simulated rainfall and infested with SWD for 5 days. Adult mortality was recorded 1, 3, and 5 days after shoots were infested, while immature stage individuals were counted 9 days after the first infestation day. All insecticides demonstrated higher adult mortality and lower immature survival compared with the untreated control at 0 mm of rainfall. Adult mortality and immature survival caused by phosmet, zeta-cypermethrin, and spinetoram were adversely affected by simulated rainfall. In all bioassays, acetamiprid was the least affected by simulated rainfall. Residue analysis demonstrated phosmet and spinetoram residues to be the most sensitive to wash-off. This study demonstrates different rainfall effects on SWD control for several compounds. This information may provide a basis for making an informed decision on whether reapplication is required.

Residual Toxicity of Insecticides to Neoseiulus fallacis (Acari: Phytoseiidae) in Apples.

Neoseiulus fallacis (Garman) is a predatory mite that is common in apple orchards and distributed throughout North America. However, N. fallacis may be susceptible to pesticides used for the management of crop pests. This study aimed to evaluate the temporal effects of commonly used insecticides on N. fallacis survival. Neoseiulus fallacis adults were exposed to field-aged residues, and mortality and lethal time were measured over 96 h of exposure. Carbaryl caused high mortality to N. fallacis and the shortest lethal time values (LT50), followed by spinetoram, with moderate lethal time values. Esfenvalerate, acetamiprid, chlorantraniliprole, and novaluron showed little to no lethality to N. fallacis following exposure to dry field-aged residues. The results of this study provide important field-relevant knowledge that is often void from laboratory-based studies, which can aid integrated pest management (IPM) decision-makers in apple production systems.

Choristoneura rosaceana (Lepidoptera: Tortricidae) Resistance to Insecticides in Michigan Apple and Cherry Orchards.

Field populations of Obliquebanded leafroller, Choristoneura rosaceana (Harris), collected from one commercial apple and one commercial cherry orchard in Kent and Newaygo Counties in western Michigan, respectively. A baseline toxicity study of eight insecticides including phosmet, bifenthrin, methomyl, indoxacarb, chlorantraniliprole, spinetoram, emamectin benzoate, and novaluron was conducted on 12- to 24-h-old larvae of the C. rosaceana field populations and compared with a susceptible strain. The resistance levels were low (<10-fold) in all cases except for indoxacarb (>10-fold) in both populations. The cherry population showed levels of resistance to spinetoram, bifenthrin, emamectin benzoate, and indoxacarb with 4.1-, 4.9-, 5.8-, and 21-fold resistance, respectively. The apple population showed levels of resistance to spinetoram, chlorantraniliprole, phosmet, bifenthrin, emamectin benzoate, and indoxacarb with 4.3-, 4.7-, 5-, 5-, 6.3-, and 620.4-fold resistance, respectively. Generally, the apple population showed lower resistance levels to more compounds than the cherry population. Resistance to these insecticides should be monitored periodically for further changes. This represents the first documented case of insecticide resistance for C. rosaceana collected from a cherry orchard in Michigan. A statewide survey of more commercial orchards would help determine the extent of insecticide resistance across Michigan's five tree fruit production regions.

Insecticide dose and seasonal timing of trunk injection in apples influence efficacy and residues in nectar and plant parts.

BACKGROUND: Trunk injection is an established method for delivering pesticides in ornamental and shade trees, but further research is needed to determine efficacy and pollinator safety in tree fruit crops. Apple trees were injected in 2013 and 2014 with the insecticides emamectin benzoate, imidacloprid, dinotefuran, spinosad, chlorantraniliprole, or abamectin. Additional emamectin benzoate and imidacloprid injections were performed in the spring and fall of 2015. Nectar and pollen were sampled in the following spring to compare the effects of application timings on insecticide loading into flowers. RESULTS: Neonicotinoids reduced Empoasca fabae density in the field. Emamectin benzoate, chlorantraniliprole, and abamectin resulted in moderate to high mortality and reduced Choristoneura rosaceana feeding in bioassays. Imidacloprid was not detected in nectar or pollen when injected in the spring, and was detected at 0.39 ng g-1 in pollen when injected the previous fall. Emamectin benzoate was not detected in nectar or pollen when injected the previous fall, and was detected at 7.36 ng g-1 (nectar) and 1.15 ng g-1 (pollen) when injected in the spring. CONCLUSIONS: This study identified a broader list of possible trunk-injectable pesticides for apple trees. This study also shows that managing the seasonal timing of injection can reduce the risk of insecticide exposure to pollinators. © 2018 Society of Chemical Industry.

Baseline susceptibility of spotted wing Drosophila (Drosophila suzukii) to four key insecticide classes.

BACKGROUND: The invasive drosophilid pest, Drosophila suzukii Matsumura, is affecting berry production in most fruit-producing regions of the world. Chemical control is the dominant management approach, creating concern for insecticide resistance in this pest. We compared the insecticide susceptibility of D. suzukii populations collected from conventional, organic or insecticide-free blueberry sites. RESULTS: The sensitivity of D. suzukii to malathion and spinetoram declined slightly across the 3 years of monitoring, whereas it was more consistent for methomyl and zeta-cypermethrin. The sensitivity of D. suzukii to all four insecticides (LC50 and LC90 values) did not differ significantly among the blueberry fields using different management practices. CONCLUSIONS: The baseline sensitivity of D. suzukii has been characterized, allowing future comparisons if field failures of chemical control are reported. The concentration achieving high control indicates that effective levels of control can still be achieved with field rates of these four insecticides. However, declining susceptibility of some populations of D. suzukii to some key insecticides highlights the need for resistance monitoring. © 2017 Society of Chemical Industry.

Reduced ultraviolet light transmission increases insecticide longevity in protected culture raspberry production.

High tunnels are large protective structures used for season extension of many crops, including raspberries. These structures are often covered in plastic films to reduce and diffuse ultraviolet light transmission for pest and disease control, but this may also affect the photodegradation and efficacy of pesticides applied under these tunnels. We compared the residue levels of ten insecticides under three tunnel plastics with varying levels of UV transmission and open field conditions. Raspberry plants placed in research-scale tunnels were treated with insecticides and residues on fruit and foliage were monitored for one or two weeks in early 2015 and early and late 2016. Plastics that reduce UV transmission resulted in 50% greater residues of some insecticides compared to transparent plastics, and 60% compared to uncovered tunnels. This increased persistence of residues was evident within 1 day and remained consistently higher for up to 14 days. This pattern was demonstrated for multiple insecticides, including bifenthrin, esfenvalerate, imidacloprid, thiamethoxam, and spinosad. In contrast, the insecticide malathion degraded rapidly regardless of the plastic treatment, indicating less sensitivity to photodegradation. Bioassays using insecticide-treated leaves that were under UV-blocking plastic revealed higher mortality of the invasive fruit pest, Drosophila suzukii, compared to leaves that were uncovered. This indicates that the activity of pesticides under high tunnels covered in UV-reducing plastics may be prolonged, allowing for fewer insecticide applications and longer intervals between sprays. This information can be used to help optimize pest control in protected culture berry production.

Seasonal and Cross-Seasonal Timing of Fungicide Trunk Injections in Apple Trees to Optimize Management of Apple Scab.

To optimize the number and timing of trunk injections for season-long control of apple scab (Venturia inaequalis), we evaluated 1 to 2 and 4 seasonal and cross-seasonal injections of potassium phosphites and synthetic fungicides and quantified residues in leaves and fruit. Phosphites accumulated in the canopy at the highest concentrations, aligned well in time with scab suppression, and gave better leaf scab control of 41.8 to 73.5% than propiconazole (16.9 to 51.5%) or cyprodinil + difenoconazole (5.4 to 17.4%). More injections of phosphites controlled leaf scab better than fewer (23.7% versus 48.2%), and more fungicide injections resulted in 21.9 to 51.1% better leaf scab control than fewer. Leaf scab control with phosphites was only 3.2 to 13.9% better with 4 cross-seasonal compared with 4 seasonal injections, while 1 to 2 seasonal compared with 1 to 2 cross-seasonal injections improved scab control only for 4.2 to 22.1%. On shoots, injected phosphites provided comparable or for 4.4 to 10.5% and 22.3 to 41.4% better scab control than spray standards. On fruit, injected phosphites slightly improved control compared with sprayed phosphites or the sprayed fungicide standard (33.4 to 40.8%). Two seasonal injections of phosphites controlled shoot scab 5.7% better than 9 spray applications. Five sprays of cyprodinil + difenoconazole controlled scab better than their injections. Fruit residues of phosphites reached 2.8 ppm and declined in all treatments except in 2 seasonal injections and phosphite sprays. Cyprodinil and difenoconazole fruit residues reached 0.02 and 0.07 ppm and declined sharply toward the end of the season. These were far below the United States, Codex, and EU MRL-s of 1, 0.8, and 0.5 ppm for difenoconazole, and 1.7, 2, and 1 ppm for cyprodinil, respectively.

Control of fire blight (Erwinia amylovora) on apple trees with trunk-injected plant resistance inducers and antibiotics and assessment of induction of pathogenesis-related protein genes.

Management of fire blight is complicated by limitations on use of antibiotics in agriculture, antibiotic resistance development, and limited efficacy of alternative control agents. Even though successful in control, preventive antibiotic sprays also affect non-target bacteria, aiding the selection for resistance which could ultimately be transferred to the pathogen Erwinia amylovora. Trunk injection is a target-precise pesticide delivery method that utilizes tree xylem to distribute injected compounds. Trunk injection could decrease antibiotic usage in the open environment and increase the effectiveness of compounds in fire blight control. In field experiments, after 1-2 apple tree injections of either streptomycin, potassium phosphites (PH), or acibenzolar-S-methyl (ASM), significant reduction of blossom and shoot blight symptoms was observed compared to water injected control trees. Overall disease suppression with streptomycin was lower than typically observed following spray applications to flowers. Trunk injection of oxytetracycline resulted in excellent control of shoot blight severity, suggesting that injection is a superior delivery method for this antibiotic. Injection of both ASM and PH resulted in the significant induction of PR-1, PR-2, and PR-8 protein genes in apple leaves indicating induction of systemic acquired resistance (SAR) under field conditions. The time separating SAR induction and fire blight symptom suppression indicated that various defensive compounds within the SAR response were synthesized and accumulated in the canopy. ASM and PH suppressed fire blight even after cessation of induced gene expression. With the development of injectable formulations and optimization of doses and injection schedules, the injection of protective compounds could serve as an effective option for fire blight control.

Spatial and temporal distribution of trunk-injected imidacloprid in apple tree canopies.

BACKGROUND: Pesticide use in orchards creates drift-driven pesticide losses which contaminate the environment. Trunk injection of pesticides as a target-precise delivery system could greatly reduce pesticide losses. However, pesticide efficiency after trunk injection is associated with the underinvestigated spatial and temporal distribution of the pesticide within the tree crown. This study quantified the spatial and temporal distribution of trunk-injected imidacloprid within apple crowns after trunk injection using one, two, four or eight injection ports per tree. RESULTS: The spatial uniformity of imidacloprid distribution in apple crowns significantly increased with more injection ports. Four ports allowed uniform spatial distribution of imidacloprid in the crown. Uniform and non-uniform spatial distributions were established early and lasted throughout the experiment. The temporal distribution of imidacloprid was significantly non-uniform. Upper and lower crown positions did not significantly differ in compound concentration. Crown concentration patterns indicated that imidacloprid transport in the trunk occurred through radial diffusion and vertical uptake with a spiral pattern. CONCLUSION: By showing where and when a trunk-injected compound is distributed in the apple tree canopy, this study addresses a key knowledge gap in terms of explaining the efficiency of the compound in the crown. These findings allow the improvement of target-precise pesticide delivery for more sustainable tree-based agriculture.

Lethality of reduced-risk insecticides against plum curculio (Coleoptera: Curculionidae) in blueberries, with emphasis on their curative activity.

BACKGROUND: Historically, management of plum curculio, Conotrachelus nenuphar (Herbst), in highbush blueberries has focused on post-bloom broad-spectrum insecticide applications targeting the adults. Here, the efficacy of different classes of insecticides against various stages of C. nenuphar was compared, and a prebloom treatment with the chitin synthesis inhibitor novaluron in combination with a post-bloom insecticide application was tested. RESULTS: Novaluron decreased the number of oviposition scars and eggs on fruit and reduced larval emergence by >60% when applied prebloom. Post-bloom applications of the oxadiazine indoxacarb and the organophosphate phosmet, but not the neonicotinoid acetamiprid, showed significant adulticidal activity. The neonicotinoids acetamiprid and thiamethoxam and phosmet showed significant curative activity on C. nenuphar larvae when applied topically to infested fruit, whereas the pyrethroid fenpropathrin, indoxacarb and novaluron were weaker curative agents. Residue profiles showed that acetamiprid and phosmet residues had the highest levels while fenpropathrin and novaluron had the lowest levels of fruit penetration. CONCLUSIONS: In blueberries, novaluron showed anti-ovipositional/ovicidal activity, indoxacarb and phosmet showed adulticidal activity, while the neonicotinoids and phosmet showed best curative (larvicidal) control on C. nenuphar. A prebloom novaluron application in combination with a post-bloom treatment with an adulticidal/larvicidal insecticide is recommended for optimal multi-life-stage management of C. nenuphar. © 2013 Society of Chemical Industry.

Rainfastness of insecticides used to control Japanese beetle in blueberries.

Field-based bioassays were used to determine the relative impact of rainfall on the relative toxicity of four insecticides, phosmet, carbaryl, zeta-cypermethrin, or imidacloprid, from different chemical classes on adult Japanese beetles, Popillia japonica Newman, in highbush blueberries, Vaccinium corymbosum L. Bioassays were set up 24 h after spraying occurred and Japanese beetle condition was scored as alive, knockdown or immobile 1, 24, and 48 h after bioassay setup. All insecticides were significantly more toxic than the untreated control and zeta-cypermethrin consistently had the greatest toxic effect against the Japanese beetles. All insecticides experienced a decrease in efficacy after simulated rainfall onto treated blueberry shoots, although the efficacy of zeta-cypermethrin was the least affected by rainfall. This study will help blueberry growers make informed decisions on when reapplications of insecticides are needed in the field with the aim of improving integrated pest management (IPM).

Penetrative and dislodgeable residue characteristics of 14C-insecticides in apple fruit.

Infinite- and finite-dose laboratory experiments were used to study the penetrative and dislodgeable residue characteristics of (14)C-insecticides in apple fruit. The differences in dislodgeable and penetrated residues of three radiolabeled insecticides ((14)C-thiamethoxam, (14)C-thiacloprid, and (14)C-indoxacarb), applied in aqueous solution with commercial formulations, were determined after water and methanol wash extractions. The rate of sorption and extent of penetration into the fruit cuticles and hypanthium of two apple cultivars were measured after 1, 6, and 24 h of treatment exposure, using radioactivity quantification methods. For all three compounds, 97% or more of the treatment solutions were found on the fruit surface as some form of non-sorbed residues. For indoxacarb, sorption into the epicuticle was rapid but desorption into the fruit hypanthium was delayed, indicative of a lipophilic penetration pathway. For the neonicotinoids, initial cuticular penetration was slower but with no such delay in desorption into the hypanthium.