Ovicidal,larvicidal and juvenilizing activity of a picolinephenoxyanilide against Cydia pomonella

N‐(4‐phenoxyphenyl)‐2‐pyridinecarboxamide (1) was synthesized from commercially available materials and its ovicidal and larvicidal activity against Cydia pomonella (L) was tested. The compound showed a LC₅₀ of 0.98 mg ml⁻¹ when eggs less than 24 h were sprayed using a Potter Tower, but it had no effect when eggs older than this were sprayed. The compound did not have larvicidal activity when larvae were treated with 1200 µg g⁻¹. However, the larval head capsules were smaller than those in the controls when treated at this concentration. To assess its possible juvenile‐hormone‐like activity, the compound was topically applied to young pupae of Tribolium confusum duVal, where it produced clear juvenilization effects, which were dependent on the applied dose. © 2000 Society of Chemical Industry     

Insecticidal efficacy of fipronil against four stored‐product insect pests: influence of commodity,dose, exposure interval,relative humidity and temperature

BACKROUND: Fipronil is an insecticidal pyrazole that is commonly used as an insecticide in field crops, urban pesticide and veterinary medicine, but there are no reports of its evaluation against stored‐product insects. Three series of laboratory bioassays were conducted to assess fipronil as a potential grain protectant against adults of Sitophilus oryzae (L.), Tribolium confusum Jacquelin du Val, Rhyzopertha dominica (F.) and Prostephanus truncatus (Horn). Factors such as dose (0.01, 0.1, 1 and 10 mg fipronil kg^?1 grain), exposure interval (24 h, 48 h, 7 days and 14 days), temperature (20, 25 and 30 °C), relative humidity (RH; 55 and 65%) and commodity (wheat, maize, barley and paddy rice) were evaluated with regard to their impact on the insecticidal activity of fipronil. Progeny production was assessed after 64 days of exposure. RESULTS: At doses of < 1 mg fipronil kg^?1 grain, efficacy of fipronil was enhanced by an increase in temperature from 20 to 25 °C against S. oryzae or R. dominica for exposures of > 48 h and against T. confusum or P. truncatus for exposures of > 24 h. A further increase in temperature from 25 to 30 °C, although it enhanced efficacy at doses of < 1 mg fipronil kg^?1 grain against S. oryzae at all exposure intervals and against T. confusum after 7 days of exposure, it was negatively associated with efficacy against R. dominica or P. truncatus for exposures of > 24 h. By contrast, increase in RH did not have a significant impact on efficacy of fipronil. Although the performance of fipronil among the tested commodities was species dependent, this substance appeared to be less effective in paddy rice than in barley, maize and wheat. Regardless of the treated commodity, progeny production of all the tested species was almost suppressed with doses higher than 0.1 mg fipronil kg^?1 grain. CONCLUSIONS: Fipronil appeared to be a very effective alternative to the existing substances in stored‐grain protection at doses equal to or higher than 1 mg fipronil kg^?1 grain, and thus these doses require further evaluation in terms of safety for the consumer and residues on stored products. Copyright © 2010 Society of Chemical Industry     

Toxicity of phosphine to five species of stored-product insects in atmospheres of air and nitrogen

The responses of five species of adult stored-product insects [Tribolium castaneum (Herbst), T. confusum (DuVal), Rhyzopertha dominica (F.), Sitophilus oryzae (L.) and S. granarius (L.)] to various doses of phosphine in atmospheres of air or nitrogen were determined. A few S. oryzae and S. granarius survived phosphine concentrations up to 80 mg litre^?1 for 24 h in normal (air) or nitrogen atmospheres. By contrast, T. castaneum, T. confusum and R. dominica could not tolerate more than 0.2 mg phosphine litre^?1 in air for 12 h. However, they could tolerate up to 10 mg phosphine litre^?1 in nitrogen for that period. Increasing the phosphine concentration resulted in increased mortalities of the last three species. The possible mechanism underlying this response is discussed. The reproductive potential of insects surviving phosphine exposure in a nitrogen atmosphere was unaffected.     

Lactones: Part 11. Feeding-deterrent activity of some bi- and tricyclic terpenoid lactones

The feeding-deterrent activities of thirteen synthetic terpenoid lactones, including isomeric bicyclic gamma-spirolactones with the limonene system and tricyclic gamma-lactones with the pinane system, were determined towards three storage pest insects: the adults of Sitophilus granarius, the adults and larvae of Tribolium confusum and the larvae of Trogoderma granarium. The configuration of chiral centres, as well as the presence of additional functional groups (double bond, iodine and hydroxy group) are important for antifeeding activity.     

Response of five species of stored-product insects to phosphine in oxygen-deficient atmospheres

Five species of stored-product insects, [Tribolium castaneum (Herbst), T. confusum (DuVal), Rhyzopertha dominica (F.), Sitophilus oryzae (L.) and S. granarius (L.)], exposed to phosphine in nitrogen and various oxygen-deficient atmospheres, showed reduced susceptibility to three concentrations of phosphine (0.02, 0.04 and 0.2 mg litre^?1). The last two species also showed reduced susceptibility to phosphine at 2.0 mg litre^?1. Generally mortality increased progressively as the level of oxygen was raised. There was a close relationship between the ability of insects to withstand anoxia and survival from phosphine treatment.     

Activity of the botanical aphicides 1,5‐diphenyl‐1‐pentanone and 1,5‐diphenyl‐2‐penten‐1‐one on two species of Aphididnae

1,5‐Diphenyl‐1‐pentanone (A) and 1,5‐diphenyl‐2‐penten‐1‐one (B) are natural products extracted for the first time from Stellera chamaejasme. Laboratory bioassay showed that the two products have strong contact activity and very good anti‐feedant activity against Aphis gossypii and Schizaphis graminum. Both products showed dose‐dependent relationships for both forms of activity against the two aphids, the contact activity of B being about twice that of A. Both products were inferior to methomyl in contact activity but superior in anti‐feedant activity against the two aphids. This is the first report of aphicidal activity in these two compounds, which may represent a new class of aphicide. © 2001 Society of Chemical Industry     

Chlorpyrifos-methyl plus bioresmethrin; Methacrifos; Pirimiphos-methyl plus bioresmethrin; and synergised bioresmethrin as grain protectants for wheat

Field trials with various pesticide combinations were carried out on bulk wheat in commercial silos in Queensland, South Australia and Western Australia. Laboratory bioassays on samples of treated grain at intervals over 8 months using malathion-susceptible and malathion-resistant strains established the following orders of efficacy: against Sitophilus oryzae (L.), chlorpyrifos-methyl 10 mg kg^?1 + bioresmethrin 1 mg kg^?1 = methacrifos 15 mg kg^?1 in aerated storage > pirimiphos-methyl 4 or 6 mg kg^?1 + bioresmethrin 1 mg kg^?1 = bioresmethrin 4 mg kg^?1 + piperonyl butoxide 16 mg kg^?1; against Rhyzopertha dominica (F.), bioresmethrin 4 mg kg^?1 + piperonyl butoxide 16 mg kg^?1 > methacrifos 15 mg kg^?1 > chlorpyrifos-methyl 10 mg kg^?1 + bioresmethrin 1 mg kg^?1 = pirimiphos-methyl 4 or 6 mg kg^?1 + bioresmethrin 1 mg kg^?1. All treatments completely prevented production of progeny in Sitophilus granarius (L.), Tribolium castaneum (Herbst), T. confusum Jackquelin du Val and Oryzaephilus surinamensis (L.). The biological efficacy of methacrifos was greater and the rate of degradation lower in aerated than in non-aerated storage. Residue levels of all compounds were determined chemically and were below proposed international residue levels to be considered by the Codex Alimentarius Commission.     

Contact and fumigant activities of constituents of Foeniculum vulgare fruit against three coleopteran stored‐product insects

The insecticidal activities of materials derived from the fruit of fennel, Foeniculum vulgare, against adults of Sitophilus oryzae, Callosobruchus chinensis and Lasioderma serricorne were examined using direct contact application and fumigation methods. The biologically active constituents of the Foeniculum fruits were characterized as the phenylpropenes (E)‐anethole and estragole, and the monoterpene (+)‐fenchone, by spectroscopic analysis. Responses varied with insect species, compound, dose and exposure time. In a filter paper diffusion test, estragole at 0.168 mg cm^?2 caused 91% mortality to S oryzae adults within 1 day after treatment (DAT), whereas (+)‐fenchone and (E)‐anethole gave over 90% mortality at 2 and 4 DAT, respectively. Against C chinensis adults, all test compounds revealed potent insecticidal activities at 0.021 mg cm^?2 at 2 DAT. Against L serricorne adults at 0.105 mg cm^?2, (E)‐anethole gave 100% mortality at 1 DAT, whereas 90 and 60% mortality at 4 DAT was achieved with estragole and (+)‐fenchone, respectively. In a fumigation test, the test compounds were much more effective against adults of S oryzae, C chinensis and L serricorne in closed cups than in open ones, indicating that the insecticidal activity of test compounds was largely attributable to fumigant action. As naturally occurring insect‐control agents, the F vulgare fruit‐derived materials described could be useful for managing field populations of S oryzae, C chinensis and L serricorne. © 2001 Society of Chemical Industry     

Composition and toxic, repellent and feeding deterrent activity of essential oils against the stored-grain pests Tribolium castaneum (Coleoptera: Tenebrionidae) and Sitophilus oryzae (Coleoptera: Curculionidae)

BACKGROUND: The composition and bioactivity of essential oils from Tagetes terniflora Kunth, Cymbopogon citratus Stapf. and Elyonurus muticus (Spreng) Kuntz were evaluated against stored‐grain pests. RESULTS: Fumigant and contact toxicities were observed with T. terniflora on adults of both pests. In contact toxicity, this oil was less toxic to Tribolium castaneum (Herbst). Essential oils from C. citratus and E. muticus showed contact toxicity on S. oryzae. All essential oils produced: (a) repellency on larvae and adults of T. castaneum and adults of Sitophilus oryzae (L.); (b) post‐ingestive toxicity on T. castaneum larvae and S. oryzae adults and alteration of nutritional index on T. castaneum and S. oryzae adults. Cymbopogon citratus reduced the relative growth rate and the efficiency of conversion of ingested food in T. castaneum larvae. Tagetes terniflora produced a feeding stimulant effect in T. castaneum adults. In addition, they had a feeding deterrent action against S. oryzae adults. The composition of essential oils from C. citratus and E. muticus varied only in one component. CONCLUSION: These results showed that the essential oils from T. terniflora, C. citratus and E. muticus should be studied further for their use in integrated pest management programmes for T. castaneum and S. oryzae control. Copyright © 2011 Society of Chemical Industry     

Ethyl formate plus methyl isothiocyanate--a potential liquid fumigant for stored grains

BACKGROUND: Methyl bromide is being phased out for use on stored commodities, as it is listed as an ozone‐depleting substance, and phosphine is the fumigant widely used on grains. However, phosphine resistance occurs worldwide, and phosphine fumigation requires a long exposure period and temperatures of > 15 °C. There is an urgent requirement for the development of a fumigant that kills insects quickly and for phosphine resistance management. This paper reports on a new fumigant formulation of 95% ethyl formate plus 5% methyl isothiocyanate as an alternative fumigant for stored grains. RESULTS: The formulation is stable for at least 4 months of storage at 45 °C. A laboratory bioassay with the formulation showed that it controlled all stages of Sitophilus oryzae (L.), Sitophilus granarius (L.), Tribolium castaneum (Herbst), Rhyzopertha dominica (F.), Trogoderma variabile Ballion and Callosobruchus maculatus (Fabricius) in infested wheat, barley, oats and peas at 80 mg L^?1 for 5 days, and in canola at both 40 mg L^?1 for 5 days and 80 mg L^?1 for 2 days at 25 ± 2 °C. After an 8–14 day holding period, residues of ethyl formate and methyl isothiocyanate in wheat, barley, peas and canola were below the experimental permit levels of 1.0 and 0.1 mg kg^?1. However, fumigated oats needed an 18 day holding period. CONCLUSIONS: The findings suggest that the ethyl formate plus methyl isothiocyanate formulation has potential as a fumigant for the control of stored‐grain insect pests in various commodities. Copyright © 2011 Society of Chemical Industry     

Synthesis and fungitoxic activity of 5‐aryl‐1‐formyl‐4,5‐dihydro‐3‐(2‐hydroxyphenyl)‐1H‐pyrazoles and their complexes

Cyclization of 3‐aryl‐1‐(2‐hydroxyphenyl)prop‐2‐en‐1‐ones with hydrazine hydrate in refluxing formic acid afforded the title ligands, 5‐aryl‐1‐formyl‐4,5‐dihydro‐3‐(2‐hydroxyphenyl)‐1H‐pyrazoles (HL¹–HL⁴, Ar = Ph, 4‐CH₃O‐C₆H₄‐, 2‐furyl, 2‐thienyl). Reaction of HL¹–HL⁴ with the divalent metal ions, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺, afforded novel complexes of the type [ML₂] (M = metal ion; L = deprotonated ligand) which were characterized by elemental analyses, molecular weight determinations, molar conductances, magnetic moments and electronic and infrared spectral data. The ligands behaved as tridentate, coordinating through the phenolic oxygen after deprotonation, N‐2 of the pyrazole ring and oxygen of the 1‐formyl group. The ligands and their complexes were evaluated for growth‐inhibiting activity against four phytopathogenic fungi. Macrophomina phaseoli was generally most sensitive followed by Alternaria alternata and Colletotrichum falcatum while Fusarium oxysporum was least sensitive to the tested compounds. The ligand HL¹ and its complexes showed the best activity against the fungi tested. © 2000 Society of Chemical Industry     

Fumigant toxicity of essential oils fromLaurus nobilis andRosmarinus officinalis against all life stages ofTribolium confusum

The essential oils from rosemary (Rosmarinus officinalis L.) and laurel (Laurus nobilis L.) obtained from Mersin Province in Turkey, were tested for their fumigant toxicity against all life stages of confused flour beetle (Tribolium confusum du Val.). GC-MS analysis showed that 1,8-cineole was found to be the major component of both rosemary and laurel essential oils. Vapors of rosemary and laurel essential oils were toxic to all life stages ofT. confusum. Only 65% mortality of the eggs was achieved when exposed to a dose of 172.6 mgl ⁻¹ air of rosemary essential oil at the longest exposure period (144 h); at the same dose, the pupae were the most resistant stage, with LT₉₀ (lethal time) value of 120.2 h. The adults were the most resistant stage to laurel essential oil, with LT₉₀ value of 77.2 h. On the basis of LT₉₀ values, tolerance of the life stages ofT. confusum to rosemary and laurel essential oils was, in descending order: pupa < larva < adult, and larva < adult < egg < pupa, respectively. Based on the concentration × time (Ct) products (g hl ⁻¹), rosemary essential oil was more toxic than laurel to the adults and larvae ofT. confusum. However, laurel essential oil was more toxic than rosemary to the eggs and pupae. Since these essential oils need such high Ct products to obtain complete mortality ofT. confusum compared with the most commonly used commercial fumigants, it would be impossible to use them on their own as a commercial fumigant against stored-product insects.     

Biological and biochemical aspects of the disruption of adult formation in Tribolium by a novel bis(thiocarbamate) R-31026 and the juvenoid R-20458

S,S-Di-isobutyl N ethylethylenebis(thiocarbamate) (R-31026) had a strong morphogenetic effect, acting by contact on the newly formed pupae of Tribolium confusum and Tribolium castaneum and thereby disrupting adult development. At a dietary concentration of 20 mg kg^?1, 95% of pupae of T. confusum produced pupa-adult intermediates; T. castaneum pupae were affected to a smaller extent. Topical application with 0.002 μg per 0–24-h-old pupa of T. confusum resulted in the formation of 88% malformed intermediates. The larvae brought into contact with R-31026 were not affected and pupated normally, hence the compound differs in its activity from that of a typical juvenile hormone compound. On the other hand, the pupal morphogenetic activity of R-31026 resembles that of the typical juvenoid compound 3-[5-(4-ethylphenoxy)-3-methylpent-3-enyl]-2,2-dimethyloxirane (R-20458). The progeny of the emerging adults from pupae treated with either R-20458 or R-31026 were strongly affected. The effective dosages were far below those required for pupal morphogenetic activity. Biochemical studies showed an increase in the soluble protein fraction during the pupal stage after treatment with either R-31026 or R-20458 indicating disturbances in protein build-up. The bis(thiocarbamate) R-31026 has more favourable practical properties than R-20458 for controlling agricultural insects, because it does not prolong the larval feeding stage.     

Fenitrothion plus (1R)-phenothrin,and pirimiphos-methyl plus carbaryl,as grain protectant combinations for wheat

Duplicate field trials were carried out on bulk wheat in commercial silos in Queensland and New South Wales. Laboratory bioassays on samples of treated grain at intervals over 9 months, using malathion-resistant strains of insects, established that treatments were generally effective. Fenitrothion (12 mg kg^?1)+ (1R)-phenothrin (2 mg kg^?1) was more effective than pirimiphos-methyl (6 mg kg^?1) + carbaryl (10 mg kg^?1) against Sitophilus oryzae (L.) and Ephestia cautella (Walker); the order of effectiveness was reversed for S. granarius (L.). Against Rhyzopertha dominica (F.), Tribolium castaneum (Herbst), T. confusum Jackquelin du Val and Oryzaephilus surinamensis (L.), both treatments effectively prevented the production of progeny. The order of persistence was pirimiphos-methyl> (1R)-phenothrin>carbaryl or fenitrothion. During processing from wheat to white bread, residues were reduced by 98% for carbaryl, >44% for (1R)-phenothrin, 98% for fenitrothion and 85% for pirimiphosmethyl.     

Long‐lasting β‐aminobutyric acid‐induced resistance protects tomato fruit against Botrytis cinerea

Minimizing losses to pests and diseases is essential for producing sufficient food to feed the world's rapidly growing population. The necrotrophic fungus Botrytis cinerea triggers devastating pre‐ and post‐harvest yield losses in tomato (Solanum lycopersicum). Current control methods are based on the pre‐harvest use of fungicides, which are limited by strict legislation. This investigation tested whether induction of resistance by β‐aminobutyric acid (BABA) at different developmental stages provides an alternative strategy to protect post‐harvest tomato fruit against B. cinerea. Soil‐drenching plants with BABA once fruit had already formed had no impact on tomato susceptibility to B. cinerea. However, BABA application to seedlings significantly reduced post‐harvest infection of fruit. This resistance response was not associated with a yield reduction; however, there was a delay in fruit ripening. Untargeted metabolomics revealed differences between fruit from water‐ and BABA‐treated plants, demonstrating that BABA triggered a defence‐associated metabolomics profile that was long lasting. Targeted analysis of defence hormones suggested a role of abscisic acid (ABA) in the resistance phenotype. Post‐harvest application of ABA to the fruit of water‐treated plants induced susceptibility to B. cinerea. This phenotype was absent from the ABA‐exposed fruit of BABA‐treated plants, suggesting a complex role of ABA in BABA‐induced resistance. A final targeted metabolomic analysis detected trace residues of BABA accumulated in the red fruit. Overall, it was demonstrated that BABA induces post‐harvest resistance in tomato fruit against B. cinerea with no penalties in yield.     

Toxicity and protectant potential of Piper guineense (Piperaceae) and Senna siamea (Fabaceae) mixed with diatomaceous earth for the management of three major stored product beetle pests

There is a dearth of knowledge on the available sources of botanical products for smallholder farmers in Africa and their bioactivity against stored-product pests. Many locally available plants across Africa exhibit both promising insecticidal, medicinal activity and are nutrient rich yet remain underutilized. Laboratory studies on toxicity of powders of Senna siamea and Piper guineense alone or combined with diatomaceous earth (DE) to adult Sitophilus granarius, Tribolium castaneum and Acanthoscelides obtectus were conducted in stored grains. Adult mortality was observed up to 7 d while progeny production was recorded 6–10 weeks. Adult A. obtectus were most susceptible (LD₅₀ 0.0084% and 0.0696% wt/wt for S. siamea and P. guineense, respectively), followed by S. granarius. T. castaneum was most tolerant (LD₅₀ 0.6589% and 0.6829% wt/wt for S. siamea and P. guineense, respectively). Combination of plant powders and DE controlled the beetles faster compared to the plant powders alone. LT₅₀ ranged from 20 h to 101 h for T. castaneum exposed to 1.0% S. siamea and 1.0% DE, and 0.5% P. guineense and 1.0% DE, respectively. Botanicals caused significant reduction of F₁ adults compared to the control. The potential of using botanicals combined with DE to control stored-product insects is discussed.     

A laboratory evaluation of the effectiveness of diflubenzuron against Dermestes maculatus De Geer and other storage insect pests

The chitin synthesis inhibitor diflubenzuron, applied as a wettable powder spray to woven polypropylene at 100–500 mg m^?2, was effective against Dermestes maculatus De Geer for at least 12 weeks. D. maculatus was unable to develop on ox hide dipped in a suspension of diflubenzuron (125 mg litre^?1), or on fishmeal dusted at 1–10 mg of active ingredient kg^?1. Diflubenzuron prevented the development of infestations of Callosobruchus maculatus (L.) on peas and of Acanthoscelides obtectus (Say) on beans dusted at 1–5 mg kg^?1. The compound was also very effective against early instar larvae of Trogoderma granarium Everts on wheat. The persistence and activity of diflubenzuron at low dosage rates against D. maculatus appear to justify larger scale trials.     

Efficacy of vaporised ethyl formate/carbon dioxide formulation against stored‐grain insects: effect of fumigant concentration,exposure time and two grain temperatures

BACKGROUND: The ethyl formate/carbon dioxide (CO₂) formulation Vapormate? is a rapid‐acting fumigant being developed for the control of stored‐grain insects. The effects have been investigated of concentration, exposure times of 1, 3, 24 and 72 h and two grain temperatures, 15 and 25 °C, on its efficacy against mixed‐stage cultures of Sitophilus oryzae (L.) Tribolium castaneum (Herbst) and strongly phosphine‐resistant Rhyzopertha dominica (F.) strain QRD569. RESULTS: High mortalities (≥92%) of mixed‐stage cultures of all three species were obtained when grain was fumigated with the formulation (193 g m^?3 ethyl formate) for 1 h. Complete control of R. dominica QRD569 and T. castaneum was achieved with 63 and 76 g m^?3 ethyl formate respectively, with exposure for 24 h, whereas mean mortality of S. oryzae was 86% under the same conditions. Mortalities of S. oryzae juvenile stages were significantly lower than adults under the conditions tested, which was due to pronounced tolerance of mid‐stage pupae to the fumigant. Reducing grain temperature from 25 to 15 °C had no effect on insect mortality. CONCLUSION: Ethyl formate/CO₂ formulation is highly effective against stored‐grain insects over a range of concentrations and exposure times. Efficacious fumigations were conducted in as little as 1 h, and a strongly phosphine‐resistant R. dominica strain was readily controlled with the fumigant. Copyright © 2009 CSIRO, Australia. Published by John Wiley & Sons, Ltd     

Insecticidal activity and mode of action of 2,4‐diaminopyrimidines

Three 2,4‐diaminopyrimidines were tested against several insect species. They were active against lepidopteran pests with LC₅₀ values <3 mg liter⁻¹ for most species tested. They were also active against two‐spotted spider mite, Tetranychus urticae, (LC₅₀ 10–40 mg liter⁻¹). Folinate, but not hypoxanthine or thymidine was found to be an effective rescue agent, requiring a concentration of 100 mg liter⁻¹ diet to rescue half of the intoxicated larvae. The results confirm dihydrofolate reductase to be the site of action for these insecticides and are consistent with the mode of action of folinate rescue in mammals. © 2000 Society of Chemical Industry     

The activity of some compounds extracts byAllium on stored-product insectsOryzaephilus surinamensis (L.),Sitophilus oryzae (L.) andTribolium castaneum (Herbst)

The bioactive metabolites of someAllium plants, all exhibiting interesting pharmacological activities, were tested for their attractive/repellent activity against saw-toothed grain beetle,Oryzaephilus surinamensis (L.), rice weevil,Sitophilus oryzae (L.), and rust-red flour beetle,Tribolium castaneum (Herbst), insects infesting the stored-products. The data obtained showed significant repellent effect of the thiosulfinates againstS. oryzae.