Acute toxicity of the bird repellent,methyl anthranilate,to fry of Salmo salar,Oncorhynus mykiss,Ictalurus punctatus and Lepomis macrochirus

Several laboratory and field studies have shown methyl anthranilate to be an effective, non-toxic and non-lethal bird repellent, with application potential for protecting crops, seeds, turf and fish stocks from bird damage. Furthermore, methyl anthranilate can be added to liquids for the purposes of protecting migratory birds, e.g. addition to waste water associated with mining and to standing water pools at airports. Mammalian toxicity data are favorable. Methyl anthranilate is used as a fragrance and food flavoring and is GRAS listed by the US Food and Drug Administration. Despite the favorable outlook for methyl anthranilate's use as a safe repellent, no data exist on its environmental fate and effects. We have tested the acute toxicity of methyl anthranilate in a static system against the fry of four species of fish. The LC₅₀ at 24 h for Atlantic salmon (Salmo salar L.) was 32.3 mg liter^?1, with the no observable effect limit at 6 mg liter^?1. The LC₅₀ at 24 h for rainbow trout (Oncorhynus mykiss Richardson) was 23.5 mg liter^?1, with the no observable effect limit at 5 mg liter^?1. The LC₅₀ at 24 h for channel catfish (Ictalurus punctatus Raf.) was estimated to be 20.1 mg liter^?1, with the no observable effect limit at 7 mg liter^?1. The LC₅₀ at 24 h for bluegill sunfish (Lepomis macrochirus Raf.) was estimated to be 19.8 mg liter^?1, with the no observable effect limit at 7 mg liter^?1..     

Acaricidal activities of Santolina africana and Hertia cheirifolia essential oils against the two-spotted spider mite (Tetranychus urticae)

BACKGROUND: Many plant essential oils show a broad spectrum of activity against pests. This study investigated the effects of two essential oils on Tetranychus urticae, one of the most serious pests in the world. RESULTS: The chemical composition of the two oils was characterised by GC‐MS. The most abundant component in the Santolina africana (Jord. & Fourr) oil was terpinen‐4‐ol (54.96%), while thymol (61%) was prevalent in the Hertia cheirifolia (L.) oil. Mortality and fecundity were measured upon treatment with oil concentrations ranging from 0.07 to 6.75 mg L^?1 with a Potter spray tower. Mite mortality increased with oil concentration, with LC₅₀ values of 2.35 mg L^?1 for S. africana and 3.43 mg L^?1 for H. cheirifolia respectively. For both oils, a reduction in fecundity was observed at concentrations of 0.07, 0.09 and 0.29 mg L^?1. Artificial blends of constituents of oils were also prepared and tested with individual constituents missing from the mixture. The results showed that the presence of all constituents was necessary to equal the toxicity of the two natural oils. CONCLUSION: S. africana and H. cheirifolia oils can provide valuable acaricide activity with significantly lower LC₅₀ values. Thus, these oils cause important mortality and reduce the number of eggs laid by females. Copyright © 2012 Society of Chemical Industry     

Effect of azadirachtin applied systemically through roots of plants on the mortality,development and fecundity of the cabbage aphid (<Emphasis Type="Italic">Brevicoryne brassicae</Emphasis>)

The effect of low concentrations of azadirachtin applied systemically through root tissues of rape plants (Brassica napus subsp.napus) on the mortality, period of development, longevity and fecundity of the cabbage aphid (Brevicoryne brassicae L.) (Sternorrhyncha: Aphididae) was studied. The concentrations of azadirachtin A tested were: 0.25, 0.05, 0.005, 0.0005 and 0.00005 mg ml⁻¹. The mortality of cabbage aphid nymphs, particularly during the period of ecdysis, increased significantly with increasing concentrations. Azadirachtin had no effect on the length of the development period of the respective immature stages of cabbage aphids. The average longevity of the cabbage aphids decreased with increasing azadirachtin concentration and time spent feeding. The fecundity of aphids decreased after the application of azadirachtin. http://www.phytoparasitica.org posting May 6, 2004.     

五种杀虫剂对苜蓿种子田中主要害虫和传粉昆虫的影响

为筛选高效、低毒的杀虫剂，测定1.5%除虫菊素、0.3%印楝素、4%阿维·啶虫脒、2.5%高效氯氟氰菊酯和70%吡虫啉5种杀虫剂对苜蓿种子田主要害虫牛角花齿蓟马Odontothrips loti和豌豆蚜Acyrthosiphon pisum的室内毒力和田间防效，并分析这5种药剂对主要传粉昆虫数量及多样性指数的影响。结果显示，0.3%印楝素对牛角花齿蓟马和豌豆蚜的毒力相对较高，LC₅₀分别为1.093 mg/L和2.864 mg/L。70%吡虫啉以及4%阿维·啶虫脒对牛角花齿蓟马和豌豆蚜均有较高的防效，最高防效均达到85.00%以上，但这2种药剂对传粉昆虫威胁较大，而0.3%印楝素则对传粉昆虫威胁较小。推荐花期苜蓿种子田使用0.3%印楝素1 000倍稀释液防控害虫，而非开花期可交替使用70%吡虫啉1 000倍稀释液和4%阿维·啶虫脒1 000倍稀释液防控害虫。     

Bioactivity of essential oils from leaves and bark of Laurelia sempervirens and Drimys winteri against Acyrthosiphon pisum

BACKGROUND: The pea aphid, Acyrthosiphon pisum (Harris), is a cosmopolitan pest that attacks a wide range of legume crops and vectors important plant virus diseases. In this project, essential oils from the leaf (L) and bark (B) of Laurelia sempervirens (Ruiz & Pavón) Tul. (L) and Drimys winteri JR Forster & G Forster (D) were extracted, and their deterrent and insecticidal activities were tested under laboratory conditions. RESULTS: By use of GC‐MS, safrole was found as the main constituent in LL and LB oils, while the main constituents were more diverse in DL and DB oils. In the deterrent bioassays with A. pisum under choice conditions, the four oils were active, with LL being the most active, followed by LB, DB and DL. The respective deterrence indices were 1.0, 0.89, 0.87 and 0.46 when aphids were exposed for 24 h to 4 µL mL^?1. Although there was no aphid mortality when oils were sprayed on faba bean leaves before aphid infestation, there was 58 and 42% mortality when settled aphids were directly sprayed with 4.0 µL mL^?1 of LL and LB respectively; DB and DL oils caused ≤18% mortality. In a third series, the essential oils of LL and LB caused 100% mortality when applied at a dose of 64 µL L^?1 air by fumigation to faba bean plants infested with A. pisum; at the same dose, DB and DL oils caused 68 and 63% mortality respectively. When fumigation was limited to 2 h, the respective LC₅₀ values for LL and LB oils were 10.6–14.3 µL L^?1 air and 9.8–13.2 µL L^?1 air. CONCLUSION: Because of their high deterrent and insecticidal activities, the essential oils from leaf and bark of L. sempervirens may be explored as potential natural aphicides. Copyright © 2010 Society of Chemical Industry     

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     

Residual toxicity and sublethal effects of chlorantraniliprole on Plutella xylostella (lepidoptera: plutellidae)

BACKGROUND: The diamondback moth (DBM), Plutella xylostella (L.), is the most important pest of cruciferous vegetables in the world. Chlorantraniliprole is a novel anthranilic diamide insecticide registered for the control of lepidopteran pests. The dose response, residual toxicity and sublethal effects of chlorantraniliprole applied for 48 h at LC₁₀ (0.02 mg L^?1) and LC₂₅ (0.06 mg L^?1) on P. xylostella were investigated. RESULTS: Leaf‐dip bioassays showed that chlorantraniliprole had a high level of toxicity against larvae of P. xylostella, and the 48 h LC₅₀ values were 0.23 and 0.25 mg L^?1 for a susceptible and field strain respectively. Chlorantraniliprole also had a long‐lasting effect when the larvae were exposed to chlorantraniliprole field sprayed on radish seedlings. Sublethal effects of chlorantraniliprole were indicated by reduced pupation, pupal weight and adult emergence rates. There was also an increase in the duration of female preoviposition period, decreased fecundity and egg hatch and decreased survival rates of the offspring. The mean values of the net reproductive rate (R₀), intrinsic rate of increase (r_m), finite rate of increase (λ) were significantly lower in the treatment than in control groups. CONCLUSIONS: These results indicate that chlorantraniliprole is effective against P. xylostella. The sublethal concentrations of chlorantraniliprole may reduce the population growth of P. xylostella by decreasing its survival and reproduction, and by delaying its development. Copyright © 2012 Society of Chemical Industry     

Effect of the ecdysone agonists,RH-2485 and tebufenozide,on the southwestern corn borer,Diatraea grandiosella

The effect of the ecdysone agonists RH-2485 (proposed name methoxyfenozide) and tebufenozide (RH-5992), was examined on eggs and larvae of the southwestern corn borer, Diatraea grandiosella Dyar. Both compounds exhibited a concentration-dependent ovicidal activity. More than 95% of eggs died when egg masses were dipped in solutions of 100 or 200 mg liter^-1 of either compound in acetone+distilled water (1+1 by volume). Although some eggs treated with 1 or 10 mg liter^-1 of the compounds hatched, the survival rate was low. Newly hatched larvae were fed for seven days on an artificial diet containing RH-2485 or tebufenozide. The LC₅₀ values were 0·049 mg kg^-1 for RH-2485 and 0·185 mg kg^-1 for tebufenozide, showing that RH-2485 was about four times more active than was tebufenozide. Although increasing the time of exposure to either compound decreased the LC₅₀ value significantly, the relative potency of RH-2485 versus tebufenozide was not changed. Newly ecdysed 4th-instar larvae fed with diets containing 0·125, 0·25 or 0·5 mg kg^-1 RH-2485 or tebufenozide ceased feeding approximately 8 h after exposure, indicating that larvae had prematurely entered a molting cycle. Larvae treated with RH-2485 ecdysed earlier and died more quickly than those treated with tebufenozide. Ingestion of sublethal concentrations of RH-2485 (0·005 and 0·01 mg kg^-1) or tebufenozide (0·03 and 0·06 mg kg^-1) retarded larval growth, and decreased pupal weight and adult emergence. Increasing exposure time to tebufenozide tended to increase the larval mortality, significantly retarded larval growth, and decreased the mean weights of male and female pupae and adult emergence. RH-2485 (0·125 and 0·25 mg kg^-1) and tebufenozide (0·25 and 0·5 mg kg^-1) were lethal to newly hatched larvae, even after diets containing these compounds were held for 20 days at 30°C under long days (16 h light: 8 h dark). Our results suggest that field trials to assess the potential of RH-2485 and tebufenozide to control D. grandiosella are warranted. © 1998 SCI     

Triterpene saponins of Quillaja saponaria show strong aphicidal and deterrent activity against the pea aphid Acyrthosiphon pisum

BACKGROUND: Saponins are a class of secondary plant metabolites consisting of a sugar moiety glycosidically linked to a hydrophobic aglycone (sapogenin) that often possess insecticidal activities. Four saponins were selected: two triterpene saponins, Q. saponaria saponins and aescin, and two steroidal saponins, digitonin and diosgenin. Their effects were investigated on an important pest species and a model piercing‐sucking insect, the pea aphid Acyrthosiphon pisum. The triterpene Q. saponaria saponins bark saponin received special attention because of its high activity. Aphids were challenged by oral and contact exposure to demonstrate aphicidal activities, and in choice experiments to support use as a natural deterrent. RESULTS: When aphids were exposed to supplemented artificial diet for 3 days, a strong aphicidal activity was recorded for three of the four saponins, with an LC₅₀ of 0.55 mg mL^?1 for Q. saponaria saponins, 0.62 mg mL^?1 for aescin and 0.45 mg mL^?1 for digitonin. The LT₅₀ values ranged between 1 and 4 days, depending on the dose. For diosgenin, only low toxicity (14%) was scored for concentrations up to 5 mg mL^?1. In choice experiments with treated diet, a deterrence index of 0.97 was scored for Q. saponaria saponins at 1 mg mL^?1. In contrast, direct contact showed no repellent effect. Spraying of faba bean plants with Q. saponaria saponins resulted in an LC₅₀ of 8.2 mg mL^?1. Finally, histological analysis in aphids fed with Q. saponaria saponins demonstrated strong aberrations of the aphid gut epithelium, and exposure of midgut CF‐203 cell lines to Q. saponaria saponins in vitro confirmed the cytotoxic effect. CONCLUSIONS: The present insect experiments provide strong evidence that saponins, as tested here with triterpene Q. saponaria saponins, can be useful as natural aphicides and deterrents. Furthermore, the insect midgut epithelium is suggested to be a primary target of saponin activity.Copyright © 2011 Society of Chemical Industry     

Susceptibility of tomato borer,Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) populations from Turkey to 7 different insecticides in laboratory bioassay

The tomato borer, Tuta absoluta (Meyrick), was first recorded in Turkey in August 2009 and rapidly became a serious pest in the Mediterranean and Aegean coastal regions in field and greenhouse grown tomatoes. Currently, insecticides are considered one of the major tools for the management of T. absoluta in Turkey. This study, investigated the efficacy of 7 different insecticides, against T. absoluta in laboratory bioassays. To determine the lethal concentration (LC) values and feeding activity of the larvae, tomato leaf parts mined by 1–3 day old L1 larvae were dipped into different insecticide concentrations. Mortality was recorded 5 days after insecticide treatments. Spinosad, chlorantraniliprole + abamectin or indoxacarb treatment resulted in 100% mortality with minimal or no feeding in all populations at their recommended doses of 120, 50.4 and 60 mg a.s. L^?1, respectively. In general, the LC₉₉ values of populations for these insecticides were similar and also lower than that of the recommended field doses. The effect of pyridalyl was low, resulting in low mortality with serious feeding damage at the dose of 125 mg a.s. L^?1. The efficacies of abamectin, metaflumizone and azadirachtin were found to be moderate to low at the recommended doses (4.5, 240 and 50 mg a.s. L^?1, respectively). However, these insecticides may affect pupation and adult emergence rates hence further studies are recommended to investigate these insecticides.     

Laboratory evaluation of the insect growth regulator lufenuron againstHelicoverpa armigera on cotton

An insect growth regulator (IGR), lufenuron (Match 5EC), was tested for its toxicity toHelicoverpa armigera on cotton. Potency of the IGR against the larval stage of the pest was demonstrated with respect to larval instars; the LC₉₀ values of 1st, 2nd, 3rd, 4th and 5th instar larvae were 5.63, 7.89, 8.03, 11.39 and 14.76 mg a.i.l ⁻¹, respectively. However, different larval instars did not differ significantly with respect to LC₅₀ and LC₁₀. IGR-treated larvae had swollen heads and were significantly smaller (1.5–2.3 mm) than the untreated control (2.9 mm). Larval weight was significantly reduced from 190 mg in the control to 50–70 mg in the lufenuron treatment. IGR treatment in the larval stage significantly affected both pupal length and pupal weight. Pupal duration of the test insect was significantly extended by IGR treatment. Pupal deformities, including an inability to shed the last larval skin and formation of larval-pupal intermediates, occurred following treatment. A significant reduction in adult emergence was recorded. In addition, abnormalities in the form of development of cavities in the forewings of adult were evident. A significant decline in fecundity was noted in the studies. http://www.phytoparasitica.org posting Feb. 3, 2003.     

Monitoring for imidacloprid resistance in the tobacco‐adapted form of the green peach aphid,Myzus persicae (Sulzer) (Hemiptera: Aphididae), in the eastern United States

BACKGROUND: Imidacloprid is the primary insecticide for controlling the tobacco‐adapted form of the green peach aphid (TGPA), Myzus persicae (Sulzer), a major pest of tobacco worldwide. This study used leaf‐dip bioassays to assess TGPA resistance to imidacloprid in the eastern United States from 2004 through 2007. RESULTS: When combined over the 4 year study, 18, 14 and 3% of the TGPA had imidacloprid resistance ratios (RRs) of 10–20‐fold, 20–30‐fold and 30–90‐fold, respectively, compared with the most susceptible colony tested. This indicates that some colonies have developed moderate levels of resistance to imidacloprid. A colony collected near Clayton, North Carolina, had the highest RR of 91 (LC₅₀ value = 31 mg L^?1). This resistance declined for six tests over a 3 year period in the laboratory culture from >130‐fold RR (LC₅₀ = 48 mg L^?1) to 40‐fold RR (LC₅₀ = 15 mg L^?1). Over the same period, the most susceptible colony and a standard colony not exposed to imidacloprid for over 7 years had consistently low LC₅₀ values. CONCLUSION: Moderate levels of resistance to imidacloprid are noticed among TGPA colonies from the eastern United States. The variation in resistance indicates that the factors responsible are present in the populations at low frequencies and are just not enough to cause field failures yet. Copyright © 2010 Society of Chemical Industry     

Organosilane insecticides. Part I: Biological and physical effects of isosteric replacement of silicon for carbon in etofenprox and MTI-800

Substitution of silicon for carbon was explored in etofenprox and MTI-800, primarily to establish the suitability of silicon for pesticide construction and to probe steric effects. It was shown that silicon is an effective building block for insecticides with subtle qualitative and quantitative differences relative to the carbon analogs. The silanes were slightly less toxic to insects than the carbon analogs (relative potency of 0.2-0.6) but the silane analog of MTI-800 was considerably less toxic to fish (0% mortality at ≥50 mg liter^?1) than MTI-800 itself (LC₅₀ = 3 mg liter^?1). The mode of action of both carbon and silicon compounds was similar in the intact, electrode-implanted cockroach and involved repetitive firing of a sensory nerve; potency measurements were also made using an in-vitro nerve assay. The possible metabolic and physicochemical contributions to the observed insecticide potencies were explored using synergism studies, physical chemistry measurements and quantum mechanical calculations.     

Bioactivity of short-chain aliphatic ketones against adults of the granary weevil, Sitophilus granarius (L.)

BACKGROUND: The granary weevil, Sitophilus granarius (L.), is one of the most damaging pests of stored grains, causing severe quantitative and qualitative losses. Sustainable control means, alternative to the commonly used fumigants and broad‐spectrum contact insecticides, are urgently needed owing to legislative limits, the development of resistant insect strains and increasing consumer demand for safe food. Short‐chain aliphatic ketones, known to be emitted by cereal grains and previously identified as repellents to adult granary weevils, were evaluated for their ability to disrupt insect orientation towards wheat grains and as possible natural fumigants. RESULTS: In behavioural bioassays, 2‐pentanone, 2‐hexanone, 2‐heptanone and 2,3‐butanedione significantly reduced insect orientation towards odours of wheat grains, with 2‐hexanone and 2‐heptanone being the most active. In fumigation tests, all compounds were effective in killing weevil adults, but they performed differently according to chemical structure, speed of action and presence of wheat grains. In the presence of grains, the highest fumigant toxicity was shown by 2‐pentanone (LC₅₀ = 8.4 ± 1.0 mg L^?1) after 24 h exposure, and by 2‐pentanone (LC₅₀ = 4.5 ± 0.3 mg L^?1), 2‐heptanone (LC₅₀ = 7.1 ± 0.3 mg L^?1) and 2‐hexanone (LC₅₀ = 8.1 ± 0.6 mg L^?1) 1 week after the treatment end. CONCLUSION: Short‐chain aliphatic ketones have potential for applications in IPM programmes for the granary weevil because of their behaviour‐altering activity and fumigant toxicity. Copyright © 2011 Society of Chemical Industry     

亚致死浓度毒死蜱对小麦禾谷缢管蚜生长和繁殖的影响

为探讨毒死蜱对小麦禾谷缢管蚜Rhopalosiphum padi(Linnaeus)的亚致死效应,采用玻璃管药膜法确定了其亚致死浓度(LC10、LC20和LC30),并研究了该浓度下毒死蜱对小麦禾谷缢管蚜生长和繁殖的影响。结果表明:以LC10、LC20和LC30浓度处理后,禾谷缢管蚜成蚜的寿命分别为(8.60±0.22)、(8.03±0.18)和(6.68±0.18)d,均显著短于对照的(10.36±0.31)d;单雌产仔量分别为(21.88±0.63)、(20.41±0.53)和(16.68±0.35)只,也均显著少于对照的(26.40±0.89)只;产仔历期分别为(7.55±0.22)、(6.69±0.17)和(5.64±0.15)d,均显著短于对照的(9.13±0.31)d;试验浓度药剂处理对下一代若蚜期的影响不显著;LC30浓度处理对下一代成蚜繁殖有显著的抑制作用,可减少单雌产仔量3.74只,缩短产仔历期1.39 d。生命表参数分析表明:LC30浓度毒死蜱处理使小麦禾谷缢管蚜的净增殖率(R0)比对照降低了34.71%,使种群加倍时间(t)比对照延长了17.37%;LC20浓度处理使小麦禾谷缢管蚜的平均世代历期(T)延长了12.59%;LC10浓度处理组各项指标与对照间无显著性差异。研究表明,亚致死浓度毒死蜱能够缩短小麦禾谷缢管蚜成蚜的寿命,降低其繁殖力,该结果对小麦禾谷缢管蚜综合防治策略的制定具有积极意义。     

Laboratory Evaluation of the Novel Naturally Derived Compound Spinosad against Ceratitiscapitata

Laboratory studies were conducted to determine the effect of the naturally derived compound spinosad on Ceratitis capitata Wied. (Diptera, Tephritidae). The organophosphate fenthion was used as a standard. Direct dose-dependent mortality and reduced fecundity were observed in oral treatment of adults with spinosad. The LC₉₀ values 14 h and seven days after treatment were 19·50 and 0·49 mg litre⁻¹ respectively. Fenthion was less active (the LC₅₀ eight days after treatment was 1·17 mg litre⁻¹) and did not affect the fecundity of the fly. Adults were also very susceptible to spinosad and fenthion via residual contact. For spinosad, 100% mortality was recorded 48 h after treatment for a dose of 10 mg litre⁻¹. Spinosad was more effective than fenthion in suppressing larval development when neonate larvae were reared on treated diet supplemented with a range of concentrations from 0·02 to 0·83 mg kg⁻¹ diet. Last-instar larvae were much less susceptible to spinosad or fenthion when exposed via dipping or when they pupated in treated medium and both products had similar performance. A lack of ovicidal activity was observed in direct egg-treatments with spinosad but significant reductions from 1 mg litre⁻¹ onwards were recorded for fenthion.     

Effects of sublethal concentrations of deltamethrin on fitness of white-backed planthopper,Sogatella furcifera (Horváth)

Sogatella furcifera (Horváth) is one of the most important migratory pests of rice in Asia. When normal concentrations of deltamethrin are applied to control lepidopteran pests of rice in the field, it is likely that S. furcifera will be exposed to sublethal concentrations of this chemical. Therefore, we examined the sublethal effects of deltamethrin on the development and reproduction of S. furcifera using the rice stem dipping method. The results showed that exposure of 3rd instar S. furcifera to LC₁₀ and LC₂₅ deltamethrin significantly increased the emergence rates compared with the F₀ generation control group, but there was no significant difference in the nymphal stage duration, adult longevity and female fecundity. Nymphal duration of the F₁ generation was significantly prolonged under both treatments. Female fecundity also increased in this generation, with a significant difference between the LC₂₅ treatment group and controls. The relative fitness of the LC₁₀ and LC₂₅ treatment groups was 0.84 and 0.80, respectively. The results showed that sublethal concentrations of deltamethrin stimulate the reproduction of S. furcifera, but decrease the relative fitness of the population. These results provided a reference point for the application of insecticides to control S. furcifera.     

Toxicity of δ‐phenothrin and resmethrin to non‐target insects

BACKGROUND: The susceptibility of adult house cricket, Acheta domesticus (L.), adult convergent lady beetle, Hippodamia convergens (Guérin‐Méneville), and larval fall armyworm, Spodoptera frugiperda (JE Smith), to resmethrin and δ‐phenothrin synergized with piperonyl butoxide (PBO) was evaluated in a laboratory bioassay procedure. RESULTS: The 1 day LC₅₀ values for resmethrin + PBO were 23.2, 32.08 and 307.18 ng cm^?2 for A. domesticus, H. convergens and S. frugiperda respectively. The 1 day LC₅₀ values for δ‐phenothrin + PBO were 26.9, 74.91 and 228.57 ng cm^?2 for A. domesticus, H. convergens and S. frugiperda respectively. The regression relationship between species mortality and concentration explained 51–81% of the variation for resmethrin + PBO and 72–97% of the variation for δ‐phenothrin + PBO. The LC₅₀ values decreased with time for these insecticides for all surrogate species. In terms of sensitivities among the insects to resmethrin + PBO and δ‐phenothrin + PBO, A. domesticus was most sensitive, followed by H. convergens and then S. frugiperda. CONCLUSION: The results indicate that resmethrin + PBO was generally more toxic than δ‐phenothrin + PBO. Based on the results, A. domesticus seems to be a good surrogate species for estimating potential non‐target terrestrial insect impacts from exposure to pyrethroids used in public health applications. Copyright © 2008 Society of Chemical Industry     

噻虫嗪对白背飞虱试验种群繁殖力的亚致死效应

为探究噻虫嗪对白背飞虱的亚致死效应,采用稻茎浸渍法以噻虫嗪亚致死浓度LC_(10)和LC_(25)胁迫白背飞虱3龄若虫,测定了F_0代和F_1代若虫的存活率、雌成虫寿命和产卵量,并组建了F_1代种群相对适合度生命表。结果表明,经噻虫嗪亚致死浓度胁迫后,F_0代白背飞虱若虫的发育历期延长,存活率降低,并且LC_(10)处理组的F_0代雌成虫寿命比对照组显著延长,而成虫产卵量无显著变化;F_1代的若虫发育历期比对照组显著延长,且产卵量有所减少,LC_(10)处理组雌成虫产卵量比对照组减少了22.24,LC_(25)处理组比对照组减少了69.96,且差异显著;LC_(10)和LC_(25)亚致死浓度处理后F_1代的种群增长趋势指数均下降,种群相对适合度分别下降了0.12和0.36。研究表明,噻虫嗪亚致死浓度胁迫均可抑制白背飞虱的种群增长。     

Effects of sublethal concentration of diazinon,fenitrothion and chlorpyrifos on demographic and some biochemical parameters of predatory bug,Andrallus spinidens Fabricius (Hemiptera: Pentatomidae) in laboratory conditions

Effects of three insecticides, diazinon, fenitrothion and chlorpyrifos on Andrallus spinidens Fabricius (Hemiptera: Pentatomidae), a predator of lepidopterous larvae in rice fields were investigated. The insecticides were applied topically at lethal dose (LD₃₀) on the fifth instar nymphs of A. spinidens and evaluated on life table and some biochemical parameters of the predatory bugs. The results showed that pre-oviposition period, fecundity and longevity of treated bugs were significantly affected compared with the control. Analysis of life table parameters of A. spinidens revealed adverse effects of insecticides on net reproductive rate (R₀), intrinsic rate of increase (r), finite rate of increase (λ), doubling time (DT) and mean generation time (T). Among the tested insecticides, fenitrothion was the most toxic insecticide. The lowest value of r was 0.060 day^?1 in fenitrothion. Effects of insecticides on the detoxification enzymes showed that all compounds had inhibitory effect on esterases, acetylcholinesterases and glutathione S-transferases. According to this study, the insecticides cause harmful effects on demographic and biochemical parameters of A. spinidens and are not compatible with the predatory bug even at sublethal concentration.