Influence of block and cell size,growing medium and insecticide dose on the behaviour and uptake of phorate by lettuce and uptake of carbofuran and chlorfenvinphos by calabrese

Phorate residues in peat blocks and lettuce were determined following incorporation of the insecticide into different block and ‘Speedling’ cell sizes. Between-block variability was influenced little by block size. Phorate oxidation was most extensive in the largest blocks containing the smallest dose. Total residue concentrations in the lettuce declined from the time of planting to harvest, although accumulation of insecticide continued and was related more to dose than to block or cell size. Residues in the lettuce at harvest exceeded the proposed maximum limit of 0.2 mg kg^?1 in some treatments. Residues at planting comprised mainly the parent sulphoxide and sulphone, but by harvest, the oxygen analogue sulphoxide and sulphone predominated. Lettuce weight was not influenced by dose but was related directly to block size. Carbofuran and chlorfenvinphos residues were determined in calabrese sown into two sizes of blocks. At planting time, carbofuran residue concentrations were 100 times greater than those of chlorfenvinphos but residues of both insecticides in the mature heads were < 0.01 mg kg^?1. Seedling weights in both sowings declined with increasing concentrations of the insecticides. It was concluded that manipulations of block size and the dose of insecticide need to be evaluated for individual insecticide/crop combinations to exploit the technique fully.     

Persistence and degradation of chlorfenvinphos,diazinon, fonofos and phorate in soils and their uptake by carrots

Analytical methods are described for the determination of residues of chlorfenvinphos, diazinon, fonofos and phorate in soils and carrots. The insecticides, applied in June 1969 at 2 kg (a.i.)/ha, persisted longer in peaty loam than in sandy loam. After 7 months, the sandy loam contained 1% of the applied diazinon and 20–30% of the applied chlorfenvinphos, fonofos and phorate, the latter as its sulphone; the corresponding figures for the peaty loam were 10, 40–50, 40–50 and 30–40% respectively. None of the residues showed any substantial change from October to January. Although high initial concentrations (up to 50 ppm) of the residues in carrots were diluted by plant growth, it is shown that concentrations >1 ppm could be present in marketable crops 12–14 weeks after application at recommended rates. Carrots harvested 26 weeks after sowing contained <0.2 ppm of all insecticides. In contrast, during the first 15 weeks of crop growth the weights of residues in the carrots increased and remained approximately proportional to the square root of the carrot mean weight. Rates of uptake declined as carrot growth declined and subsequently the amounts of chlorfenvinphos, diazinon and fonofos residues in the carrots changed very little, while phorate sulphone steadily declined.     

Control of wireworms with organophosphorus and carbamate insecticides

Carbaryl, chlorfenvinphos, diazinon, disulfoton, parathion, phorate, fenitrothion, thionazin and trichlorphon were tested for their effectiveness in killing wireworms by broadcast treatments. Each insecticide was tested once or more in two field trials cropped with wheat and two cropped with potatoes. Phorate and parathion were very lethal to wireworms at 4 Ib active ingredient per acre (4–48 kg/ha). Thionazin and diazinon were intermediate in effectiveness and the other insecticides ineffective.     

The Efficacy and Residual Toxicity of certain Granular Insecticides against Mustard Aphid,Lipaphis erysimi (Kalt)

Abstract

The systemic activity of four granular insecticides (phorate 10%, Temik 10%, diazinon 5% and Sevidol [8% carbaryl + 8% gamma-BHC]) was evaluated for the control of mustard aphid, Lipaphis erysimi (Kalt). The granules were applied in the soil to one month old mustard plants transplanted in pots. 3rd and 4th instar nymphs were used for the trial. Mortality counts were made 24 hours after release. Of the insecticides tested, phorate and Temik at 1 lb a.i./ac proved most effective. Temik had a quick knockdown effect as compared to phorate, as it gave 100% control within 24 hours, while with phorate 100% kill was obtained only after 72 hours. Diazinon at 4 lb a.i./ac gave 83.3% kill after 72 hours. Sevidol proved ineffective as an aphidicide. Residual toxicity of three of the granular insecticides, namely phorate, Temik and diazinon, was tested. Phorate and Temik at 1 lb a.i./ac exhibited the same residual toxicity up to 4 weeks, i.e. 100% and 76% kill obtained at the end of 2 and 4 weeks respectively. Although the toxicity of both pesticides gradually declined there was no significant difference in percentage kill over a period of 5 weeks. After 6 weeks, however, the mortality recorded with Temik was 37.1% and with phorate was 51.1%. The residual toxicity of phorate was further found to last up to 8 weeks, when the mortality obtained was 40%. The residual toxicity of diazinon sharply declined within 2 weeks.     

Persistence and degradation of chlorfenvinphos,chlormephos, disulfoton,phorate and pirimiphos-ethyl following spring and late-summer soil application

Granular formulations of chlorfenvinphos, chlormephos, disulfoton, phorate and pirimiphos-ethyl were broadcast at 2 kg a.i./ha and incorporated to 100 mm into a sandy-loam soil either in May or in September 1971. The relative persistence of their residues, including insecticidally active oxidation products, after both application dates was disulfoton > chlorfenvinphos > phorate > pirimiphos-ethyl > chlormephos. When applied in September all the insecticides persisted for longer than when applied in May. Degradation was slower during the winter while the mean soil temperature at 100 mm depth remained below 6 to 7°C. Rising soil temperature in the following spring rapidly increased the rates of degradation of chlorfenvinphos, chlormephos and pirimiphos-ethyl residues but not of disulfoton- and phorate-derived residues, predominantly the parent sulphones, which had been leached deeper. Ten months after the September application, half the total residues derived from disulfoton and phorate were found below the initial incorporation depth, whereas the other insecticides showed relatively little downward movement. It was concluded that late summer/early autumn applications for carrot fly control would leave appreciable residues of some insecticides in the soil at the beginning of the next growing season which may contribute to the terminal residues in crops. These would be minimised if moderately persistent compounds were used or if doses of persistent ones were substantially reduced.     

Effects of placement and distribution on the performance of granular formulations of insecticides for carrot fly control

Effects of granule distribution relative to carrot rows are discussed and further results described. Placing insecticides 5 to 10 cm deep 7.5 cm away from the centre line of the carrot row usually, but not always, improved their performance compared with bow-wave applications. Both sides of the row need to be protected. The efficiency of chlorfenvinphos in a sandy loam, and phorate in a peaty-loam, decreased with increasing distance from the row but they were slightly effective even 19 cm away. The optimum depth for side-placing granules at sowing time varied from 5 to 10 cm, and combining side-placement with a bow-wave application did not greatly enhance efficiency. The most effective combination on a peaty-loam was a bow-wave application of 3 kg phorate/ha at sowing time followed 6 to 9 weeks later by a similar amount side-placed 7.5 cm deep 7.5 cm from the row centre. Comparison of the performance of phorate broadcast, applied by the bow-wave method or deep side-placed indicated that efficiency was improved by restricting the granule distribution but that higher concentrations of granules were then needed in the treated zones to be equitoxic with more uniformly broadcast granules. Uptake by the carrot root system is an important factor in the action of insecticides against carrot fly larvae.     

Uptake of chlorfenvinphos and phorate from soil by carrots as influenced by mode of application and cultivar

Granular formulations of chlorfenvinphos and phorate were applied to sandyloam soil at 2 kg a.i./ha either broadcast and incorporated to 2.5 cm, broadcast and incorporated at 10 cm or by the bow-wave method along the carrot rows. Depth of incorporation did not influence the rates of residue decline in the soil. Bow-wave applications produced the highest residues in root and foliage and also reduced the rate of oxidation of phorate. 30 weeks after sowing the carrots, all treatments gave the highest residue concentrations in the uppermost 6 cm of carrot root. The peel of carrots grown in the soil treated to a depth of 10 cm contained 88 % and 23 % of the total chlorfenvinphos and phorate residues respectively. Significant differences were found in the residue concentrations in five carrot cultivars treated with chlorfenvinphos and phorate by the bow-wave method at 1.5 kg a.i./ha. The concentrations were inversely correlated with root size so that amounts of insecticide (μg/carrot) were similar in all cultivars. Prolonged growth of cv. Norfolk Giant slightly extended the period of uptake of chlorfenvinphos, but the uptake of phorate was ultimately less than its rate of dissipation. Neither the method of application nor the selection of carrot cultivar extended the period of uptake very greatly but differences which were obtained in residue concentrations in the carrot may become significant in the event of regulatory control of residue levels.     

Effects of phorate placement on carrot fly control,seedling density and terminal residues in the crop

The application of granules containing 10 % phorate at 1.12,2.24 or 4.48 kg a.i./ha in a narrow slit together with carrot seed significantly reduced seedling emergence in both a mineral and peat soil. When the granules were applied at 2.24 or 4.48 kg a.i./ha in a narrow slit 2.5 cm below the seed, seedling emergence was adversely affected only at the higher rate in the mineral soil. Phorate granules applied with the seed in the peat soil gave a significantly lower plant density than when applied below the seed, but subsequent carrot yields were unaffected because much larger roots were produced. All phorate treatments gave effective reduction of carrot fly larval damage to the roots. On the peat soil, there were significant increases in total phorate residues present in mature carrots with increasing rate of phorate granules placed with the seed. Placement of the granules 2.5 cm below the seed resulted in a 50% reduction in total residues of phorate in whole carrots compared with placing the granules with the seed. Residues resulting from 1.12 kg a.i./ha with the seed or 2.24 kg a.i./ha 2.5 cm below the seed were not significantly greater than residues in untreated carrots.     

4种杀虫剂对花生蛴螬的防治效果及农药残留研究

测定了35%辛硫磷微囊悬浮剂、25%毒死蜱微囊悬浮剂、10%二嗪磷颗粒剂、3%辛硫磷颗粒剂4种常用防治蛴螬杀虫剂在播种期和开花下针期使用对花生的保果效果和防虫效果。结果表明：25%毒死蜱微囊悬浮剂和35%辛硫磷微囊悬浮剂播种期使用的保果效果与防虫效果均优于开花下针期;而10%二嗪磷颗粒剂、3%辛硫磷颗粒剂开花下针期使用的保果效果和防虫效果均优于播种期。花生收获后对果仁的农药残留分析结果表明：在试验剂量下,各农药处理后花生仁中的农药残留水平均在0.01 mg/kg以下,符合日本肯定列表对各类农药残留限量的要求。     

Dissipation rates of insecticides in six minor vegetable crops grown on organic soils in Ontario,Canada

Dissipation rates of diazinon, endosulfan, leptophos, methamidophos, methomyl, parathion and pirimicarb were studied on five minor vegetable crops, including cos and head lettuce, endive, cauliflower and Chinese cabbage. Residues from foliar treatment generally followed an exponential rate of decline. The number of days for residues to drop to below acceptable tolerances was highly dependent on the magnitude of the initial residue; large variations in initial residues were observed between years, between insecticides, and between crop types. Residues of five insecticides and two fungicides used in furrow treatments for onions intended for pickling were determined in the onions at harvest and after pickling. Fensulfothion and fonofos levels were below the accepted tolerance of 0.1 mg kg^?1 at harvest, while chlorfenvinphos, chlorpyrifos and ethion were present above this level; fungicide residues were not detected. Following pickling, only ethion residues were still present in the onions at levels greater than 0.1 mg kg^?1.     

Insecticide granules in mushroom culture

In laboratory tests, chlorfenvinphos granules were distributed in various ways in mushroom casing (a peat/chalk mixture) to relate efficiency of mixing to effectiveness against larvae of Lycoriella auripila. Amounts giving complete control when thoroughly mixed, killed only 40% when “clumped”. Whenever untreated patches were provided, some larvae survived. Pulverising granules, however, improved control in thorough mixes. By using fluorescent granules it was found that insecticide incorporation in mushroom compost was very irregular after mixing in a spawning machine. At best, only half the compost was acceptably treated; that is, it received between a half and double the intended dose.     

Dislodgeable residues and persistence of diazinon,chlorpyrifos and isofenphos following their application to turfgrass

In laboratory experiments, residues of diazinon applied to turfgrass, Poa pratensis L., that could be dislodged by rubbing with cheese-cloth, declined from c. 10% of the total applied when the grass was vigorously rubbed immediately after application to 0.3% after 1 day. Sunlight did not influence the rate of decline in dislodgeable residues or residues remaining on or within the leaf blades. In field experiments where 4.5 kg ha^?1 of diazinon was applied in liquid or granular form, about 20 times more diazinon was dislodged from the liquid formulation immediately after application than from the granular. By 1 day after application the percentage of the total applied diazinon that could be dislodged was equal for both formulations. Rainfall had a significant effect on the amount dislodged from grass blades, but mowing did not. Similar rates of decline in the dislodgeable fraction of diazinon, chlorpyrifos and isofenphos were observed in field experiments. Recovery of the dislodgeable fraction declined to 0.25% or less of the total amount of any of these insecticides by 1 day after application. However, residues in the thatch remained sufficiently high for control of insects for up to 7 days after application for diazinon and 14 days for chlorpyrifos and isofenphos.     

Residue levels of three organophosphorus insecticides in sweet pepper grown in commercial greenhouses

The degradation rates and residue levels of diazinon, pirimiphos-methyl and chlorpyrifos in the leaves and fruits of pepper plants grown in commercial greenhouses were studied using g.l.c. Analysis of leaves at intervals following application showed that the initial residue of diazinon was higher than that of the other two insecticides, while its dissipation rate was faster. The dissipation of chlorpyrifos in fruits was faster than diazinon. The maximum residue levels (m.r.l.) of diazinon (0.5 mg kg^?;1) and chlorpyrifos (0.1 mg kg^?;1) were reached after 13 and 8 days of application respectively. With diazinon and pirimiphos-methyl, sprayed 3 weeks before inflorescence, very low concentrations of both insecticides were found in fruits, although these compounds have no systemic behaviour. Chlorpyrifos residue level of 0-2 mg kg ^?;1 in harvested fruits did not drop below m.r.l. after 11 days holding period.     

Uptake of phorate by lettuce

Following experimental and commercial applications to soil of a granular formulalation of phorate (O,O-diethyl S-ethylthiomethyl phosphorodithioate), residues in the soil and in lettuce were determined by gas-liquid chromatography. When applied by the bow-wave method as a continuous logarithmically-changing dose ranging from approximately 0.9 to 16.0 kg a.i. ha^?1, the proportional rate of oxidation in soil of phorate sulphoxide to phorate sulphone was inversely related to dose. Ten weeks after application, total phorate residues in the soil had declined by about 35% at all dose levels. Residues in mature lettuce, from the 1-5 kg ha^?1 dose-range, comprised the parent and oxygen analogue sulphoxides and sulphones; the relative proportions of the individual metabolites were independent of dose. Over this dose-range, total residue concentrations in the crop became proportionally slightly greater with increasing dose. When single doses of 1.1, 2.0 or 2.2 kg a.i. ha^?1 were applied at drilling, the total residue concentrations in the lettuce declined from 5 mg kg^?1 in seedlings from some treatments to <0.05 mg kg^?1 at harvest. In plants raised in peat blocks containing 10 or 20 mg a.i. per block, however, residues in seedlings totalled 45-47 mg kg^?1 and declined to only 0.7 mg kg^?1 at harvest. It was concluded that bowwave applications of phorate when field-sowing lettuce were unlikely to lead to unacceptable residues in the harvested crop, but that residues in lettuce raised in phorate-treated peat blocks may be unacceptably high.     

Insecticidal control of hessian fly (Mayetiola destructor say: Dipt., Cecidomyiidae) on wheat and barley in cyprus

Hessian fly was controlled to a maximum of 95% with organophosphate insecticides, in terms of the number of puparia and percentage tiller infestation at harvest. Granules: phorate at 1.68 kg/ha (1 1/2 lb/acre) as 10% granules in the seed furrow was most effective on durum wheat in 1967–8, with 69–92%, control, of tillers infested. 1.12 kg/ha gave 74–89% control, 0.56 kg/ha in the seed furrow 35–54%. Seed furrow treatment was more effective than band or broadcast treatment over young plants, although granules broadcast over young barley at 1.68 kg/ha of phorate gave 74% control in 1967–8. Fonofos (Dyfonate) granules at 1.55 kg fonofos/ha were most effective on barley in 1968–9, with 66% control. After fonofos and phorate, disulfoton at 1.68 kg disulfoton/ha was next in effect, with up to 86%, control in 1967-8 and 24% in 1968–9, but variable and not much more effective than at 0.56 kg/ha. Other insecticides were less effective. Seed dressings: disulfoton was the most effective, giving 79% control in 1967-8 on wheat and 77% on barley at a high rate of application that was phytotoxic in 1968–9. Diazinon, bromophos and ethion gave 15–38%, control and chlorfenvinphos and dimethoate less. Carbaryl dust at 1.12 kg carbaryl/ha gave 32% control. Yields were poor, but grain yield was increased by up to 33% in wheat in 1967-8, averaging about 15%. Barley yield was increased by 7% in 1967–8, and from 9–23% in 1968-9 by fonofos and phorate granules. Insect control reduced the number of tillers, increased the number of heads and increased the grain weight per head. In observation plots, chlormequat (CCC) spray alone at the 5-leaf stage reduced infestation of wheat by between 22% and 43%, but CCC with fertilizer, and fertilizer alone had no conclusive effect. High fly populations are partly due to leaving crop residues in the field at harvest. When these can be ploughed in, infestation should decrease. The use of insecticides may not be economic unless more consistent increases in yield can be obtained.     

Biological effects of combining carboxin,organomercury fungicides and insecticides as seed dressings for wheat,and the effect of these combinations on adherence of the pesticides to the seed

When seeds of winter wheat were carefully dressed in the laboratory with combinations of fungicides (organomercury alone or organomercury plus the systemic fungicide carboxin) and insecticides (aldrin, carbophenothion or chlorfenvinphos as liquid formulations, or a γ-BHC powder formulation) so as to ensure that nearly all the recommended amounts of the active ingredients stuck to them, the insecticides gave good insect control, but γ-BHC with organomercury fungicide decreased the number of plants that germinated, and γ-BHC with carboxin and organomercury was even more damaging. Commercially dressed seeds had only about 30 to 60% of the target dose of fungicides, but more than 80% of the target doses of the liquid insecticides aldrin, carbophenothion and chlorfenvinphos. With combinations of powder fungicide and liquid insecticide, greater amounts of pesticide on the seed were obtained if the insecticide was put on first. Because of unusually late sowings and little fungal infestation, neither laboratory nor commercially treated seeds provided good tests for control of smut.     

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.     

Single and simultaneous exposure of acetylcholinesterase to diazinon, chlorpyrifos and their photodegradation products

In vitro inhibition of electric eel acetylcholinesterase (AChE) by single and simultaneous exposure to organophosphorus insecticides diazinon and chlorpyrifos, and their transformation products, formed due to photoinduced degradation, was investigated. Increasing concentrations of diazinon, chlorpyrifos and their oxidation products, diazoxon and chlorpyrifos-oxon, inhibited AChE in a concentration-dependent manner. IC₅₀ (20 min) values, obtained from the inhibition curves, were (in mol/l): (5.1 ± 0.3) × 10⁻⁸, (4.3 ± 0.2) × 10⁻⁶ and (3.0 ± 0.1) × 10⁻⁸ for diazoxon, chlorpyrifos and chlorpyrifos-oxon, respectively, while maximal diazinon concentration was lower than its IC₅₀ (20 min). Calculated K_I values, in mol/l, of 7.9 × 10⁻⁷, 9.6 × 10⁻⁶ and 4.3 × 10⁻⁷ were obtained for diazoxon, chlorpyrifos and chlorpyrifos-oxon, respectively. However, 2-isopropyl-4-methyl-6-pyrimidinol (IMP) and 3,5,6-trichloro-2-pyridinol, diazinon and chlorpyrifos hydrolysis products, did not noticeably affect the enzyme activity at all investigated concentrations. Additive inhibition effect was achieved for lower concentrations of the inhibitors (diazinon/diazoxon ?1 × 10⁻⁴/1 × 10⁻⁸ mol/l i.e., chlorpyrifos/chlorpyrifos-oxon ?2 × 10⁻⁶/3 × 10⁻⁸ mol/l), while an antagonistic effect was obtained for all higher concentrations of the organophosphates. Inhibitory power of 1 × 10⁻⁴ mol/l diazinon irradiated samples can be attributed mostly to the formation of diazoxon, while the presence of non-inhibiting photodegradation product IMP did not affect diazinon and diazoxon inhibitory efficiencies.     

Brief exposure of Blattella germanica (Blattodea) to insecticides formulated in various microcapsule sizes and applied on porous and non-porous surfaces

BACKGROUND: The authors explored how microcapsule size and brief exposure affected the bioavailability of five microencapsulated insecticide formulations, chlorpyrifos 23.1 g L(-1) CS (Detmol-PRO), chlorpyrifos 20 g L(-1) CS (Empire 20), fenitrothion 20 g L(-1) CS (Detmol-Mic), cyphenothrin 10 g L(-1) CS (Detmol-CAP) and diazinon 30 g L(-1) CS (Diacap), to Blattella germanica L. on porous and non-porous surfaces. The hypothesis was tested that microencapsulated (CS) insecticides comprising larger microcapsules show higher efficacy on porous surfaces than formulations with smaller microcapsules. RESULTS: Brief exposure was accomplished by allowing B. germanica to cross a 0.3 m insecticide barrier in 30 s (1.01 cm s(-1)). Such short exposure did not lead to 100% mortality in any formulation or surface tested. Significant differences in bioavailability on the porous and the non-porous surfaces were found: the largest difference was observed in Empire 20 and Detmol CAP, while bioavailability of Detmol MIC did not differ on porous and non-porous surfaces. Comparison of their microcapsule size spectra revealed that formulations containing larger microcapsules had higher efficacy on porous surfaces than formulations with smaller microcapsules. In order to explain the difference in efficacy, the variance of microcapsule sizes was regressed on the efficacy ratio on porous versus non-porous surfaces. Although negative correlation was evident between size of capsules and the efficacy ratio on porous and non-porous surfaces, the difference in the slope parameter was not statistically significant. CONCLUSION: Brief contact of B. germanica with insecticide spray residues, which is common in barrier treatment, may lead to low efficacy, especially on porous surfaces. The latter should be preferably treated with CS insecticides containing a fraction with large capsules. In addition to the size of the microcapsules, the role of other factors, such as wall capsule thickness and chemical composition, on CS insecticide activity on various surfaces should be examined in future work.     

灰飞虱对杀虫剂抗药性的研究进展

灰飞虱对杀虫剂产生抗药性是其近年来暴发频繁的重要原因。本文综述了国内外关于灰飞虱抗药性的研究成果,包括灰飞虱抗药性的发展、交互抗性、抗性机理、抗性遗传及生物适合度等。田间灰飞虱种群对多种药剂产生了不同程度的抗药性,其中对新烟碱类药剂吡虫啉和昆虫生长调节剂噻嗪酮产生了高水平到极高水平抗性(抗药性倍数分别为44.6～108.8倍和超过200倍),对有机磷类药剂毒死蜱和乙酰甲胺磷(抗药性倍数分别为10～12.6倍和9～13倍)、氨基甲酸酯类药剂甲萘威和残杀威(抗药性倍数分别为29.8～45.3倍和40.1～131.5倍)和拟除虫菊酯类药剂高效氯氰菊酯和溴氰菊酯(抗药性倍数分别为7.8～108.8倍和12～21倍)产生了中等水平到高水平的抗药性,对氟虫腈、阿维菌素和噻虫嗪没有产生抗药性(抗性倍数5倍)。长期大面积使用化学药剂是灰飞虱产生抗药性的重要原因。因此,必须加强灰飞虱的抗性治理,以延缓其抗药性进一步发展。