Induction of detoxifying enzymes by allelochemicals and host plants in the fall armyworm

The effect of various plant substances and host plants on the microsomal oxidases and glutathione S-transferase was investigated in the fall armyworm (Spodoptera frugiperda (J. E. Smith)) maintained on a meridic diet. The glucosinolate, sinigrin, and the hydrolytic products of glucosinolates, β-phenylethylisothiocyanate, indole 3-acetonitrile, and indole 3-carbinol, and flavone were found to be potent inducers of the glutathione S-transferase in the armyworm. An 18-fold increase in the transferase activity was observed when larvae were fed a diet containing 0.2% indole 3-acetonitrile for 2 days. These compounds, with the exception of β-phenylethylisothiocyanate which appeared to be inhibitory, also stimulated the microsomal aldrin epoxidase significantly. In all instances, no induction of the microsomal oxidase or glutathione S-transferase was observed by the plant hormones, indole 3-acetic acid and gibberellic acid; the terpenoids, stigmasterol, sitosterol, and β-carotene; the polyphenolic gossypol; and the flavonol, quercetin; some of them were found to be inhibitory. Using corn, potato, and sweet potato as inducers of various microsomal oxidases, it was found that the inducing pattern of the N-demethylase was different from the two epoxidases and O-demethylase. Corn leaves were the most active compared with other aerial parts of corn (silks, developing corn, and husk) in inducing the microsomal oxidase. The microsomal oxidase in the younger larvae appeared to be less inducible by host plants than in the older larvae.     

Insect juvenile hormones: Induction of detoxifying enzymes in the housefly and detoxication by housefly enzymes

The cecropia juvenile hormone and three of its analogs were compared as inducers of microsomal epoxidase, O-demethylase, and DDT dehydrochlorinase in the housefly, Musca domestica L. The compounds were the cecropia juvenile hormone, methoprene, hydroprene, 6,7-epoxy-3,7-diethyl-1-[3,4-(methylenedioxy)phenoxy]-2-octene, and piperonyl butoxide, a well known insecticide synergist. The compounds were administered by feeding at levels up to 1% in the diet for 3 days to 1-day-old female adults. Enzymes were then prepared and assayed for their activity using heptachlor, p-nitroanisole, and DDT as substrates.There was approximately a twofold increase in the microsomal oxidases and a 50% increase in DDT dehydrochlorinase after the treatment with the cecropia juvenile hormone, while methoprene had some activity as an inducer of the epoxidase (30% increase) but no activity in the case of the O-demethylase or the dehydrochlorinase. Hydroprene had no effect on any of the enzyme systems, while 6,7-epoxy-3,7-diethyl-1-[3,4-(methylenedioxy)phenoxy]-2-octene was an inhibitor of the two microsomal oxidases. The latter compound and piperonyl butoxide were strong inducers of DDT dehydrochlorinase, causing approximately twofold increases in the activity of this enzyme.There was evidence that the microsomal preparations were able to metabolize and inactivate methoprene and hydroprene, the action being oxidative in the case of methoprene and both oxidative and hydrolytic in the case of hydroprene. The oxidative metabolism of the two juvenile hormone analogs by the microsomal preparations was inducible by the cecropia juvenile hormone and by phenobarbital and dieldrin.     

Phenobarbital induction of detoxifying enzymes in resistant and susceptible houseflies

Houseflies, Musca domestica, L., were treated with the drugs phenobarbital and 3-methylcholanthrene to study the effects of these compounds as inducing agents of the microsomal oxidases, heptachlor epoxidase, and p-nitroanisole O-demethylase, and of DDT-dehydrochlorinase. Phenobarbital was active when applied by injection or as part of the diet but inactive when topically applied. The resulting increases in heptachlor epoxidase activity were as much as 25-fold that of the untreated controls. The net increase in enzyme activity after phenobarbital treatment was greater in an insecticide-susceptible strain, WHO-SRS strain, than in a carbamate-resistant strain. However, the phenobarbital induced increases in DDT-dehydrochlorinase were greater, about 2-fold, in the resistant strains than in the susceptible strain.The optimum dose for phenobarbital was 1% in the diet for a period of 3 days. None of the treatments with 3-MC, feeding, injection, exposure to residues, or topical, were effective in induction.     

3种防御酶在水稻抗稻曲病中的活性变化

不同水稻品种对稻曲病抗性存在明显差异。本研究选用12个不同抗、感病水稻品种,在抽穗前7~10 d,用注射法接种稻曲病菌分生孢子悬浮液。结果表明,在抗病品种中苯丙氨酸解氨酶（PAL）、过氧化物酶（POD）和多酚氧化酶（PPO）3种酶活性接种后迅速提高,变化幅度较大;而感病品种的酶活性在接种后缓慢增加,变化幅度小。由此说明,这3种防御酶与水稻抗稻曲病有一定的关系。     

Interactions between Trichoderma harzianum and defoliating Verticillium dahliae in resistant and susceptible wild olive clones

Verticillium wilt (VW) in olive is best managed by an integrated disease management strategy, of which use of host resistance is a key element. The widespread occurrence of a highly virulent defoliating (D) Verticillium dahliae pathotype has jeopardized the use of commercial olive cultivars lacking sufficient resistance to this pathogen. However, the combined use of resistant wild olive rootstocks and Trichoderma spp. effective in the biocontrol of VW can improve the management of VW in olive. In vivo interactions between D V. dahliae and Trichoderma harzianum were studied in olive and wild olive plants displaying different degrees of resistance against this pathogen using confocal microscopy. This multitrophic system included wild olive clones Ac‐4 and Ac‐15, olive cv. Picual, and the fungal fluorescent transformants T. harzianum GFP22 and V. dahliae V138I‐YFP, the latter being obtained in this study. In planta observations indicated that V138I‐YFP colonizes the roots and stems of the olive and wild olive genotypes, and that GFP22 grows endophytically within the roots of them all. YFP fluorescence signal quantifications showed that: (i) the degree of root and stem colonization by the pathogen varied depending upon the susceptibility of the tested wild olive genotype, being higher in Ac‐15 than in Ac‐4 plants; and (ii) treatment with T. harzianum GFP22 reduced the extent of pathogen growth in both clones. Moreover, root colonization by strain GFP22 reduced the percentage of pathogen colonies recovered from stems of olive and wild olive plants.     

Specific and total activities of the allelochemicals identified in buckwheat

The various organs of the Polish cultivars of buckwheat were evaluated for their flavonoid content (rutin, quercetin, (+)-catechin, and (−)-epicatechin) and for their phenolic acid content (chlorogenic, caffeic, ferulic, and gallic acids) to test their contribution to buckwheat allelopathic activity. The main compound found in the above-ground organs of buckwheat was rutin, followed by chlorogenic acid, and then (−)-epicatechin. The allelopathic activity, based on the specific activity of the identified compounds on lettuce seedling growth, was evaluated. Gallic acid had the highest specific activity and quercetin had the lowest. The specific activity of rutin was at the medium level compared to the other examined compounds, but as a consequence of its high concentration, its total activity was very high. The growth inhibitory effects of the aqueous extracts of the buckwheat leaves and inflorescences were higher than that of the stems. The higher inhibitory activity of the extracts compared to the leaves and inflorescences was explained by the high presence of rutin in them. Therefore, based on the total activity, as calculated by its concentration and its growth inhibitory effect, it seems that rutin, among the other tested compounds, is the major allelochemical in Polish buckwheat.     

2016年－2019年河南信阳黏虫的种群动态及虫源性质分析

为了解河南信阳黏虫的发生情况,本研究利用高空探照灯对2016年-2019年黏虫成虫的种群动态进行了监测及分析。结果表明,2016年-2019年在河南信阳监测的黏虫成虫主要为东方黏虫(又称为黏虫)和劳氏黏虫,均一年发生5代,整个监测期间均出现多个高峰期。其中,东方黏虫以一代为主,占全年总诱虫量的54.62%～82.96%,并且大部分虫源向外迁出,少部分留在本地;劳氏黏虫以三代或四代为主,以留在本地或迁入为主,只有少数向外迁出。本研究为河南省信阳地区黏虫的预测预报和防控提供了参考。     

菜心不同抗病品种感染炭疽病菌后丙二醛含量及几种酶活性的变化

菜心Brassica parachinensis Bailey是华南地区栽培规模较大的蔬菜,炭疽病是菜心的一种常见病害,高温高湿的气候条件特别适宜该病害的发生.作者选用了4个对炭疽病抗性不同的菜心品种,测定在被炭疽病菌侵染后叶片内丙二醛(MDA)含量及几种酶活性的变化,以期为菜心抗病品种选育中生理、生化指标的确定和对抗性资源的合理利用提供依据.     

不同抗性玉米品种接种甘蔗花叶病毒(SCMV)后4种防御酶活性变化研究

 植物在长期进化过程中,不断抵御外部伤害,包括有害生物的入侵,其体内逐渐形成了一套完整的保护机制。     

Herbicidal potential and quantification of causative allelochemicals from several Compositae weeds

Compositae plants contain biologically active substances that are allelopathic to weed species. Aqueous extracts from leaves of 16 plants were bioassayed against lucerne (Medicago sativa) to determine their allelopathic effects, and the results showed the highest inhibition for the extracts from Lactuca sativa, Xanthium occidentale and Cirsium japonicum. The extracts applied to filter paper in Petri‐dish bioassay tests significantly inhibited root growth of lucerne. Extracts of 40 g dry tissue L^?1 from L. sativa, X. occidentale and C. japonicum were completely inhibitory to lucerne root growth, but hypocotyl growth of lucerne was less sensitive. Although allelopathic effects of methanol extracts were much less than those of coumarin or alachlor, early seedling growth of both lucerne and Echinochloa crus‐galli was significantly reduced by methanol extracts. Mixture of L. sativa, X. occidentale and C. japonicum extracts had more inhibitory effects on test plants than each single extract treatment. By means of high‐performance liquid chromatography, responsible causative allelopathic substances present in L. sativa, X. occidentale and C. japonicum were isolated from various fractions and identified as coumarin, trans‐cinnamic acid, o‐coumaric acid and p‐coumaric acid. These results suggest that some Compositae have various herbicidal potentials, and that their activities, types and amount of causative compounds differ, depending on the plant species.     

The insecticidal potential of Piper ribesioides (Piperales: Piperaceae) extracts and isolated allelochemicals and their impact on the detoxification enzymes of Spodoptera exigua (Lepidoptera: Noctuidae)

Phytoparasitica - The dried twigs of Piper ribesioides were used to prepare various extracts in different solvents. Each extract was evaluated for their toxicity against 2nd instar larvae of...     

Metabolic detoxication and synergistic ratio of lindane analogs in house flies

Biodegradability of lindane analogs using house fly whole body, microsomes, and microsome supernatant fraction was examined. It decreased in the order of alkoxy ～ methylthio > methyl analogs > lindane in the whole body experiments, as well as with microsomes in the presence of NADPH. With the supernatant in the presence of glutathione, a different trend was observed. The synergistic effects of piperonyl butoxide when used together with lindane analogs were mostly explained in terms of the inhibition of the microsomal metabolism. Piperonyl butoxide was also shown to inhibit the penetration of compounds into the fly body and to make the central nervous system of the American cockroach less sensitive to the action of insecticides causing after and repetitive discharges. It was observed that the value of the percentage of metabolic disappearance of insecticides after a certain period decreases as the dose level initially applied in the whole body experiments increases. The synergistic ratio parallels the percentage of disappearance value after the insecticidal activity test period when a dose corresponding to the unsynergized LD₅₀ is initially applied. When quantitative comparisons are required for biodegradability of insecticides using house flies as the test insects, it should be on the basis of direct metabolism experiments using a fixed dose throughout the series of insecticides, but not on the basis of the synergistic ratio.     

Larvicidal activity of Cnidium monnieri fruit coumarins and structurally related compounds against insecticide-susceptible and insecticide-resistant Culex pipiens pallens and Aedes aegypti

BACKGROUND: An assessment was made of the toxicity of imperatorin and osthole identified in Cnidium monnieri fruit, 11 related compounds and five insecticides to larvae from insecticide‐susceptible Culex pipiens pallens (KS‐CP strain) and Aedes aegypti and wild C.p. pallens (YS‐CP colony) using a direct‐contact mortality bioassay. Results were compared with those of the conventional larvicide temephos. RESULTS: Imperatorin (LC₅₀ = 3.14 and 2.88 mg L^?1) was 1.9‐, 3.7‐ and 4.2‐fold and 2.4‐, 4.5‐ and 4.6‐fold more toxic than isopimpinellin, isoimperatorin and osthole against susceptible C. p. pallens and A. aegypti larvae respectively. Overall, all of the compounds were less toxic than temephos (0.011 and 0.019 mg L^?1). The toxicity of these compounds was virtually identical against larvae from the two Culex strains, even though YS‐CP larvae were resistant to fenthion (resistance ratio RR = 390), deltamethrin (RR = 164), cyfluthrin (RR = 14) and temephos (RR = 14). This finding indicates that the coumarins and the insecticides do not share a common mode of action. The structure–activity relationship indicates that the chemical structure and alkoxy substitution and length of the alkoxyl side chain at the C8 position are essential for imparting toxicity. CONCLUSION: The C. monnieri fruit‐derived coumarins and the related coumarins described merit further study as potential insecticides or lead molecules for the control of insecticide‐resistant mosquito populations. Copyright © 2012 Society of Chemical Industry     

Interactions of insecticides with erythrocyte membranes

Insecticides exert antilytic effects on pig erythrocytes by preventing osmotic disruption of membranes in critical hypotonic saline media. The order of effectiveness is the following: lindane > aldrin ≈ azinphos > parathion ≈ DDT > malathion; empirical protective indexes estimated for K⁺ leakage, at 0.09 M NaCl, were 5.6, 3.9, 2.9, 2.8, and 2.0, respectively. Erythrocytes swell and hemolyze in solutions containing glycerol below 0.6 M. At higher concentrations and temperatures below 20°C, the extent of cell lysis is very limited and virtually nil in 1 M glycerol. In hypertonic glycerol solutions, cells swell until the initial equilibrium volume is reached and, then, the swelling process ceases. Swelling in 1 M glycerol is related to its permeation through hydrophobic membrane domains. The activation energies of permeation are similar to the dehydration energies of glycerol molecules. As the temperature is increased above 20°C, erythrocytes undergo lysis. The organophosphorus insecticides, parathion and azinphos (10^?4M), significantly increase the swelling rates and the extent of cell lysis. Malathion and chlorinated insecticides do not exert apparent effects. However, these compounds are effective in liposomes reconstituted with lipids extracted from erythrocyte membranes.     

Hydrolytic activation and detoxication of 2,4-dichlorophenoxyacetic acid esters in mosquito fish

Insecticide-resistant mosquito fish (Gambusia affinis) were found to be slightly more tolerant to two thiol esters of 2,4-dichlorophenoxyacetic acid (2,4-D) than were fish of a susceptible population. DEF (S,S,S,-tributyl phosphorotrithioate), at 0.1 ppm for 24 hr, slightly decreased the toxicity of both esters to both populations. Comparison of esterase activities in gill and liver preparations showed that the resistant fish had lower levels of liver esterases than the susceptible fish, but results with gill preparation were not consistent. With the ethyl thiol ester, susceptible fish had the higher activity, but with butyl thiol ester, resistant fish had the higher activity. DEF inhibited activities in both tissues of both populations, but inhibition was appreciably greater in the liver. Results suggest that (i) hydrolysis in the liver activaties 2,4-D esters, (ii) hydrolysis in the gill is a detoxication reaction, (iii) the slight increase in tolerance in the insecticide-resistant fish is primarily the result of decreased activation, and (iv) antagonism by DEF is the result of a greater inhibition of activation than of detoxication.     

Interactions of insecticides with biological membranes

Many insecticides (e.g. DDT, lindane, pyrethroids) are hydrophobic molecules which bind extensively to biological membranes. Binding of insecticides to phospholipid bilayers frequently shows saturation, with binding increasing with increasing insecticide concentration up to some limit, beyond which no further insecticide is incorporated into the bilayer. For lindane, this limit has been shown to correspond to the concentration at which the aqueous phase becomes saturated. Simple alkanes show similar saturation phenomena, and binding of halogenated alkanes can be followed by fluorescence quenching methods. It is shown that effects of hydrophobic molecules on bilayer fluidity are small. Effects of alkanes and insecticides on the activity of the (Ca²⁺-Mg²⁺)-ATPase purified from sarcoplasmic reticulum follow from direct binding to the ATPase, at sites which are not at the lipid-protein interface of the ATPase.     

油菜对千金子的化感作用及其化感物质分离鉴定

研究了油菜茎根水提液对后茬稻田中恶性杂草千金子的化感作用,并分离鉴定了化感物质。结果表明,不同品种油菜的水提液对千金子种子萌发有抑制作用,对幼苗生长无影响,同时对水稻种子萌发及幼苗生长安全。利用室内生测及GC-MS方法鉴定抑制千金子种子萌发的化感物质为有机酸,抑制率达100%。其主要成分为油酸、棕榈酸、芥酸、亚油酸、硬脂酸、二十碳烯酸及山嵛酸。     

Herbicidal potential of allelochemicals from Lantana camara against Eichhornia crassipes and the alga Microcystis aeruginosa

In the field, the growth of the aquatic weed Eichhornia crassipes and the alga Microcystis aeruginosa may be inhibited by fallen leaves of Lantana camara. This study showed that extracts of L. camara leaves and their fractions reduced the biomass of E. crassipes and M. aeruginosa within 7 days under laboratory conditions. Two fractions with highly inhibitory activity from the extract were isolated and subsequently identified as the pentacyclic triterpenoids, lantadene A and lantadene B. Both compounds significantly inhibited E. crassipes and M. aeruginosa growth, even at a low concentration. At all concentrations tested, their inhibitory activities were much higher than that of salicylic acid, a putative allelochemical from L. camara. The results indicated that the predominant allelochemicals involved in L. camara against either E. crassipes or M. aeruginosa are not phenolic acids, but lantadene A and lantadene B. Field trials showed that released levels of lantadene A and lantadene B were significantly correlated with amounts and decomposition periods of L. camara leaves floated in water. The amount released from 5 kg L. camara leaves was over the inhibition threshold of both E. crassipes and M. aeruginosa and reached a maximum at days 15–20. This study suggested that allelochemicals of L. camara could potentially be used to improve the management of weeds and algae in aquatic systems.