Host plant induction of glutathione S-transferase in the fall armyworm

The influence of various host plants on glutathione S-transferase activity was studied in the fall armyworm, Spodoptera frugiperda (J. E. Smith). Fall armyworm larvae were maintained on a semidefined artificial diet until the end of the fifth instar. The newly molted sixth instar larvae were then fed fresh leaves of various host plants for 2 days prior to glutathione S-transferase assays using 3,4-dichloronitrobenzene as substrate. The order of the midgut glutathione S-transferase activity of larvae after the worms fed on these plants was: mustard > turnip > cowpeas > peanuts > cotton > corn > cucumber > potato > Bermudagrass > millet > sorghum > soybeans. The difference in the transferase activity between soybean- and mustard-fed larvae was 10-fold. Kinetic study revealed a quantitative, but no qualitative difference in the glutathione S-transferase between soybean- and cowpea-fed larvae. Monoterpenes, such as α-pinene, β-pinene, menthol, and peppermint oil, had no effect on the enzyme. Cowpea-fed larvae were more tolerant of the insecticides diazinon, methamidophos, and methyl parathion than soybean-fed larvae were. These new observations help explain what has been happening in the field and might be of use in the development of pest management programs.     

Induction of microsomal oxidases by host plants in the fall armyworm,Spodoptera frugiperda (J. E. Smith)

Larvae of the fall armyworm (Spodoptera frugiperda (J. E. Smith)) were maintained on a semidefined artificial diet until the end of the fifth instar and the newly molted sixth-instar larvae were then fed fresh leaves of various host plants for 2 days prior to microsomal oxidase assays. The order of the midgut aldrin epoxidase activity of larvae after feeding on these plants was: corn > Bermuda grass > cotton > cowpeas > cabbage > peanuts > sorghum > alfalfa > millet > soybean. The ratios of aldrin epoxidase, p-nitroanisole O-demethylase, and p-chloro-N-methylaniline N-demethylase activities for soybean- and corn-fed larvae were 4.5, 6.3, and 2.7-fold, respectively. The induction was affected by the age and developmental stage of the corn plant with mature leaves from old plants being more active. Higher epoxidase activities were also observed in mature larvae reared on corn plants since egg stage as compared with those on soybean plants. Monoterpenes such as α-pinene, β-pinene, limonene, menthol, and peppermint oil were found to induce the midgut epoxidase activity. Corn-fed larvae were more tolerant of the insecticides methomyl, acephate, methamidophos, diazinon, trichlorfon, monocrotophos, permethrin, and cypermethrin than soybean-fed larvae.     

Host plant induction of microsomal monooxygenase activity in relation to diazinon metabolism and toxicity in larvae of the tobacco budworm Heliothis virescens (F.)

The effect of the wild tomato, Lycopersican hirsutam F. glabratam (accession PI 134417), on susceptibility to and metabolism of diazinon, 0,0-diethyl-0-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate, in larvae of the tobacco budworm, Heliothis virescans F., was studied. The larvae were over 4-fold more tolerant to diazinon toxicity when fed on leaves of wild tomato than when fed on an artificial diet. Diazinon injected into fifth instar larvae is converted into two chloroform-soluble and five water-soluble metabolites. Degradation of diazinon was faster in larvae fed tomato leaves (88.1%) than in larvae fed on the artificial diet (68.4%). Some oxon (13.0%) was detected in the latter case but none in larvae fed tomato leaves. The major metabolite was hydroxypyrimidine and its formation was higher (73.2%) in larvae fed tomato leaves than in larvae fed the artificial diet (49.2%). In vitro studies revealed that both diazinon and its oxon were metabolized primarily by the microsomal cytochrome P-450-dependent monooxygenase system which was induced 2.5- to 3.7-fold by feeding on tomato leaves. It was concluded that diazinon was degraded in H. virescens larvae through desulfuration, hydroxylation of the ring-alkyl side chain, and oxidative dearylation reactions, all of which were increased by varying amounts after feeding on tomato leaves. Treatment of the larvae with 2-tridecanone, a naturally occurring toxin in tomato leaves, resulted in increased tolerance to diazinon and increased in vitro degradation of diazinon and its oxon, the induction being dependent on the magnitude of 2-tridecanone treatment. The microsomes of tomato fed larvae had a 1.5- to 2.1-fold higher concentration of cytochrome P-450, accompanied by a 1–2 nm shift in the λmax of the cytochrome P-450 carbon monoxide complex.     

Influence of three diets on susceptibility of selected insecticides and activities of detoxification esterases of Helicoverpa assulta (Lepidoptera: Noctuidae)

The oriental tobacco worm, Helicoverpa assulta Guenée, is one of the most destructive pests of tobacco and peppers in China. We determined the susceptibility of H. assulta reared on an artificial diet, chili pepper and tobacco to four insecticides (fenvalerate, phoxim, methomyl, indoxacarb) under laboratory conditions associated with the activities of acetylcholinesterase (AChE), carboxylesterase (CarE) and glutathione S-transferase (GST) in its larvae. H. assulta larvae that were fed with chili pepper were more susceptible to fenvalerate, indoxacarb, and phoxim than those that were fed with tobacco and the artificial diet, but not to methomyl. The larvae that were fed with chili pepper were 3.65-, 2.49-, 1.92- and 2.44-fold more susceptible to fenvalerate, phoxim, methomyl, and indoxacarb than those fed with tobacco, respectively. The AChE activities of H. assulta larvae that were fed with chili pepper and tobacco were 2.12 and 1.07 μmol mg⁻¹ 15 min⁻¹, respectively, almost 2-fold difference. The CarE activity of H. assulta larvae that were fed with chili pepper, tobacco and the artificial diet was 4.12, 7.40 and 7.12 μmol mg⁻¹ 30 min⁻¹, respectively. Similarly, the GST activities of H. assulta larvae that were fed with chili pepper, tobacco and the artificial diet was 52.02, 79.37 and 80.02 μmol mg⁻¹ min⁻¹, respectively. H. assulta larvae that were fed with chili pepper were more resistance to the tested insecticides. The low activities of AChE and the high activities of CarE and GST lead to H. assulta become more susceptible to the tested insecticides.     

Inducibility of metabolic insecticide defenses in boll weevils and tobacco budworm caterpillars

Of five cotton allelochemicals, (+)-α-pinene, β-caryophyllene, gossypol, umbelliferone, and scopoletin, all except gossypol induced cytochrome P-450 content, N-demethylation, and epoxidation activities more in tobacco budworm larval midguts than in adult or larval boll weevils. All except gossypol also induced glutathione transferase activity in tobacco budworm larval midguts and adult boll weevils. Microsomal esterase activity was unaffected or suppressed by all five allelochemicals. Soluble esterase activities were unaffected, or induced only in boll weevil larvae. The contrast in insecticide resistance development between the tobacco budworm and the boll weevil may be, in part, related to superior inducibility of cytochrome P-450 and associated activities in the former species in addition to overall higher uninduced activities (26).     

转基因棉和常规棉叶片对抗Cry1Ac近等基因系棉铃虫生长发育的影响

利用室内饲喂法,以抗Cry1Ac近等基因系棉铃虫为材料,比较转基因棉花33B和SGK321及其对照亲本DP5415和石远321对抗、感棉铃虫生长发育的影响。结果表明,抗性棉铃虫在取食常规棉叶后表现出一定的适合度代价。取食DP5415和石远321两种常规棉花后,抗性品系棉铃虫的幼虫存活率显著低于敏感品系,取食33B和SGK321两种转基因棉花的抗性棉铃虫,不仅其幼虫存活率显著高于敏感品系,而且致死中时间也比敏感品系延长。取食9天后,抗性品系在常规棉花石远321和DP5415上发育到3龄和4龄幼虫的比例显著低于敏感品系,取食33B和SGK321转基因棉花的抗性品系发育到3龄幼虫的比例均显著高于敏感品系。抗性品系在常规棉上的蛹重均显著低于敏感品系,部分取食转基因棉花的抗性品系棉铃虫可以化蛹,而敏感品系不能在转基因棉花上化蛹。     

Antifungal activity of the essential oil of Zanthoxylum bungeanum and its major constituent on Fusarium sulphureum and dry rot of potato tubers

The composition of the essential oil of Zanthoxylum bungeanum was analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 35 components, which constitute 99.10% of the oil, were identified. The major constituent was α-pinene (19.59%). Minimum inhibitory concentrations (MICs) of the essential oil and α-pinene against Fusarium sulphureum were determined to be 6.25% and 12.50%, respectively. A determination of the antifungal activity and inhibitory effect of the essential oil and α-pinene showed that the essential oil more significantly decreased cell membrane integrity and inhibited spore germination than α-pinene. Observations using scaning electron microscope revealed morphological modification including mycelium asymmetry, hyphal swelling, curling, and a secretory appearance. Ultrastructural alterations were also observed including cell empty cavity and osmiophilic granule generation. In vivo testing showed that the oil and α-pinene effectively controlled dry rot of potato inoculated with F. sulphureum. These findings indicated that the oil and α-pinene directly inhibit fungal growth, and the essential oil showed pronounced potential than α-pinene.     

莲草直胸跳甲在几种非靶标植物上的适合度比较

莲草直胸跳甲是防治入侵杂草喜旱莲子草的引进天敌,为检测莲草直胸跳甲对非靶标植物的影响,选取了29种具有代表性的植物对该天敌进行了3种选择和1种非选择性压力的测试.在全组植物或移除喜旱莲子草组中,莲草直胸跳甲成虫和幼虫对喜旱莲子草和非靶标近缘种莲子草的取食面积均显著大于其它非靶标植物,幼虫还可取食非靶标植物若蘧、反枝苋等;成虫在无喜旱莲子草时可取食若蘧和甜菜.当移除喜旱莲子草和莲子草时,成虫和幼虫对若蘧和甜菜的取食面积分别提高22.33、4倍和1.76、16.42倍.在非选择测试中,成虫和幼虫对喜旱莲子草和莲子草的取食显著高于其它组,其它植物均不能满足其正常发育和生存.研究表明,莲草直胸跳甲对莲子草属植物的适合度最高.     

不同食料对黄地老虎生长发育和繁殖的影响

幼虫在不同食料饲养中,以灰藜最好,苘麻最差。前者幼虫期平均23～30.9天,脱皮4～5次,自然死亡率4.3～8.0％;后者则各为46.1～47.1天、6～7次、45％。各种食料饲养的蛹重,以白菜和灰藜较重,马铃薯较轻。蛹重不是决定成虫产卵高低的主要因子,而与幼虫取食食料种类关系较为密切。如幼虫取食白菜、棉花及玉米、马铃薯混杂草者,较取食旋花、马铃薯及玉米者产卵量高0.15～2.23倍,产卵期和寿命亦较长。取食混合食料的幼虫,发育速度和成虫产卵量,一般均较取食单纯一种食料为高。在成虫取食各种花蜜饲养中,以供食蜂蜜红糖水、马蔺花和向日葵花者产卵率和产卵量最高,白菜花、苜蓿花和清水者最低,前者为后者产卵量的1.99～14.06倍,雌蛾产卵率高11.1～35.7％,产卵期和寿命亦以前者为长。从幼虫和成虫取食不同营养对产卵量的对比来看,成虫期补充营养较幼虫期营养更为重要。因而某一地区蜜源植物的种类、分布密度以及蜜源植物花期与成虫发生期的符合程度,是决定某地区黄地老虎种群密度高低、为害轻重的最主要因素之一。     

The effect of BAY SIR 8514 onspodoptera littoralis (Boisduval) eggs and larvae

The chitin biosynthesis inhibitor diflubenzuron and its analog BAY SIR 8514 are equitoxic for eggs ofSpodoptera littoralis. BAY SIR 8514 residues on alfalfa fed toSpodoptera larvae were more toxic than diflubenzuron residues, whereas BAY SIR 8514 topically applied to these larvae was consistently twice as toxic as diflubenzuron, according to different criteria.     

Development of immature tiger-fly <Emphasis Type="Italic">Coenosia attenuata</Emphasis> (Stein) reared on larvae of the fungus gnat <Emphasis Type="Italic">Bradysia impatiens</Emphasis> (Johannsen) in coir substrate

The development of immature tiger-fly Coenosia attenuata (Stein) was examined when reared in coir substrate and fed third-instar larvae of the fungus gnat Bradysia impatiens (Johannsen). Single larvae of C. attenuata were fed 3, 5, 7 and 9 prey per day and two larvae were fed 6, 10, 14 and 18 prey per day. Optimal prey density was determined for larval developmental rate, time to adult eclosion, larval survival, and percentage of pupation. Other biological characteristics, such as pupal weight, pupal length, and adult body length, continued to increase with an increase in prey density. The use of coir for a rearing substrate resulted in a more efficient use of prey, less cannibalism, and improved developmental time, and survival than previously reported when agarose gel or a mixture of soil and coir were used for rearing substrates. These improvements in rearing methods are significant advancements for the use of C. attenuata as a biological control agent against whiteflies, leaf miners, fungus gnats and winged-aphids. Additionally, coir substrate serves as a mulch layer when fungus gnats are controlled with C. attenuata, such as Bradysia odoriphaga (Yang et Zhang) in Chinese chive, and B. impatiens in potted ornamental plants.     

Effects of four host plants on susceptibility of Spodoptera litura (Lepidoptera: Noctuidae) larvae to five insecticides and activities of detoxification esterases

BACKGROUND: The tobacco cutworm, Spodoptera litura (F.), is one of the most destructive polyphagous pests worldwide. The susceptibility of S. litura larvae reared on tobacco, Chinese cabbage, cowpea and sweet potato to phoxim, chlorfenapyr, methomyl, fenvalerate and emamectin benzoate under laboratory conditions was determined. RESULTS: Spodoptera litura larvae reared on tobacco were most tolerant to all insecticides, whereas those that fed on sweet potato were most susceptible. When larvae were reared on each host plant for three generations, the susceptibilities to phoxim of larvae that fed on Chinese cabbage and cowpea were similar, whereas the susceptibility of larvae that fed on sweet potato decreased by the third generation, and on tobacco the susceptibility decreased in each consecutive generation. When nicotine was added to their diet for three consecutive generations, the tolerance of larvae to phoxim increased twofold, and to emamectin benzoate 3.1‐fold, but the tolerance of larvae to fenvalerate and chlorfenapyr did not change. The acetylcholinesterase activities of the larvae that fed on sweet potato and cowpea were greater than the activities of those that fed on Chinese cabbage and tobacco. In contrast, the carboxylesterase activities of the larvae that fed on tobacco and Chinese cabbage were greater than the activities of those that fed on sweet potato and cowpea. The glutathione S‐transferase activities of larvae were highest when they fed on tobacco, followed by Chinese cabbage and cowpea, and the lowest activities were observed when larvae fed on sweet potato. CONCLUSION: Feeding on tobacco or with nicotine added to the diet, the larvae became more tolerant to insecticides, especially to phoxim and emamectin benzoate. Copyright © 2010 Society of Chemical Industry     

氯虫苯甲酰胺和氟虫双酰胺对不同虫态甜菜夜蛾的毒力作用

采用浸叶法、点滴法、夹毒叶片法、成虫药膜法、饲喂毒营养液法测定了氯虫苯甲酰胺、氟虫双酰胺对甜菜夜蛾卵、2~4龄幼虫、成虫的活性和对4龄幼虫的拒食活性,以明确氯虫苯甲酰胺和氟虫双酰胺对不同虫态甜菜夜蛾的毒力作用。结果表明,两种杀虫剂均不具有杀卵活性,但可以明显降低初孵幼虫存活率;氯虫苯甲酰胺、氟虫双酰胺均对2龄幼虫活性最高,分别为3龄幼虫的1.50、6.17倍和4龄幼虫的22.25、44.95倍,对4龄幼虫胃毒活性分别为触杀活性的14.10、8.44倍;氯虫苯甲酰胺对甜菜夜蛾成虫毒力为氟虫双酰胺的25.53~34.19倍。氯虫苯甲酰胺、氟虫双酰胺对甜菜夜蛾幼虫表现出较强的拒食作用, 至处理后48 h拒食率达到最高, 分别为 82.73%、84.15%,显著高于对照药剂甲维盐各浓度处理,处理试虫虫体皱缩、体节缩短,体重增加率明显低于对照和甲维盐各处理。     

Phagostimulation and phagodeterrency in the larva

The phagostimulatory response of the larvae of the gypsy moth,Porthetria dispar, to ethanolic-aqueous extracts of the leaf powder of different host and non-host plants, was assayed in no-choice experiments using the Styropor® method.Quercus robur L. was the most active at all concentrations tested;Picea excelsa Link, was highly active only at 4%;Pyrus malus L. showed an intermediate activity at 4%; and very slight or no feeding occurred with the extracts ofPinus silvestris L.,Ilex aquifolium L. andTaxus baccata L. The phagodeterrent effect of thePinus silvestris andIlex aquifolium extracts was demonstrated by treating the lamellae with a mixture of each one of them with the highly phagostimulatory extract ofQ. robur. The following monoterpenes tested were highly phagodeterrent at 0.2%: α-pinene, β-pinene, 3-carene; camphene was totally deterrent even at 0.05%, whereas limonene was not phagodeterrent even at 0.2%. Among other substances coumarin and lactic acid were active at 0.2%, whereas citric acid, oxalic acid and tannic acid were not phagodeterrent even at 0.2%.     

Locomotory behaviour of susceptible and resistant <Emphasis Type="Italic">Plutella xylostella (Linnaeus)</Emphasis> (Lepidoptera: Plutellidae)

Locomotory behaviour of insecticide-resistant and susceptible populations of diamondback moth, Plutella xylostella (Linnaeus), a challenging insect-pest of cruciferous vegetable crops round the globe, was studied with the help of Ethovision. Larvae from the susceptible population of P. xylostella travelled more distance on insecticide-treated or untreated surface and consequently their speed was also more as compared to those taken from the insecticide-resistant population.Whereas, the turn angle of larvae from insecticide-resistant population was significantly higher as compared to those from susceptible population. The resistant larvae travelled significantly less distance (260.68 cm/5 min) on treated-surface (with LC₅₀ value of endosulfan, quinalphos, fenvalerate and spinosad) with more value of turn angle (231.16°) than the susceptible ones which moved faster (517.23 cm/5 min) with less value of turn angle (100.63°). Influence of varying temperatures on locomotory behaviour of larvae from the susceptible and resistant population of P. xylostella was also studied and observed that susceptible P. xylostella larvae travelled significantly greater distance as compared to the larvae from insecticide-resistant population, at different temperatures. Locomotory behaviour of larvae of P. xylostella also changes with food conditions. Resistant larvae starved for 24 h travelled significantly lesser distance (147.29 cm) as compared to unstarved ones (332.50 cm). Similar trend in behaviour was also recorded with respect to speed of larvae of P. xylostella. Larvae turn more frequently when kept without food (starved) than those fed normally; the turn angle was significantly higher (290.07°) for resistant larvae and for susceptible larvae it was lesser i.e. 151.55°, when kept at starved conditions. Hence, certain pronounced behavioural differences were registered in locomotion of insecticide-resistant P. xylostella as compared to the susceptible one and this knowledge would help to find effective management solutions to P. xylostella.     

转cry1Ab/cry2Aj玉米对亚洲玉米螟的抗性评价

为探讨转cry1Ab/cry2Aj玉米对亚洲玉米螟Ostrinia furnacalis(Guenée)的抗性,采用室内生测和田间人工接虫鉴定方法评价了6个转cry1Ab/cry2Aj玉米品系对亚洲玉米螟的杀虫效果,并利用酶联免疫吸附法(ELISA)测定了Cry1Ab蛋白在各品系主要组织的表达水平.结果显示,亚洲玉米螟幼虫取食转基因玉米各品系雄穗、苞叶、花丝和雌穗48 h后死亡率在90％左右,取食心叶的死亡率在70％左右,96h后大部分幼虫死亡,而取食非转基因玉米的死亡率为3.3％～8.7％;春播和夏播田转基因玉米叶片、茎秆、雌穗基本没有被害,而对照玉米叶片、茎秆、雌穗被害严重,春播和夏播玉米平均每株分别有2.9、2.3头幼虫和蛹,2.8、3.4个蛀孔,隧道长度为7.5、14.2 cm,雌穗被害级别为5.3和5.1;6个转基因玉米品系中Cry1Ab蛋白在心叶、雄穗、花丝、苞叶和雌穗中稳定表达.综合评价认为,转基因玉米各品系在整个生育期内对亚洲玉米螟有很好的抗性,其中N50品系抗虫效果最佳,可以作为抗虫转多基因玉米育种的备选材料.     

Cry1Ac和Cry2Ab蛋白对大草蛉生长发育及酶活力的影响

为明确转Cry1Ac和Cry2Ab基因棉花对大草蛉的影响,运用Bt蛋白与人工饲料混合的方法,以大于转基因棉花叶片中蛋白含量20倍的剂量饲喂大草蛉初孵幼虫,初步研究了Cry1Ac和Cry2Ab对大草蛉生物学参数和消化酶、解毒酶活性的影响。结果表明：取食含Bt蛋白饲料的大草蛉幼虫的发育历期、体重、蛹重、成虫体重、羽化率等生物学参数与对照相比均没有显著差异;在大草蛉幼虫体内可以检测到含量较高的Cry1Ac和Cry2Ab蛋白,分别为974.92~1 282.39 ng/g鲜重和5 592.62~6 082.92 ng/g鲜重,而在大草蛉成虫体内检测到的Cry1Ac和Cry2Ab蛋白含量非常低,分别为0.29~0.39 ng/g鲜重和50.34~56.71 ng/g鲜重;取食含Bt蛋白的饲料对大草蛉幼虫的类胰蛋白酶、类胰凝乳蛋白酶、氨肽酶和谷胱甘肽-S-转移酶活性有一定的影响,但对大草蛉成虫影响与对照差异不显著。表明大草蛉取食含Bt蛋白的人工饲料后,虽然体内可以检测到一定含量的Bt蛋白,但对大草蛉的生长发育并没有显著的直接不利影响。     

The effect of IKI-7899, a new chitin synthesis inhibitor,on larvae ofTribolium castaneum andSpodoptera littoralis

The effect of IKI-7899 and diflubenzuron on larval development and emergence ofTribolium castaneum and ofSpodoptera littoralis was determined. The LC₅₀ of IKI-7899 at adult emergence ofT. castaneum larvae fed the compound in their diet and the ED₅₀ of S.littoralis larvae treated topically were approximately one-sixth those of diflubenzuron.     

Effects of β-pinene,a nonsubstituted monoterpene,on rat liver mitochondria

β-Pinene uncouples oxidative phosphorylation and inhibits respiration in isolated rat liver mitochondria. The uncoupling effects are observed at lower concentrations (100 to 200 μM) than the inhibition of respiration (400 μM). At low concentrations, the effects observed could be explained by an increase of the passive permeability of the mitochondrial membrane produced by the terpene. Higher concentrations seemed to inhibit respiration through an effect on the electron transport chain. At the highest concentrations tested (600 to 1200 μM), β-pinene seemed to produce a partial resealing of the mitochondrial membrane. All effects can be explained by the interaction of β-pinene with the mitochondrial membrane. Other hydrophobic molecules tested do not show the effects of β-pinene or limonene on mitochondria.     

荧光增白剂对Cry1Ac抗感棉铃虫围食膜的影响及增效作用

为了提高Bt的杀虫活性,运用扫描电镜、SDS-PAGE电泳和生物测定技术,研究了荧光增白剂FB28对棉铃虫Cry1Ac抗性和敏感品系围食膜的影响及对Cry1Ac杀虫蛋白的增效作用。结果表明,正常棉铃虫围食膜表面光滑致密,没有空洞和缝隙。用含1%FB28的人工饲料饲喂刚蜕皮的5龄棉铃虫幼虫2 h后,抗感棉铃虫围食膜表面均出现许多空洞,且敏感棉铃虫的空洞明显大于抗性棉铃虫;随着处理时间的延长,围食膜上的空洞逐渐变小,13 h后恢复正常。用1%FB28离体或活体处理抗、感品系棉铃虫,均可造成围食膜蛋白被降解。用1%FB28与Cry1Ac杀虫蛋白混合饲喂抗、感棉铃虫初孵幼虫,可明显提高棉铃虫的死亡率,且对抗性品系的增效作用明显大于敏感品系,对敏感和抗性品系棉铃虫的增效比分别为2.23和9.34;1%FB28还可以明显增加对抗、感品系3龄棉铃虫幼虫的生长抑制作用。