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.     

The effect of CME 134 onSpodoptera Littoralis Eggs and larvae

CME 134, a new benzoylphenyl urea chitin synthesis inhibitor, was less active than diflubenzuron and BAY SIR 8514, when tested againstSpodoptera littoralis eggs by a dipping method. AgainstS. littoralis larvae the compound was tested by feeding treated alfalfa, topical application and contact with crystalline residues on glass, followed by observation until the adult stage. With both 200–250 and 360–440-mg larvae 100% mortality was obtained by one-day feeding of alfalfa treated with 0.15 ppm a.i. Topical application to 100- and 200-mg larvae showed CME 134 to be about five and nine times more active than BAY SIR 8514 and diflubenzuron, respectively. These differences were even much greater in the contact tests. Cotton field plots were sprayed with either CME 134 or diflubenzuron formulations, leaves were collected at different intervals and fed for one day toS. littoralis larvae in the laboratory. 0.0009% a.i. CME 134 residues gave complete kill of 30–50-mg larvae after 5 and 20 days, and 86% kill after 28 days of aging. With 0.003 and 0.009% a.i., complete kill was obtained in 200–250-mg larvae until 50 days after spraying.     

The effect of BAY SIR 8514, diflubenzuron,and Hercules 24108 on growth and development ofTribolium confusum

Phytoparasitica - The effect of BAY SIR 8514, diflubenzuron and Hercules 24108 on larval growth, pupation and emergence ofTribolium confusum was determined. BAY SIR 8514 was about twice as active...     

Properties and inhibition of insect integumental chitin synthetase

Chitin polymerization is catalyzed by cell-free enzyme complexes from the integument of Trichoplusia ni larvae and wing tissue of developing Hyalophora cecropia pupae obtained on extraction of homogenates for 16 hr at 5°C in 25 mM Tris-HCl buffer, pH 7.2, containing 10 mM MgCl₂, 1 mM dithiothreitol, 10 mg/ml bovine serum albumin, and 4 mg/ml digitonin. In contrast, integumental preparations from Boarmia selenaria, Earias insulana, Heliothis virescens, Oncopeltus fasciatus, Spodoptera exigua, and Tribolium castaneum exhibit little or no chitin synthetase (CS) activity. H. cecropia CS requires magnesium ions but not N-acetyl-d-glucosamine for normal activity and is almost insensitive to nikkomycin and polyoxin D. CS activity is not detected in diapausing H. cecropia pupae but synthesis of this enzyme is induced or its activity is stimulated by the molting hormone, ecdysterone, indicating possible hormonal control. T. ni CS requires magnesium ions and N-acetyl-d-glucosamine for optimal activity and is sensitive to inhibition by uridine di- and triphosphates, polyoxins B and D, and particularly nikkomycin. T. ni integumental CS activity decreases in starved larvae or those about to pupate. Both T. ni and H. cecropia CS enzymes as prepared and assayed are sensitive to captan but not to the potent insecticides diflubenzuron and BAY SIR 8514, two effective benzoylphenyl urea in vivo chitin synthesis inhibitors.     

Effect of triflumuron on two species of nitidulid beetles,Carpophilus hemipterus andUrophorus humeralis

Egg hatch of two nitidulids,Carpophilus hemipterus L. andUrophorus humeralis F., was affected by the chitin synthesis inhibitor triflumuron (Alsystin; BAY SIR 8514)via the adult stage of the beetle. This occurred by exposure to treated diets, by a brief dip of the adults in aqueous dilutions of the toxicant, or by contact with a treated plastic netting cage. Exposure of adults ofC. hemipterus for 24 h to 0.0125%, 0.00125%, 0.00025% or 0.000125% and ofU. humeralis to 0.0125% a.i.-treated diets completely prevented hatch of eggs laid during the subsequent 48 h on an untreated diet. Although at first sterile eggs were obtained with adults of either nitidulid species transferred to an untreated diet after 24 h exposure to the 0.0125%-treated diet, egg viability gradually recovered. The speed of recovery and the course of mortality of larvae that hatched from eggs laid by treated adults, indicated thatC. hemipterus was more susceptible thanU. humeralis to triflumuron. DippingC. hemipterus adults — males or females — in 0.0125% a.i. triflumuron also resulted in complete prevention of egg hatch. Similar results were obtained by a 1-h contact of adults with treated cages. Triflumuron had no direct ovicidal activity against the two species at the concentrations used but was very effective against larvae of both species. At 0.0125% a.i., 3-5-mm-long larvae ofU. humeralis were more tolerant than newly hatched larvae and than 3-5-mm-long larvae ofC. hemipterus. Application of 0.0125% a.i. triflumuron in a date palm grove did not prevent fruit infestation by nitidulid adults but, due to prevention of egg hatch, almost no larval development was observed.     

溴甲烷、二硫化碳熏蒸处理对苹果蠹蛾的效果及水果安全范围的研究

1984—1986年作者等进行水果熏蒸处理苹果蠹蛾研究,得出溴甲浣、二硫化碳处理苹果(2个品种),梨(6个品种)的熏蒸安全范围及不同温度、不同浓度下的杀虫效果。溴甲烷在15—18℃100％杀虫效果的CT值(浓度×时间)为90;22—24℃为60—70;28—30℃为50。二硫化碳在15—18℃为600;22—23℃为520;28—30℃为300。处理苹果、梨的残留量的分析研究得出,用40克/米~3溴甲烷处理4小时,80克/米~3二硫化碳处理6小时,散气12小时,只在皮层发现溴甲烷残留0.07—0.09ppm,二硫化碳0.15—0.16ppm。果肉内均未检出这两种熏蒸剂的存在。在熏蒸处理安全范围内处理的水果,其味道无不良影响。     

Inhibition of chitin synthesis in an insect cell-line

An epithelial cell-line from Chironomus tentans, able to synthesise chitin in considerable amounts, was used as a test system to study the influence of tunicamycin (I₂₀=750 nM), the benzoylphenylurea derivative SIR 8514 (I₅₀=100 nM), oligomycin (I₅₀=200 nM), avermectin (I₅₀=5 μM) and nikkomycin Z (I₅₀,=50 μM) on the rate of glucosamine incorporation into chitin. Chitin synthesis was diminished by application of 20-hydroxyecdysone.     

Comparative toxicity of several insecticides to eggs,larvae and adults of the Egyptian cottonworm,Spodoptera littoralis,in laboratory trials

Insecticides commonly used in cotton fields in Israel against lepidopterous pests were tested against eggs, as well as against 2nd-instar larvae and adults raised from eggs ofSpodoptera littoralis (Boisduval) collected in cotton fields in the Bet She’an Valley. Methomyl, chlorpyrifos, methidathion, monocrotophos, ethyl parathion, and methyl parathion were effective against eggs even at low doses, profenofos and phosfolan were less active, and azinphos-methyl was ineffective. The doses needed for 90% kill (LD ₉₀ ) of the 2nd-instar larvae were 8.5, 35, 280, 1300 and 3400 g a.i./1000 m ² for chlorpyrifos, methomyl, profenofos, methyl parathion and ethyl parathion, respectively; monocrotophos was inactive against 2nd-instar larvae even at relatively high doses. The LD ₉₀ of adults was reached with 16, 32, 1700 and 6100 ga.i./l000 m² of chlorpyrifos, methomyl, ethyl parathion and profenofos, respectively. Only chlorpyrifos and methomyl gave successful control of all three stages of the insect tested, at doses close to those generally used with aerial applications.     

五种昆虫生长调节剂对韭菜迟眼蕈蚊的致毒作用

为明确昆虫生长调节剂对韭菜迟眼蕈蚊幼虫的毒力差异、作用特点和田间控制效果,采用药液定量滴加法比较了5种昆虫生长调节剂对其不同龄期幼虫的毒力、LC50对4龄幼虫生长发育和繁殖的影响,以及药剂致毒的温度效应和盆栽防效。结果表明:5种昆虫生长调节剂对韭菜迟眼蕈蚊2龄和4龄幼虫的毒力均以虱螨脲最高,LC50分别为0.173 mg/L和0.295 mg/L,氟铃脲和氟啶脲次之,均高于对照药剂辛硫磷;而吡丙醚和灭蝇胺低于辛硫磷。5种昆虫生长调节剂以LC50处理4龄幼虫后,虱螨脲、氟铃脲和氟啶脲对其存活幼虫后续发育历期、成虫羽化率和繁殖力的影响较大,尤其是单雌产卵量较清水对照分别降低72.6%、57.8%和58.1%;灭蝇胺也可使成虫产卵量降低;吡丙醚可引起卵孵化率下降。该类药剂对其幼虫的毒力基本不受环境温度的影响;虱螨脲、氟铃脲和氟啶脲7.5、15 g a.i./667 m2处理对当代4龄幼虫的防效较低,但对下一代幼虫的防效可达93%以上;虱螨脲、氟铃脲和灭蝇胺与新烟碱类的噻虫胺混用,可显著提高药剂的速效性,且持续控制作用好。     

茶皂素、生石灰等防治稻田福寿螺的效果评估

福寿螺已成为我国南方局部稻区严重危害水稻的有害生物,为解决常用的化学杀螺剂污染环境和农产品的问题,分别在室内和大田环境下研究了生石灰、碳酸氢铵、茶麸和茶皂素4种替代物质防治福寿螺的效果。茶皂素、茶麸和生石灰对稻田福寿螺有很好的防治作用。在室内试验中40 mg/L和50 mg/L茶皂素处理在48 h 即达到了100%的防效;在大田试验中茶皂素6.0 g/m²的处理在第4天、1.5 g/m²的处理在第16天均达到了100%的防治效果,且速效性和持效性也显著优于其它物质。30 g/m²和45 g/m²的茶麸处理以及45 g/m²的生石灰处理在大田试验第16天的防治效果也在80%以上。这3种物质对稻田稗草还有很好的抑制作用。碳酸氢铵对福寿螺防治效果较差,且能促进稻田稗草的发生。研究结果表明,茶皂素、茶麸和生石灰可作为化学杀螺剂的替代物质在大田中推广应用。     

Insecticidal,repellent and fungicidal properties of novel trifluoromethylphenyl amides

Twenty trifluoromethylphenyl amides were synthesized and evaluated as fungicides and as mosquito toxicants and repellents. Against Aedes aegypti larvae, N-(2,6-dichloro-4-(trifluoromethyl)phenyl)-3,5-dinitrobenzamide (1e) was the most toxic compound (24 h LC₅₀ 1940 nM), while against adults N-(2,6-dichloro-4-(trifluoromethyl)phenyl)-2,2,2-trifluoroacetamide (1c) was most active (24 h LD₅₀ 19.182 nM, 0.5 μL/insect). However, the 24 h LC₅₀ and LD₅₀ values of fipronil against Ae. aegypti larvae and adults were significantly lower: 13.55 nM and 0.787 × 10⁻⁴ nM, respectively. Compound 1c was also active against Drosophila melanogaster adults with 24 h LC₅₀ values of 5.6 and 4.9 μg/cm² for the Oregon-R and 1675 strains, respectively. Fipronil had LC₅₀ values of 0.004 and 0.017 μg/cm² against the two strains of D. melanogaster, respectively. In repellency bioassays against female Ae. aegypti, 2,2,2-trifluoro-N-(2-(trifluoromethyl)phenyl)acetamide (4c) had the highest repellent potency with a minimum effective dosage (MED) of 0.039 μmol/cm² compared to DEET (MED of 0.091 μmol/cm²). Compound N-(2-(trifluoromethyl)phenyl)hexanamide (4a) had an MED of 0.091 μmol/cm² which was comparable to DEET. Compound 4c was the most potent fungicide against Phomopsis obscurans. Several trends were discerned between the structural configuration of these molecules and the effect of structural changes on toxicity and repellency. Para- or meta- trifluoromethylphenyl amides with an aromatic ring attached to the carbonyl carbon showed higher toxicity against Ae. aegypti larvae, than ortho- trifluoromethylphenyl amides. Ortho- trifluoromethylphenyl amides with trifluoromethyl or alkyl group attached to the carbonyl carbon produced higher repellent activity against female Ae. aegypti and Anopheles albimanus than meta- or para- trifluoromethylphenyl amides. The presence of 2,6-dichloro- substitution on the phenyl ring of the amide had an influence on larvicidal and repellent activity of para- trifluoromethylphenyl amides.     

Malathion carboxylesterase enzymes in Anopheles arabiensis from Sudan

Malathion resistance in Anopheles arabiensis from Sudan is monofactorially inherited and is expressed in the adults but not in the larvae. The resistance is suppressed by the esterase synergist, triphenylphosphate. Semipurification of the soluble esterase enzymes by Sephadex G-25 and Sephacryl S-200 gel filtration revealed no difference between the enzymes of the resistant and susceptible strains with α- or β-naphthylacetate (NA) with a fixed substrate concentration in either the adults or larvae. However, with the malathion-specific assay a second peak of activity was observed in the adult resistant strain which was not present in either the larvae of this strain or the larvae and adults of the susceptible strain. A corresponding threefold difference in the K_m value for α-NA was also observed in the resistant adults over the range of this second peak, but there was no change in the K_m with β-NA.     

Properties of Tribolium gut chitin synthetase

An insect chitin synthetase (CS) is readily assayed using the microsomal fraction (～0.5 mg protein) from an homogenate of Tribolium castaneum larvae. This enzyme preparation is incubated at 22°C with uridine 5′-diphospho-N-acetyl[³H]glucosamine in 355 μl of 25 mM Tris-HCl buffer containing 10 mM MgCl₂, 17 mM N-acetylglucosamine, and 1 mM dithiothreitol. Other divalent cations and amino sugars are less effective activators or are inhibitory. T. castaneum CS is strongly inhibited by polyoxin D and uridine 5′-diphosphate. These activation and inhibition properties of Tribolium castaneum gut CS are similar to those of fungal CS. The polymerization product formed by the Tribolium enzyme is stable in alkali but hydrolyzed by chitinase. Enzymes of Tribolium confusum, Tribolium brevicornis, Tenebrio molitor, and Galleria mellonella are also active under the same conditions. These enzymes are from the gut and probably from the peritrophic membrane. Integumental CS activity is not detected under the indicated assay conditions.     

Parasitism byMeteorus rubens onAgrotis ipsilon as affected by supplementary food and kairomone, field studies

Field experiments in clover field showed that releasing of 10 matedM. rubens females/m², increased parasitism amongA. ipsilon larvae from 16.7% at 0 to 43,3% after 10 days. Also, releasing 10 females/m² after spraying 3% molasses in tomato field increased parasitism from 4% at 0-day to 27.5% after 10 days amongA. ipsilon larvae. Spraying molasses and kairomone together on maize plants, increased markedly the rate of parasitism amongS. cretica larvae comparing with parasitism obtained when each of them was sprayed alone. The release ofM. rubens in a rate of 10 females/m² after spraying molasses and kairomone induced a significant increase in the rate of parasitism amongS. cretica larvae after 10 and 15 days compared to releasing 3 or 4 females of the parasitoid. A significant increase in parasitism amongS. cretica larvae on tomato after 10 and 15 days was recorded whenM. rubens was released at the rates of 5 and 10 females/m², after spraying molasses and kairomone, compared to other treatments.     

Rosewood polyphenols alter phenoloxidase activity from the mantle of the marine bivalve mollusc, Modiolus demissus dillwyn

Phenoloxidase from the mantle of the marine bivalve Modiolus demissus Dillwyn slowly catalyzes the oxidation of the rosewood ingredient obtusastyrene (K_m 0.13 mM, V_max 0.30 mM/min/mg). However, in the presence of another rosewood ingredient, obtusaquinone, the oxidation rate is increased to a limiting maximal velocity of 11 mM obtusastyrene/min/mg, without a concommitant change in the K_m. The oxidation products of either the slow reaction or the obtusaquinone-enhanced reaction inhibit the catechol dehydrogenase function of phenoloxidase. The phenoloxidase-modifying properties of obtusaquinone and obtusastyrene may be related to the inhibition of shell formation in wood-boring bivalve larvae settling on rosewood.     

Effect of insecticide injection on pyruvate kinase of the insect Tenebrio molitor (Coleopteran)

In the present study, we report on the changes observed in the kinetic properties of pyruvate kinase (PK) from whole body homogenate in the three developmental stages of the insect Tenebrio molitor after insecticide or acetone injection, and after injury and 24 h starvation. The apparent K_m value of the enzyme towards phosphoenolpyruvate was higher in the pupae stage than in the rest developmental stages although the same enzyme type appears to be present throughout the life span of the insect as judged by its V_max and sensitivity towards ATP and Alanine. The highest specific activity, twice as high as that of larvae and pupae, was observed in adults. Starvation resulted to activation of the enzyme by increasing the K_m value in the two feeding stages, namely larvae and adult, while injury had the opposite effect. Acetone injection did not have any significant effect at any stage. Insecticide injection had varying effects, depending upon the developmental stage, the dose and the type of the insecticide. In larvae, low doses of methyl paraoxon and methyl parathion activated the enzyme but as the dose increased the K_m value returned to normal levels. Low dose of decamethrin activated the enzyme also but at high dose it caused a severe inactivation as judged by a fivefold increase of the observed K_m. In pupae, decamethrin had no effect, methyl parathion had similar effects to those observed in larvae, and methyl paraoxon caused activation of the enzyme at any dose given. In the adult stage none of the injected insecticides had any effect on the K_m value although V_max and specific activity were significantly altered.     

Effects of some foliar fungicides on the chrysomelid beetle Gastrophysa polygoni (L.)

The effects of the fungicides benomyl, thiophanate-methyl and triadimefon on the chrysomelid beetle Gastrophysa polygoni were investigated in the laboratory. Contact with a suspension of benomyl (1.5 g a. i. litre^?1 did not affect the hatchability of the eggs. Larvae were reared on shoots of knotgrass (Polygonum aviculare) that had been sprayed with suspensions of benomyl, ranging in concentration from 0.1 to 5.0 g a. i. litre^?1. The mortality to the adult stage, of larvae reared on shoots treated with concentrations of benomyl of 0.5 g a. i. litre^?1 and above, was significantly higher than that of control larvae. At concentrations of 2.0 g a. i. litre^?1 and above, no larvae survived to the adult stage. The LD₅₀ was 0.78 g a. i. benomyl litre^?1. The LT₅₀ values at concentrations of 1.0, 2.0 and 5.0 g a. i. benomyl litre^?1 were 22.6, 12.6 and 5.3 days, respectively. The mean weights of adults bred from larvae that had been reared on shoots treated with benomyl (0.5 and 1.0 g a. i. litre^?1) were significantly less than those of adults bred from control larvae. The mortality of larvae, reared on shoots of P. aviculare treated with triadimefon (0.5 g a. i. litre^?1) or thiophanate-methyl (1.0 g a. i. litre^?1), was also significantly higher than that of control larvae. Females kept on plants of P. aviculare treated with benomyl (1.5 g a. i. litre^?1) laid similar numbers of eggs to those kept on untreated plants, and the hatchability of the eggs was not affected.     

Several field tests of Abate larvicides for Aedes control

Abstract

In preliminary field tests in woodlands swamps of southern Morava, ?SSR, it was found that Abate 500E at the rate 0.1 g/m² of water surfaces killed Aëdes vexans, A. cinereus and A. sticticus larvae 3 instar during 24 hours, but in other case at the rate 0.05 g/m² of water surfaces killed not the A. vexans pupae.

In southern Morava, CSSR a new larvicide, Abate^* was tested for Aëdes larvae and pupae control in the field. Abate (0,0,0¹,0¹ -tetramethyl 0,0¹ -thiodi-p-phenylene phosphorothioate) is an organophosphate insecticide that has been highly effective when tested against many different species of mosquito larvae. It is of very low toxicity to man and presents a minimum hazard in control. A well timed application of Abate will control the mosquito larva before it can develop into a pupa. Barnes and Webb (1968) applied one briquette of 0.58 g or 0.78 g/10 cu. ft. water in woodland pools, against Aëdes canadensis (Thio.). A. cantator (Coq.). A. vexans (Mg.) and Culex restuans Theo. Early spring treatment controlled all species as they normally appear in chronological sequence until early fall. One treatment of 6 pools gave excellent larval control throughout the 176-day test period; 23 pools were retreated on day 57, but this may have been unnecessary. No deleterious effects were noted on aquatic organisms. The US Department of Health and Welfare (1968) reports that 1% granules of Abate (0.002–0.06 lb/ac) satisfactorily kills A. vexans larvae. Lewis et al. (1965) applied 43% ec. and 1% granules of Abate (0.075 to 0.2 lb/ac; or 0.084 to 0.22 kg/ha) to log ponds. Both formulations gave excellent initial and residual (up to 18 days) control at dosages used. The e.c. seemed to act for a longer period. It was used for Culex peus Speiser, C. pipiens L., C. tarsalis (Coq.) and Culiseta larvae control.

In southern Morava Abate 500E, a 50% (W/v) emulsifiable concentrate containing 500 g a.i./l was tested in the woodland swamps – mosquito breeding places – against A. vexans, A. cinereus Mg. and A. sticticus (Mg.) instar larvae or A. vexans pupae.

In the first experiment 10g Abate 500E were used on 100 m² of water surface, mixed with water at 1:100. The insecticide was applied on two sites and a third chosen as control. Larvae were counted from 250 ml samples from each site. Table 1 shows the average number of larvae from each site.     

三种除草剂对大型溞Daphnia magna存活、生长和繁殖的影响

为了制定除草剂在水环境中的允许浓度和排放标准,参照美国公共卫生协会等编著的《水和废水标准检验法》以及我国制定的大型溞Daphnia magna毒性测定方法,进行了丁草胺、吡嘧磺隆、苄嘧磺隆 3种稻田常用除草剂对大型溞的21 d慢性毒性试验。结果发现:随着除草剂浓度的升高,大型溞的产前发育期、产幼间隔期均缩短,每胎产幼数量先增加后减少;丁草胺各浓度处理组中,内禀增长率(rm)在0.157 2~0.314 0 d-1之间,变化较大;吡嘧磺隆各个浓度组的rm相对平稳, 为0.206 6~0.276 8 d-1;大型溞在苄嘧磺隆处理组中的rm比在其他两种除草剂中的高,为0.334 1 ~0.397 1 d-1。在丁草胺处理组中,大型溞的日生殖量较少,低于吡嘧磺隆和苄嘧磺隆处理组。     

麦蚜对吡虫啉的敏感性及吡虫啉有效用量的评价

室内测定结果表明 ,禾谷缢管蚜对吡虫啉的敏感性比麦长管蚜高 ,其LC₅₀之比为1∶3左右。田间试验结果明确 ,吡虫啉持效性好 ,其持效期与吡虫啉用量和麦蚜种类有关。小麦穗蚜发生始盛期是吡虫啉防治麦蚜的最佳时期 ,防治禾谷缢管蚜最佳有效用药量为1g/667m²,麦长管蚜为2g/667m²。