THE EFFECT OF BODY WEIGHT ON THE RESISTANCE TO INSECTICIDES OF THE LAST-INSTAR LARVA OF DIATARAXIA OLERACEA L., THE TOMATO MOTH

At a constant temperature of 24° C. the final larval instar of Diataraxia oleracea lasts about 10 days, during which its resistance to DDT and γ-BHC as contact insecticides progressively increases up to the 5th or 6th day. It then suddenly decreases, this coinciding with cessation of feeding and the beginning of prepupal formation.
Between the 2nd and the 6th days the gross body weight of the last-instar larva increases from about 0.27 to 0.65g. Under the conditions of the experiments, the LD50 of parathion, as a stomach poison, was linearly related to body weight; on the same basis TEPP was slightly less, and lead arsenate, slightly more, toxic to the larger than to the smaller larvae. However, DDT as a stomach or contact insecticide, and γ-BHC as a stomach poison were notably less toxic to the larger larvae. For example, the increase in LD50 for an increase in larval body weight of × 2 was about × 11 for DDT as a stomach poison and about × 12 as a contact insecticide.
The order of effectiveness of the above insecticides as stomach poisons for the last-instar larva of D. oleracea was parathion > DDT > γ-BHC > TEPP = lead arsenate. Zinc fluoarsenate and rotenone were relatively non-toxic. Larvae of D. oleracea were repelled by food leaf treated with an extract of natural pyrethrins.     

Strategies, systems, value judgements and dieldrin in control of locust hoppers.

The physiology and field biology of locusts have been extensively studied, and ecological control of Red Locusts has been investigated by field experiment. No fruitful or even promising non-insecticidal method of control has emerged. An effective and economical system requires an insecticide that is: (i) effective at very small area dosages, as a stomach poison placed on the natural vegetation can be, if it is also cumulative; (ii) persistent enough in sunshine and rain to retain effectiveness over the locust's non-feeding periods; (iii) capable of being well distributed by well-tried methods; and (iv) not dangerous to users or consumers and posing a minimal overall risk. Only one insecticide, dieldrin, satisfies all these requirements. Dieldrin is not in the small class of insecticides that are dangerous to man by skin absorption (such as parathion, arsenicals, DNC) and, at the area dosages needed for locust control, is not dangerous to stock. The Sayer exhaust sprayer in a Land Rover, with work rates of the order of square kilometres per hour is excellent for many situations; aircraft spraying at he rate of square kilometres per minute is quicker and less subject to difficulties of terrain, but requires trained and appropriately directed aircrew. Apart from checking, aircraft methods require no party on the ground to find, assess and control locust hoppers. Several ideas about dieldrin are found to be based on insufficient evidence and are probably not true: for example that dieldrin in the atmosphere at a few parts in a million million (10(12)) becomes concentrated in a food web and harmful to man, or that dieldrin is carcinogenic in man. It is noteworthy, however, that one species of antelope in South Africa is exceptionally susceptible to dieldrin poisoning, though harm occurs at area dosages considerably greater than are required in the method of aircraft spraying of Courshee & McDonald (1963). To attack tsetse flies, emissions two orders of magnitude greater have been used. Care must be taken with any insecticide, but the risks of using dieldrin as properly used in locust hopper control have been exaggerated by propaganda. If harm is to be expected, then a quantitative comparison of that with the undoubted benefits of locust control is required to enable one to make a value judgement.     

THE CUMULATIVE TOXICITY OF γ-BHC AND DIAZINON APPLIED IN SMALL DOSES TO LOCUSTS

The toxicity of γ-BHC and Diazinon when applied over a period of time to adults of the desert locust, Schistocerca gregaria (Forsk.), has been determined. The insecticides were applied in oil solutions, by means of the micro-drop syringe, to the ventral surface of the abdomen.
When doses were applied in two equal portions with a 72 hr. interval, or in four equal portions at 24 hr. intervals, no significant decrease in toxicity, in comparison with a single dose, could be detected with either insecticide. It is concluded, therefore, that if similar effects occur when locusts are sprayed with these insecticides in the field, successive spraying will be fully cumulative over a period of 72 hr. Previous work using DNC has shown that doses applied over 4 days were only half as effective as equivalent single doses and that continued dosing after 4 days brought about very little increase in kill.
The sexes were similar in resistance to γ-BHC when the doses were measured in μg./g., but females were considerably more resistant to Diazinon than males.     

STUDIES OF THE TOXICITY TO WORKER HONEY-BEES (APIS MELLIFERA L.) OF CERTAIN CHEMICALS USED IN PLANT PROTECTION

Laboratory techniques are described for the estimation of the stomach poison, direct and residual film contact poison and fumigant poison effects of chemicals to adult worker honey-bees.
The toxicity of eleven chemicals used in plant protection has been investigated by these methods. The order of effectiveness as stomach and contact poisons was: parathion, TEPP, γ-BHC, dieldrin, aldrin, chlordane, o , o -diethyl- o -ethylmercaptoethyl thiophosphate (constituent of Systox), bisdimethylamino fluorophosphine oxide, toxaphene and the sodium salts of 2:4-D and MCPA: as residual films, dieldrin, aldrin, γ-BHC, parathion, chlordane, and o , o -diethyl- o -ethylmercapto-ethyl thiophosphate (constituent of Systox); toxaphene, TEPP and bisdimethylamino fluorophosphine oxide had no measurable effect; as fumigants, dieldrin, γ-BHC, aldrin, parathion, and chlordane; the remainder had no measurable effect.     

Short‐term assessment of dung beetle response to carbosulfan treatment against desert locust in Sudan

The beneficial role of dung beetles (Coleoptera: Scarabaeidae) is well known. Potential risks to these beetles from the widespread use of insecticides against the desert locust, a significant plant pest in Africa, the Near East and South West Asia, have not been studied previously. Short‐term responses of dung beetles to carbamate carbosulfan (Marshal®, ultra low‐volume formulation, 100 g active ingredient ha^?1) were assessed during desert locust control operations at five sites within two major biotopes: Acacia tortilis shrubland and cultivated wetland; on the Red Sea Coast of Sudan. The study took place during January–February 2004. At each site, fresh dung from Zebu cows was placed in areas targeted for desert locust control. Dung pats were placed in plots in two areas and left for 24 h, before and after insecticide application. Beetles were extracted by floatation. There was a significant decrease in abundance between the pre‐ and post‐spray period in treated areas for the Scarabaeinae species Onthophagus margaritifer (a dark colour morph). In contrast, it was found that Aphodius lucidus and beetles at the subfamily level of Aphodiinae increased in numbers after insecticide treatment. Mortality and sublethal impacts as well as a repellent effect of the insecticide may explain the decrease in Onthophagus margaritifer, while the increase in Aphodiinae beetles could be an indirect response to lower numbers of Scarabaeinae beetles in competing for the same resource. These organisms and the applied methodology may be useful for environmental monitoring of desert locust control, thus further studies are suggested. The assessment also revealed a marked difference between the two biotopes with high abundance and species richness of dung beetles in A. tortilis shrubland, while these measures were low in the cultivated wetland. Five new species of dung beetles for Sudan were found in this study.     

辛硫磷和溴氰菊酯混剂对家蝇抗性发展的影响

以家蝇(Musca domestica vicina Macquart)为试虫,用辛硫磷溴氰菊酯单剂及不同配比的混剂进行汰选试验。所有混剂选育的家蝇抗性发展都很缓慢,而单剂抗性发展都很快。增效试验表明,辛硫磷与溴氰菊酯混配有明显增效作用,特别是对抗性品系。生化分析结果表明,对澳氰菊酯的抗性发展与酯酶的酶活升高有关。对辛硫磷抗性发展与多功能氧化酶的酶活升高和乙酰胆碱酯酶敏感性降低有关。混剂选育的家蝇其对单剂的敏感性的变化及酶系的变化,随着混剂的配比而变化。     

辛硫磷和溴氰菊酯混剂对家蝇抗性发展的影响

以家蝇（ＭｕｓｃａｄｏｍｅｓｔｉｃａｖｉｃｉｎａＭａｃｑｕａｒｔ）为试虫,用辛硫磷溴氰菊酯单剂及不同配比的混剂进行汰选试验。所有混剂选育的家蝇抗性发展都很缓慢,而单剂抗性发展都很快。增效试验表明,辛硫磷与溴氰菊酯混配有明显增效作用,特别是对抗性品系。生化分析结果表明,对溴氰菊酯的抗性发展与酯酶的酶活升高有关。对辛硫磷抗性发展与多功能氧化酶的酶活升高和乙酰胆碱酯酶敏感性降低有关。混剂选育的家蝇其对单剂的敏感性的变化及酶系的变化,随着混剂的配比而变化     

Adipokinetic hormones concentrations in the haemolymph of Schistocerca gregaria,measured by radioimmunoassay

A new procedure for the measurement of adipokinetic hormone (AKH) concentrations in locust (Schistocerca gregaria) haemolymph is described: Haemolymph is extracted with chloroform/methanol/water and the aqueous layer is fractionated with reverse-phase cartridges and HPLC. The fractions corresponding to AKH-I (Lom-AKH-I) and AKH-II (Scg-AKH-II) are then measured in a competitive binding assay using specific antibodies and [3H]AKHs. The procedures could be applied to any peptides containing N-terminal pyroglutamate residues including all members of the adipokinetic/hyperglycaemic/red pigment concentrating hormone family. Results show that the concentrations of both AKH-I and AKH-II increase within 5 min of initiation of flight and are maintained at approx. 15-fold (AKH-I) and 6-fold (AKH-II) the resting levels over flights of at least 60 min. Poisoning of locusts with either the insecticide deltamethrin or with potassium chloride also caused release of hormones. Starvation for 6 h caused elevation of hormone levels in 5th instar nymphs, but starvation for 6 or 20 h had little effect on hormones in adults, despite an increase in haemolymph diacylglycerols at 20 h.     

水解猪血粉对药物性肝损伤的保护作用

本文报道了水解猪血粉对药物性肝损伤的保护作用,比用氨基酸纯品便宜、方便。     

Deltamethrin-induced deregulation of the water balance in the migratory locust,Locusta migratoria

1. Several insecticides were tested for their ability to induce a water deregulation in the larval migratory locust. All of them provoked an accelerated dehydration (when compared to sham-operated insects). Deltamethrin and baygon were the most potent.2. This enhanced dehydration due to deltamethrin in adult locust resulted from an increase in the water loss through the feces. This increase was not due to a direct effect of deltamethrin on urine production by the Malpighian tubules but to a hormonal deregulation.3. Intoxicated insects produced large amounts of the vasopressin-like insect diuretic hormone. This higher synthesis activity occurs within the hours following the insecticide injection and is accompanied by an increase in water loss.4. These hormonal and metabolic modifications are transient. Hormonal level and diuresis rate both return to the basal levels 7 hr after the insecticide injection.     

取食不同寄主植物的棉铃虫对溴氰菊酯敏感性的变化

本文利用生物测定和生物化学的方法,就取食不同寄主植物的棉铃虫Heliothis armigera(Hübner)对溴氰菊酯敏感性及体内酶的活力变化进行了初步探索.结果表明,不同寄主植物具有诱发棉铃虫对药剂敏感性发生变化的可能性.羧酸酯酶是引起这种变化的重要因素之一,这种酶广泛分布于昆虫体内务组织中,以消化道内的活力为最高.专一性酶抑制剂的增效试验显示,TPP与溴氰菊酯混配是溴氰菊酯单用时的9倍,证实羧酸酯酶是棉铃虫代谢溴氰菊酯杀虫剂的主要途径之一.     

广东小菜蛾对苏芸金杆菌的抗性研究

广东省深圳,东莞、惠阳及博罗等供香港(以下简称供港)菜区小菜蛾对有机化学农药的抗性与广州内销菜区相近或稍高,对Bt杀虫剂的抗性则是供港菜区明显高于广州内销菜区。几种酶抑制剂TPP、SVl及Pb对Bt制剂无明显增效作用,可见小菜蛾对Bt制剂的抗性与酯酶和多功能氧化酶(MFO)的关系不大。用Bt制剂Dipel(大宝)连代选育小菜蛾敏感品系,选育18代,小菜蛾的抗性较选育前提高35倍。该抗性品系小菜蛾对个别菌株Bt及巴丹、杀虫双、速灭杀丁、万灵、敌敌畏等无交互抗性,而对昆虫生长调节抑制剂有轻微交互抗性。相反,用巴丹和杀虫双选育出的小菜蛾抗性品系对npel仍表现敏感。抗性品系小菜蛾在无触毒条件下饲养,抗性会自然减退,但不同类杀虫剂的抗性减退速率不尽相同。     

抗溴氰菊酯家蝇在不同用药方式下的敏感性变化及其机制

以具有极高抗水平的抗溴氰菊酯家蝇Musca domestica vicina Macquart DR0品系为试虫,模拟田间几种常见的用药方式(混用、轮用、使用增效剂),在室内进行平行汰选,并以不用药和继续用原药汰选的为比较,研究试虫在这几种用药方式下的敏感性变化及其变化机制。抗性家蝇用辛溴混剂、辛硫磷以及溴氰菊酯＋SV₁汰选后,在F₁₆(F₁₇)代以前,对溴氰菊酯及汰选药剂的抗性发展相对都比较缓慢;F₁₆(F₁₇)代以后,用溴氰菊酯＋SV₁汰选的家蝇对溴氰菊酯的敏感性迅速下降,抗性发展很快。家蝇对溴氰菊酯的敏感性变化与药剂中溴氰菊酯的选择压有关。生化分析结果表明,在不同用药方式汰选下,家蝇体内酯酶、多功能氧化酶、谷胱甘肽-S-转移酶、乙酰胆碱酯酶的酶活或特性发生了不同的变化。     

宁虫素对蔬菜、水稻害虫的毒力及药效特性研究

本研究了复方生物农药宁虫素对蔬菜、水稻害虫的毒力及药效特性,结果表明,该药集速效性、特效性于一体,对蚜虫、褐飞虱的毒力分别为：0.63ppm和2.00ppm。田间试验表明,宁虫素可有效地控制蔬菜蚜虫、小菜蛾、菜青虫、稻飞虱等的危害,防效显。田间使用宁虫素后,平均蛛虱比明显优于噻嗪酮和吡虫啉,生态安全性好。     

Impact of planting dates and insecticide strategies for managing crucifer flea beetles (Coleoptera: Chrysomelidae) in spring-planted canola

Integration of cultural practices, such as planting date with insecticide-based strategies, was investigated to determine best management strategy for flea beetles (Phyllotreta spp.) (Coleoptera: Chrysomelidae) in canola (Brassica napus L.). We studied the effect of two spring planting dates of B. napus and different insecticide-based management strategies on the feeding injury caused by fleabeetles in North Dakota during 2002-2003. Adult beetle peak emergence usually coincided with the emergence of the early planted canola, and this resulted in greater feeding injury in the early planted canola than later planted canola. Use of late-planted canola may have limited potential for cultural control of flea beetle, because late-planted canola is at risk for yield loss due to heat stress during flowering. Flea beetle injury ratings declined when 1) the high rate of insecticide seed treatment plus a foliar insecticide applied 21 d after planting was used, 2) the high rate of insecticide seed treatment only was used, or 3) two foliar insecticide sprays were applied. These insecticide strategies provided better protection than the low rates of insecticide seed treatments or a single foliar spray, especially in areas with moderate-to-high flea beetle populations. The foliar spray on top of the seed treatment controlled later-emerging flea beetles as the seed treatment residual was diminishing and the crop became vulnerable to feeding injury. The best insecticide strategy for management of flea beetle was the high rate of insecticide seed treatment plus a foliar insecticide applied at 21 d after planting, regardless of planting date.     

EMBRYONIC DEVELOPMENT AND ESTERASE ACTIVITY OF EGGS OF PIERIS BRASSICAE IN RELATION TO TEPP POISONING

The embryological development of eggs of Pieris brassicae was studied in relation to the occurrence of enzymes hydrolysing phenyl acetate and acetylcholine. Phenyl acetate is hydrolysed at a high rate at all stages of development of the embryo. Hydrolysis of acetylcholine only becomes appreciable in the later stages of development. The first significant level of hydrolysis of acetylcholine can be correlated with the development of a nervous system in the embryo to a stage where it may be functional.
Aqueous solutions of TEPP were applied to eggs soon after they were laid. Low doses of TEPP allowed a high percentage of eggs to develop to the point of hatching before death occurred. Most fully developed embryos became active before they died. As the dose was increased less development took place and with very high doses little development occurred.
The significance of these results is discussed. The available evidence does not indicate that the poison penetrates slowly nor that it is 'locked up' and later released. The explanation that seems to fit the evidence best is that the poison penetrates rapidly and reacts irreversibly with, probably phosphorylates, one or more components of the egg, the extent of subsequent development depending upon the proportion of a biochemical system or the number of systems inactivated. Whilst inhibition of cholinesterase may play a part in the poisoning process, at least under some conditions, the evidence indicates that the death of the embryo may result from some other cause.     

Effect of Paranosema (Nosema) locustae (Microsporidia) on morphological phase transformation of Locusta migratoria manilensis (Orthoptera: Acrididae)

Field and laboratory studies demonstrated that Paranosema (Nosema) locustae had significant effects on the morphological phase transformation of Locusta migratoria manilensis (Meyen 1835). In the field, spraying P. locustae on gregarious locusts caused a substantial population reduction by 16 days after treatment, with most of the surviving locusts being phase solitaria. However, the effects of P. locustae on locust phase transformation began before direct mortality had caused a substantial reduction in locust density: locust numbers were still high at day 10, but locusts had already transformed to phase transiens. Laboratory assays showed that while a low dose of P. locustae had no effect on phase transformation, at a higher dose of 1×10⁵ spores/mL, locusts had F/C ratios that were significantly (P<0.05) more solitaria than untreated locusts, with locusts having ratios that were either phase solitaria or on the solitaria side of phase transiens. In a second laboratory experiment that analysed the effects of locust density on phase transformation by P. locustae, there was no obvious effect of density on female locusts 10 days later as all were solitaria at all locust densities. At day 16, female locusts were transiens at higher densities, but were solitaria at 4/cage. With males there were lesser effects. These results provide new evidence for P. locustae having sub-lethal effects on locust phase transformation at a wide range of locust densities.     

THE EFFECT OF REPEATED SPRAYING OF INSECTS ON THEIR RESISTANCE TO INSECTICIDES

The administration of carbon dioxide in sublethal concentrations or for sublethal periods of time gave rise to an increased resistance to its effect in a strain of Drosophila melanogaster susceptible to the toxic effects of this gas. The effect did not appear to be permanent.
The successive administration by spraying of sublethal concentrations of DDT and BHC did not increase the resistance of a strain of D. melunoguster to their effects, either in the insects sprayed or their progeny. Only when the dosages were such as to give a high death-rate did a significant increase of resistance of the progeny of the treated insects take place; the tendency was if anything to increase susceptibility, although the indications were not in favour of DDT acting as acumulative poison.
In a preliminan series of tests the topical application of D D T in sublethal doses to the adult insects resulted in a reduction in the amount or in the rate of egg laying.     

寄主抗药性对菜蛾绒茧蜂生物学特性的影响

以小菜蛾Plutella xylostella敏感品系SP作寄主饲育的菜蛾绒茧蜂Cotesia plutellae SC品系分别寄生于小菜蛾的SP品系(SC-SP组合)或抗性RP品系(SC-RP组合),还以小菜蛾RP品系作寄主饲育的菜蛾绒茧蜂RC品系分别寄生于小菜蛾的SP品系(RC-SP组合)或RP品系(RC-RP组合),均在幼虫中期施用氰戊菊酯,考察了药剂对该蜂生物学特性的影响。结果发现：在不施用杀虫剂时,SC-RP组合中蜂的结茧率为45.8%,显著低于其它组合, 所结茧长0.76 mm,育出雌蜂前翅和后足胫节长分别为3.28 mm和2.33 mm,也分别小于其它各组合的结果,表明寄主抗药性对该蜂有不利影响;施用杀虫剂后,RC-RP、SC-RP组合中,蜂的结茧率分别为95.5%和37.8%,显著高于SC-SP和RC-SP组合中蜂的结茧率（22.5%,25.8%）,表明寄主抗性能保护其体内的幼蜂少受杀虫剂的影响;RC-SP组合在受到和未受到杀虫剂作用时茧的羽化率分别为95.2%和93.6%,无显著差异,卵+幼虫及雌蛹的发育历期在处理和对照间也无显著差异,表明用抗性寄主饲育的菜蛾绒茧蜂在寄生敏感寄主时仍表现一定的耐药性,有利于该蜂抗药性的发展,即寄主 寄生蜂之间在抗药性方面存在协同进化。     

TEXTURE OF SWEET ORANGE GELS BY FREE-CHOICE PROFILING

Texture of orange gels prepared with 15% fruit pulp, sucrose up to 55° Brix and five different gelling agents — kappa-carrageenan, kappa-carrageenan plus locust bean gum, alginate, gellan gum, and gellan, xanthan and locust bean gums — was studied by Free-Choice Profile (FCP) analysis. Maximum rupture force and deformation at rupture were also determined by uniaxial compression in an Instron texturometer. Generalized Procrustes Analysis applied to FCP data permitted differentiation between samples and informed on the textural attributes responsible for the observed differences. Sensory differences were in general in accordance with mechanical differences. However, carrageenan and gellan gum gels were differentiated with the sensory method applied but not with mechanical tests.