THE TOXICITY OF CERTAIN SYNTHETIC ORGANIC COMPOUNDS TO THE FRUIT-TREE RED-SPIDER MITE

The acaricidal activity of ninety synthetic organic compounds has been investigated in the laboratory. Considerable differences were found between the winter eggs, the summer eggs and the adult female stages of the fruit-tree red-spider mite (Meta-tetranychus ulmi (Koch)) in their susceptibility to many of the compounds but two substances, namely azoxybenzene and n-dodecyl thiocyanate, were appreciably toxic to all three stages. Of the compounds showing promise against summer eggs and mites, bis-( p -chlorophenyl) methyl carbinol and 4-chloroazobenzene were the best, being highly toxic to both summer stages. Of the remainder, diphenylsulphone, 4-chlorodiphenylsulphone, azobenzene and hydrazobenzene were highly ovicidal, while C₁₂-C₁₃ alkyl thiocyanates and sec .-dodecyl thiocyanate gave high kills of the adult female mite.
Relationships between molecular structure and acaricidal activity have been sought. In a series of compounds characterized by the presence of two benzene nuclei connected by certain bridging groups, it has been found that activity to the summer stages of the mite can be influenced by alterations to the bridging group and by substitution in the benzene nuclei. Maximum activity appears to be associated with chlorine substitution in the para position in one nucleus and also with compounds of this type having unsubstituted nuclei.     

THE TOXICITY OF SOME INSECTICIDES TO FIFTH-INSTAR NYMPHS OF THE DESERT LOCUST

The toxicities of the insecticides γ-BHC, diazinon, dieldrin, DNC, heptachlor and parathion to fifth-instar hoppers of the desert locust were determined. Parathion and dieldrin were the most toxic, followed in descending order by heptachlor, γ-BHC, diazinon and DNC. The resistance of the hoppers to γ-BHC and DNC changed appreciably with age within the instar.
The effects of some factors which might influence the resistance of the insects were examined and are discussed.     

“六六六”在“空仓消毒”使用上浓度测定的研究

引言 “空仓消毒”是消灭空仓内存在的害虫,以预防新粮感染害虫的有效措施,现在我国各地粮仓普遍应用。消毒的药剂,需要兼有接触毒效与持久效力的杀虫剂。它的浓度需要足以杀死害虫而不感染粮食。 目前我国空仓消毒使用的药剂是“六六六”。中华人民共和国粮食部规定的浓度与用量是:“应用6％可湿性‘六六六’1公斤加水9公斤,喷在250—350平方公尺的面     

THE APHICIDAL ACTION OF SOME SYSTEMIC INSECTICIDES APPLIED TO SEEDS

When large seeds such as broad bean are soaked in certain systemic insecticides, notably demeton, the plants which they produce are toxic to aphids. With small seeds the effect is difficult to detect.
Experiments with demeton solutions and broad beans show that equal quantities of water and demeton are absorbed. Beans vary greatly in the rate at which they absorb solution, so, to reduce variations, about 24 hr. soaking is necessary. The insecticidal activity of the plant is directly related to the quantity of solution absorbed by the seed. Larger bean seeds absorb more solution than small beans and the plants are more toxic. After short periods of soaking (4 hr.) there is more insecticide in the seed coat than in the cotyledons, after 24 hr. there is more in the cotyledons. Some of the toxic material in the seed reaches the growing plant via the soil and roots. The material in the cotyledons can pass directly to the growing plant. As some of the material absorbed by the seed passes into the soil, any factors such as an increase in soil volume or heavy watering which tend to dilute the insecticides reduce the quantity of toxic material reaching the plant. The same quantity of demeton is more effective when absorbed by a seed than when watered on to the soil around it. Seeds soaked in insecticide, dried, and stored for one month produced plants toxic to aphids.     

ACUTE TOXICITY OF SOME BLUEGREEN ALGAE TO THE PROTOZOAN PARAMECIUM CAUDATUM1

Four species of bluegreen algae were tested for possible effect on the protozoan Paramecium caudatum Ehrenberg. Toxicity was demonstrated using lyophilized cells of Fischerella epiphytica Ghose and Gloeotrichia echinulata (Smith) Richter. Nostoc linckia (Roth) Bornet & Thuret failed to show any effects when lyophilized but became toxic when sonified. Anabaena flos-aquae (Lyngb.) Bréb. was nontoxic in all tests. G. echinulata was lethal at 0.1 mg·ml^?1 which is comparable to the toxic concentration of Aphanizomenon flos-aquae (L.) Ralfs reported for microcrustaceans.     

THE STRIP TEST APPLIED TO COMMERCIAL QUATERNARY AMMONIUM COMPOUNDS. THE EFFECT OF DIFFERENT CONDITIONS

SUMMARY: The strip test, using a minimum of four treatments, has been used to examine the suitability of quaternary ammonium compounds for use on the dairy farm. Sodium hypochlorite was the basis for comparison. None of the quaternary ammonium compounds was considered effective in the concentrations used. Two of them, both containing alkyldimethylbenzylammonium chloride, were almost as effective as sodium hypochlorite.     

RELATIONSHIPS BETWEEN THE CHEMICAL CONSTITUTION AND FUMIGANT TOXICITY OF THE ALKYL IODIDES

Nineteen alkyl iodides have been tested as fumigants against the grain weevil, Calandragranaria , using the technique previously described. Relative toxicities, and also the toxicities of mixtures of selected pairs of iodides, were determined.
Secondary and tertiary isomers were in general less toxic than the primary, irrespective of whether the toxicity was measured by molar LD 50' or the corresponding relative saturation (Pt/pB) values. Despite differences in LD 50', isomeric primary iodides often acted at about the samep,/p, value. It is suggested that these observations provide evidence that, although chemical reactivity appears to be the principal factor determining the values of LD so's in the iodide series, such physical factors as phase distribution also play their part, and their effect becomes noticeable for the primary isomers, for which the chemical reactivities may be nearly the same.
The deaths of individual grain weevils which had been exposed to iodides were more or less delayed. The change of the kill with time was, under standard conditions, the same when all except methyl and the tertiary iodides were used, which suggests that with these possible exceptions, all the iodides have the same type of chemical action on the organisms. The toxicities of mixtures of selected iodides tended to confirm this, for they varied from about 1.0 to 1.25 times the value predicted from the toxicities of the single iodides using the similar action equation. Despite the apparent similarity in mode of action the LD 50's and pt / p8 values varied widely, as did the ratios of the LD 50's of successive homologues in different isomeric series. This suggests that neither the magnitude of the pt / p8 value, nor the way in which it changes from member to member in a series, gives always a useful indication of the type of action shown by a compound or group of compounds.     

某些杀虫剂对数种寄生蜂的触杀活性

以不同类型的十三种杀虫剂对菜田三种寄生蜂(凤蝶金小峰、菜粉蝶绒茧蜂和啮小蜂)进行了室内触杀活性研究.拟除虫菊酯类杀虫剂对寄生蜂的击倒速度,通常较有机磷制剂快,但其杀虫活性较有机磷制剂小.在四种拟除虫菊酯中,杀灭菊酯和中西除虫菊酯对凤蝶金小蜂的毒性,较氯氰菊酯和二氯苯醚菊酯小.马拉硫磷对凤蝶金小蜂的击倒速度最快.乙酰甲胺磷等七种有机磷制剂对凤蝶金小蜂的活性都很大.微生物制剂浏阳霉素对凤蝶金小蜂无杀虫活性,但和乐果复配后.杀虫活性明显增加.在试验条件下,凤蝶金小蜂接触4.35×10^-4毫克/平方厘米药膜后,开始击倒的速度顺序为:马拉硫磷>氯氰菊脂二氯苯醚菊酯>中西除虫菊酯>敌百虫氧化乐果>甲胺磷>乙酰甲胺磷;活性顺序为:氧化乐果>马拉硫磷甲胺磷>敌百虫乙酰甲胺磷>氯氰菊酯二氯苯醚菊酯>中西除虫菊酯.杀灭菊酯对菜粉蝶绒茧蜂的击倒速度较三唑磷快,但活性较三唑碟小.杀灭菊酯和中西除虫菊酯对菜粉蝶绒茧蜂的重寄生蜂啮小蜂的活性较三唑磷小.接触拟除虫菊酯后,个别中寄或死亡的风蝶金小蜂和啮小蜂,有缓解现象.