Experiments have been carried out on the insecticidal action of p-, m- and o-iodo-nitrobenzene and their dichlorides. The real toxicity of these substances was estimated with the micro-injection method of Dresden, the contact action with the petri-dish method of Krijgsman & Berger. The real toxicity of the p- compounds appeared to be somewhat higher than that of their isomers. The dichlorides showed a somewhat higher toxicity than the other compounds. The contact action of the p- compounds is much higher than that of their isomers. This is caused by considerable differences in permeation velocity. The position of the iodine atom affects the permeation velocity very considerably but has much less influence on the real toxicity. It is suggested that the enhanced effect of the p- position on the permeation velocity is a general rule.

P-iodo-nitrobenzenedichloride shows such a high permeation velocity that it must be considered as a promising contact insecticide despite the fact that its real toxicity is low as compared with several other modern insecticides.

♂ (Type). Antennae somewhat longer than the head and pronotum together. Frontal ridge flat, punctured, gradually narrowed to the apex, its margins obtuse. Fastigium of the vertex slightly concave, oval, with rounded apex and almost smoothed lateral carinulae. Occiput with a scarcely distinguishable median carinula.

Au mois de mars de l'année 1933 j'ai accepté l'invitation de Monsieur E. Guest, Officier inspecteur de l'Agriculture en Iraq et en même temps Botaniste, de visiter l'Iraq pour lui aider dans quelques travaux qu'il voulait poursuivre, et le 30 mars j'ai quitté Jérusalem, accompagné par Monsieur Guest et par Monsieur M. Zohary, mon assistantet collaborateur. Arrivant à Baghdad les premiers jours d'avril, j'ai été invité par Monsieur le Ministre des Economies et des Communications et par le Directeur Général de l'Agriculture de faire cette visite au compte du Gouvernement Iraquien et de m'intéresser pendant mon tour spécialement aux problèmes de la botanique appliquée et particulièrement au problème des sauterelles et du reboisement et de l'afforestation. J'ai accepté volontiers cette invitation. Il me fallait prolonger le séjour en Iraq de dix jours de plus qu'il a été projeté d'abord. Ces dix jours étaient presque entièrement consacrés à l'étude de la végétation des champs de ponte des sauterelles.

The inheritance of white eye in Lucilia cuprina (Wied.) was investigated by means of a series of back-crosses repeated through ten generations. Since an approximate 1:1 ratio of white-eyed: red-eyed flies was observed throughout, it is concluded that white eye is due to a single recessive gene (w). Earlier work establishing that w is on an autosome is discussed.

A test for the existence of a linkage group containing genes for white eye and dieldrin-susceptibility was then made. The exposure of back-cross progeny to discriminating levels of insecticide, and the pattern of mortality observed with scalar concentrations of dieldrin, indicated that genes for white eye (w) and dieldrin-susceptibility (rdi) are on different chromosomes.

The adults of the weevil, Euthyrrhinus meditabundus, Fabr., were frequently taken in the forest country to the south of Darwin, Northern Territory, and on several occasions they were bred from the branches of two species of indigenous trees and from custard apples, Poincianas and two unidentified species of introduced ornamental trees growing in the Darwin Botanic Gardens. As a rule the infestation of these trees was not heavy, although Poincianas occasionally showed considerable injury. Mango trees, which were frequently badly damaged and sometimes destroyed by termites (Mastotermes darwinensis), appeared to be immune from attack by Euthyrrhinus, even when growing in close proximity to infested trees of other kinds.

The insecticidal Potencies of DDT, dieldrin, isobenzan, malathion, diazinon and arprocarb were assessed both by topical application of oil solutions to test insects any by exposing the latter to residues on glass, using young male and non-pregnant female adults of Glossina morsitans submorsitans Newst., G. austebi Newst., and Chrysomya putoria (Wied.).

By topical application, dieldrin and isobenzan were 10–23 times as potent as DDT, but their residues were on ly 2.2–6.3 times as effective; arprocarb was likewise more effective by topical application than as a residue, being, respectively, 9 and 3.5 times as effective as DDT. In contrast, diazinon, and, especially, malathion tended to be more efficient, relative to DDT, as residues than might be expected from application tests.

It is presumed that the difference between the ralative potency of an insecticide as a reesidue and as applied topically reflects the physical factors affecting contamination and penetration of the insect, but these matters have nor been stuided with tsetse flies.

It is known that, in solutions of some organic solvents such as pyridine, chloroform, ethylene dichloride and acetone, rotenone changes by oxidation to various derivatives, giving the solution a characteristic yellow colour (Jones & Haller, 1931). There is an accompanying loss in toxicity. Now that various intermediate solvents for rotenone in oils are being studied, it becomes of interest to know the stability of rotenone in these solutions.

Exitianus curvipenis (representing a new sixth species-group) from rice-field grasses in Nigeria, and E. upenis (okahandia-group) from open grassland in Abyssinia are described as new.

Medical Officers and others interested in tropical sanitation often find great difficulty in rapidly identifying adult mosquitos. Four Anophelines have been found in the Zanzibar Protectorate, two of these being well-known malaria carriers. The identification of the two latter with the aid of a pocket lens is quite simple.

Pomello and lemon seedlings kept for different time periods in various nutrient solutions were examined for their degree of infestation with Aceria sheldoni (Ewing), the citrus bud mite. Chemical analyses indicated that seedling leaves and buds had a higher nitrogen content in a potassium-free solution, and a lower nitrogen content in a nitrogen-free solution, when compared with their respective contents in a standard solution; in buds these differences were also shown by certain amino acids. Infested seedlings kept in a potassium-free solution had significantly more mites than those kept in a nitrogen-free solution, and the latter had significantly fewer mites than those kept in a standard solution. No increase in mite populations was noted on seedlings kept in high-nitrogen solutions. The relationship between the levels of potassium, nitrogen, magnesium and manganese and the mite population is discussed. No effect on mite reproduction was noted when sodium or calcium was used as a substitute for potassium.

The persistence, as assessed by biological and chemical methods, of field deposits on apples from two spray programmes, each of DDT, carbaryl or azinphos-methyl, was compared throughout eight weeks following the first application in an orchard in south-eastern England. Newly emerged larvae of the codling moth, Cydia pomonella (L.), were used to assess, in the laboratory, the biological activity of the deposits. The spray programmes studied were (1) two applications of conventional concentrations (i.e., 0·1 per cent, for DDT and for carbaryl, 0·04 per cent, for azinphos-methyl) three weeks apart and (2) three applications of half these concentrations at two-weekly intervals. DDT wettable powder, carbaryl and azinphos-methyl were compared in 1961, DDT emulsion, DDT wettable powder and carbaryl in 1963. Results of biological and chemical assessment of the deposits are presented graphically. Over-all, the performance of the three-application programmes was as satisfactory as that of the two-application programmes, although a smaller amount of chemical was used. The serious reduction in deposit caused by heavy rain shortly after the first application of DDT wettable powder and of carbaryl in 1961 is noted. In the absence of heavy rain, carbaryl was biologically the most persistent, but the best performances of the other chemicals were almost as good as that of carbaryl.

LD50 values of fresh deposits obtained by field spraying were shown to be similar to those obtained by laboratory dipping.

Comparison of the toxicity of fresh and weathered field deposits of similar magnitude indicated that the biologically available proportion of a DDT deposit from either formulation decreases as a result of weathering. This phenomenon was not found to occur with carbaryl and either not at all or to a much lesser extent with azinphos-methyl.

The deposits obtained in the comparison of the spray programmes were separated into their fresh and aged components, so that differences in the contribution to the final deposit provided by each application could be seen. With the very persistent DDT emulsion, only about half of the six-week deposits was composed of chemical from the final application, but, with the much less persistent carbaryl and azinphos methyl, the six-week deposits were almost entirely derived from the final application. By substitution in an equation to obtain the rates of decay of the deposits from the three-application programmes of all chemicals, it is shown that deposits from the second and third applications were, in all cases, more persistent than those from the first. Possible reasons for this difference are discussed.

The significance, in terms of field control, of the results for the larvicidal activity of the deposits from the different spray programmes is indicated. It is concluded that data on the LD90 of insecticidal deposits on apples, together with measurement of their persistence in the field, can be used to assess the probable field performance of codling-moth insecticides and to determine the most efficient means of employing them, although the deposit level that ensures 90 per cent, larval mortality in the field is higher than the LD90 determined in the laboratory.

Investigations undertaken by the writer involved the determining and sexing of a large number of fleas daily, and it became clear that this would be a laborious process unless an apparatus could be designed which would facilitate separation and examination of the insects by making the process as automatic as possible. The technique finally used, though designed primarily for handling fleas, could be adapted for use with other insects of comparable size where examination under magnification is necessary.

A recent study on ladybird, Menochilus sexmaculatus (Fabricius) demonstrates that males perform post-copulatory mate guarding in the form of prolonged mating durations. We investigated whether food resource fluctuation affects pre- and post-copulatory behaviour of M. sexmaculatus. It has not been studied before in ladybirds. For this, adults were subjected to prey resource fluctuations sequentially at three levels: post-emergence (Poe; 10 days), pre-mating (Prm; 24 h) and post-mating (Pom; 5 days; only female). The food resource conditions at each level could be any one of scarce, optimal or abundant. Pre-copulatory and post-copulatory behaviour, and reproductive output were assessed. Post-emergence and pre-mating nutrient conditions significantly influenced the pre-copulatory behaviour. Males reared on scarce post-emergence conditions were found to require significantly higher number of mating attempts to establish mating unlike males in the other two food conditions. Under scarce post-emergence and pre-mating conditions, time to commencement of mating and latent period were high but opposite result was obtained for mate-guarding duration. Fecundity and per cent egg viability were more influenced by post-mating conditions, with scarce conditions stopping oviposition regardless of pre-mating and post-emergence conditions. Present results indicate that pre- and post-copulatory behaviour of ladybird is plastic in nature in response to food resource fluctuations.

Food-baited dishes were used to monitor the impact of ground-sprayed DDT (4% WP @ approx. 200 g/ha) and deltamethrin (0.05% SC @ 2.6 g/ha) for tsetse fly (Glossina spp.) control, on epigeal ants in mopane woodland in north-western Zimbabwe. Twenty species of ants were recorded at dishes baited with various types of food. Pheidole spp. and Monomorium opacum Forel (Formicidae: Myrmicinae) were predominant, both in the number of baits attended and in the number of workers present at individual baits. Season apparently had a greater effect on the composition and activity of the ground foraging ant assemblage than did either pesticide. There was a decline in the rate at which baits were found and in species richness of the ant assemblage as the dry season progressed and several species also showed changes in their ability to locate baits. There was no major pesticide induced disruption of the species richness or food finding ability of the diurnal ground foraging ant assemblage sampled. However, foraging success by Platythyrea cribrinodis (Gerstaecker) (Formicidae: Ponerinae) was reduced immediately after spraying with deltamethrin. Subtle effects of either insecticide on rarer species cannot be discounted from the results of this study.

Chickpeas (Cicer arietinum L.) belong to the Fabaceae family and are one of the most grown crops in the world and an important source of protein for humans. Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) is a polyphagous pest that causes significant crop damage. The objective of this study was to examine antibiosis to S. frugiperda in chickpea genotypes. The following genotypes were studied: Jamu 96 and Blanco Sinaloa 92 (Mexico); Nacional 29 (Cuba); BG 1392 (Spain), and BRS Kalifa, BRS Cristalino, BRS Toro, Nacional 27, 004UP, 003UP, BRS Cícero, and BRS Aleppo (Brazil). The chickpea genotypes influenced the biological parameters of S. frugiperda, of which larval period, larval weight, and pupal period were most affected. Nacional 29 caused high mortality in the larval and pupal stages of S. frugiperda. The larvae on BRS Aleppo had the longest larval stage, lowest weight, and longest pupal stage. The genotypes Nacional 29, Nacional 27, and BRS Cícero showed antibiosis resistance to S. frugiperda. These genotypes could be used as a source of resistance to S. frugiperda in conjunction with other methods of pest control in integrated pest management programs for chickpea crops. These resistant genotypes could also be used as donor sources in breeding programs for insect resistance.

The carnation tortrix moth, Cacoecimorpha pronubana (Hübner, [1799]) (Lepidoptera: Tortricidae), is one of the most economically important insect species affecting the horticultural industry in the UK. The larvae consume foliage, flowers or fruits, and/or rolls leaves together with silken threads, negatively affecting the growth and/or aesthetics of the crop. In order to understand the polyphagous behaviour of this species within an ornamental crop habitat, we hypothesized that different host plant species affect its life history traits differently. This study investigated the effects of the host plant species on larval and pupal durations and sizes, and fecundity (the number of eggs and the number and size of egg clutches). At 20°C, 60% RH and a 16L:8D photoperiod larvae developed 10, 14, 20 and 36 days faster when reared on Christmas berry, Photinia (Rosaceae), than on cherry laurel, Prunus laurocerasus (Rosaceae), New Zealand broadleaf, Griselinia littoralis (Griseliniaceae), Mexican orange, Choisya ternata (Rutaceae), and firethorn, Pyracantha angustifolia (Rosaceae), respectively. Female pupae were 23.8 mg heavier than male pupae, and pupal weight was significantly correlated with the duration of larval development. The lowest and the highest mean numbers of eggs were produced by females reared on Pyracantha (41) and Photinia (202), respectively. Clutch size differed significantly among moths reared on different host plants, although the total number of eggs did not differ. This study showed that different ornamental host plants affect the development of C. pronubana differently. Improved understanding of the influence of host plant on the moth's life history parameters measured here will help in determining the economic impact that this species may have within the ornamental plant production environment, and may be used in developing more accurate crop protection methodologies within integrated pest management of this insect.

The relative contributions of host plant, herbivore species and clone to variation in the interaction between cereal aphids and wheat were investigated using five clones each of three species, Rhopalosiphum padi (Linnaeus), Sitobion avenae (Fabricius) and Schizaphis graminum (Rondani), on seedlings of two cultivars of Triticum aestivum L. and one cultivar of Triticum durum Desf. More individuals and biomass of R. padi than of the other two species were produced on seedlings. The three wheat cultivars lost similar amounts of biomass as a result of infestation by aphids, with the amount lost depending on aphid species: S. avenae caused the lowest loss in biomass. Variation in aphid biomass production was due mostly to differences among aphid species (70%), less to the interaction between wheat type and aphid species (7%), and least to aphid clone (1%). The specific impact of the aphids on the plants ranged from 1.7 to 3.7 mg of plant biomass lost per mg of aphid biomass gained, being lowest for R. padi and highest for S. graminum. Variation in plant biomass lost to herbivory was due mostly to unknown sources of error (95%), probably phenotypic differences among individual seedlings, with 3% due to aphid species and none attributable to aphid clone. For these aphid–plant interactions, differences among aphid clones within species contributed little to variation in aphid and plant productivity; therefore, a small sample of clones was adequate for quantifying the interactions. Furthermore, one clone of each species maintained in the laboratory for about 200 parthenogenetic generations was indistinguishable from clones collected recently from the field.