The flight activity of Hydrotaea irritans (Fall.) was investigated in western Scotland using an unbaited suction trap, a carbon-dioxide-baited suction trap and a Manitoba trap. Consistently more female flies were caught than males. Trapping experiments showed that carbon dioxide and visual or thermal stimuli influence long-range attraction and short-range orientation in host-seeking flies. The seasonal activity of adults was determined from the geometric means of catches from a suction trap baited with carbon dioxide and a Manitoba trap. H. irritans was shown to be univoltine. The activity of females was greatest in the middle of July and declined sharply in the first week of August. Male activity reached a peak at the same time as that of the females, then declined until no males were caught after mid-August. Females were most active between 10.00 and 18.00 h B.S.T., with a peak about 13.00 h. There was no variation in sex ratio during the day. Multiple regression equations of climatic and seasonal factors with log catches of flies were very similar for the two types of trap. Radiant temperature, illumination, wind speed and date were shown to influence activity of females and, with the exception of illumination, male activity also. Seasonal activity curves calculated from the regression equations were plotted for both sexes in the two traps.

In the “Bulletin of Entomological Research” for December 1920 Dr. J. M. Dalziel deals in a most interesting and instructive way with the various, and sometimes curious breeding-places of mosquitos in Lagos. He mentions the occurrence of mosquito larvae in saline waters, and in a foot-note refers to a number of salt-water species.

A distinct black species of Cicadulina from sugar-cane in East Africa is described as new, and notes on the distribution of other Cicadulina spp. are given.

An Hha 1 based polymerase chain reaction (PCR) assay developed for the detection of Brugia malayi, the causative agent of Brugian lymphatic filariasis, was evaluated for its sensitivity in the laboratory and for its usefulness in measuring changes in transmission of the disease in the field. Laboratory studies showed that the new assay was highly sensitive in comparison with the standard dissection and microscopy technique. The assay can detect as little as 4 pg of parasite DNA or a single microfilaria in pools of up to 100 mosquitoes. The optimum pool size for convenience was found to be 50 mosquitoes per pool. The efficacy of PCR assay was evaluated in filariasis control programmes in operation in endemic areas of Kerala State, South India. The infection rates obtained by the Hha I PCR assay and the conventional dissection and microscopy technique were 1.2% and 1.7% respectively in operational areas and 8.3% and 4.4% respectively, in check areas, which were not significantly different (P < 0.05). Thus, the Hha I PCR assay was found to be as sensitive as the conventional technique and hence it can be used as a new epidemiological tool for assessing parasite infection in field-collected mosquitoes.

Parthenogenesis is the main mode of reproduction of aphids. Their populations are therefore composed of clones whose frequency distribution varies in space and time. Previous population genetic studies on aphids have highlighted the existence of highly abundant clones (‘super-clones’), distributed over large geographic areas and persisting over time. Whether the abundance of ‘super-clones’ results from their ecological success or from stochastic forces, such as drift and migration, is an open question. Here, we looked for the existence of clines in clonal frequency along a climatic gradient in the cereal aphid Rhopalosiphum padi (Linnaeus, 1758) and examined the possible influence of geographical distance and environmental variables in the buildup and maintenance of such clonal clines. We investigated the spatial distribution of the commonest genotypes of R. padi by sampling populations along an east–west transect in maize fields in the northern half of France in both spring and late summer. Individual aphids were genotyped at several polymorphic loci, allowing the assessment of frequency distributions of multilocus genotypes (MLGs) across the cropping season. We found several MLGs showing longitudinal clines in their frequency distribution in both spring and summer. In particular, two dominant asexual genotypes of R. padi showed inverted geographical clines, which could suggest divergent adaptations to environmental conditions. We concluded that while the distribution of some ‘super-clones’ of R. padi seems most likely driven by the action of migration and genetic drift, selection could be also involved in the establishment of longitudinal clines of others.

Programmes involving mosquito research and surveillance are normally focused on the study of aquatic larval stages, but sampling methods are varied and not systematized, which hinders the comparative analysis of ecological data. A standardized method for assessing the richness and abundance of mosquito larval populations of value for the analysis of mosquito diversity is presented. Based on the study of all the aquatic sites in a one hectare sample area with a proportional number of dips according to the size of the aquatic habitat, comparative data can be obtained on species richness and relative abundance of species found between pairs of sites or in the same area at different times. This technique provides information on the total mosquito fauna at each site, helps recognize species of medical importance and estimates the abundance of each species; parameters that are not estimated by the current entomological indexes used in surveillance programmes. The quality of the inventory is obtained by estimation of the efficiency effort. Procedures for calculating alpha, beta and gamma diversity are presented. The technique was validated in a natural and an urban zone at La Mancha, Veracruz, Mexico, over two years of sampling made during different climatic seasons.

Plantation forests with timber production as the major function are highly fragmented and disturbed regarding the tree species composition and stand area. Their closed canopies also have different microclimatic conditions compared with better studied conservation areas. We studied three beetle families (click, longhorn, and rove beetles) with different ecological demands in lowland plantation forests dominated by Sessile oak and Norway spruce in the Czech Republic. Our main interest was how their species richness, abundance, diversity, body length, rarity, red-list status, species composition and individual species were driven by the main tree species, stand area and canopy openness. We analyzed 3466 individuals from 198 beetle species and the results revealed complex and contrasting responses of the studied beetle families – click beetles mostly preferred sun-exposure and spruce as the dominant tree species, longhorn beetles mainly preferred large stands, whereas rove beetles were mostly influenced by oak as the dominant tree species and increasing area. We also observed that some species had different preferences in plantation forests than is known from the literature. The main conclusions of our results are that the dominance of non-natural spruce plantations and a large stand area (both originating from artificially replanted large clear-cuts) did not affect the majority of the studied taxa as we expected. On the other hand, our results might have been influenced by other factor, such as the current small total area of the former vegetation, which in the past might have led to extinction debt; or a large area of other conifers in the surroundings that might have promoted conifer-associated fauna.

Prodiplosis longifila is reported as a pest of a wide range of species cultivated in America, including citrus, solanaceous species and asparagus. This species has different behavioural traits that are primarily centred on the oviposition habit and the feeding of larvae, which can change depending on the host. However, scarce information is available on population studies and the natural history of this insect, and uncertainty exists about the taxonomic identity and the geographic distribution of this species. The main objective was to perform a phylogenetic and genetic study of P. longifila populations and to define whether the North American and South American populations belong to the same species or whether a differentiation process had occurred due to geographic distance. A second objective was to determine whether this species showed genetic differentiation by host specialization in South America. The phylogenetic and population analyses based on DNA barcodes (cytochrome oxidase I gene) and a region of the ribosomal DNA (ITS2) revealed divergent clades attributable to geographic distance and host specificity. The North American and South American P. longifila insects were confirmed to be genetically distinct, and the genetic distances exceeded the values expected for intraspecific variation. In South America, the population analysis of P. longifila from tomato, sweet pepper (Solanaceae), Tahiti lime and key lime (Rutaceae) hosts evidenced high genetic differentiation between populations associated with different hosts and an absence of gene flow between these groups, suggesting the corresponding formation of cryptic species.

The Mekong River is known to act as a boundary between a number of terrestrial and freshwater species, including various parasites and their intermediate hosts as well as endangered mammal species. Little information is available, however, on the genetic differentiation between terrestrial invertebrates to the east and the west of this wide river. The genetic diversity among eight natural populations of Brachytrupes portentosus (Lichtenstein, 1796) (Orthoptera: Gryllidae) collected from Thailand and the Lao People's Democratic Republic (PDR) were analyzed by multilocus enzyme electrophoresis. The allelic profiles of 20 enzymes encoding 23 loci were analyzed. An average of 41% fixed differences was detected between the populations from Thailand and Lao PDR, which are separated by the Mekong River. The percent fixed differences ranged between 4% and 26% within the populations from Thailand and between 4% and 22% within the populations from Lao PDR. A phenogram shows that the eight populations fell into two major clusters based on the Thai and Lao sampling sites. The genetic distance between the samples within Thailand and within Lao PDR was related to the distances between sampling areas. The genetic variability between populations of this cricket indicates that genetic relationships are influenced by a natural barrier as well as by the geographical distance between these allopatric populations.

The possibility that mosquitoes are diverted from protected people sleeping outdoors in a bednet to an unprotected person immediately adjacent was investigated during field trials conducted in an Afghan refugee village. The presence of an untreated bednet covering three people sleeping adjacent to the subject did not cause a significant rise in the biting rate on that subject. At the dose rates studied, biting rates in the presence of an ImperatorR treated bednet fell slightly (although not significantly). K-OthrineR treated bednets had no discernible effect on biting rates. Similar studies conducted within giant net traps showed that the ImperatorR treated bednet, and to a lesser extent the K-OthrineR treated bednet, did repel mosquitoes. Within these net traps, biting on the unprotected subject decreased considerably in the presence of the imperatorR treated bednets (P < 0.05 for both culicines and Anopheles stephensi Liston in the presence of the ImperatorR treated bednet). The net traps held in volatile components from the treated bednets in much the same way as the walls of a well ventilated room. We conclude that while sleeping next to a treated bednet may be of considerable benefit inside, where one sleeps in relation to a bednet outside is of little importance. Further studies revealed that for each mosquito species, insecticide induced mortality was highest when the bednet contained the preferred host of that species. This suggests that selection for pyrethroid resistance by bednets may be relatively slow to develop in areas where the primary vectors of malaria are zoophilic.

Organic greenhouse (OGH) production is characterized by different systems and agricultural practices with diverse environmental impact. Soil arthropods are widely used as bioindicators of ecological sustainability in open field studies, while there is a lack of research on organic production for protected systems. This study assessed the soil arthropod abundance and diversity over a 2-year crop rotation in three systems of OGH production in the Mediterranean. The systems under assessment differed in soil fertility management: SUBST – a simplified system of organic production, based on an input substitution approach (use of guano and organic liquid fertilizers), AGROCOM – soil fertility mainly based on compost application and agroecological services crops (ASC) cultivation (tailored use of cover crops) as part of crop rotation, and AGROMAN – animal manure and ASC cultivation as part of crop rotation. Monitoring of soil fauna was performed by using pitfall traps and seven taxa were considered: Carabidae, Staphylinidae, Araneae, Opiliones, Isopoda, Myriapoda, and Collembola. Results demonstrated high potential of ASC cultivation as a technique for beneficial soil arthropod conservation in OGH conditions. SUBST system was dominated by Collembola in all crops, while AGROMAN and AGROCOM had more balanced relative abundance of Isopoda, Staphylinidae, and Aranea. Opiliones and Myriapoda were more affected by season, while Carabidae were poorly represented in the whole monitoring period. Despite the fact that all three production systems are in accordance with the European Union regulation on organic farming, findings of this study displayed significant differences among them and confirmed the suitability of soil arthropods as bioindicators in protected systems of organic farming.

Salivary oxidation has been hypothesized as a possible means by which spotted alfalfa aphid (Therioaphis trifolii maculata (Buckton)) deals with deleterious phenolics in the susceptible host plant, lucerne (Medicago sativa). In this study, some basic questions about this hypothesis were examined. Constitutive flavonoids and a crude phenolic extract from lucerne leaves were shown to be deterrent to the aphid in a choice test. Phenolics were oxidized by phenoloxidase in the saliva of the aphid. Fresh sap expressed from aphid-infested, oxidatively-reactive leaves was phagostimulatory to the aphid, compared to that from non-infested healthy leaves. Oxidative reaction was responsible for at least part of the phagostimulation, since addition of ascorbic acid into the sap deleted the phagostimulatory activity. Ascorbic acid was itself not deterrrent and its titre decreased in leaves after aphid feeding. The results provide further information on the Oxidative interaction between spotted alfalfa aphid and lucerne plants and support the previous suggestion that oxidation of phenolics and anti-oxidation by reductants affects feeding activity of this aphid.

No reduction in the amount of feeding or in the oviposition rate was observed when females of Rhyzopertha dominica (F.) were supplied with whole rather than with cut wheat grains. Although there was a marked reduction in feeding when females were supplied with cut grains of paddy and a further reduction when they were supplied with cut grains of hulled rice, the oviposition rate observed on these two types of grain was only slightly lower than on wheat.

The difference in the oviposition rates observed on wheat and rice may be due to a difference in the nutritional values of these grains or it is possible that the harder texture of the rice kernel limits the feeding rate of the female sufficiently to affect the rate of egg production.

Eggs are laid preferably in crevices and on rough surfaces rather than on smooth, and these preferences often overweigh the tendency shown by the female to avoid laying on the grain on which it is feeding.

The results of experiments on egg distribution in paddy are in agreement with Crombie's (1942) observation that females of R. dominica tend to lay all the eggs for a given day in one short period of intense ovipositing activity. Thus, although suitable oviposition sites may be numerous, if they are individually able to accommodate all the eggs laid on one day, eggs will usually be concentrated in fewer oviposition sites than are available.

Sitona humeralis Steph. was successfully reared from egg to adult on potted lucerne plants. Soil pH was adjusted to 6·9, and soil additives were mixed with a ‘standard potting mix’ to produce a potting mix suitable for lucerne growth and S. humeralis development. Development was faster at 20 than at 15°C, but higher mortalities occurred at 20 than at 15°C.

The diploid chromosome number of G. austeni Newst. from the Langford colony is 2n = 14 ± 2, + XX/XY. Chromosomes have been karyotyped and include a pair of large submetacentrics (L1), a pair of shorter metacentrics (L2) and a group of small telocentries (S). The X and Y elements constitute a heteromorphic pair. The S chromosomes together with the Y element display allocyclic behaviour during nuclear division. Pre-meiotic RNA synthesis has been followed by autoradiography, and differential staining of DNA with quinacrine dihydrochloride by fluorescence microscopy.

The influence of ageing, larval dietary nitrogen and adult carbohydrate diets on development of the male and female reproductive systems of Samea multiplicalis Guenée are described. Mature oocytes appeared in the ovarioles of one-day-old females and remained constant in number from one to three days after eclosion. Females from larvae that fed on plants of Salvinia molesta matured fewer oocytes (65 vs. 138) when the plants had lower (0·94% vs. 2·74%) levels of nitrogen. Resorbing oocytes were identified in the ovarioles of females 1–3 days old. The proportion of females with resorbing oocytes increased with age but not with larval dietary nutrition. Following high levels of larval dietary nitrogen, the seminal vesicles in males increased in length, while their width increased with age but not with diet. High levels of larval dietary nitrogen and an intake of adult dietary carbohydrate were both necessary for maximum fecundity. Higher levels of larval dietary nitrogen resulted in greater adult size, as measured by forewing length.

The English specimens listed below were captured on wild examples of the brown rat by the author, and those from Scotland by Waterston. Several of these mites have already been recorded by Dr. A. C. Oudemans and other authors as occurring on this host. Only three of the species (Laelaps echidninus, Notoedres muris and Myobia ensifera) can be regarded with certainty as being practically restricted to Mus norvegicus, but this is possibly also the case with Haemogamasus oudemansi, which so far has only been found on this host. The other species are frequently found on other mammals or in their nests, especially in that of the mole (see Oudemans, Acarologisches aus Maulwurfsnestern, Arch. Naturg. Berlin, 1913).

Five experiments in the use of insecticides against Calandra oryzae (L.) in stored maize are described. The results with statistical analysis and deductions are given. The insecticides used were BHC, DDT, pyrethrum, pyrethrin-piperonyl butoxide mixtures; the diluting dusts used were a local diatomite, a local bentonitic clay, and a local soapstone.

Among the chief conclusions are the following:—

The insect damage in conditioned grain did not reach, throughout an eight-month period, the high level which it did in unconditioned grain, the conditioning process alone therefore is a valuable treatment for insect control.

Bentonite alone is not a protectant and its addition to grain may on the contrary provide a more favourable environment for Calandra.

A Kenya soapstone (from Kisii) is not an effective protectant but had some effect in reducing Calandra populations over the period when an initial increase was occurring in control bags.

Kenya diatomite is a protectant. It reduces the percentage of grain damaged, but when used in bagged grain this is not proved to be due solely to intrinsic toxicity, but may in fact be due chiefly to the slippery nature of the material inhibiting insect distribution through the bulk of grain.

Gamma BHC at 1 p.p.m. is completely effective for 16 months.

Gamma BHC at 0.5 p.p.m. has some protectant effect but is not fully effective.

DDT at 7 p.p.m. has not a protectant effect.

Laboratory experiments showed that piperonyl butoxide (PB) is a powerful synergist of pyrethrins in Shell oil P31.

The toxicity of PB alone to different species of insects was determined. Tribolium castaneum was resistant to direct sprays of PB in P31, but appreciably susceptible to films : the toxic action of the films on this species was unusually delayed. Ptinus tedus and Calandragranaria were resistant to films, but C. oryzae somewhat susceptible.

In view of claims that PB makes pyrethrum films more persistent, an experiment specifically designed to reveal such an effect was carried out. This failed to show that PB makes the films any more persistent.

A formula was obtained giving the approximate pyrethrin equivalent of different pyrethrin-PB mixtures applied to T. castaneum as films on filter paper. It was shown, however, that the pyrethrin equivalent of a given pyrethrin-PB mixture could differ according to the method of application and according to the species of test insect.