Three volatile solid insecticides (DFDT, γ BHC and aldrin) were tested against two species (Oryzaephilus surinamensis and Tribolium castaneum) at two temperatures (30°C. and 11°C.) in simple laboratory fumigation tests. DFDT killed both species faster at 11°C. than 30°C.; γ BHC killed O. surinamensis faster at 11°C. than 30°C., but T. castaneum faster at 30°C. than 11°C.; aldrin killed both species faster at 30°C. than 11°C.

Observations were made in Ceylon from March 1970 to February 1971 on the post-mortem incidence of Oestrus ovis L. in goats. The incidence of O. ovis was 30−2% in Jamnapari goats but 16−2% in a South Indian breed. Peaks in incidence, seen only in Jamnapari goats, and peaks in the numbers of larvae per carcase, followed the monsoons. There was a significant association between O. ovis attack and symptoms of pleuropneumonia.

Members of the genus Leptocorisa have long been known in the East as serious pests of rice. A great deal of confusion, however, has existed between the various species, and in many cases there has been considerable uncertainty as to the identity of the insect responsible for damage in any given locality. L. varicornis, F., and L. acuta, Thunb., in particular, have been constantly confused. Leopoldo Uichanco, for example, expressed some doubt as to the determination of the species described by him in his paper on the Philippine rice bug (Philippine Agric. Review, xiv, 1921, pp. 87–125). This confusion was due, no doubt, not only to the general similarity of the two species and the briefness of the original descriptions, but also to the existence of other closely allied species.

The characteristics of feeding lesions and the relationship between cocoa pod size/age and surface area were determined as a basis for examining in detail the effects of pod age on feeding and oviposition by Helopeltis theivora Waterhouse. In no-choice and choice experiments in the field, adults made few feeding lesions on the youngest cherelles and, given a choice, made many fewer on full size, ripe yellowing pods than on old cherelles and growing pods. Old cherelles and growing pods were equally attractive based on numbers of feeding lesions per cherelle or pod, but in terms of available surface area for feeding there were more on the cherelles. These distinctions in feeding choice are even more striking for oviposition, with no eggs laid on young cherelles and old pods, and old cherelles/young pods strongly preferred on a per cherelle or pod basis, and especially per unit area of surface. It is suggested that the female chooses to oviposit on relatively old cherelles and young pods because its nymphs may benefit by feeding during a nutritious growing phase of pod development. It is also significant that eggs are rarely laid on ripe pods on which newly hatched nymphs cannot survive, nor are they laid on young cherelles, most of which, unlike the oldest, will die from cherelle wilt. The female lays a large proportion of eggs within, or very close to, feeding lesions, including those made earlier by males. Yet, this does not benefit egg viability. Males did not make feeding lesions on previously laid eggs.

The identification of mosquito larvae, especially of the genus Anopheles, is now so common a practice in the Tropics that the need of a simpler method of mounting has been widely felt. Whereas in many instances a larva can be identified by examining it alive in a drop of water, in countries where many similar forms are met with mistakes are sometimes made. A great deal of identification work is doneby Health Inspectors who have not the practice necessary for determining species while they are alive, and in Malaya, where some species cannot be separated by an examination of the anterior clypeal hairs alone, a quick method of mounting so that occipital hairs and other structures can be seen is required.

Both p, p′DDT and a sample of commerical DDT have been compared with γ BHC as insecticides acting in the vapour phase. Both the direct fumigant action of the insecticides and the toxicity of the vapours sorbed on to stored products have been examined. After storage in atmosphere saturated with the vapours for six months, wheat retained sufficient of all three insecticides to control adults of Calandra graria (L.) and inhibit the develpment of larval Sitotroga ceraalella (Ol.). This control and inhibition was complete for BHC, and stronger for commercial than for p, p′DDT. Similar results were obtained when the insecticides sorbed on flour were tested using the eggs or larvae of Tribolium confusum Duv., or when fumigated groundnut kernels were tested against T. confusum, but such groundnut produced little toxic action against Oryzaephilus surinamensis (L.).

Many anti-malarial workers have recorded the larval habitats of Anopheline species, and while their records usually reveal a variety of types of breeding-places for the same species even in one and the same country, the characterisation of the breeding waters usually lacks precision. This is hardly surprising, since descriptions are based upon naked eye observations, and only physical aspects of the breeding-places, or in addition only the most striking characteristics of the associated forms of vegetation are recorded, more or less casual information being given concerning the depth, clear or muddy character, and stagnation or currency, of the water, together with even more incomplete statements relating to the plants growing in or near it. The statement, not unimportant in itself, is, for example, often volunteered that larvae of a particular species are found in streams or pools with grassy margins, while information is usually lacking relating to the species of even the more conspicuous plants which grow in the water itself, and which are characteristic of it or of the presence of particular Anopheline larvae. For example, it has been found that in Malaya in ricefields on the flat coastal plain, the presence of the floating plant Utricularia flexuosa is widely associated with larval associations in which Anopheles sinensis predominates over A. barbirostris, other Anophelines being generally absent (Williamson, 1925). It seldom if ever happens, however, that an aquatic plant has the same range of adaptability as the associated mosquitos. For example, in the case quoted, U. flexuosa abounds over many square miles in the Krian rice-fields, from which all Anopheline larvae are absent, despite the proximity of their breeding-grounds; and conversely, A. sinensis and A. barbirostris are very commonly found unassociated with Utricularia.

Studies on insect natural enemies and their effects on host populations are of immense practical value in pest management. Predation and parasitism on a citrus pest, the leafminer Phyllocnistis citrella Stainton, were evaluated by sampling over 3 years in four locations within a world leading lemon producing area in Northwest Argentina. Both mortality factors showed seasonal trends consistent across locations, with predation exerting earlier and more sustained pressure than parasitism, which showed wider seasonal variations. The dominant parasitoids, native Cirrospilus neotropicus and introduced Ageniaspis citricola, showed different seasonal trends: C. neotropicus was dominant in spring whereas A. citricola superseded it in autumn and winter. Although parasitism rates were relatively low, the native C. neotropicus revealed favourable features as potential control agent, by showing density-dependence, parasitism rates comparable with those of the specific A. citricola during part of the cycle, and earlier synchronization with the host. The study provides highly relevant information for a sustainable management of this worldwide pest, for which biological control is considered the best long-term option.

Existing attempts to estimate the survival rate of tsetse flies from ovarian age distributions generally assume that the population is stationary. The fact that the survival rate cannot be dissociated from the growth rate by these methods poses a problem. Under the assumption of a stable age distribution, we propose a maximum likelihood method to estimate the ‘apparent survival rate’ for three categories of females: nulliparous (β0), young parous (β1) and old parous flies (β2). The rate depends both on ‘real survival rates’ a0, a1 and a2, and a growth rate λ: β0 = a0/λ, β1 = a1/λ, and β2= a2/λ. We used a matrix model, which can be parameterized if the pupal survival rate and the pupal period are known. Replacing a0, a1 and a2 by β0,λ, β1λ, and β2λin the projection matrix, the problem amounts to calculating its dominant eigen-value λ, and hence a0, a1 and a2. The application to a field population of Glossina palpalis gambiensis Vanderplank in Burkina Faso showed there was a marked difference in survival rate according to age category. The average survival rate increased with age with decreasing variability. The results suggested that sampling (by trapping) may have had an effect on the dynamics of this tsetse population by ageing it artificially. This method may be a useful tool for monitoring tsetse control.

Les larves d'Oestrides qui font l&objet de la présente note ont été récoltées sur le continent africain et nous ont été soumises pour détermination par Monsieur Guy A. K. Marshall, Directeur du Bureau Impérial d'Entomologie de Londres. Elles appartiennent à quatre des sous-families auxquelles on rapporte les diptères que l'on convient de désigner communément sous le nom d'Oestrides : les Gasterophilinae, les Oestrinae, les Hypoderminae et les Cobboldiinae.

The development of the Mediterranean flour moth, Ephestia kuehniella (Zeller), was evaluated at 10, 15, 17.5, 20, 22.5, 25, 27.5, 30 and 32.5°C with no lighting. None successfully completed development at 10 and 32.5°C. The total development time from egg to adult emergence was 164, 140, 98, 76, 61, 62 and 50 days, respectively, at the remaining temperatures. The developmental rate of E. kuehniella was described by the common linear model and six non-linear models. The lower temperature threshold for the immature stages and the thermal constant for E. kuehniella were 9°C and 1111 degree-days (DD) to complete development from egg to newly emerged adult. Non-linear models estimated the lower and upper thermal thresholds (Tmin and Tmax) and optimal temperature (Topt). The values of Tmax calculated by three nonlinear models ranged from 34°C to 46°C; Topt for each stage of development varied from 24 and 31°C, consistent with the temperature (30°C) at which the most rapid development occurred. Information on the threshold temperatures for development and thermal requirements can be utilized to predict E. kuehniella population dynamics and phenology and to evaluate optimal temperature conditions for mass rearing in stored products.

♀♂. Cadmium-yellow; vertex and occiput medianly, mesonotum posteriorly in the angle formed by the notauli, black (fig. 1); scape above and flagellum very dark brown to black; hind tarsi very dark brown to black with flavescent pilosity; the apical tergites above commonly with a small dark mark; ovipositor red, the sheaths brown with flavescent pilosity; wings slightly and evenly infumated, except at apex, where they are decidedly darker, that is to say, in the forewing the apical half of the 3rd cubital and 2nd discoidal cells, and the apical fourth of the 2nd brachial cell, and in the hind wing the apical third of the radial, about the apical third of the cubital, and the extreme apex of the discoidal cells; the majority of the wing-veins dark redbrown, but black in the basal half of the forewing; in the forewing, the stigma, the costal vein (as opposed to the subcostal vein), and the medial at base, in the hindwing all veins at base of wing, and the majority of the anal vein in both wings, yellow testaceous, but often appearing rather darker owing to setae.

The following species of mealybugs have been collected from Coffea arabica in Kenya Colony :—

Pseudococcus lilacinus, Ckll.

Pseudococcus citri, Risso.

Pseudococcus simulator, sp. n.

Pseudococcus virgatus, Ckll.

Pseudococcus perniciosus, Newst. & Willc.

Pseudococcus longispinus, Targ.

It is possible that additional species may be collected, especially from the coffee districts of Western Kenya, which are very distant from Nairobi, but undiscovered species, if they exist, can be little more than entomological rarities.

In discussing the African Trypetidae some mention should be made of the work of the late Dr. Mario Bezzi, who has perhaps done most work on the higher Diptera of Africa and on the Trypetidae in particular. In 1924 in his papers in Vol. xv of the “ Bulletin of Entomological Research ” and in Vol. xix of the “ Annals of the South African Museum,” Bezzi left the classification of the African Trypetidae in as satisfactory a condition as any systematic group could be expected to be at any given time. Some discrepancy was apparent, however, between the classification of the African and of the European Trypetidae, the general classification of the latter apparently not having been touched since Loew's early work. The appearance, therefore, of Dr. F. Hendel's monograph on the Palaearctic Trypetidae in Lindner's “ Die Fliegen der Palaearktischen Region ” was greatly to be welcomed. At the same time, his classification does not agree with that of Bezzi ; Hendel has made numerous nomenclatorial and systematic changes, and the correlation of the two systems will not always be easy.

Communication between adult male and female Diparopsis castanea Hmps. was disrupted by ultra-low-volume spraying of cotton in a 0·2-ha field cage and in an open-field plot in Malawi with a polyurea-based microencapsulated formulation of the mating inhibitor 80% (E)- and 20% (Z)-9-dodecenyl acetate (IIA). When sprays containing 38·7 or 105·3 g IIA/ha were applied at 6-day intervals within the cage, reductions in mating of 62–66% and in oviposition of 72–78% resulted. Larval infestation was reduced by an average of 61% over a 52-day period. Effective release rates during these experiments were 4–19 mg/IIA/ha. Spraying at 6-day intervals with 15·9 g IIA/ha, however, had no significant effect on mating, and applications of 25·8 g of IIA/ha at 12–14 day intervals in the presence of high moth populations produced a reduction in female mating of only 19% despite a release rate of 4·4–53·0 mg/ha/h. Physical and chemical evaluations of microcapsule deposition on cotton plants indicated a low application efficiency, with an ‘effective’ spray deposition on plants of only 3·25–20·05% between pre-flowering and maturity. In an open-field spraying trial, applications of 38·7 g IIA/ha at 14–15 day intervals reduced oviposition by 75% from expected levels. Application of 15·7 g IIA/ha, however, had no disruptive effect in the field. Gas-liquid chromatographic analysis revealed no chemical interaction or marked effect on the release rate of IIA when carbaryl and IIA were sprayed in combination. Indirect evidence indicated that the microencapsulated formulations used possessed a considerable ability to withstand rain when applied to plants.

The use of Bt cotton varieties has greatly reduced the amount of conventional insecticides required to control lepidopteran pests, Helicoverpa armigera and Helicoverpa punctigera, in Australia, but the possibility that these moths might become resistant to Bt remains a threat. Consequently, a Resistance Management Plan, which includes the mandatory growing of refuge crops (pigeon pea and non-Bt cotton; both C3 plants), has been established for Bt cotton farmers. However, knowledge of the relative contributions made to overall moth populations from the many host origins (both C3 and C4 plants) available to these insects throughout cotton production regions remains limited, as do the scales of movement and spatial mixing of moths within and between these areas. This study used stable isotope signatures (in particular δ13C) to help identify where moths fed as larvae within separate cotton production regions which differed in their proportions of C3 and C4 host crops (e.g. cotton and sorghum, respectively). C3-derived moths predominated in the early season, but C4-derived moths increased in frequency later. The overall proportion of C4 moths was higher in H. armigera than in H. punctigera. Whilst the relative proportions of C3 and C4 moths differed between regions, no differences in such proportiorns were found at smaller spatial scales, nor were there significant correlations between crop composition and isotope signatures in moths. Overall, these results suggest that C4 host plants are likely to be very important in offsetting the development of Bt resistance in these insects and such influences may operate across multiple regions within a single growing season.

Collections of mosquitoes of the Anopheles gambiae Giles complex were made from the geothermal springs and surrounding area in the Semliki Valley, Bwamba County, Uganda, which is the only known locality of A. bwambae White. Specimens were analysed in one of three ways: rDNA-PCR for unequivocal species identification, allozyme electrophoresis to determine superoxide dismutase (Sod) and octanol dehydrogenase (Odh) genotypes, or both methods. Ribosomal DNA-PCR identification revealed the presence of A. bwambae and A. gambiae. Allozyme electrophoresis of 181 individuals showed that A. bwambae possessed the Sod105and Sod100 alleles and was not monomorphic for Sod105as reported previously. In adults reared from collections made in the vicinity of the geothermal springs, the frequency of Sod105 was found to be 0.614. Anopheles gambiae was fixed for Sod100. The majority of individuals homozygous for the Sod100 allele could be identified to species using Odh. Odh95 was found to be common in A. bwambae (frequency = 0.988) while A. gambiae appeared to be fixed for Odh100. Since Odh100occurred at a frequency of 1.2% in A. bwambae (concomitant with Sodgenotypes of 105/105, 100/105 or 100/100), individuals homozygous for Sod100 and Odh100 could be either species. Among 25 A. bwambae specimens homozygous for Sod100, one (4%) was also homozygous for Odh100. At present, this subset of the A. bwambae population can only be correctly identified to species using rDNA-PCR analysis.

Intraguild predation is the killing and consuming of a heterospecific competitor that uses similar resources as the prey, and also benefit from preying on each other. We investigated the foraging behaviour of the gallmidge, Aphidoletes aphidimyza, a predator of aphids used for biological control that is also the intraguild prey for most other aphid natural enemies. We focus on how aphid alarm pheromone can alter the behaviour of the gallmidge, and predation by the anthocorid bug Orius laevigatus (O. laevigatus). We hypothesised that gallmidges would respond to the presence of (E)-β-farnesene (EBF) by leaving the host plant. Since feeding by Aphidoletes gallmidge larvae does not induce EBF emission by aphids, this emission indicates the presence of an intraguild predator. We found that gallmidge larvae reduced their foraging activities and left the plant earlier when exposed to EBF, particularly when aphids were also present. Contrastingly, gallmidge females did not change the time visiting plants when exposed to EBF, but lay more eggs on plants that had a higher aphid density. Lastly, EBF reduced the number of attacks of the intraguild predator, O. laevigatus, on gallmidge larvae, potentially because more gallmidges stopped aphid feeding and moved off the plant at which point O. laevigatus predated on aphids. Our work highlights the importance of understanding how intraguild predation can influence the behaviour of potential biological control agents and the impact on pest control services when other natural enemies are also present.

Several collections of pupae and adults of Simuliid Diptera were made in British Honduras between 9th January and 18th February 1958. Samples were collected in the Mountain Pine Ridge and El Cayo areas in the west, and along the highway traversing the eastern part of the country between Caves Branch and Stann Creek.

Thirteen species of Simulium were found, nine of which are named, including S. quadrivittatum Lw. and S. metallicum Bellardi which are very annoying biters. A, few observations on distribution and habits are recorded.

Of the two anthropophilic species of Simulium found, one is known to be a vector of onchocerciasis, if only of secondary importance, and the capability of the other to transmit the disease is unknown. The disease has apparently never been established in British Honduras and is present in Guatemala. The risk of infection to settlers moving into territory near Guatemala cannot be assessed without detailed knowledge of the epidemiology of the disease in Central America.

A study has been made of the rate of oviposition, on parboiled milled rice, of the small strain of the rice weevil, Calandra oryzae (L.), under normal laboratory conditions of temperature and relative humidity (means 27°C., 80% R.H.) in Sierra Leone, and of the utilisation of grains for oviposition.

On the average, a female laid 68 eggs in all, over an oviposition period of 71 days, the peak of egg-laying being reached during the third week. Only 13 per cent, of grains were utilised. Differences between the results obtained and those recorded by previous workers are discussed.

The mean length of life of male and female weevils was found to be 113 and 97 days, respectively.