The horse-chestnut leaf miner, Cameraria ohridella, is an invasive alien species defoliating horse-chestnut, a popular ornamental tree in Europe. This paper presents quantitative data on mortality factors affecting larvae and pupae of the leaf miner in Switzerland and Bulgaria, both in urban and forest environments. Two sampling methods were used and compared: a cohort method, consisting of the surveying of pre-selected mines throughout their development, and a grab sampling method, consisting of single sets of leaves collected and dissected at regular intervals. The total mortality per generation varied between 14 and 99%. Mortality was caused by a variety of factors, including parasitism, host feeding, predation by birds and arthropods, plant defence reaction, leaf senescence, intra-specific competition and inter-specific competition with a fungal disease. Significant interactions were found between mortality factors and sampling methods, countries, environments and generation. No mortality factor was dominant throughout the sites, generations and methods tested. Plant defence reactions constituted the main mortality factor for the first two larval stages, whereas predation by birds and arthropods and parasitism were more important in older larvae and pupae. Mortality caused by leaf senescence was often the dominant mortality factor in the last annual generation. The cohort method detected higher mortality rates than the grab sampling method. In particular, mortality by plant defence reaction and leaf senescence were better assessed using the cohort method, which is, therefore, recommended for life table studies on leaf miners.

Seventy species of Tabanids occur in the Sudan. Many of the inhabitants are pastoralists, and the Tabanids have a profound effect on them, largely by causing them to remove their animals from infested areas in the rains and to undertake extensive annual migrations. New problems will arise when economic development involves permanent settlement of certain infested areas. This paper sets out the problem, and satisfactory control measures have yet to be devised.

The country is briefly described.

The section on individual species consists mainly of lists of localities which are shown on maps.

In a general discussion of distribution faunal areas are designated for discussing Tabanids in the Sudan. The composition of the Tabanid fauna, which is mainly Ethiopian, is described. Types of habitat are indicated, and distribution is discussed in relation to systematic position. The area in which Tabanids are abundant, and their seasonal prevalence, are indicated.

There are brief references to habits, particularly the attraction to inanimate objects and the fact that some species bite man on some occasions and not others.

The economic effect, namely, the direct effect of bites and probable role of the flies in the transmission of cattle and camel trypanosomiasis and human loiasis, are described, mainly from published sources.

The effect of Tabanids on the distribution and annual migrations of pastoral tribes is described. Attacks by flies on domestic animals and the search for pasture and water are the main causes of the very extensive rainy season migrations which are shown on a map.

The problem of control is very briefly discussed.

Additional information on some of the foregoing subjects is given in notes on faunal areas.

The holotypes and allotypes of all species described as new in this paper are to be deposited in the British Museum and paratypes in the United States National Museum. All the species described in this paper are parasitic in scale-insects or mealybugs.

Some of the classifications presented in these papers on African Encyrtidae are tentative only, for in the case of closely related variable species it is impossible to make final identifications on the basis of a few museum samples. The exact degrees of relationship can be expressed only when the insects are known intimately throughout their entire range and a knowledge of the limits and degrees of variation obtained. Even with this knowledge it is not always possible to make final determinations with assurance.

Catches in light-traps adjoining cotton were obtained at the time of seasonal southward movement of the Inter-Tropical Front (ITF) in October, and during most of the following two months. Taxa studied were mostly Orthoptera and moths, many associated with sorghum, others long-distance migrants. Suction-trap catches at three heights up to 50 ft were obtained for short periods in October and November, and aircraft catches at 250 ft were also available on two days. Suction-trap catches of grass-feeding Homoptera suggest that displacement of these insects was associated with changes in wind direction marking movement of the ITF in October. The exact form of the displacement system in relation to the front cannot be reconstructed from catches at a single place, but it seems likely that proximity of the front at or soon after the time of a brief period of crepuscular activity stimulates insects to take flight and rise to 50 ft or more so that they are displaced. In many taxa, light-trap catches showed a regular pattern of increase, with only slight nightly fluctuations from a logarithmic trend, following full moon. Other increases were superimposed on this pattern at times when the ITF passed north of the trap site, and in some taxa particularly when it was far north. The pattern of change after full moon, shown most clearly in taxa with source populations close to the trap, was related to the moon's influence on the range of trap effectiveness. But various qualitative variations suggest that, in addition, aspects of behaviour or development may have adaptive relationships to the lunar cycle; variations include differences between taxa, particularly in timing of catch changes, and increasing proportion and decreasing maturity of females of certain taxa at the time of the regular increases in catch.

Anopheles minimus Theobald was studied in four villages that had experienced differing levels of DDT application during malaria control operations in the foothills of northern Thailand. During times of high population level, the behaviour of the mosquito was assessed with respect to man-biting indoors and outdoors and feeding from domestic bovids. Its responses in villages recently treated with DDT differed from those in villages that had not been treated for several years, so that the insecticide had little direct lethal effect. Furthermore, the influence of the insecticide on the behaviour of the insect was considerably longer than is the lethal effect of the chemical. There was a suggestion that the taxon A. minimus may include two or more morphologically-cryptic species.

Flight activity of aphids during 1969–71 in a Sitka spruce plantation in north-eastern Scotland was recorded by means of sticky traps. Two flight periods occurred, June–August and September–October. Fewer aphids were caught at 120 and 180 cm than at 60 cm above ground during June–August, while fewer were caught at 60 cm in September–October. After accounting for differences in wind speed at these heights, it was shown that aerial density was consistently higher at 60 cm. The first flight which comprised mostly Elatobium abietinum (Wlk.) was three weeks early in 1971; this was associated with the rapid increase in aphid population on spruce shoots, due to the preceding mild winter. Reinfestation by this species after spraying could follow under similar circumstances. Adelges laricis Vail. and A. viridis (Ratz.) sexuparae were caught in the first flight, and A. cooleyi (Gill.) gallicolae in the second; all galls on Sitka were by gallicolae of A. cooleyi. Aphis fabae Scop, was the most common species in the second flight.

The ovarian cycle in Culicoides barbosai Wirth & Blanton and C. furens (Poey), two biting midges of considerable importance in Jamaica, was studied in the laboratory. In C. furens, a single blood-meal was sufficient for development of a substantial number of eggs; in C. barbosai, which took a relatively smaller blood-meal, very few eggs were matured (usually between 10 and 20 but sometimes fewer than 10), and some females failed to produce any eggs at all.

A high degree of gonotrophic harmony was observed in C. furens, but in C. barbosai the degree of harmony was low and a large proportion of the ovarian follicles degenerated; these differences may be associated with the relative size of the blood-meals of the two species.

The duration of the gonotrophic cycle (from feeding to the appearance of mature eggs in the ovaries) at 68, 77, 85 and 91°F. was 156, 104, 82 and 72 hr., respectively, in C. barbosai and 102, 59, 42 and 36 hr. in C. furens.

In experiments on the effect of temperature and carbohydrate feeding on egg production, temperature did not influence egg production in C. barbosai, and greater numbers of eggs were not matured by females given access to honey during the period of egg development. However, access to honey did increse the proportion of individuals surviving the period of egg maturation and also the numbers that mastured any eggs at all. Females of C. furens kept at 77°F. matured more eggs than those kept at 91 or 85°F.; access to honey improved survival, but its effects on egg production were inconclusive in these experiments.

Observations indicated that adults of both species are probably in the habit of taking carbohydrate food in nature.

Females of both species may be autogenous, though the proportion of such individuals varied considerably between populations from different breeding sites. Autogenous females of both species emerged from the pupa with ovaries already relatively well developed; in C. barbosai the ovarian follicles were in Stage IIB or III, in C. furens they were in late Stage IIA or IIB. Large numbers of eggs were matured by autogenous females of the former, and the same is probably true of the latter.

The egg stage is apparently of longer duration C. barbosai than in C. furens. At 68, 77, 85 and 91°F., most eggs of C. barbosai hatched on days 12, 6–7, 5–6 and 5, respectively, whereas at the three higher temperatures most eggs of C. furens hatched on days 4, 3 and 2. Percentage fertility varied between individual egg batches of both species.

Control of the malaria vector An. gambiae is still largely obtained through chemical intervention using pyrethroids, such as permethrin. However, strains of An. gambiae that are resistant to the toxic effects of pyrethroids have become widespread in several endemic areas over the last decade. The objective of this study was to assess differences in five life-history traits (larval developmental time and the body weight, fecundity, hatch rate, and longevity of adult females) and energy metabolism between a strain of An. gambiae that is resistant to permethrin (RSP), due to knockdown resistance and enhanced metabolic detoxification, and a permethrin susceptible strain reared under laboratory conditions. We also quantified the expression levels of five antioxidant enzyme genes: GSTe3, CAT, GPXH1, SOD1, and SOD2. We found that the RSP strain had a longer developmental time than the susceptible strain. Additionally, RSP adult females had higher wet body weight and increased water and glycogen levels. Compared to permethrin susceptible females, RSP females displayed reduced metabolic rate and mitochondrial coupling efficiency and higher mitochondrial ROS production. Furthermore, despite higher levels of GSTe3 and CAT transcripts, RSP females had a shorter adult life span than susceptible females. Collectively, these results suggest that permethrin resistance alleles might affect energy metabolism, oxidative stress, and adult survival of An. gambiae. However, because the strains used in this study differ in their genetic backgrounds, the results need to be interpreted with caution and replicated in other strains to have significant implications for malaria transmission and vector control.

Muscidifurax raptorellus Kogan & Legner is a gregarious pteromalid ectoparasitoid that attacks pupae and pharate adults from several families of the higher Diptera. Egg-to-adult development time, adult parasitoid size and emerging offspring ( = secondary) sex ratio of M. raptorellus were compared with clutch size in two hosts that differed greatly in mass, the small Musca domestica Linnaeus and the larger Calliphora vomitoria Linnaeus. The mean number of emerging parasitoids did not vary significantly with host species, although slightly higher clutch sizes were recorded in C. vomitoria. Irrespective of offspring sex, parasitoids completed development more rapidly in M. domestica than in C. vomitoria. In the small host, the development time and adult size of M. raptorellus were negatively correlated with clutch size. By contrast, female parasitoid size was unaffected by clutch size in the larger host, C. vomitoria. In both hosts, female parasitoids were significantly larger than male parasitoids. The secondary sex ratio (percentage males) of emerging parasitoids was significantly lower in C. vomitoria, and varied with clutch size in both hosts. In C. vomitoria, the greatest proportion of females emerged from hosts with the highest clutch sizes, whereas in M. domestica hosts with the highest clutch sizes produced the lowest proportion of female progeny. The results described here show that the development of M. raptorellus is profoundly affected by interspecific differences in host quality. Our results suggest that mating structure and host quality have potentially different effects on sex ratio decisions in M. raptorellus, and perhaps other gregarious parasitoids.

Fifty-five species of exotic dung beetles have been introduced into Australia and in many areas, several species are now established and often abundant. Controversy exists in the dung beetle literature concerning the use of ivermectin as an anthelmintic treatment for livestock and its subsequent lethal and sub-lethal effects on adult dung beetles. A study was conducted in the field exposing replicate dung pats containing residues of ivermectin excreted 0–15 days post-injection. At the time of the study, the introduced species of dung beetle Onthophagus taurus (Schreber) was present in high numbers (>1000 beetles per pat). After 24 h exposure, dung pats collected from cattle treated 7 and 10 days earlier with ivermectin were dispersed significantly less than untreated dung. A similar pattern was evident in the numbers of dung beetles present in each pat. This study is discussed in the context of anthelmintic usage in cattle and their potential ecotoxic effects against dung beetles.

Dry grain legume seeds possessing αAI-1, an α-amylase inhibitor from common bean (Phaseolus vulgaris), under the control of a cotyledon-specific promoter have been shown to be highly resistant to several important bruchid pest species. One transgenic chickpea and four cowpea lines expressing αAI-1, their respective controls, as well as nine conventional chickpea cultivars were assessed for their resistance to the bruchids Acanthoscelides obtectus (Say), Callosobruchus chinensis L. and Callosobruchus maculatus F. All transgenic lines were highly resistant to both Callosobruchus species. A. obtectus, known to be tolerant to αAI-1, was able to develop in all transgenic lines. While the cotyledons of all non-transgenic cultivars were highly susceptible to all bruchids, C. chinensis and C. maculatus larvae suffered from significantly increased mortality rates inside transgenic seeds. The main factor responsible for the partial resistance in the non-transgenic cultivars was deduced to reside in the seed coat. The αAI-1 present in seeds of transgenic chickpea and cowpea lines significantly increases their resistance to two important bruchid pest species (C. chinensis and C. maculatus) essentially to immunity. To control αAI-1 tolerant bruchid species such as A. obtectus and to avoid the development of resistance to αAI-1, varieties carrying this transgene should be protected with additional control measures.

The current study reports mortality and effects on cellular immune response of several entomopathogenic fungi including isoleates BB1, BB2 and BB3 of Beauveria bassiana, Metarhizium anisopliae, Isaria fumosoroseus and Lecanicilium lecanii against larvae of Chilo suppressalis. Prohemocytes, granulocytes, plasmatocytes and oenocytoids were identified as the main circulating hemocytes in the hemolymph of larvae using Giemsa staining solution. Entomopathogenic fungi caused differential mortality on larvae: BB1, BB3, M. anisopliae lead to the highest mortality on larvae and L. lecanii caused the lowest mortality. The highest numbers of total hemocytes were observed 3 h post-injection of B. bassiana isolates and 6 h for the other treatments. The highest numbers of plasmatocytes were observed 3 h post-injection of BB1 and Tween 80, whereas BB2, BB3, M. anisopliae, I.fumosoroseus and L. lecani caused plasmatocyte increase 6 h post-injection. Similar results were obtained in case of granulocytes but only Tween 80 showed the highest number of hemocytes 3 h post-injection. The highest numbers of nodules were found at various time intervals after injection of fungal isolates and latex bead. The highest activities of phenoloxidase were observed 12 h post-injection by BbB1, BbB3, M. anisopliae and latex bead; 3–6 h post-injection by BbB2, 6 h post-injection by I. fumosoroseus and 3–6 h post-injection by L. lecanii. Our data demonstrate the possibility of utilizing different fungal extracts in the field to help reduce the risk of resistance evolution in C. suppressalis and encourage experimentations aimed to increase the number of biological control agent for insect pests such as the striped rice stem borer C. suppressalis.

Necremnus tutae is native to the Mediterranean region where it has been observed in greenhouses parasitizing the invasive Tuta absoluta on tomato. The objective of the present study was to determine whether augmentative releases of N. tutae can improve existing biological control of T. absoluta based on predation by Nesidicoris tenuis. Two experiments were carried out, of which the first evaluated different N. tutae release rates (1 and 2 N. tutae m−2 week−1). The parasitoid reduced plant and fruit damage, especially at the higher rate. However, such reduction was considered insufficient given the large numbers of parasitoids needed and still unacceptable level of fruit damage. The second experiment focused on combining the most efficient rate of N. tutae of those evaluated during the first experiment, with the pre- and post-planting release of N. tenuis and supplemental additions of Ephestia kuehniella eggs. Addition of N. tutae decreased leaf damage by T. absoluta regardless the release method for N. tenuis, but the pre-plant release of N. tenuis alone was sufficient to prevent fruit damage by T. absoluta. This suggested that the addition of N. tutae may not be necessary to obtain satisfactory control of T. absoluta following pre-plant application of N. tenuis, although different options for using N. tutae in commercial crops may still be possible.

The performance of the egg parasitoid Uscana lariophaga Steffan was studied when reared on eggs of the bruchid storage pest, Callosobruchus maculatus (Fabricius) developing in seeds of cowpea, chickpea and pigeonpea. The beetle laid more and larger eggs on pigeonpea than on cowpea and chickpea, indicating that there was not a trade-off between number and size of the eggs. The bruchid larvae reared on pigeonpea exhibited a longer development time and a higher mortality than those reared on cowpea and chickpea. The resulting males weighed less than those reared on cowpea and chickpea. The trichogrammatid U. lariophaga parasitized more eggs when C. maculatus was reared on chickpea than when reared on the other hosts. Parasitoid larvae developed slowest and had the highest mortality in eggs of C. maculatus reared on pigeonpea compared to those reared on cowpea and chickpea; the sex ratio (% of females) of the resulting adults was also higher. The high mortality and long development time of C. maculatus reared on pigeonpea indicated that this legume was less favourable to C. maculatus than chickpea or cowpea. This was probably also true for the parasitoid since the mortality was higher and development longer in eggs of C. maculatus reared on pigeonpea compared to those reared on cowpea and chickpea. Therefore, when host eggs were larger and of lower nutritional quality, the proportion of female egg parasitoids was greater.

Seasonal patterns of abundance of Musca vetustissima Walker and scarabaeine dung beetles were measured at Busselton in south-western Australia for two years before and three years after, the introduction and establishment of two species of summer-active dung beetles, Oniticellus pallipes (F.) and Onthophagus binodis (Thunberg). Previously, only a single winter-active native dung beetle species, O. ferox Harold, occurred in this area. The mean dry weight of dung beetles trapped in December (early summer) was unaffected by the establishment of the additional species, and fly populations remained high. In January, however, dung beetle dry weight increased more than 60-fold and M. vetustissima abundance fell to 12% of its previous value, essentially halving the duration of major fly problems in the area. Virtually no flies emerged from cattle dung after December, when dung beetle activity reduced egg-adult survival of M. vetustissima to only 0·5%. It is proposed that better M. vetustissima control could be achieved in much of south-western Australia by introducing additional dung beetle species that are abundant in November and December.

A method for the purification of elevated esterase B2 from the Sri Lankan Pel RR strain of Culex quinquefasciatus (Say) has been developed, using sequential column chromatography. The pure enzyme is stable, with no decrease in specific activity after several months, if stored in the presence of 25 mM dithiothreitol and 50% glycerol at –20°C. The enzyme has a pl of 5 and an estimated molecular weight for the monomeric enzyme of 63 kD from SDS-PAGE. In all Culex strains with elevated B2, another esterase (A2) is always co-elevated. The strains with these esterases are resistant to a broad range of organophosphorus insecticides. The previous purification and characterization of A2 from Pel RR indicated that the role of this enzyme was primarily to sequester rather than metabolize organophosphates. Purified B2, rapidly binds malaoxon, the activated form of malathion, but not malathion itself. The turnover rate of bound malaoxon is slow, suggesting that the role of this esterase in malathion resistance is also sequestration. The similar bimolecular rate constants for both A2 and B2 with malaoxon suggest both esterases are important in resistance, which may explain the almost complete linkage disequilibrium that the elevated forms of these two esterases are maintained in when under pesticide selection pressure.

Resistant and normal colonies of the blowfly Chrysomyia putoria (Wied.) were obtained from the Congo and cultured in London. By selection and inbreeding, sub-colonies homogeneous for resistance to (a) the BHC/dieldrin group of chlorinated insecticides and (b) malathion, were obtained. Homogeneous resistant colonies were markedly less fertile and were difficult to perpetuate.

Toxicological investigations of the BHC/dieldrin-resistant colony revealed a characteristic resistance spectrum similar to that of six other insect species. Genetical experiments with the BHC/dieldrin-resistant strain indicated inheritance by a single gene pair, intermediate in dominance, very similar to that reported in nine other insect species.

Toxicological investigations of the malathion-resistant colony, including tests with 19 organophosphorus insecticides, showed a resistance largely specific to malathion and malaoxon. This was rather similar to malathion-resistant strains of two other species, for which data were available. It is known that the toxic action of malathion on mammals can be potentiated by prior treatment with small doses of certain organophosphorus compounds, which inhibit an aliesterase that detoxifies malathion by carboxylic hydrolysis, and furthermore that potentiation has been found in malathion-resistant strains of the house-fly, Musca domestica L. Accordingly, the phenomenon was investigated in C. putoria by adding non-lethal amounts of EPN or tri-o-cresyl phosphate (TOCP) to malathion. It was found that specific malathion-resistance was virtually abolished by this means, a result that suggests that such resistance in this species depends on a carboxyesterase. Genetical experiments with the malathion-resistant strain indicated inheritance by a single gene pair, with nearly complete dominance, similar to that in three other insect species.

It is concluded that both types of resistance in C. putoria have much in common with those occurring in analogous strains of other insect species.

In order to investigate the possible means of controlling introduced plant pests, the course that has been considered advisable to follow has been that of a general biological survey of the particular species under its native conditions and, so far as is possible, a comparison between this and a similar survey in the country to which it has become introduced. Such a survey should include the following aspects :—

Germination of seed : Normal percentage germination, germination of fresh and old seed, dormancy, “ hard ” seed, effect of varying external conditions or previous treatment upon germination of hard seed (if present). Seed reserves in soil ; continuous or discontinuous germination.

Establishment of seedlings : Effect of grass, leaf debris, bare soil, etc. ; root development ; causes of mortality.

Flowering : Periods of flowering, number of flowers ; mode of pollination.

Seeds and dispersal : Number of seeds, manner of dispersal, mortality before germination.

Relation to plant communities.

Relation to climate and soil types.

Geographical distribution.

Relation to insects : Insects found on the plant at different seasons ; nature and extent of damage to vegetative parts, flowers and fruits.

Thaumetopoea wilkinsoni, Tams, is known only in Cyprus, where it abounds, attacking all species of pine, but chiefly Pinus halepensis, Mill.

In the plains the adults emerge from the end of August to the beginning of October. The eggs are laid, shortly after emergence, in cylindrical masses round pine needles, the masses averaging 150 eggs. Only one mass is laid by each female. The incubation period is about 45 days.

The five larval instars are described, as well as the differences in the habits and nests in the various instars. The length of the larval life varies from 116 to 173 days. Only in the fourth do larvae remain in the same nest throughout the instar, as they frequently migrate, moving in single file to new feeding grounds, and there construct a new nest. Six such migrations have been observed for one colony during its three earlier instars.

Pupation, which commences in the plains about the middle of March, takes place in the ground in silken cocoons at a depth of ¼ to 3 inches, the pupal life lasting all through the hot weather.

Altitude considerably influences the life-history—the greater the altitude the earlier the emergence of the adult and the later the pupation of the fully-grown larvae, with consequent alterations in the length of the larval periods.

Of the checks, two species of Chalcid egg-parasites have been shown to occasion a parasitism of over 17 per cent., and three species of Tachinid larval parasites sometimes to occasion a parasitism of at least 30 per cent. There is also an Ichneumonid larval parasite. This latter aestivates in the pupa of its host ; the Tachinids leave their larval hosts and pupate in the nest of the processionary.

Re-afforestation in Cyprus, both natural and artificial, being an urgent necessity, this processionary is of great economic importance, as stands of young trees suffer very heavily from its attacks, one colony of larvae being sufficient to strip and, if the late rains fail, to kill a small tree. The writer considers, however, that control is possible by encouraging the parasites and predators, methods for which are outlined.