Clones have been in the forefront of biological interest for many years. Even so, open discussions continue to surround the concept of clonality, which has been recently much debated in the scientific literature, both in terms of philosophical meaning as well as empirical determination. Philosophically, the clone is the horizontally produced lineage from a single fertlized egg (e.g. mammals by division of the fertilized egg and representing a single generation) or vertically produced offspring (e.g. aphids representing different successive generations) from a single asexual stem mother (originally for a particular lineage, following hatching of the overwintering sexual egg in the spring); empirically, the aspect of genetic fidelity is also considered important, so-called clones being assumed to have an identical genome among clone mates. In reality of course, such members of a clonal lineage must differ at various regions of the genome, since mutation is a fundamental property of the DNA itself. Yet few studies have so far set out to show this empirically in eukaryotic organisms, which indulge in periods of asexual reproduction, sometimes, as in aphids, over many generations. In the present study, we have investigated asexual lineages of the grain aphid, Sitobion avenae (F.), a global pest of cereals, over five successive generations employing AFLP-PCR molecular techniques. Our main interest was to see how much variation was present in the early generations and if this variation was transmitted through the asexual lineages. By monitoring AFLP-based polymorphisms, we show that, in this aphid species, of a total of 110 individuals from two lineages tested (termed SA and SB), random mutations (band deletions, more rarely additions) were apparent from the third generation onwards, and although some mutations were found to be transmitted transgenerationally, others were rarely transmitted through the particular lineages they were detected in. Using Arlequin v. 2.0, average gene diversity within the lineages was found to be 0.024 ± 0.013 and 0.031 ± 0.016 for SA and SB, respectively. It was also found from the rearing of the lineages that one lineage, SA, was more fecund than the other lineage, SB, over the five generations (N = 818 vs. N = 358 total stem mothers plus nymphs for the two lineages, respectively).

The genealogy and diversity of the mitochondrial cytochrome oxidase subunit II (COII) gene were investigated for Ostrinia furnacalis in Japan. A preliminary examination of mitochondrial lineages in China and the Philippines was also made. Two lineages (A and B) were found in the COII gene. Lineage A was frequent throughout the Japanese main islands (Hokkaido, Honshu, Shikoku and Kyushu), while the frequency of lineage B varied among these islands. No clear patterns of geographical population structure were found. Population genetic features suggested that the O. furnacalis population harboring the lineage A mitochondria expanded in the recent past, while lineage B showed weak signals of a population expansion. It is not clear whether the two lineages of mtDNA evolved in separate or identical geographical regions. We discuss two hypotheses regarding the two lineages of mtDNA: a cryptic race/species hypothesis and a selective sweep hypothesis.

Data are presented from five series of 240 adults of Rhipicephalus appendiculatus Neumann kept in the laboratory, in which a steady decline in the numbers of granules in e cells of type 3 acini of the salivary glands occurred. This was readily detected in whole gland preparations of the salivary glands stained with methyl green and pyronin, and the same specimens could be used for detecting Theileria parasites in the salivary glands. Characteristics for grading these ticks into three physiological age grades are given, and a formula is provided for incorporating the age grade with infection rate. This gives a value for comparative estimates of the challenge posed by field populations of ticks for the transmission of Theileria to cattle.

The coffee leaf-miners of the genus Leucoptera, Hübner, are serious pests of coffee wherever it is cultivated and they have often caused great anxiety to planters in many parts of the world. Leucoptera coffeella, Guér., is known from the West Indies, Central and South America, Central Africa, Madagascar, Réunion and Ceylon. Another species, L. daricella, Meyr., seems to be responsible for still more damage in Africa.

The success of the chrysomelid beetles, Chrysolina hyperici (Forster) and C. quadrigemina (Suffrian), used widely for biological control of St John's wort (Hypericum perforatum) seems to depend on the synchronization of their phenologies with climate. The factors governing the termination of diapause in the field and laboratory were assessed in New Zealand. Before summer diapause, C. hyperici made up more than 70% of adult beetles in the field. Both species entered summer diapause at the beginning of January, but C. quadrigemina terminated diapause 3–4 weeks earlier (early March) than C. hyperici. Both male and female C. quadrigemina and male C. hyperici adults became sexually mature during summer diapause but C. hyperici females still had immature ovaries. Females of C. quadrigemina began laying eggs immediately after summer diapause but females of C. hyperici did not oviposit until more than 2 weeks after they terminated diapause in late March. In the laboratory summer diapause was terminated in both species by short day length, not by simulated rainfall, contradicting previous assumptions that autumn rainfall is the critical factor. The demonstrated differences in phenology are reflected in different overwintering strategies for the two species. Because C. hyperici overwinters in the egg stage, this species will be a more successful biological control agent of St John's wort in countries with cold winters than C. quadrigemina, which overwinters in the more vulnerable larval stage. However, in countries with mild winters C. quadrigemina is more successful in controlling St John's wort than C. hyperici, since it has a developmental lead with its larvae feeding and growing during the winter.

In the laboratory, the trail pheromone methyl 4-methylpyrrole-2-carboxylate (M4MP2C) when added to bait particles acts as an attractant to leaf-cutting ants, increasing the pick-up of pheromone-impregnated bait compared with plain bait. However, field trials in Trinidad, Brazil and Paraguay were disappointing. Bait with and without pheromone was scattered in the foraging area, and the proportion of each taken to the nest by Atta sexdens rubropilosa Forel, A. cephalotes (L.) and Acromyrmex octospinosus (Reich) was assessed. In only one of the experiments (A. octospinosus foraging bait with 50 p.p.m. of M4MP2C) was increased pick-up detected. Four reasons for this are suggested: (1) small pheromone effects are difficult to measure as scattering bait produced a patchy distribution and heterogeneous replicates, whilst choice trials on plain and pheromone-impregnated bait placed close together were difficult to interpret, as the pheromone probably excited the ants, increasing pick-up of plain bait; (2) A. octospinosus workers, the subject of detailed studies, were less sensitive to M4MP2C in the field than in the laboratory; (3) as the pheromone only attracts, it does not produce a comparable increase in the number of pieces picked up, contact/pick-up ratios of sucroseimpregnated discs increasing from 2·26 at 5 pg pheromone to 16·39 at 50 ng; and (4) soyabean oil, citrus-pulp extract and orange juice were found to be attractive, and when pheromone was added, its effects were not additive. Early studies used sucrose-impregnated paper discs, and as these have no attractants of their own, the addition of M4MP2C had a more marked effect. It is concluded that M4MP2C is not a cost-effective addition to current leaf-cutting ant baits which possess food odours, a much cheaper source of attractiveness.

The following description is based on material submitted for determination by the Imperial Bureau of Entomology.

Reports of the African armyworm, Spodoptera exempta (Walker), in eastern Africa for sixteen seasons (1972–73 to 1987–88) were analysed together with weather records to identify the most frequent locations of outbreaks and their relationships with weather. Outbreaks were classified into ‘primary’ outbreaks (derived from low density parent populations), ‘secondary’ outbreaks (derived from previous out breaks) and ‘critical’ outbreaks (leading to many subsequent outbreaks). Differences in seasonal severity of armyworm infestations in relation to the timing and location of primary outbreaks and early season rainfall were also examined. Trajectory analysis was used to estimate migrations of windborne moths, and the distribution of rainstorms was used to help estimate the timing of moth concentration leading to outbreaks of S. exempta. First reported armyworrn outbreaks from October to December in Kenya and Tanzania were usually primary. Critical primary outbreaks mostly occurred in east-central Tanzania, north-east Tanzania and the adjacent Taveta district of Kenya, and east-central Kenya. Strategic control (to prevent subsequent, downwind outbreaks) is best carried out in these areas. Migration direction was largely determined by seasonally dominant winds, although windfield disturbances were occasionally important. Three seasons in which very low numbers of S. exempta were reported, had heavy, persistent October to December rainfall leading to high larval mortality. Seasons with many outbreaks often had rainstorms separated by dry periods, during the rainy seasons.

Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae) is a pupal parasitoid under consideration for introduction into Canada for the control of the invasive leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae). Since study of the parasitoid outside of quarantine was not permitted in Canada at the time of this project, we assessed its efficacy via field trials in its native range in central Europe. This was done by simulating introductory releases that would eventually take place in Canada when a permit for release is obtained. In 2007 and 2008, experimental leek plots were artificially infested with pest larvae to mimic the higher pest densities common in Canada. Based on a preliminary experiment showing that leek moth pupae were suitable for parasitism up to 5–6 days after pupation, D. pulchellus adults were mass-released into the field plots when the first host cocoons were observed. The laboratory-reared agents reproduced successfully in all trials and radically reduced leek moth survival. Taking into account background parasitism caused by naturally occurring D. pulchellus, the released agents parasitized at least 15.8%, 43.9%, 48.1% and 58.8% of the available hosts in the four release trials. When this significant contribution to leek moth mortality is added to previously published life tables, in which pupal parasitism was absent, the total pupal mortality increases from 60.1% to 76.7%. This study demonstrates how field trials involving environmental manipulation in an agent's native range can yield predictions of the agent's field efficacy once introduced into a novel area.

The presence of Glossina pallidipes in the great tsetse belts of Central Tanganyika has long been recognised, but owing to its relative scarcity in comparison with G. morsitans and G. swynnertoni it has not merited hitherto the attention and study which has been devoted to these latter species.

The construction and functioning of a light-trap designed to catch only insects in flight at a height of greater than 5·5 m is described. The trap segregates the catch into hourly samples throughout the night.

Xylebrous morstatti Hag. is a shot-hole borer which is well known as a pest of coffee. It has also been recorded from avocado pear (Persea americana) in Fiji, and is here reported attacking the same tree in the Seychelles, where it appears to be too scarce so far to do any serious damage.

The infestations and nature of the damage on avocado pear are described and illustrated, and the recorded geographical distribution of the insect is summarised.

A method of insecticidal control is described which, on the small scale on which it was carried out, appears to have been successful.

Difficulties were experienced in determining the susceptibility status of populations of Rhipicephalus evertsi evertsi Neum. to organochlorine acaricides. A susceptible strain of this species was found at Maswa, Shinyanga District, Tanzania. Susceptibility for toxaphene, dieldrin and γ–BHC was assessed by means of an FAO recommended test method, the oil-based packet test. A homogeneously responding resistant strain was built up from larvae from Ngong, near Nairobi, Kenya, that had survived a discriminating dieldrin concentration of 0·2%. These showed resistance factors of 10·8 for toxaphene, 30 for γ-BHC and 95 for dieldrin. The F1 cross between susceptible and resistant populations responded homo-geneously and was intermediate in resistance between the parental strains, with resistance factors of 8·7, 9 and 8·1 for ithese compounds, respectively. Larvae from backcrosses of F1 adults with the parental strains showed stepped ld-p lines such as would be expected in a case of inheritance of a single gene allele with partial dominance for resistance. A population of R. e. evertsi near Dar es Salaam, Tanzania, was controlled by application of 0·3% toxaphene despite it having resistance factors similar to those of the F1 hybrids.

The room used for housing a colony of Anopheles punctulatus punctulatus is described. Its main features were an insulation system to enable some degree of temperature control during the winter months, and eight windows to ensure that the room had good natural lighting.

The adults were kept in breeding cages, which were large enough to allow the insects to manoeuvre during mating and oviposition, and designed to ensure a high humidity and at the same time expose the adults to daily fluctuations in light intensity. Provision was made for easy access to the interior during feeding and management operations.

The essential feature of larval management was that the larvae were kept throughout their development as separate batches, representing daily age groups. During the first three days after hatching they were left in the dishes containing soil and water in which the eggs were laid. From the third day, they were reared in shallow glass dishes. They were fed with Farex at intervals throughout the day.

Tibraca limbativentris (Hemiptera: Pentatomidae) is a major pest in Neotropical rice agroecosystems. In autumn–winter, this pest takes refuge in rice stubble and in native vegetation, which allows it to re-colonize the crop during the rice growing season. However, it is still unknown whether this vegetation is a pest sink or is actually a natural trap that contributes to pest population biocontrol. Here we present information on the insect's alternative host plants, a preliminary outline of the relationship between plant phylogeny and insect abundance, and the impact that winter natural enemies have in pest population. Also, we include a proposed methodology for pest density analysis in winter hosts. Our results show significant differences in the abundance/density that T. limbativentris reaches in the 12 host plant species present in our study areas, with a plant-use pattern significantly related to the phylogenetic clade of Poales. Stink bug winter populations mainly comprised diapause adults, and 40% of insect digestive tracts had content. Survival of T. limbativentris was 56.92% in winter hosts. About mortality, 10% was due to undetermined causes and 33.08% due to entomopathogenic fungi, showing a natural regulation of the pest population. Our results suggest that native vegetation impacts winter survival of T. limbativentris. Although these plants offer shelter, they offer a greater contribution to Integrated Pest Management: the natural regulation of winter pest populations through entomopathogenic attack. Further studies on T. limbativentris population dynamics and the preservation of native areas near rice fields will be required for the development of best control practices.

Observations, largely based on regular catches along a fly-round, were made over the five years 1959–64 on a population of Glossina morsitans submorsitans Newst. in the Northern Guinea Savannah of Nigeria. The results showed that the largest numbers of flies were caught in the early dry season (November–January) and that, as the climate became progressively drier and more severe, fly numbers declined to reach their annual minimum at the end of the dry season or in the early rains (March–May). These results are tentatively interpreted in terms of the true density of the flies and their activity. Differences occurred between the various years, some of which could be explained by climatic differences.

Of the 7,412 flies caught over the five years, 1,128 (15·2%) were females; the percentage of females was highest in the dry season, rising to a peak of 24·1 per cent, in February, and was below 10 per cent. during the wet season. Many more females were caught on the bodies of the catching team than on vegetation or the ground near the team.

The flies rarely fed on civet cat (Civettictis civetta) or duiker (Cephalophus rufilatus, Sylvicapra grimmia), which were the potential hosts most frequently observed in the experimental area, but fed mainly on wart-hog (Phacochoerus aethiopicus) and man, the next most commonly observed potential hosts.

During the heavy rains, males of G. m. submorsitans were evenly distributed over the fly-round, but at all other seasons they were concentrated to some extent in areas of thicker vegetation. During the dry season, pupae were found in the dry soil of forest islands and riverine vegetation in the savannah; the wet season breeding sites were not discovered. Previously published data on the resting sites and trypanosome infection rate of G. m. submorsitans in the area are summarised.

The results are discussed and compared with the conclusions reached by other workers from earlier more extensive studies on G. m. morsitans Westw. in Tanganyika and on G. m. submorsitans in the Sudan Savannah vegetation zone of Northern Nigeria.

Microplastics (MPs) pollution has been a hot research topic in recent years. MPs are ubiquitous throughout the ecological environment and are eventually accumulated in organisms through inhalation or ingestion. However, given that MPs are inert pollutants, their effects on organisms are not clear. In previous study, we have investigated the effects of polyethylene terephthalate MPs on physiology of Drosophila. What is the effect of polypropylene microplastics (PP-MPs)? The results of our experiments show that being exposed to high concentration of PP-MPs have significant effect on Drosophila. PP-MPs exposure can significantly increase locomotor activity and shorten the time of group sleep in Drosophila. In the presence of high concentrations of PP-MPs, the triglyceride content was reduced in females and their ability of egg production was affected. However, there was no significant effect on the level of protein and carbohydrate, or on the food intake. Our experimental results can provide some preliminary data for assessing the potential hazard of PP-MPs to other organisms.

Neoseiulus barkeri (HUGHES) is the natural enemy of spider mites, whiteflies and thrips. Screening for chemically-resistant predatory mites is a practical way to balance the contradiction between the pesticide using and biological control. In this study, the number of eggs laid by fenpropathrin-susceptible and resistant strains of N. barkeri was compared. Additionally, we cloned three N. barkeri vitellogenin (Vg) genes and used quantitative real-time polymerase chain reaction to quantify Vg expression in susceptible and resistant strains. The total number of eggs significantly increased in the fenpropathrin-resistant strain. The full-length cDNA cloning of three N. barkeri Vg genes (NbVg1, NbVg2 and NbVg3) revealed that the open reading frames of NbVg1, NbVg2 and NbVg3 were 5571, 5532 and 4728 bp, encoding 1856, 1843 and 1575 amino acids, respectively. The three N. barkeri Vg possessed the Vitellogenin-N domain (or lipoprotein N-terminal domain (LPD_N)), von Willebrand factor type D domain (VWD) and the domain with unknown function 1943 (DUF1943). The NbVg1 and NbVg2 expression levels were significantly higher in the resistant strain than in the susceptible strain, while the NbVg3 expression level was lower in the resistant strain. Thus, we speculate that the increased number of eggs laid by the fenpropathrin-resistant strain of N. barkeri may be a consequence of changes in Vg gene expression.

Ivermectin injected subcutaneously into calves at the rate of 200 μ/kg body weight completely eliminated females of Psoroptes ovis (Her.) in 22 days. Injection of ivermectin also adversely affected the number and hatch of eggs and the proportion of adult males forming attachment pairs. The reduced number of eggs recovered in skin scrapings was apparently the result of a significantly lower fecundity among females that temporarily survived on treated calves. Females that were exposed to ivermectin for only three days did not recover their full reproductive potential even though they were transferred to calves not injected with ivermectin. The proportion of ovigerous females among survivors was not significantly affected five days after injection. Since the number of eggs recovered in skin scrapings was substantially reduced after only three days, the effect of ivermectin on female fecundity was not primarily gonadal. Reduction in the number of P. ovis eggs three days after treatment probably occurred because of a combination of mortality of adult females and reduced oviposition by ovigerous females surviving in the population.

Since my previous report on the Chalcidoid parasites of Glossina appeared (Bull.Ent. Res., vi, pt. 1, p. 69, 1915) a second important collection has been received by the Imperial Bureau of Entomology from Dr. W. A. Lamborn, their Entomologist in Nyasaland. In this materal five species are represented, of which three here described are believed to be new. The status of the remaining two, Stomatoceras micans, Wtrst., and Syntomosphyrum glossinae, Wtrst., may now be regarded as established, in the former case from its recurrence on the same host in two widely separated localities, in the latter from Dr. Lamborn's valuable notes. Six species of Chalcidoids have now been bred from puparia of Glossina spp., and all from G. morsitans.