Acclimation had a beneficial effect on Scottish clones of Aulacorthum solani (Kaltenbach) as seen in enhanced reproduction and development at 5°C, compared with non-acclimated clones at this temperature. In contrast, not all Myzus persicae (Sulzer) clones tested benefited. When reared at 5°C for a second generation, both species had slower nymphal development and M. persicae also had less efficient adult reproduction (a longer pre-reproductive period and reduced fecundity) compared with the first generation. Both species demonstrated a high capacity for recovery from low temperatures, A. solani being the better of the two. In general however, the ability of clones to survive, reproduce and develop at low temperatures or upon transfer to high temperatures, was variable and was not related to annual cycle, origin or organophosphorus resistance. These differing responses support previous results and are suggested as being an efficient means of ensuring variability in aphid populations surviving after winter.

Two types of municipal solid waste (MSW), newly arrived and 2 weeks old, were sampled from a sanitary landfill in Pulau Pinang, Malaysia at a fortnightly interval and kept under field conditions for 2 weeks. A total of 480 kg of each type of MSW was sampled to study species composition and impact of delays in cover soil applications on filth fly emergence. Out of 960 kg of MSW sampled, 9.2 ± 0.5 flies emerged per kilogram. Weekly adult fly emergence rates of newly arrived and 2-week-old waste did not differ significantly and MSW remained suitable for fly breeding for up to 1 month. Eight species of flies emerged from the MSW: namely, Musca domestica, Musca sorbens, Synthesiomyia nudiseta, Hydrotaea chalcogaster, Chrysomya megacephala, Lucilia cuprina, Hemipyrellia ligurriens and Sarcophaga sp. Newly arrived waste was determined to be the main source for M. domestica, C. megacephala and L. cuprina in the landfill owing to significantly higher mean emergence compared with 2-week-old waste. Musca sorbens was found in newly arrived waste but not in 2-week-old waste, suggesting that the species was able to survive transportation to landfill but unable to survive landfill conditions. Hemipyrellia ligurriens, H. chalcogaster and S. nudiseta were not imported into the landfill with MSW and pre-existing flies in and around the landfill itself may be their source. The results show that landfills can be a major source of fly breeding if cover soil or temporary cover is not applied daily or on a regular schedule.

The tettigoniid Barbitistes vicetinus Galvagni & Fontana was described in 1993 as an endemic and rare bush-cricket of north-east Italy. Since 2008, this species has become a pest, causing repeated outbreaks with severe defoliations in broadleaf forests and neighbouring crops. Few data are currently available on ecology and life-cycle of this species, in particular about how temperature regulates egg-diapause and hatching phenology. The present work reports a field study regarding hatching phenology of B. vicetinus, surveyed with 84 emergence traps over four consecutive years (2013–2016). Moreover, the effect of temperature on the hatching was tested in the laboratory, exposing eggs to different temperatures. Field observations showed that hatching occurred between the end of March and beginning of April. In warmer years, hatching started early in the spring and lasted longer, while in colder years, hatching started later and was concentrated in a few days. Moreover, a significant effect of both elevation and exposure on the hatching start was observed. Results obtained from laboratory suggested the ability of the species to develop in the post-final diapause in a wide range of thermal conditions. After the diapause (terminated by a prolonged common exposure to low temperature) B. vicetinus was able to hatch from 6 to 23°C although, due to prolonged post-diapause development, hatching took place progressively later at colder temperatures. To manage B. vicetinus outbreaks, forecasting the seasonal phenology of egg hatching and its duration is important for an effective pest control.

1. At 27°C. the life-cycle of Dysdercus howardi occupies approximately 32 days.

2. Copulation (at 27°C.) takes place approximately 2·8 days after the last moult of the female insect.

3. At 27°C. oviposition begins about 8 days after the last moult of the female, and 5–6 days after mating.

4. The average number of eggs laid by one female is 141·9 and the average number of batches is two.

5. Mortality appears to be highest among the 5th stage nymphs.

6. The ratio of females to males is 1: 1·27.

7. The average length of adult life in the female Dysdercus howardi is eleven days.

8. A table comparing D. howardi with other species of the genus Dysdercus is given.

The giant sugarcane borer, Telchin licus, has been reported as an economically important sugarcane pest in Colombia; however, its taxonomic status has been scarcely investigated and previous reports offer an ambiguous characterization of both the immature and adult stages. The objective of this work is to identify Telchin species affecting sugarcane and alternative hosts in different departments of the country by integrating molecular analysis and conventional morphology. To date, T. licus has been found in the departments of Caquetá, Casanare, and Meta, while T. atymnius has been found in Antioquia, Caldas, Nariño, and Valle del Cauca. Sugarcane, Musaceae, and Heliconiaceae have been found to be hosts to both species. Additionally, the species T. cacica has also been registered in the department of Nariño, affecting heliconias and plantains. Genetic variation within the species allowed differentiation at the molecular level of subspecies of T. licus and T. atymnius, confirming that the subspecies present in Colombia are T. licus magdalena, T. atymnius humboldti, and T. atymnius atymnius. The haplotype diversity of populations is closely related to their geographical distribution, indicating low gene flow between populations and possible speciation inside the country. Analysis of genetic variance showed significant differences among and within T. atymnius populations, which may suggest a high genetic structure along the regions where it is found and the possible presence of additional subspecies to those previously reported. To understand the geographical and environmental conditions that determine the pest's distribution in Colombia, this information needs to be complemented with ecological considerations of possible geographical isolation and association of alternative hosts.

A review is given of estimates, both published and unpublished, of numbers in some types of desert locust (Schistocerca gregaria (Forsk.)) populations, and suggestions are made for further work in this field. For swarming adult populations, estimates of volume and area density and of the relative sizes of settled and flying swarms have been reviewed. For gregarious nymphal (hopper) populations, the area density of late-instar bands and the infestation rate following gregarious breeding have been examined. There is insufficient evidence to give estimates of the average numbers in any of these types of population with confidence, or to be able to estimate the environmental and physiological factors with which variation in density is correlated. It is not possible to make generally valid estimates of the densities of non-gregariously behaving populations. Practically no research has been done on population estimation methods suitable for such populations, although, in practice, estimates are made during field surveys. The principles underlying valid sampling techniques, and valid selection of the sample in various situations, are described.

Larvae of 18 species of mosquitoes were found in the region of Lake Manyara, a saline lake in Tanzania. Aedes natronius Edw., Culex tenagius van Som. and C. nakuruensis Mattingly bred in salinities ranging from 0 to over 8% NaCl; five species, including Anopheles gambiae Giles, bred only in fresh and brackish waters, while the remainder were found only in fresh water. The saline habitats were also alkaline. C. tenagius occurs only in association with hot springs throughout East Africa, but larvae were found in salinities of 0- > 8% NaCl, alkalinities of 0.05–0.32N, pH 7.8- > 11 and at temperatures of 22–42 C. C. tenagius, C. nakuruensis and C. telesilla De Meillon & Lavoipierre were new records for Tanzania, as was Ae. lineatopennis (Ludl.) collected from a nearby settlement. It is considered that the species able to breed in both fresh and salt water, namely, Ae. natronius, C. tenagius and C. nakuruensis, may comprise a complex of fresh-water and salt-water races, or even species.

The resistance of two melon lines (CHI-7 and BUS-7) selected for resistance to the carmine spider mite, Tetranychus cinnabarinus (Boisduval), and of the susceptible line (NY), was studied under field and laboratory conditions. Significant differences among lines were observed at different growth stages. Throughout the season, the resistant lines had reduced populations of mites, 35–100% lower on CHI-7 and 25–100% lower on BUS-7, compared with the susceptible line NY. Laboratory evaluation of antibiosis to the mite at different plant growth stages showed that on CHI-7 and BUS-7 mite fecundity was reduced by 29–60% and 43–83%, respectively.

The following lines may be regarded as a first additional note to a former paper of the author's (Zion. Organ. Agr. Expt. Sta., Bull. 1, July 1924). It contains 14 species not recorded in the first list, two of which are new to science. The numeration follows that of the former paper. I wish to tender my acknowledgements to Mr. W. J. Hall, Cairo, for determining some species of Diaspinae and to Mr. H. Aron for preparing the illustrations.

The Chinese white pine beetle Dendroctonus armandi (Coleoptera: Scolytinae) typically displays bivoltinism at altitudes below 1700 m in the Qinling Mountains, China. The periods of host colonization and larval overwintering are two important phases in the life cycle of bark beetles, as it is during these periods that they have to contend with host plant defences and periods of intense cold, respectively. Although during different seasons, the females and males of Chinese white pine beetles show varying tolerances to host plant terpenoids, the sex ratio and survival physiology condition of the two beetle generations are unknown. We investigated the sex ratio of individuals, and also examined the body mass, energy stores, and detoxication enzymes of males and females in each of the two generations in order to determine the overall population stability of each generation. We identified a female-biased sex ratio among adults in both generations. Furthermore, patterns of body mass, energy stores, and detoxication enzymes were found to differ between the two sexes and two seasons. Compared with the males, the females have a larger body mass and higher amounts of stored lipids, which are assumed to be adaptations designed to overcome host resistance and facilitate subsequent oviposition.

Aphids parasitized in later instars can give birth to several nymphs before their reproduction is curtailed by the developing parasitoid. We examined the life histories of Aphis fabae Scopoli born to mothers parasitized by Lysiphlebus fabarum Marshall, and their suitability as subsequent hosts, to test the ‘fecundity compensation’ hypothesis. Maternal parasitism negatively impacted life history parameters, resulting in reduced estimates of population increase (rm, R0, and λ), and increased generation time (GT) and doubling time (DT). These impacts were greater when the larva developing in the mother turned out to be female rather than male, and greater still when mothers were superparasitized. Maternal parasitism produced aphids with shorter hind tibia (HTL), at birth and at maturity, but their developmental time was unaffected. Although female L. fabarum readily accepted such aphids for oviposition, rates of mummification and wasp emergence were lower, and more so when the maternal parasitoid was female. The resulting parasitoids took longer to develop than progeny from control wasps, had shorter HTLs, lower egg loads, smaller eggs, and produced fewer mummies with lower rates of adult emergence, all differences that were more pronounced when the maternal parasitoid was female. The progeny of these wasps exhibited similar impairments to these biological parameters as their parents, demonstrating that the negative impacts of development in maternally parasitized hosts extended for at least two generations. Thus, our results do not support fecundity compensation, but suggest that any benefits of post-parasitism reproduction will be offset by reduced fitness in both aphid progeny and the parasitoids that develop in them.

Resistance to carbaryl, lindane and methidathion was studied in field and laboratory strains of Dysdercus fasciatus Sign., D. nigrofasciatus Stål, D. superstitiosits (F.) and D. cardinalis Gerst. from Kenya. Four-day old fifth-instar female nymphs were found to be the most convenient for bioassay. The LC50s of carbaryl, lindane and methidathion for D. fasciatus were 372, 240, and 110 mg/litre, respectively, those for D. nigrofasciatus 337, 294, and 111 mg/litre, and that for carbaryl for D. cardinalis 147 mg/litre. The Meru and Ngwata strains of D. fasciatus had resistance factors of ×5·3 and ×6·1, respectively, to carbaryl. The field strains of all four species showed slight resistance (up to ×3·4) to lindane and methidathion. The poor control of Dysdercus spp. experienced in Eastern Province, Kenya, is probably due to the development of resistance to carbaryl. A laboratory and a field strain of each of D. fasciatus and D. nigrofasciatus were subjected to carbaryl selection pressure for six generations of doses equivalent to the LC50-LC70. The laboratory strain of D. fasciatus was also subjected to lindane selection for six generations. The laboratory and field strains of D. fasciatus developed resistance to carbaryl of ×3·7 and ×5·7, respectively, and cross-resistance to lindane of up to ×2·7. No significant increase in resistance was observed in D. nigrofasciatus after selection. The laboratory strain of D. fasciatus developed resistance to lindane of ×5·5 after selection and cross-resistance to carbaryl of ×4·3.

The spreading of larvicidal oils is hindered by the presence of natural films upon the surface of standing water. The film pressure, which measures the resistance offered to the spreading of oil, can be determined in the field by a simple method depending on the use of standard spreading liquids.

It seemed reasonable to suppose that by making tests on the waters at many different places it should be possible to estimate the optimum spreading properties required in a larvicidal oil before its distribution began in a particular district. An attempt to do this was made in a part of the Gold Coast in 1944 and the investigation showed that in that region, and at that time, the spreadability of an oil with spreading pressure equal to 30 dynes/cm., approximately, would have been adequate for larvicidal purposes. It was also found that the natural films, which could be either visible or invisible, were of two physical types distinguishable as “uniform” and “non-uniform” according to the observed variation of the film pressure at a single site.

Surveys were completed in Eritrea, Ethiopia, Kenya, Madagascar, Mozambique, Tanzania, Uganda and Zanzibar to assess the lepidopteran stem borer species diversity on wild host plants. A total of 24,674 larvae belonging to 135 species were collected from 75 species of wild host plants belonging to the Poaceae, Cyperaceae and Typhaceae. Amongst them were 44 noctuid species belonging to at least nine genera, 33 crambids, 15 pyralids, 16 Pyraloidea species not yet identified, 25 tortricids and three cossids. The noctuid larvae represented 73.6% of the total number of larvae collected, with 66.3, 3.5 and 3.8% found on Poaceae, Cyperaceae and Typhaceae, respectively. The Crambidae, Pyralidae, Tortricidae and Cossidae represented 19.8, 1.9, 2.5 and 0.1% of the total larvae collected, respectively, with 90.4% of the Crambidae and Pyralidae collected from Poaceae, and 99.7% of the Tortricidae collected from Cyperaceae. The lepidopteran stem borer species diversity in the wild host plants was far more diverse than previously reported.

The biology and host specificity of a South American moth, Acigona infusella (Wlk.), were studied in quarantine facilities in Australia. In choice tests on the host specificity of A. infusella, slight feeding by larvae occured on ginger, lettuce, banana, bullrush (Typha orientalis) and water primrose (Ludwigia peploides), but in starvation tests only waterhyacinth (Eichhornia crassipes) and pickerel weed (Pontederia cordata) supported complete development. A decrease in larval mortality and increase in egg-mass size of A. infusella occured when a microsporidian, Vairimorpha sp.; infecting the colony was eliminated, suggesting that these insects may then perform more effectively as biological control agents in Australia than in South America. The damage to waterhyacinth cause bu larvae of A. infusella may complement attack by other biological control agents already established in Australia.

The cibarial armatures of Anopheles albitarsis Lynch Arribálzaga, A. aquasalis Curry, A. bellator Dyar & Knab and A. homunculus Komp are described for the first time. Ten to 15 minutes after blood feeding, higher levels of blood haemolysis were observed among A. bellator (14.9%) and A. homunculus (14.0%) mosquitoes which possessed type C cibarial armatures than among A. albitarsis (3.3%) and A. aquasalis (3.2%) which possessed type B cibarial armatures. In contrast, there were no significant differences among the four species in levels of extra-erythrocytic haemolysis when measured immediately and after one hour. The blood processing physiology observed for the four anopheline species is discussed at the enzymatic, mechanical and taxonomic levels as it relates to innate vector competence.

Triatoma infestans (Klug) (Hemiptera: Reduviidae) is the main vector of Chagas disease in the Southern Cone of America and resistance to pyrethroid insecticides has been detected in several areas from its geographical distribution. Pyrethroid resistance presents a complex geographical pattern at different spatial scales. However, it is still unknown if the toxicological variability is a common feature within villages of the Gran Chaco were high resistance was descripted. The objectives of this study were to determine: (a) the microgeographical distribution of the deltamethrin-resistance in insects from Pampa Argentina village, (b) the performance of the insecticide impregnated paper bioassay to evaluate deltamethrin-resistance in field collected insects and (c) the lethal activity of the fumigant canister containing DDVP against insects resistant to deltamethrin. High survival of T. infestans exposed to discriminant dose was observed in the samples of all the evaluated dwellings, suggesting that the resistance to deltamethrin is homogeneous at the microgeographical level. Resistance determination by impregnated paper bioassay was similar to traditional topical determination, highlighting the use of this rapid methodology in field large-scale monitoring. The fumigant canister was not effective against resistant insects, remarking the need to develop suitable formulations that ensure minimal toxicological risk and high effectivity.

The results of a general mosquito survey of the Liberian hinterland are presented together with the findings of previous workers in this country.

Liberia is almost entirely in the Upper Guinean Forest region with an annual rainfall from over 140 in. on the coast to about 80 in. in the hinterland.

A list is given of all species recorded from Liberia.

A brief account is given of the distribution, bionomics and relation to malaria of the Anophelini, with some taxonomie notes. Thirteen species or forms of Anophelines are listed, of which ten were found in the hinterland as well as on the coast.

A summary of the distribution and bionomics of the Megarhinini and Culicini of Liberia is given, with the writer's field notes and those of earlier workers, and some taxonomic notes. Seventy one or 72 species or forms are included, of which 59 were found in the hinterland. If the first mention of some species in the two previous papers in this series be included, 41 additions to the Liberian list, three of them new species, have been made.

Trichosirocalus horridus sensu lato has been used as a biological control agent of several invasive thistles (Carduus spp., Cirsium spp. and Onopordum spp.) since 1974. It has been recognized as a single species until 2002, when it was split into three species based on morphological characters: T. horridus, Trichosirocalus briesei and Trichosirocalus mortadelo, each purported to have different host plants. Because of this taxonomic change, uncertainty exists as to which species were released in various countries; furthermore, there appears to be some exceptions to the purported host plants of some of these species. To resolve these questions, we conducted an integrative taxonomic study of the T. horridus species complex using molecular genetic and morphological analyses of specimens from three continents. Both mitochondrial cytochrome c oxidase subunit I and nuclear elongation factor 1α markers clearly indicate that there are only two distinct species, T. horridus and T. briesei. Molecular evidence, morphological analysis and host plant associations support the synonymy of T. horridus (Panzer, 1801) and T. mortadelo Alonso-Zarazaga & Sánchez-Ruiz, 2002. We determine that T. horridus has been established in Canada, USA, New Zealand and Australia and that T. briesei is established in Australia. The former species was collected from Carduus, Cirsium and Onopordum spp. in the field, whereas the latter appears to be specific to Onopordum.

The taxonomic status of Caryedon pallidus (Olivier) is discussed and its identity related to a species found in West Africa breeding in seeds of Cassia obtusifolia. Specimens of Caryedon breeding in Cassia senna from the Nile basin are shown to be a distinct species. This, and a further species from Armenia, both of which had been previously misidentified as Caryedon pallidus, are described as new.