Owing to the wide divergences of opinion at present current among those in the Sudan who are interested in leaf-crinkle of cotton, it is thought that the present paper, incomplete as it is, may be of some value in indicating what little knowledge has so far been obtained by observations and direct controlled experiments, and in outlining the more obvious and important directions in which further investigations should proceed.

A host choice experiment was carried out to determine the host range of some potential biological control agents of yellow starthistle (Centaurea solstitialis), a Mediterranean plant which has become a serious rangeland weed in western USA. This paper describes the results of that experiment and discusses its taxonomic implications. The experiment confirmed the extreme host specificity of some species. However, two reputedly polyphagous species, Acanthiophilus helianthi (Rossi) and Urophora quadrifasciata (Meigen), attacked a narrower range of hosts than expected. The results of this and similar host choice experiments are discussed and it is concluded that this sort of anomaly can be caused by the existence of host races, unrecognized sibling species, or by varieties of plants naturally resistant to attack. These complex patterns of host relationship highlight the need to interpret host catalogue data cautiously, as they oversimplify complex biological systems. The identity of one species reared in the experiment, Terellia luteola (Wiedemann), is discussed; a key is presented for its separation from other Terellia species, and it is removed from synonymy with T. colon (Meigen).

This is the first report of microsatellite markers (simple sequence repeats, SSR) for fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), an important quarantine pest in some European and Asian countries. Here, we developed 48 microsatellite markers for H. cunea from SSR enrichment libraries. Sequences isolated from libraries were sorted into four categories and analyzed. Our results suggest that sequences classified as Grouped should not be used for microsatellite primer design. The genetic diversity of microsatellite loci was assessed in 72 individuals from three populations. The number of alleles per locus ranged from 2 to 5 with an average of 3. The observed and expected heterozygosities of loci ranged from 0 to 0.958 and 0 to 0.773, respectively. A total of 18 out of 153 locus/population combinations deviated significantly from Hardy–Weinberg equilibrium. Moreover, significant linkage disequilibrium was detected in one pair of loci (1275 pairs in total). In the neutral test, two loci were grouped into the candidate category for positive selection and the remainder into the neutral category. In addition, a complex mutation pattern was observed for these loci, and FST performed better than did RST for the estimation of population differentiation in different mutation patterns. The results of the present study can be used for population genetic studies of H. cunea.

The taxonomy of a complex of parasites associated with mealy-bugs on cacao in Trinidad is dealt with. The descriptions of nine species new to science are given and species not new have been treated in comparable detail. Fresh taxonomic or other data have been given for some related species.

The inclusion of an aberrant Thysanid species of biological importance necessitated a comparative study of characters that have been used within this group. In this connection, Thysanid parasites of Tachinidae attacking moth larvae in sugar-cane were considered and found separable into three closely related species, two of which are described as new.

Studies have been made of the effect of feeding adults of the Mustard Beetle, Phaedon cochleariae (F.), on diets of watercress leaves (Nasturtium officinale) taken from plants grown in water cultures of known nutrient composition.

Significant reductions in egg-production were recorded when individual beetles were supplied with leaves deficient in nitrogen, phosphorus, potassium or iron, as compared with the egg-production of the same beetles supplied with leaves from plants grown in complete-nutrient solution.

A marked alteration in the rate of egg-production occurred within two or three days of changing the diet from “complete-nutrient” leaves to mineral-deficient leaves or vice versa.

The larval characters of 33 species (largely Palaearctic) of the genus Apanteles have been examined and studied in relation to the division of the species of the genus into four major groups on the characters of the adults. Ingeneral, the larval characters indicate a grouping of the species which is very similar to the grouping of the adults. Groups S and U contrast sharply with groups A and F on the form of the mandible. The form of the mandible also allows group A to be distinguishedfrom group F. The relationships of four aberrant and some other species are discussed.

I wish to thank Mr. J. F. Perkins of the British Museum (Natural History) and Professor G. C. Varley of the Hope Department of Entomology, Oxford, for permission to study material. Mr. G. E. J. Nixon's advice on the relationships indicated by the characters of the adults of the species of the genus Apanteles has been invaluable.

Trichogrammatoidea bactrae Nagaraja (Hymenoptera: Trichogrammatidae) is an important natural enemy of many species of lepidopterous pests. The effects of heat stress temperature (33, 36, and 39 °C), duration of exposure (2, 4, 6, and 8 h), and developmental stage during exposure (embryo-first instar larvae, second instar larvae, prepupae, and pupae) on the development and reproduction of parasitoid T. bactrae were investigated in the laboratory. When exposed to 39 °C for 8 h during pupal stage, only 19.90% adults emerged from host eggs, and more than 14% were deformed (wings were folded or incomplete). Parasitoid females exposed to 39 °C for 8 h as prepupae only lived for 1.45 days and parasitized about 23.5 host eggs. Moreover, life-table parameters of T. bactrae were also influenced by exposure to heat stress temperatures during each preimaginal developmental stage. Based on these results, we propose that T. bactrae is susceptible to high temperatures, especially at 39 °C. Thus, this parasitoid may be more effectively controlling lepidopterous pests during cooler weather conditions.

In his catalogue of the Anophelini (1924) Christophers admitted only one genus the tribe, which he divided into five subgenera: Anopheles (s. str.), Nyssorhynchus, Myzomyia, Bironella and Chagasia. The position of the first three as subgenera Anopheles is now universally accepted, but the arguments in favour of recognising the other two as distinct genera are worth consideration.

The biology of seventeen common species of rain forest bark beetles was studied during a six month visit to Fiji in 1973. Geographical and altitude ranges, and host plants are given; breeding galleries and brood composition are described in detail, and the significance of competitors, associates, and parasites is noted. The biology of an Ozodendron sp. is described for the first time, and of Cryphalomorphus sp. for the first time outside Africa. Most Fijian bark beetles show strong host preferences, and some of the most common endemics, such as Cryphalomorphus grosse-punctatus Browne, Hypocryphalus laticollis Browne and Ozodendron fijianus (Schedl) are apparently host specific. Among dominant trees of the rain forest only Myrtaceae and conifers (Dacrydium, Podocarpus), which are thin barked, are apparently free of bark beetles. Of note among biological features is the habit, not previously recorded for tropical bark beetles, of packing the egg galleries with frass after egg-laying has finished. Five species are potential pests of pines—Cryphalus variolosus Schedl, Cyrtogenius granulifer (Beeson), Ozodendron fijianus (Schedl), Poecilips cyperi (Beeson), P. fijianus Schedl. All were taken in endemic Pinaceae, and some in Pinus plantations as well. Lying within the tropical hurricane belt, living coniferous exotics in Fiji are potentially vulnerable to bark beetle attack when trees are under stress, as often occurs in the dry season.

In an attempt to define the favoured hosts of Culex portesi Senevet & Abonnenc and C. taeniopus D. & K., one bat, ten rodents, four marsupials, two birds and one crustacean, one amphibian and one reptile were exposed in groups of six in suction traps located in a forest in Trinidad. Each group of six baits included two white mice as a standard. The numbers of mosquitoes caught at each bait on three or six replicate exposures were analysed by an analysis of variance to separate population and site variations. Baits were then compared for ‘attractiveness’ by ranking according to an adjusted mean catch for each mosquito species. The proportion of each mosquito species that engorged on individual baits was also determined. In some cases, attraction and engorgement varied widely, and this was attributed to defensive action on the part of the bait animal. It was concluded that C. taeniopus was particularly attracted by the opossum Didelphis, which was superior to all indigenous mammals, while C. portesi was attracted to a wide range of rodents and marsupials. Neither was attracted by the cold-blooded animals. Both mosquitoes engorged well on the relatively insensitive marsupials with long bare tails, Dideiphis, Marmosa and Caluromys, and also on the well-furred but diurnal squirrel. Of the mainly nocturnal remainder, Culex portesi showed higher engorgement rates than C. taeniopus, suggesting a more aggressive or persistent feeding behaviour.

In view of the great diversity of opinion on the subject of sex ratio and order of emergence of the two sexes of adults in laboratory-bred mosquitos and those occurring in nature, 70 experiments spread over a period of 1 year, were conducted in the laboratory at room temperature to study (a) the order of emergence of the sexes, (b) proportions of sexes in the total output in a brood, (c) the effect of larval and pupal mortality, (d) the effect of food, and (e) of temperature on sex ratio. The common species, C. fatigans, was chosen for the purpose.

By a statistical evaluation and graphical representation of the data it has been shown that males hatch out significantly earlier than females, and that the larval life of the males is significantly shorter than that of the females.

It is concluded that the sexes emerge in a 1: 1 ratio, although a small number of aberrant cases with a significant preponderance of one sex or the other may occur.

Larval as well as pupal mortality below 20 per cent. does not seem to affect the sex ratio; nor has it been possible to establish any relationship between sex ratio and mortality in any of the aquatic stages.

This paper is one of a series analysing the quantitative effects of various factors on the biting rates of Culicoides furens (Poey) and C. barbosai Wirth & Blanton in Jamaica. It is concerned with the relationship between their biting rates and four meteorological variables: wind speed, temperature, illumination and saturation deficit. The methods used and the full data have already been published.

Five new species of Platygastridae associated with mango pests in India are described. Synopeas procon sp. n., S. temporale sp. n., S. mangiferae sp. n. and Inostemma oculare sp. n. parasitise mango leaf gall midges, Procontarinia spp. (Cecidomyiidae), while Inostemma apsyllae sp. n. is associated with the psyllid Apsylla cistellata (Buckt.). Notes on a further two species, the platygastrid Trichacoides indicus Jackson and the ceraphronid Aphanogmus sp., associated with Procontarinia are given. A key to separate these parasites as well as comments on their biology and distribution are presented.

1. Simple trials of the effect on mosquitos of single applications of DDT to the internal surfaces of houses were initiated in British Guiana during the period 27th January to 20th April, 1945.

2. The solution used in the first two trials was 4·6 per cent. DDT (72 per cent. para para) in kerosene applied at the rate of about 2 quarts per 1,000 square feet (i.e., approximately 100 mg. of crude DDT per square foot).

3. An apparent reduction in the house population of Anopheles darlingi, the chief malaria vector, followed the treatment. Reduction exceeded 99·7 per cent. over eight weeks in the treated houses on one estate and 98·8 per cent. over six weeks on another.

4. In a third trial with a small variety of simple formulations, promising results were obtained with a 6 per cent. emulsion and a 2½ per cent. solution. But mosquito catches over a short period suggest that mud walls, thatch and whitewash may interfere to some extent with the action of DDT.

5. The cost of applications was of the order of one shilling and sixpence for each room (or small hut) of about 1,000 sq. feet internal wall and ceiling surface. This estimate does not include European supervision or the initial cost and depreciation of apparatus.

The efficiency of modified CDC miniature light-traps for sampling adult mosquitoes was evaluated in comparison with indoor resting, outdoor resting, indoor man-landing and outdoor man-landing collections in the hilly district of Koraput, Orissa, India. Overall, light-traps captured 78% of adult mosquitoes collected by all methods. Of the 16 anopheline species recorded in the study area, light-traps effectively sampled 13, contributing about 72% of the total anophelines collected by all methods. Light-traps also caught a large number of female Culex vishnui Theobald (96%). As fully-fed mosquitoes were predominant (82%) and caught alive, light-traps can be used to catch large numbers of vector mosquitoes for studies on vector prevalence, distribution, vector incrimination and also for laboratory bioassays. Light-trap and indoor resting collections revealed similar seasonal trends in numbers of Anopheles culicifacies Giles, A. fluviatilis James, A. jeyporiensis James, A. vagus Doenitz, and A. splendidus Koidzumi. Age-structure of the samples did not vary significantly between the two methods. Light-traps could be used as an alternative to daytime indoor resting collections to monitor the seasonal fluctuations in the abundance and parity rates of these species. The light-trap collections correlated with indoor and outdoor man-landing collections of A. jeyporiensis and the outdoor man-landing collections of A. maculatusTheobald in measuring seasonal trends. Light-trap collections can thus be used as a substitute for man-landing collections of A. jeyporiensis and A. maculatus.

The bird cherry-oat aphid Rhopalosiphum padi (L.) is one of the most important wheat pests with polyphagia and autumn migrants. And, chemosensory genes were thought to play a key role in insect searching their hosts, food and mate. However, a systematic identification of the chemosensory genes in this pest has not been reported. Thus, in this study, we identified 14 odorant-binding proteins, nine chemosensory proteins, one sensory neuron membrane protein, 15 odorant receptors, 19 gustatory receptors and 16 ionotropic receptors from R. padi transcriptomes with a significantly similarity (E-value < 10−5) to known chemosensory genes in Acyrthosiphon pisum and Aphis gossypii. In addition, real-time quantitative polymerase chain reaction (RT-qPCR) was employed to determine the expression profiles of obtained genes. Among these obtained genes, we selected 23 chemosensory genes to analyze their expression patterns in different tissues, wing morphs and host plants. We found that except RpOBP1, RpOBP3, RpOBP4 and RpOBP5, the rest of the selected genes were highly expressed in the head with antennae compared with body without head and antennae. Besides that, the stimulation and depression of chemosensory genes by plant switch indicated that chemosensory genes might be involved in the plant suitability assessment. These results not only provide insights for the potential roles of chemosensory genes in plant search and perception of R. padi but also provide initial background information for the further research on the molecular mechanism of the polyphagia and autumn migrants of it. Furthermore, these chemosensory genes are also the candidate targets for pest management control in future.

A strain of Anopheles culicifaciesGiles (species B) originally collected from Aurangabad, Maharashtra State, India, showed highly specific resistance to malathion. Homogenates of one-day-old adults metabolized 14C-labelled malathion at a level comparable with strains of A. stephensi Liston and A. arabiensis Patton known to possess the malathion carboxylesterase resistance mechanism and at a higher rate (6.4 and 7.8 times, respectively) than malathion-susceptible strains of these species. The major metabolite obtained was malathion dicarboxylic acid, a carboxylesterase product, which suggests that this may be the principal resistance mechanism in this strain. Levels of non-specific esterase activity in larvae and adults were similar to those shown by both the susceptible and resistant strains of A. stephensi, implying that no quantitative increase in esterases had occurred. Microtitre plate assays on individual mosquitoes provided no evidence for the presence of the insensitive acetylcholinesterase resistance mechanism.

Apis mellifera is infected by more than 24 virus species worldwide, mainly positive-sense, single-stranded RNA viruses of the Dicistroviridae and Iflaviridae families. Among the viruses that infect honey bees, Deformed wing virus is the most prevalent and is present as three master variants DWV-A, B, and C. Given that the ectoparasitic mite Varroa destructor vectors these virus variants, recombination events between them are expected, and variants and their recombinants can co-exist in mites and honeybees at the same time. In this study, we detect, through RT-qPCR, the presence of DWV-A and B in the same samples of adult bees from colonies of Argentina. Total RNA was extracted from pools of ten adult bees from 45 apiaries distributed across the main beekeeping Provinces of Argentina (Buenos Aires, Santa Fe, Córdoba, Santiago del Estero, Río Negro, and Mendoza); then RT-qPCR reactions were performed to detect DWV-A and B, with specific primer pairs. After the amplifications, PCR products (204 and 660 bp amplicons for DWV-B, and ~250 bp for DWV-A) were purified and sequenced to verify that they corresponded to reported sequences, analyzing them using the Blast software. Of the 45 samples analyzed by RT-qPCR, over 90% were infected with DWV-A and 47% were also positive for DWV-B, where it was found in high prevalence specifically in colonies of A. mellifera of the Buenos Aires Province. Future studies will determine the impact of this type of the virus and its ability to recombine with the other DWV types in the apiaries of our country.

The mirid bug Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae) is a major pest on cotton, fruit trees and other crops in China. A. lucorum adults often switch host plants in the agro-ecosystem, and such host-plant switching may promote more rapid population growth of A. lucorum. Here, we examined the population fitness of A. lucorum on different combinations of two plant foods [fresh maize kernels (Zea mays) and green bean pods (Phaseolus vulgaris)] in the laboratory when reared either individually or in groups. Our results suggested that, compared with A. lucorum nymphs reared on green bean alone, the survival rate, developmental rate, and adult weight significantly increased when they were fed fresh maize kernels for both rearing methods. Both two-plant combinations of foods (i.e., maize as nymphal food then green bean as adult food, and green bean as nymphal food then maize as adult food) generally prolonged adult longevity, improved female fecundity, and higher egg hatching rate compared with maize or green bean as food for both nymphs and adults. The combination of nymphs with maize and adults with green bean showed the highest population growth rate for both individual and group rearing of mirid bugs. Host food switching greatly promoted the population growth of A. lucorum, and suggests a new diet for laboratory rearing of A. lucorum.