The Asian corn borer, Ostrinia furnacalis enters diapause as fully grown larvae. Owing to geographical variation in photoperiodic control of diapause, the subtropical strain from Hefei city (HF) enters diapause in response to short daylengths, whereas the tropical strain from Ledong county (LD) exhibits almost no diapause under the same conditions. The two strains were used in crosses to study the inheritance of diapause. The HF strain showed a typical long-day response with a critical daylength of approximately14.97 h at 22 °C, 14.60 h at 25 °C and 13.68 h at 28 °C. The LD strain showed weak photoperiodic responses at 22 and 25 °C; and the F1 progeny also showed a long-day response with significantly shorter critical daylength compared with the HF strain. However, the LD × HF (F × M) crosses had significantly longer critical daylengths than HF × LD crosses, indicating a sexual bias in the inheritance of diapause induction, with the male parent having more influence on the F1 progeny. The critical daylength in a backcross to HF was significantly longer than a backcross to LD. Whether the inheritance of diapause fits an additive hypothesis or not depended on photoperiod, with results from different photoperiods showing additive inheritance or incomplete dominance of either diapause or non-diapause. Unlike diapause induction, the duration of diapause for reciprocal crosses was equally influenced by each parent, suggesting that diapause incidence and maintenance are controlled by separate systems in O. furnacalis.

Epigaeic ants were sampled by pitfall trapping in three South African citrus orchards supporting low levels of Aonidiella aurantii(Mask.). All three were similar except that chemical control of the scale was in progress in one, biological control in the second, while the third was in transition from chemical to biological control. Within-orchard variation was statistically zero at the chemical and biological control sites, both of which had constant species abundances and rank-abundance sequences throughout. Within the transition site, rank-abundance sequences were constant but species abundancies varied. Despite the statistical constancy of rank, within-orchard samples at the transition and chemical control sites varied in their dominant ants. The biological control site was dominated throughout by Pheidole megacephala(F.). Individuals of the dominant species made up between 59 and 69% of the total, and as the dominant species varied, this high figure suggested strong interspecific competition. Log-normal models were fitted to the site rank-abundance plots. The interquartile index, Q, was higher when based on an underlying log-series model (α) than on a log-normal one; it was about 2·0, which is low compared with most other studies. The total numbers of individuals and species of ants were higher in the biological control than chemical control orchard. Diversity, as measured by α or Q log-normalwas lowest in the chemical control site, medium in the biological controlone, and highest in the transition site. Between-site variation showedvariation in general ant abundance. As with the within-orchard results, those between orchards were relatively constant. Ant management in relation to community structure is critically appraised on the basis of limiting factors (especially abundance of honeydew as food for potentially dominant ants) and rank-abundance sequences.

Life-cycles and voltinism are described for Rhyzobius ventralis (Erichs.) and R. forestieri (Muls.) living in the region of Sydney, Australia, and also the role each plays in its particular biocoenosis. Colour variation and wax production are described for the larvae, prepupae, pupae and adults of both species, also the defensive and feeding behaviour. New and known host records are listed for both species. Reasons are suggested for the success, partial failure or failure of the species as biological control agents in various parts of the world.

The spatial analysis by distance indices (SADIE) technique was developed to evaluate the spatial pattern of point-referenced count data as well as the spatial association between two sets of data sharing the same point locations. This paper presents an analysis of spatial patterns in aphid count data and the association of these data with climate across north-west Europe. The paper tests the applicability of the technique to large geographical areas. Aggregation and cluster indices were calculated for the total annual abundance of the peach–potato aphid Myzus persicae (Sulzer) and for the annual mean rainfall and temperature at aphid monitoring sites. Association indices demonstrated the stability in time of aphid spatial structures and the correlation between aphid density and climate patterns. Groups of relatively large numbers of aphids, termed patches, and groups of relatively small numbers of aphids, termed gaps, were located and their mean size estimated. The aphid patterns were quite stable in time and the spatial patterns of temperature and rainfall were weakly associated with M. persicae annual abundance. Similarities were observed between the results of SADIE and those from the more widely used technique of spatial autocorrelation (SAC). However, the SADIE association index has the advantage of quantifying the possible associations between aphid data and the factors that determine population distribution. Thus, high temperature and low rainfall were identified as environmental factors that were positively associated with aphid abundance across north-west Europe.

Adults of Zonocerus variegatus (L.) from the dry-season population in southern Nigeria were shown to exist in two forms, one with relatively long wings and the other with relatively short wings. The wet-season population normally existed as the short-winged form, but the insects had the capacity to develop long wings. Long-winged insects had welldeveloped flight muscles and were capable of flight. Flight in the field occurred before sexual maturation and may have led to downwind displacement of individuals over considerable distances.

Climate changes can affect the distribution and intensity of insect infestations through direct effects on their life cycles. Experiments were carried out during three consecutive generations to evaluate the effect of different temperatures (25°C, 28°C, 31°C, 34°C and 37±1°C) on biological traits of the velvetbean caterpillar Anticarsia gemmatalis Hübner, 1818 (Lepidoptera: Noctuidae). The insects were fed on artificial diet and reared in environmental chambers set at 14 h photophase. The developmental cycle slowed with the increase in the temperature, within the 25°C to 34°C range. Male and female longevities were reduced with an increase in temperature from 25°C to 28°C. Egg viability was highest at 25°C, and the sex ratio was not influenced by temperature, in the three generations. There was no interactive effect between development time and temperature on pupal weight. The results suggested that the increase in the temperature negatively impacted A. gemmatalis development inside the studied temperature range, indicating a possible future reduction of its occurrence on soybean crops, as a consequence of global warming, mainly considering its impact on tropical countries where this plant is cropped. A. gemmatalis was not able to adapt to higher temperatures in a three-generation interval for the studied temperature range. However, a gradual increase and a longer adaptation period may favor insect selection and consequently adaptation, and must be considered in future studies in this area. Moreover, it is important to consider that global warming might turn cold areas more suitable to A. gemmatalis outbreaks. Therefore, more than a future reduction of A. gemmatalis occurrence due to global warming, we might expect changes regarding its area of occurrence on a global perspective.

Bactrocera oleae (Rossi) (Diptera: Tephritidae) is considered the most devastating pest of the olive tree worldwide. In an effort to develop management and biological control strategies against this pest, new molecular tools are urgently needed. In this study, we present the design of B. oleae-specific primers based on mitochondrial DNA sequences of cytochrome oxidase subunit I (COI) gene. Two pairs of B. oleae-specific primers were successfully designed and named as SBo1-F/SBo1-R and SBo2-F/SBo1-R, being able to amplify 108 and 214 bp COI fragments, respectively. The specificity of designed primers was tested by amplifying DNA from phylogenetically related (i.e. Diptera order) and other non-pest insects living in olive groves from the Mediterranean region. When using these primers on a PCR-based diagnostic assay, B. oleae DNA was detected in the gut content of a soil-living insect, Pterostichus globosus (Fabricius) (Coleoptera: Carabidae). The detection of B. oleae DNA in the guts of arthropods was further optimized by adding bovine serum albumin enhancer to the PCR reaction, in order to get a fast, reproducible and sensitive tool for detecting B. oleae remains in the guts of soil-living arthropods. This molecular tool could be useful for understanding pest–predator relationships and establishing future biological control strategies for this pest.

We examined previous reports of Lema praeusta (Fab.) (Coleoptera: Chrysomelidae) as a minor pest of turmeric, eggplant, bottle gourd and pumpkin leaves, but no feeding damage by larvae and adults of L. praeusta were recorded by us on these leaves. We observed feeding by the larvae and adults of L. praeusta on ten species of Commelinaceae plants in no-choice tests. The biology, fecundity and life table parameters of L. praeusta on two Commelinaceae weeds, Commelina benghalensis L. and Murdannia nudiflora (L.) Brenan were determined under laboratory conditions (27 ± 1°C, 65 ± 5% RH and 12L:12D). Total larval development times of L. praeusta were 6.36 ± 0.07 and 7.28 ± 0.11 days (mean ± SE) on C. benghalensis and M. nudiflora, respectively. Adult females lived 106.25 ± 1.17 and 77.65 ± 0.91 days (mean ± SE) on C. benghalensis and M. nudiflora, respectively. Each female laid 272.95 ± 2.39 and 224 ± 1.74 eggs (mean ± SE) during a lifetime on C. benghalensis and M. nudiflora, respectively. The net reproductive rate (Ro), intrinsic rate of increase (rm), generation time (Tc), doubling time (DT) and finite rate of increase (λ) were 136.48, 0.14, 36.17, 5.10 and 1.41 on C. benghalensis, respectively, whereas Ro, rm, Tc, DT and λ were 112, 0.20, 23.64, 3.47 and 1.51 on M. nudiflora, respectively, suggesting that L. praeusta could be a potential biocontrol agent against C. benghalensis and M. nudiflora in the fields of rice, maize, sorghum, soybean, mung bean, peanut and cotton.

Galeruca daurica (Joannis) is a new outbreak pest in the Inner Mongolia grasslands in northern China. Heat shock protein 10 and 60 (Hsp10 and Hsp60) genes of G. daurica, designated as GdHsp10 and GdHsp60, were cloned by rapid amplification of cDNA ends techniques. Sequence analysis showed that GdHsp10 and GdHsp60 encoded polypeptides of 104 and 573 amino acids, respectively. Sequence alignment and phylogenetic analysis clearly revealed that the amino acids of GdHsp10 and GdHsp60 had high homology and were clustered with other Hsp10 and Hsp60 genes in insects which are highly relative with G. daurica based on morphologic taxonomy. The mRNA expression analysis by real-time PCR revealed that GdHsp10 and GdHsp60 were expressed at all development stages and in all tissues examined, but expressed highest in eggs and in adults’ abdomen; both heat and cold stresses could induce mRNA expression of GdHsp10 and GdHsp60 in the 2nd instar larvae; the two Hsp genes were expressed from high to low with the extension of treatment time in G. daurica eggs exposed to freezing point. Overall, our study provides useful information to understand temperature stress responses of Hsp60 and Hsp10 in G. daurica, and provides a basis to further study functions of Hsp60/Hsp10 relative to thermotolerance and cold hardiness mechanism.

Salicylic acid (SA), a phytohormone, has been considered to be a key regulator mediating plant defence against pathogens. It is still vague how SA activates plant defence against herbivores such as chewing and sucking pests. Here, we used an aphid-susceptible wheat variety to investigate Sitobion avenae response to SA-induced wheat plants, and the effects of exogenous SA on some defence enzymes and phenolics in the plant immune system. In SA-treated wheat seedlings, intrinsic rate of natural increase (rm), fecundity and apterous rate of S. avenae were 0.25, 31.4 nymphs/female and 64.4%, respectively, and significantly lower than that in the controls (P < 0.05). Moreover, the increased activities of phenylalanine-ammonia-lyase, polyphenol oxidase (PPO) and peroxidase in the SA-induced seedlings obviously depended on the sampling time, whereas activities of catalase and 4-coumarate:CoA ligase were suppressed significantly at 24, 48 and 72 h in comparison with the control. Dynamic levels of p-coumaric acid at 96 h, caffeic acid at 24 and 72 h and chlorogenic acid at 24, 48 and 96 h in wheat plants were significantly upregulated by exogenous SA application. Nevertheless, only caffeic acid content was positively correlated with PPO activity in SA-treated wheat seedlings (P = 0.031). These findings indicate that exogenous SA significantly enhanced the defence of aphid-susceptible wheat variety against aphids by regulating the plant immune system, and may prove a potential application of SA in aphid control.

This is an account of two different inquiries carried out on the same safari in the Lumbwa country of Kenya Colony early in 1920. The problems are of the same type, the suspected transmission of disease by blood-sucking flies, and the second investigation arose out of the first. It therefore seems best to deal with them both in a single paper.

‘Blind’ trials using laboratory-bred females that had completed 0–3 gonotrophic cycles showed that Polovodova's method of assessing parity, by noting the presence of follicular dilatations, is applicable to Lutzomyia flaviscutellata (Mangabeira) and L. furcata (Mangabeira). However, at the resolution of the techniques used, classification is limited to a simple division into nulliparous and parous flies. The presence of granules in the ovarian accessory glands was found to be an unreliable indicator of parity for both species.

Nine species of Cecidomyiid midges, including Contarinia sorghicola. (Coq.), C. andropogonis Felt, C. caudata Felt, C. palposa Blanch., Stenodiplosis sp., ? Lestodiplosis sp., Clinodiplosis sp., a species of Lasiopterariae and an undescribed species of Bifila, have been recorded from the inflorescences of cultivated sorghums (Sorghum vulgare) and related wild hosts. New morphological and other studies of this complex, involving the use of new techniques which are described, have elucidated the complex without recourse to biological testing.

Contarinia, sorghicola with which C. andropogonis and C. palposa are placed in synonymy, and a new species, Stenodiplosis sorghi, here described, are the only valid species which are primary feeders on cultivated and wild species of the genus Sorghum. Contarinia caudata is a distinct species reared from the grass Apluda varia. Contarinia gambae, a second species described as new, on the basis of specimens reared from the grass Andropogon gay anus, was formerly misidentified as C. sorghicola. C. sorghicola, S. sorghi and C. gambae are described and figured in detail. A species tentatively placed in Lestodiplosis and a species of Clinodiplosis are comparatively rare and of no economic importance. The record of a species of Lasiopterariae from a wild sorghum is believed probably to have been based on a misidentification of the host, and a species previously referred to as the ‘ 3rd Bifila ’ from A. gayanus has no real connection with the sorghum midge complex.

A series of trials examining the feasibility of an attracticide technique for control of Spodoptera littoralis (Boisduval) are described. The technique combined the sex pheromone of S. littoralis with pyrethroid insecticide, λ-cyhalothrin, in 500 point-sources/ha at low rates of application of both components. It was envisaged that male moths would be attracted to contact the sources and subsequently suffer lethal or sub-lethal effects which would prevent mating. The pheromone was applied either as a sprayable microencapsulated (MC) formulation or in polyvinyl-chloride lures; emulsifiable concentrate and MC formulations of the insecticide were employed. Treatments were assessed by monitoring pheromone trap catches, mating of tethered females and, in one trial, numbers of eggmasses found in experimental areas. Mating levels and trap-catch in treatment plots were siginificantly reduced, compared to controls, for periods up to 5 and 24 nights after treatment, respectively. However despite a continuous period of mating suppression, achieved by repeated applications, no treatment-related reduction in egg-masses was observed. Two trials compared attracticide with mating-disruption treatments in which the insecticide was omitted. Similar levels of mating and trap-catch suppression were observed in the two treatments. It was concluded that the mating suppression observed in attracticide plots was due principally to disruption of chemical communication between the sexes, not to male mortality arising from contact with the insecticide sources. None of the attracticide treatments represented a viable control technique. Other practical and theoretical considerations arising from the results are discussed.

When Telenomus nawai Ashmead or Trichogramma ostriniae Pang & Chen (Hymenoptera: Trichogrammatidae) was inoculated into intact egg masses of Spodoptera litura (Fabricius) that were covered with a scale-hair layer, T. nawai emerged from 76% of the eggs, while emergence of T. ostriniae was from only 3% of the eggs. When the hair layer was removed before inoculation, the rate by the latter increased to 21%. These observations confirmed that the hair layer effectively protects S. litura egg masses from attack by T. ostriniae, and that T. nawai parasitism is more effective. In order to assess the feasibility of T. nawai as a biological control agent for S. litura, parasitism rate, development time and adult longevity were examined in the laboratory. Emergence of T. nawai was observed in more than 95% of 0- and 1-day-old separated eggs of S. litura, but the rate decreased to 60% and 0% for 2- and 3-day-old eggs, respectively. The emergence rates of T. nawai were near 95% for temperatures in a range from 25°C to 35°C, but decreased to 80% at 20°C. No parasitoids emerged at 15°C. The developmental periods decreased as temperature increased from 20°C to 35°C. The developmental threshold occurred at 13.7°C and 13.9°C, and the effective accumulative temperatures from egg to adult emergence were 149.3 and 147.1 degree-days for females and males, respectively. Mean longevity of the adult females decreased with increasing temperature; 87.0 days at 15°C and 9.5 days at 35°C. The feasibility of the use of T. nawai for controlling S. litura is discussed.

1. From the study of the historical records of European invasions by Locusta from the 14th century to the present day, it is concluded that the subspecies concerned was L. m. migratoria originating in the West Pontian outbreak area. This area formerly comprised the lower courses of rivers draining into the Black Sea from the Danube to the Dniepr inclusive, and is now confined to the delta of the Danube. From here swarms migrated into central Europe and the eastern part of the north European plain. The northern part of the plain, the British Isles and Fenno-Scandia, lie on the outskirts of the invasion area, and as a rule were only reached by small detachments from swarms. The decline of the West Pontian outbreak centres was accompanied by the gradual decline of the area subject to invasions by large swarms, but during outbreaks small groups and separate individuals of ph. gregaria continue to reach the further limits of the invasion area.

2. The distances covered within a single generation by swarms of L. m. migratoria in temperate Europe (up to 1,600 miles) were comparable in extent to those traversed by L. m. migratorioides in tropical Africa.

3. Long-range migrations to the extreme limits of the invasion area are not confined to L. m. migratoria ph. gregaria but occur also in ph. solitaria. This is shown by the arrival of individuals of this phase in the British Isles during theperiod when the West Pontian outbreak areas are in a quiescent state. From this and from literature data on other locust species it is concluded that long-range migration is a regular seasonal phenomenon in swarming acrididae, independent of the presence of large numbers or the phase.

4. The late summer immigration of L. m. migratoria into the British Isles may be a part of a more general east to west movement of flying insects which may occur in Europe at that season.

5. It is probable that L. m. migratoria sometimes oviposit in the British Isles, for they may arrive in a mature state, or during exceptionally hot summers in southeastern England they may reach sexual maturity after arrival. The eggs, however, are apparently unable to survive winter conditions.

The investigations herein recorded show that DDT is more toxic to bed-bugs when available on a surface as an oil solution than as a dry film, and that the toxicity of the latter is determined to some extent by the volatility of the medium in which DDT is applied. The results of trials on filter paper, glass and unpainted wood suggest that the minimum period of exposure to a dry film of DDT necessary for the insect' to acquire a lethal dose is one hour, and that this critical period is constant irrespective of the nature of the DDT-treated material to which the insect is exposed. Tests with bugs on DDT-impregnated filter paper show that this period can be curtailed considerably by the addition of a fine oil spray.

The direction of mosquito flight near the ground, in relation to wind direction, was investigated at Keneba in The Gambia, West Africa. Directional flight traps facing eight directions sampled mosquitoes flying between ground level and 1·4 m, and unbaited and baited catches with a calf at the centre of the trap circle were performed. Data on non-host-oriented flight were obtained for unfed female Anopheles melas (Theo.), Culex thalassius Theo. and C. tritaeniorhynchus Giles from the unbaited catches, and from all catches of unfed females of the C. deceits group, and gravid and male mosquitoes, which did not respond to the calf. The baited catches included large numbers of A. melas, C. thalassius and C. tritaeniorhynchus, and fewer Anopheles squamosus Theo. and A. ziemanni Grünb. In both unbaited and baited situations, flight appeared to be in a predominantly upwind direction, although mere was some indication, in the presence of a calf, of convergence into the host stream.

The intergenic spacer region of the rRNA cistron was used as a molecular fingerprinting probe to study clonal diversity in Schizaphis graminum (Rondani). A high degree of clonal diversity was found in overwintering populations on wheat from Kansas, Texas and Oklahoma. Out of 184 individuals tested, 132 unique maternal lineages wereidentified. Overall, clonal diversity of overwintering populations was no less than in spring and summer populations. However, in some fields there were more instances where individuals of the same genotype were identified. By partitioning the total population diversity into various sampling components (fields, counties and states), 93.1% of the total diversity was found among individual S. graminum within fields. Overwintering of many genetically distinct clones as parthenogenetic morphs is one mechanism by which clonal diversity is maintained in populations of S. graminum. The incidence of clonal diversity further substantiates the importance of the S. graminum holocycle for generating genetic heterogeneity in the USA.

During two years (1924 and 1925) spent in Samoa by Dr. P. A. Buxton and myself, while employed in research on filariasis for the London School of Hygiene and Tropical Medicine, we made notes of such agricultural pests as came our way, though (our main interests being medical) we were not able to investigate them at all thoroughly. For this reason the fact of an insect being recorded only on one occasion is no indication that it did not occur in other months, or even that it was uncommon, since we frequently did not continue to make notes of the occurrence of a species we had once recorded. Though our observations make no claim to completeness, they are perhaps worthy of publication in view of the scarcity of records from this group of islands. Our observations on medical and veterinary entomology have been published as a Memoir of the London School of Hygiene and Tropical Medicine. In that Memoir we have published maps, and short accounts of the structure, flora and climate, of Samoa.