Sampling in Northumberland, England, and southern Scotland of pasture soils, the major larval habitat of Hydrotaea irritans (Fall.), showed larvel densities of between 0 and 30/m2; 15 different sites were examined, and all produced larvae. Larvae were found from September until June, larvael development continuing in the soil for about eight months. A study of the distribution within a single field that larvae were not confined to the wooded margins but occurred in significant numbers throughout the field. Higher numbers of larvae were present in the soil beneath cow pats than in the open field, but the proportion relative to the total population is small. Larvae prey was predominantly dipterous and coleopterous larvae. Pupation took place in the top 5 cm of pasture soil during May and lasted until late June. Emergence of adults took place from June until late July; males and females emerged over the same period

The daytime resting sites of adult Conopomorpha cramerella (Snellen), a serious pest of cocoa in south-east Asia, were identified as a possible target to which insecticide could be selectively applied. Field observations were made on 126 resting moths in a cocoa plantation in East Malaysia. All moths were found on the undersides of branches 45° or less from horizontal, and 1·5 cm or more in diameter; 90% were found in the lower half of trees. A field trial was conducted in which 25 ppm deltamethrin was applied with knapsack sprayers to these sites. Five applications were made at ten day intervals, each crop season (6 months), over a two year period. Mean estimated losses in the sprayed area were 12.1 to 33.7 percentage points lower than in the control area, giving an estimated net benefit of up to RM978 ha in one season, assuming a cocoa price of RM4000 per tonne. Losses in the sprayed area still ranged from 7.0% to 43·1% and did not decline over successive seasons. There was some evidence for immigration into the sprayed area, but it is suggested the rapid recovery of populations following spraying is also due to the high potential rate of increase of the insect in susceptible cocoa varieties. In susceptible cocoa varieties control is always likely to be difficult, but in less susceptible varieties, and with well maintained trees, chemical control by selective application to adult resting sites can be a practical component of integrated control.

Body size is an important life-history trait in eusocial insects which plays a key role in colony fitness. The division of labour, represented by caste polyethism, correlates with divergent morphological traits. Size polymorphism has been noted in the tropical fire ant, Solenopsis geminata; however, little is known regarding the differences in the size distributions of workers performing foraging tasks. In the present study, task partitioning was observed in the foraging activities of S. geminata. Two subgroups among foraging workers of S. geminata were discovered using the Gaussian mixture model: a large worker group (head width ≥ 0.924 mm) and a small worker group (head width < 0.924 mm). The foraging worker population comprised two distinct groups – 25.64% were large workers and 74.36% were small workers. Larger workers delivered heavier seeds faster than smaller workers, but this difference became less apparent when lighter seeds were being carried. When large prey such as crickets was encountered during foraging, S. geminata partitioned their tasks into cutting and transportation. The large workers were observed to cut cricket prey into fragments with their longer mandibles, and the small workers then transported these fragments back to the nest. These results present evidence of task partitioning among tropical fire ants, with different tasks being performed by ants of different castes.

Plants not only respond to herbivorous damage but adjust their defense system after egg deposition by pest insects. Thereby, parasitoids use oviposition-induced plant volatiles to locate their hosts. We investigated the olfactory behavioral responses of Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae) to volatile blends emitted by maize (Zea mays L.) with singular and stacked events after oviposition by Spodoptera frugiperda Smith, 1797 (Hymenoptera: Trichogrammatidae) moths. Additionally, we examined possible variations in gene expression and on oviposition-induced volatiles. We used a Y-tube olfactometer to test for the wasp responses to volatiles released by maize plants oviposited by S. frugiperda and not-oviposited plants. Using the real-time PCR technique (qRT-PCR), we analyzed the expression of lipoxygenase and three terpene synthases genes, which are enzymes involved in the synthesis of volatile compounds that attract parasitoids of S. frugiperda. Olfactometer tests showed that T. pretiosum is strongly attracted by volatiles from transgenic maize emitted by S. frugiperda oviposition (VTPRO 3, more than 75% individuals were attracted). The relative expression of genes TPS10, LOX e STC was higher in transgenic hybrids than in the conventional (isogenic line) hybrids. The GC-MS analysis revealed that some volatile compounds are released exclusively by transgenic maize. This study provides evidence that transgenic hybrids enhanced chemical cues under oviposition-induction and helped to increase T. pretiosum efficiency in S. frugiperda control. This finding shows that among the evaluated hybrids, genetically modified hybrids can improve the biological control programs, since they potentialize the egg parasitoid foraging, integrating pest management.

The European cherry fruit fly, Rhagoletis cerasi (Diptera: Tephritidae), is a univoltine species that overwinters at pupal stage. Under optimum overwintering conditions pupae will develop into adults the next spring. Shorter or longer than optimum chilling periods induce prolonged pupae dormancy. Pupae that enter prolonged dormancy due to a short chilling period exhibit high emergence rates after a second cycle of cold/warm periods. Adults found to be larger and less fecund compared to their counterparts from pupae with annual diapause. On the other hand, extreme long chilling periods at pupal stage results in high mortality rates. However, for one Greek population, a substantial number of adults emerged following prolonged chilling of pupae (ca. 18 consecutive months). In this study, we used three R. cerasi populations in order to address possible geographical variation in fitness cost of adults from pupae with prolonged dormancy. In addition, the fitness traits of these adults emerging after prolonged pupae chilling were compared with that of their counterparts from pupae with annual diapause or prolonged dormancy. Our results reveal no population-specific variation in fitness cost of adults from pupae with prolonged dormancy. Within a population, lifetime fecundity did not differ between adults emerged from pupae with prolonged dormancy and those emerged after prolonged pupae chilling. Adults emerged from pupae exposed to prolonged chilling suffer an additional reduction in adult longevity compared to adults from pupae with prolonged dormancy. Hence, fitness of R. cerasi adults is regulated by diapause regimes of pupae.

Early in the month of January 1931 a large swarm of the Pyrrhocorid bug, Melamphaus faber, F., invaded trees of Hydnocarpus anthelmintica, Pierre, and H. wightiana, Blume, at the Government Experimental Plantation, Serdang, Selangor, Federated Malay States.

This paper deals with a number of Coccids which have been forwarded through the Imperial Bureau of Entomology from the following countries: The Dutch West Indies, Barbados, British Guiana, Zanzibar, Uganda, Nyasaland, and Nigeria. Five species are herein described as new to science, the others, for the most part, are Avell-known pests affecting cultivated plants in various parts of the world.

Mr. Malcolm E. MacGregor's interesting paper, “The Influence of Drought upon Mosquito Life in Surrey” (Bull. Ent. Res. xii, p. 205), has led me to examine our records of observations made in that county in connection with inquiries into indigenous malaria in England. As regards certain areas of the country during the past year, our experience of the scarcity of some kinds of mosquitos is the same as Mr. MacGregor's, but (if it is desired to draw conclusions for the country as a whole) it seems important also to note that there are other areas in which the findings differ from those in the particular locality upon which he reported. Dorking, Epsom and Arbrook Common, which are within a few miles of Wisley, are examples of such areas. In these and some other localities in the county we have obtained larvae of A. bifurcatus without difficulty throughout the year. At Epsom, large numbers of larvae of this species in the fourth instar were found early in February this year in a well-shaded permanent pool, which we have examined regularly since 1917, and adults were caught in the open in April. Larvae were numerous throughout the year, and adults, both male and female, were captured in the open as late as 22nd October. At Dorking, larvae of bifurcatus were plentiful in several natural collections of water throughout the year. One of them—the “Mill Ponds stream”—is only 100 yards from a row of houses; another—the “Stonebridge stream”—yielded bifurcaus larvae on 19th August at every place examined along a stretch of 400 yards. On the same day many larvae of this species were found, along with larvae of C. pipiens, in the rainwater barrel of a house about 200 yards from the stream.

Diparopsis watersi (Roths.) is the principal pest of cotton in the Abyan Delta, West Aden Protectorate, an almost rainless area where the crop is sown in August–September on floodland watered by seasonal streams rising on the Yemen plateau. From December onwards, a large proportion of the pupae formed exhibit a facultative diapause, and adults emerging from these are responsible for infesting the following season's crop, the size of the initial population in which depends upon the extent to which this moth flight is intercepted by cotton in a suitable stage for breeding. When initial populations are low, most of the crop is set before the population has greatly increased by short-cycle breeding, shedding of flower buds and young bolls following attack by D. watersi is slight in relation to natural shedding, and little crop loss is attributable to this boll-worm. When a large part of the moth flight is intercepted, initial populations are high, heavy shedding is caused, and varying degrees of loss ranging up to virtual crop failure can result.

Investigations show that, when land is watered, emergence from diapause pupae is almost completed within six weeks; it is thought that watering reduces soil temperature below the high level that appears to inhibit diapause development throughout the summer. The resulting moth flight is largely spent before flower buds become available and the initial population in the crop is low. When land that was under cotton the previous year is not watered, soil temperatures remain high, and this is thought to account for a delay in emergence until temperatures fall, giving rise to a moth flight extending from November to January. Much of this is intercepted by cotton in a condition suitable for breeding by D. watersi, the initial population is high and heavy losses can result. The annual variation in the volume of the floods results in corresponding fluctuations in cotton acreage, a varying proportion of the previous year's cotton land remaining unwatered. The histories of the four cotton crops 1958–59 to 1960–61 indicate the extent to which infestation of the crop depends on this factor. In a year of poor floods following a large acreage in the previous year, infestations tend to be severe, and, conversely, a large crop following a smaller one the year before is normally lightly attacked. Failure to observe a close season may also promote heavy infestation, since it results in the provision of a food supply for the offspring of the main emergence from diapause pupae, which otherwise would not survive.

Endrin has proved very effective in the control of D. watersi, and Sevin also shows promise, but several applications over the two months following the first flower buds are necessary and it is doubtful whether these could be economic. A close season is essential, and the effects of its violation have been seen in recent years. The available flood water should be used more economically, using a system of area rotation of crops whereby cotton would be followed by another crop and that in turn by a dry fallow. The spring floods, which normally run to waste, could thus be utilised, and this would reduce the incidence of unwatered cotton land.

There appear to be two main causes of “ blight,” namely, the attacks of the froghoppers (Tomaspis saccharina) and the attacks of root fungi (Marasmius and Odontia).

The susceptibility of the cane to the attacks of these root fungi has been shown to be largely due to unsatisfactory conditions as regards the health of the plant and particularly to conditions of drought—physiological or actual. Moreover, this root disease tends to intensify the effect of the water-shortage. It is suggested that a careful analysis of the evidence might also show that the susceptibility to froghopper attack is due to causes which disturb the water balance of the cane, a disturbance which would be even more marked where root disease was present.

The balance in the water content is dependent upon the simultaneous working of the absorption that takes place through the roots and the transpiration that takes place through the leaves ; if transpiration is excessive the plant makes too great a demand upon the supply of available water in the soil. The humid climate of Trinidad is, therefore, particularly favourable to the growth of the sugar-cane. A favourable climate can, however, be offset by unfavourable soil conditions. The distribution of the rainfall, the conditions of the soil, the degree of atmospheric humidity, the effect of the disturbance of the water-balance upon the nature of the cell-sap, etc., all need to be taken into account. As regards rainfall and blight, it would appear that : (1) Prolonged periods of drought, or of excessive rainfall ; and (2) periods of drought following on spells of excessive wet weather, are both particularly harmful.

In view of the part played by root absorption in the maintenance of the water-balance, a detailed consideration of the root system of the sugar-cane in connection with blight might possibly throw fresh light upon the subject.

A disturbance of the water-balance may also affect the cane's susceptibility to the attacks of insects through its effect upon the physiology of the cane. Is it possible that drought (physiological or actual) or other unfavourable climatic and soil conditions may affect the concentration or constitution of the sugars in the sap in such a way as to render them more attractive to sap-feeding insects ?

The problem is extremely complex. We have seen that root disease is dependant upon the weakness and debility of the cane, resulting from unfavourable environmental conditions and from shortage of water ; that the root disease thus caused intensifies the effect of this water-shortage by lowering the plant's capacity for root absorption ; that the plant, susceptible in any case to attacks of froghoppers as the result of any disturbance in the water-balance, is rendered even more susceptible as a result of root disease. On the other hand, root disease is said to be due to a lack of vitality in the plant ; a plant attacked by froghopper is greatly reduced in vitality, and thus the tendency to root disease is increased.

We have considered the interrelation between the absorption of water by the roots and the transpiration of water through the leaves, and the effect of the water content on the physiology of the plant. We must also consider the interrelation between the attacking froghopper and root fungus, and the cane which is attacked.

Can we decrease the number of attacking organisms, or is it more feasible to increase the cane's resistance to their attack ? In the past the economic entomologist has directed his attention almost entirely to answering the first question ; it is now realised that an answer to the second question is quite as, perhaps even more, urgently demanded. Unhealthy canes are undoubtedly more susceptible to attack than healthy canes, that is, if we use the term “ health ” in its rightful sense as denoting vigour and the capacity to resist adverse environmental conditions, and not merely luxuriant growth.

During the early part of 1929, a specially severe infestation of locusts occurred in the northern provinces of Tanganyika Territory, an extension of the plague already felt in Kenya. Laying was known to have taken place more or less continuously over the drier country all the way from Longido, west of Kilimanjaro, to the West Usambara Mountains. Successive broods of young locusts had to be dealt with; and in the same area it was possible to see newly hatched hoppers and insects almost full-grown and able to fly. An ample supply of extra food was therefore provided for any birds that might care to avail themselves of it, except the smallest, and certain specialists such as the Hirundines. I was anxious to get some idea of how the birds would react to these abnormal food-conditions, and by the kindness of Dr. and Mrs. R. R. Le G. Worsley, the former of whom was in charge of a sector of the locust campaign, I was able during the first week of June 1929 to make observations in a very heavily infested area between the Middle Pangani River and the South Pare Mountains. I have also to thank the Director E.A.A.R.S. for certain facilities in this connection.

Theresia (Procris) ampelophaga, Bayle, a moth of the family Anthroceridae (Zygaenidae) is one of the most important pests of the vine in various countries, but the existing accounts of its bionomics are very contradictory and not free from inaccuracies.

The melon fruit fly, Bactrocera cucurbitae (Coquillett), is a serious agricultural pest which has defied the various control measures employed against it. Protease inhibitors present in plants which have the potential to inhibit the growth and development of associated insect pests can be a possible alternative which can be manipulated for developing resistance in plants to the pest. In the present study, winged bean (Psophocarpus tetragonolobus) protease inhibitor isolated through affinity chromatography was explored for its potential to disrupt the development of melon fruit fly, B. cucurbitae. Different concentrations (12.5, 25, 50, 100, 200, and 400 µg ml−1) of the winged bean protease inhibitor (WBPI) were incorporated into the artificial diet of the second instar (64–72 h old) larvae of B. cucurbitae. The WBPI significantly delayed the larval, pupal, and total development period. The percentage pupation and adult emergence of the treated larvae was reduced as compared with control. The activities of major digestive enzymes (trypsin, chymotrypsin, leucine aminopeptidase, and elastase) decreased significantly in the larvae treated with different concentrations (50, 100, 200, and 400 µg ml−1) of WBPI. The findings reveal that the inhibitor holds considerable promise for the management of the melon fruit fly.

Colorado potato beetle (Leptinotarsa decemlineata, Say) is the main pest of Solanaceae and its survival is mainly dependent on the carbohydrate digestion. Characterizing the gut enzymes may help us with finding effective inhibitors for plant protection. Activity measurements revealed that gut extracts contain α- and β-glucosidase in addition to α-amylase. For larvae, amylase activity was detected only in gut saturated with nutrients. Leptinotarsa decemlineata α-amylase (LDAmy) had optimum pH of 6.0 and was active under 30–40°C temperature measured on a selective α-amylase substrate, 2-chloro-4-nitrophenyl-4-O-α-D-galactopyranosyl-maltoside. HPLC analysis demonstrated dimer, trimer, and tetramer reducing end amylolytic products from 2-chloro-4-nitrophenyl-maltoheptaoside substrate in similar ratio than that of during porcine pancreatic α-amylase (PPA) catalyzed hydrolysis. The 4,6-O-benzylidene-modified substrate (BzG7PNP) is very stable toward hydrolysis by exo-glycosidases, therefore is very useful to monitor the digestion catalyzed by α-amylases exclusively. Similarly to PPA active site, three glycon and two aglycon binding sites are suggested for LDAmy based on the pattern of early hydrolysis products of BzG7PNP. The observed similarity between LDAmy and PPA raises the possibility of using known inhibitors of mammalian α-amylases to protect the potato plant from attack of Colorado potato beetle.

Tuta absoluta (Meyrick) is considered as a major pest of tomato worldwide that causes significant losses in the crop production. This study aimed to evaluate integration of two effective and environmentally safe methods (host plant resistant and biological control) for sustainable management of the pest under greenhouse conditions. The experiment was conducted based on the factorial design with ten replicates under greenhouse conditions (22 ± 3°C, 50 ± 10 RH and 14 L:10 D photoperiod). Infestation to T. absoluta was conducted at the first-flowering stage of the plants by introducing a pair of newly emerged adults (one female and one male) per plant. Ten days later, the biological agent, Trichogramma brassicae, was released on the treatments by hanging a card contained 50 parasitized eggs in each replicate. Observation was performed weekly on ratio of infested leaves per plant (%), number of larvae/plant, number of mines/leaf and ratio of infested fruits/plant (%). Results indicated that the susceptible variety alone (Izmir) supported the highest ratio of infested leaves (42.92 ± 1.95%), number of larvae/plant (12.86 ± 0.71), number of mines/leaf (1.29 ± 0.07) and infested fruits/plant (18.8 ± 1.10%), whereas the lowest (6.12 ± 0.42%, 1.85 ± 0.13, 0.18 ± 0.02 and 0.12 ± 0.06%, respectively) were observed in combined resistant variety (Cherry) and parasitoid released treatment. Integration of these methods not only decreases damage caused on tomato leaflets and fruits, but also reduces insecticide applications which are adversely impact human health and environment.

Sternechus subsignatus Boheman (Curculionidae: Sternechini) is one of the primary Curculionidae species that reduces soybean yield in Brazil. Initially, outbreaks were reported in southern Brazil in 1973; but, more recent, outbreaks were reported in Bahia (summer 1997–1998) and Maranhão (summer 2003–2004), two states in northeastern Brazil. A putative related species, S. pinguis (Fabricius), was first detected in Salta Province, Argentina. The objective of this study was to evaluate intraspecific molecular polymorphisms of geographically distinct Sternechus populations. Randomly amplified polymorphic DNA (RAPD) profiles and partial mitochondrial cytochrome B (CytB) gene sequences were used to determine whether individual soybean stalk weevils were one of two different species and to infer pest invasion pattern. Putative S. pinguis and S. subsignatus populations were collected in San Agustin (Cruz Alta, Tucumán Province, Argentina) and different sampling sites in the Brazilian states of Paraná, Bahia and Maranhão. Polymorphic bands were obtained by RAPD and analyzed by Dice coefficients. Populations from southern Brazil were more closely related genetically to an Argentinean group than the populations sampled in northeastern Brazil. The Londrina Co., Brazil population displayed the highest intra-population genetic similarity. Most of the soybean stalk weevils collected from San Agustin, Tucumán, Argentina were divergent from those collected in Brazil. Sequencing and parsimony analysis of CytB did not differentiate specimens collected in Argentina and Brazil. Thus, our data show that soybean stalk weevil outbreaks and population increases in northeastern Brazil involved local genotypes.

Crossing experiments were conducted with 43 different parental clones of Myzus persicae (Sulzer) to clarify the genetic bases of esterase variations detected by electrophoresis. A total of 468 F1 clones obtained were analysed for variants at six polymorphic esterase loci, including one associated with resistance to organophosphorus insecticides (RAE). In addition, the effect of six different host plants on the activity of esterases was examined. The inheritance of variants at two loci could be explained by two-allele models, and that at three other loci by three-allele models, while segregation ratios at the RAE locus suggested a cumulative effect of the multiple genes. An interdependent assortment was found between two loci. The activity of the esterases detected in the alimentary canal was affected by the host plant. By combining the variants at the six polymorphic esterase loci with those in body colour, a total of 2592 colour-esterase forms were distinguishable. Thus esterases could be useful as genetic markers to study the genotypic composition and its dynamics of M. persicaepopulations.

Phosphoglucose isomerase (PGI) plays an important role in energy metabolism, and it is documented that PGI exhibits an extensive polymorphism which can affect insects' fitness and adaptation. In this paper, we studied the structural characteristics and polymorphism of pgi gene in the fall webworm (Hyphantria cunea), an important invasive pest in some European and Asian countries. A 2110-bp pgi full-length cDNA encoding a polypeptide of 556 amino acids was obtained from H. cunea. The pgi full-length in the H. cunea genomic DNA was 14,332 bp with 12 exons and 11 introns, similar to the structures of pgi in other Lepidoptera species. We compared the structures of pgi in different insect species. Moreover, thirteen pgi genotypes comprised of five alleles were identified in the Chinese population. Genotypes pgi-cd, pgi-cc and pgi-ce were the most prevalent with over 70% of individuals allocated to them. Four out of five alleles were sequenced the cDNA full-length. Thirty stably variable sites were found among them with five non-synonymous mutation sites. The frequencies of alleles and genotypes were variable in different Chinese geographic subpopulations. Moreover, comparison of pgi mRNA expression levels in each stage of the moth's lifecycle showed that a high expression level was in the 6th instar larval stage, followed by that in the egg and adult stages. The results will provide a basis for further study of the role of different alleles and genotypes of PGI on fitness and adaptation of the moth H. cunea.

The present paper, which is the last of the series, contains additional data obtained between November 1939 and December 1945.

In 1939, Helopeltis bergrothi, Reut., was found feeding on cacao pods and shoots at Owena by the writer; it was evident that this species was distinct from the cotton Helopeltis, which had been identified as bergrothi by the Imperial Institute of Entomology in 1924. The species attacking cotton is H. sanguineus, Popp., and this name should be substituted for bergrothi in the three papers on food-plants published in 1935, 1937 and 1940.

During 1963–69 the United States Department of Agriculture sponsored investigations on scale insects and their natural enemies in West Pakistan.* In the course of the survey Lepidosaphes conchiformis (Gmel.)† was collected from several localities. It occurred sporadically, but infestations were heavy on most of the plants on which it was found. In the hills it was commonly parasitised by Aphytis maculicornis (Masi). The potential importance of the scale and its parasite merited laboratory studies at Rawalpindi.