bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Entomology of Swollen Shoot of Cacao. II.—The Bionomics and Ecology of the Species involved
Authors: Strickland A. H. 
Published: July 2009

A method for the routine quantitative estimation of mealybug populations on cacao trees is described and the results obtained from 24 successive monthly samples are tabulated.The quantitative results obtained are of such variability that only gross differences in population density are shown as statistically significant.From a series of analyses based on the survey data the following conclusions have been reached with regard to P. njalensis, the most important mealybug vector of swollen shoot virus :—(a) The species is almost invariably attended in the field by Crematogasterine ants, the most important ant species building protective carton tents over the mealybug colonies.(b) Crematogaster density is closely correlated with mealybug density and the ants construct their carton tents in relation to the numbers of mealybugs to be protected. Some of the arboreal Crematogasterine groups investigated are shown to be consistently associated with higher mealybug populations, and to have a more advanced tent building habit, than others.(c) Tree to tree variation in mealybug density is shown to be largely dependent on the identity of the dominant ant group.(d) No direct correlation is apparent between mealybug density and incidence of swollen shoot though populations in areas devastated by virus are usually smaller than in areas in which virus is actively spreading.(e) The factors of importance in the natural control of P. njalensis populations have been discussed in some detail. It is clear that the species is maintained by ant protection at a density level considerably above that prevailing amongst closely related pseudococcid species which are not ant attended to the same extent. At this level of “ protected steady density ” balance is maintained partly by losses during crop harvesting, and partly by swollen shoot rendering the host plants unsuitable as feeding stations. It is concluded, however, that natural enemies must, in the last analysis, be responsible for maintaining balance.(f) Since the protected density of P. njalensis is a direct result of ant associations it follows that factors tending to control the attendant ant species will have a delayed effect on mealybug density. In this respect it is believed that Oecophylla, which is strongly negatively correlated with Crematogaster spp., is of importance. Any attempts that may in the future be made to control the mealybugs by killing the ants will have to be designed as specific against the Crematogasterini and non-lethal to Oecophylla and the other large predatory ants common on cacao.
Studies on the Responses of the Female Aëdes Mosquito. Part II.—The Action of Liquid Repellent Compounds
Authors: Sarkaria D. S. , Brown A. W. A. 
Published: July 2009

A number of liquid mosquito repellents were assessed for vapour repellency power in an olfactometer mounted in a very large cage filled with females of Aëdes aegypti. They were also tested for their knockdown power in fumigation bottles. Their vapour pressures were determined by the Ramsay-Young method.All the liquids showed vapour repellency, and in 39 out of the 42 tested this effect was highly significant. The highest vapour repellency ratings were shown by compounds already known to be the most effective repellents.Although the more volatile compounds such as citronellal tend to show the highest repellency ratings, nevertheless compounds of low vapour pressure such as indalone, DMP and isobornyl morpholinoacetate may also show high vapour repellency. It is concluded that vapour repellency, although in the first instance dependent upon volatility, can vary independently of vapour pressure, so that compounds may be found which afford not only a long protection period due to their nonvolatility, but also a high vapour repellency due to the potency of the comparatively few molecules that are volatilised.The vapours of most of the repellents were found to induce knockdown of mosquitos, but there was no correlation between the speed of this process and the vapour repellency of the compounds.
Physiological Investigations into the Heart Function of Arthropods
Authors: Krijgsman B. J. , Krijgsman-Berger Nelly E. 
Published: July 2009

Perfusion of the isolated heart ofPeriplaneta americanawith caffeine, digitalin, acetylcholine, nicotine and lobeline shows that the pacemaker of this heart is different from the “ myogenic centre ” of the vertebrate heart.The action of strychnine, morphine and apomorphine on this heart preparation affords evidence of the existence of a neurogenic pacemaker.This pacemaker is stimulated by suitable concentrations of acetylcholine, nicotine, lobeline and pilocarpine, while it is inhibited by atropine. Acetylcholine and tetraethyl pyrophosphate show a synergistic action. Atropine and tetraethyl pyrophosphate, like acetylcholine and curare, show an antagonistic action. These results prove that the neurogenic pacemaker possesses cholinergic properties.Adrenaline stimulates the insect heart and ergotamine inhibits it, thus suggesting that the insect heart probably also has adrenergic properties.On the basis of the present work and the results obtained by other investigators, a theory is put forward that the heart mechanism of most arthropods consists of a neurogenic pacemaker with adrenergic properties, controlled by a cholinergic accelerating nerve. This mechanism bears some resemblance to the sympathetic nerve system of vertebrates.Rotenone strongly counteracts the action of acetylcholine, tetraethyl pyrophosphate, nicotine, lobeline, pilocarpine and digitalin on the insect heart. Its point of action, however, remains obscure at the moment.The opposing action of rotenone and tetraethyl pyrophosphate is an indication that a combination of these insecticides for pest control is not to be recommended.
Pink Bollworm, Platyedra gossypiella (Saund.), as a Pest of Cotton at Zeidab, Northern Sudan
Authors: Darling H. S. 
Published: July 2009

Losses from Pink Bollworm (Platyedra gossypiella) and from Spiny Bollworm (Earias insulana) were studied in the American Upland cotton crop grown on Zeidab pump irrigation scheme in the Northern Province of the Sudan. In 1948, a year of normal attack, 12·9 per cent. of the estimated potential yield was destroyed by bollworms. Pink Bollworm was responsible for 10·7 per cent. or a loss of 135 pounds of seed cotton per acre. Spiny Bollworm damaged 2·2 per cent. or 28 pounds per acre.Four-fifths of the total yield is derived from the bottom crop which is harvested before the end of September and consists of high grade seed cotton. The other fifth is produced as a top crop and consists of low grade seed cotton ripening in October and November. Only 3·5 per cent. of the bottom crop is lost on account of Pink Bollworm as against 33·3 per cent. of the top crop. The corresponding figures for Spiny Bollworm are 1·6 per cent. and 4·1 per cent.Some factors influencing the extent of pink bollworm attack are outlined. The Zeidab crop escapes serious damage through rapid maturity and even growth. Correct agricultural management is of great importance. Attack by Laphygma exigua in the seedling stage may result in increased damage by Pink Bollworm in the ripening crop.The origin of the initial pink bollworm infestation is discussed. Available evidence, which is not conclusive, suggests that local carry over of the dead season may not be sufficient to account for the initial infestations observed in the crop.Atmospheric water vapour saturation deficit appears to influence the duration of larval diapause in Pink Bollworm in the northern Sudan. Maximum emergence of moths from resting larvae in three areas occurs at or near the lowest saturation deficit of the year. The possibility is discussed that the degree of fixity of the diapause may be related to the gradient of the saturation deficit curve during the development of the resting larvae in the crop, a rising curve being associated with a well fixed diapause which lasts until the saturation deficit falls, and a falling curve being associated with a poorly fixed diapause which does not last but begins to break at once.
The Rôle of Aëdes leucocelaenus in the Epidemiology of Jungle Yellow Fever in Brazil
Authors: Kumm Henry W. , Cerqueira Nelson L. 
Published: July 2009

Aëdes leucocelaenus transmits yellow fever virus readily in the laboratory and has twice been found infected in nature.Except in south Brazil this species is much less common than Haemagogus spegazzinii among day-biting sylvan mosquitos captured with human bait.A. leucocelaenus has a wide distribution throughout the forested area of this country.As a natural vector of jungle yellow fever in the northern part of Brazil it is of secondary importance when compared to H. spegazzinii.
Seasonal Variation in the Incidence ofTrypanosoma vivaxinGlossina palpalis(R.-D.)
Authors: Squire F. A. 
Published: July 2009

Over 3,000 examples ofG. palpaliswere age-grouped and dissected forT. vivaxover a period of a year. The incidence of infection throughout was highest in Age-group 3 and lowest in Age-group 1. There was a marked seasonal fluctuation, the incidence being highest during the months of heavy rainfall,i.e., August to October, and lowest in the driest.It has been suggested that the rise in the rate of infection during the rains is merely due to the increasing average age of the fly population, but by the method of age grouping it is shown that this is not the case.The degree of infection inG. palpalisin Sierra Leone is comparable with that ofG. tachinoidesin Nigeria.It is not thought that the seasonal variation in the incidence of infection can be ascribed to changes in the type and abundance of food. The true cause of the fluctuating incidence of infection like the source of infection is unknown.The failure to recognize seasonal differences in the rate of infection has led to some important practical misconceptions.
The Effect of Parathion Dusts on Eurygaster integriceps Put. (Hem.)
Authors: Talhouk A. S. 
Published: July 2009

Eurygaster integriceps is a serious pest of wheat in Syria against which various methods of control have been tried.Laboratory tests with a 0·8 per cent. parathion dust applied at the rate of 0·1 mg./sq. cm. are described.Three sets of field experiments were carried out with 0·75 per cent. and 0·8 per cent. parathion dust. Applied at a rate of 75 kg. /ha. these were very efficient but not economical. Applications of 0·8 per cent. dust with a knapsack duster at between 15 and 17·5 kg. /ha. gave about a 20 per cent. reduction in the infestation. A larger experiment in which 0·75 per cent. dust at a rate of 48 kg. /ha. was applied to a hectare of wheat, by means of a 6 h.p. duster mounted on a Jeep fitted with a drag sheet, gave a 70 per cent. control.
Studies on Beetles of the Family Ptinidae
Authors: Howe R. W. 
Published: July 2009

An account is given of an attempt to estimate changes in the rate of egg laying in a warehouse and in an unheated outbuilding at the laboratory. Small samples of food were placed on pieces of newspaper on the floor, and were renewed regularly, weekly or fortnightly in the warehouse and daily at the laboratory. Larvae were bred from these food samples and counted.The rate of oviposition was found to depend on temperature, especially in winter, and on relative humidity, especially in summer. It was seldom cold enough indoors, in unheated premises, to prevent oviposition entirely for more than a few days at a time, 5°C. being the approximate minimum temperature for oviposition. It was never so dry at the laboratory that egg laying stopped but this did happen at the warehouse in July, 1946. Free drinking water is necessary for continued oviposition and this was available from rain in both buildings.Darkness causes an increase in activity and in oviposition and most of the eggs in the foods supplied were laid at night. Foods placed near the daytime hiding places of adults were most used for oviposition.
Review of the Biological Control of Coccids on Coconut Palms in the Seychelles
Authors: Vesey-FitzGerald D. 
Published: July 2009

Reference is made to the several species of scale insects which were pests on coconuts and to the Coccinellids which were introduced to combat them.The introduction and life-history of Chilocorus nigritus is described.The survival of the introduced Coccinellids and the part each has played in controlling the several species of scale is noted.The habits of some indigenous Coccinellids are recorded.The coconut-feeding Coccids of the Seychelles are listed and their economic role mentioned.The incidence of “sooty-mould” and the species of Coccids responsible for its growth are discussed.An estimate is made of the value of the control effected by the Coccinellids in terms of increased copra production.
The Rate of Digestion of Blood Meals of various haematophagous Arthropods as determined by the Precipitin Test
Authors: Weitz B. , Buxton P. A. 
Published: July 2009

The period of digestion of the blood meal of 10 different blood-sucking arthropods which had been artificially and naturally fed on known hosts was studied by means of specific precipitin tests.A large proportion of positive feed (80–100 per cent.) was found with midges and mosquitos up to 24 hours, whether naturally (Anopheles aquasalis) or artificially fed (A. maculipennis atroparvus, Culex molestus, Culicoides nubeculosus, Aëdes aegypti).Tsetse flies showed greater differences between the rate of digestion of captive flies (Glossina morsitans), which showed 90–100 per cent. positive feeds at 3 days after the experimental blood meal, and wild flies (G. swynnertoni) which showed only 28 per cent. positive meals after a similar period of digestion. Arachnids showed both the longest period of digestion, more than 6 months for Ornithodoros moubata and also the shortest period as represented by Bdellonyssus bacoti (about 1 day).Cimex lectularius showed 90 per cent. positive feeds after 10 days.
Studies on Beetles of the Family Ptinidae IX.—A Laboratory Study of the Biology ofPtinus tectusBoield
Authors: Howe R. W. , Burges H. D. 
Published: July 2009

Ptinus tectusoccurs on a large range of foodstuffs in all types of storage places, in warehouse refuse and in the nests of birds. It is widely distributed in cool and temperate areas but is very rarely found in hot climates. In Britain it can survive the winter when exposed in a Stevenson screen to outdoor shade conditions.P. tectusis seldom found on imported cargoes inspected aboard ship, but many British warehouses carry a population of the species resident in the fabric of the premises.The larva is able to bore through cellophane, card and textiles and can also make impressions on wood. The fully fed larva spins a cocoon on the fabric of containers and buildings. Holing of packages and contamination by silk of high grade produce form the chief economic losses caused by the species, but occasionally large populations are found, sufficient to reduce the food value of produce. Unlike the larvae, adult beetles cannot penetrate sound linen bags, but lay eggs through the meshes.In a series of consecutive experiments, performed identically as far as possible, variations in the length of developmental period and in emergence weight of adult beetles were greater than would be expected by chance. The variations could not be related to any single observed or suspected inconsistency of technique or environment. It is desirable therefore to conduct comparative experiments simultaneously.
Studies of British Anthomyiid Flies
Authors: Miles Mary 
Published: July 2009

Onions and related crops are attacked by the onion fly, D. antiqua (Mg.), and by the bean seed flies, D. cilicrura (Rond.), and D. trichodactyla (Rond.). The eggs, larvae and puparia of the three species are similar in form, and the only morphological difference so far observed is in the number of processes of the anterior spiracles of the larvae. In D. antiqua the anterior spiracles have 10–13 processes; in D. cilicrura and D. trichodactyla, the immature stages of which cannot yet be distinguished from each other, the anterior spiracles have 5–8 processes.Onion flies and bean seed flies have different habits and consequently the circumstances of their attacks differ. The onion fly is a specific feeder and its attacks are likely to be serious in spring and early summer. The bean seed flies are general feeders and attack on onions in spring is unlikely because the preparation of the soil, which attracts the flies, is usually completed before they emerge from the over-wintering puparia. Bean seed fly attack on onions is likely to take place in August when onions for bunching are sown. The preparation of the seed bed attracts the flies of the third generation from the surrounding crops and the soil may become heavily infested with larvae which subsequently destroy the germinating seeds. In August and September it is unlikely that young crops will attract onion flies from the mature crops on which they are established.
Intensification of insecticide resistance in UK field populations of the peach-potato aphid, Myzus persicae (Hemiptera: Aphididae) in 1996
Authors: Foster S.P. , Denholm I. , Harling Z.K. , Moores G.D. , Devonshire A.L. 
Published: July 2009

AbstractThe well-established carboxylesterase-based resistance to insecticides in Myzus persicae Sulzer has recently been accentuated by the appearance of aphids with a modified acetylcholinesterase (MACE) insensitive to pirimicarb and the novel aphicide, triazamate. This target site resistance mechanism was found in M. persicae from crops in the UK for the first time in 1996, together with especially large proportions of aphids with R2 and R3 levels of carboxylesterases, a combination that was associated with serious insecticide failures. This paper describes the incidence of both mechanisms and discusses the implications for future recommendations for aphid control in the UK.
Evaluation of Shin-Etsu twist-tie rope dispensers by the mating table technique for disrupting mating of the cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae), and the pink bollworm, Pectinophora gossypiella (Lepidoptera: Gelechiidae)
Authors: Kehat M , Anshelevich L , Gordon D , Harel M , Dunkelblum E 
Published: July 2009

AbstractDifferent Shin-Etsu twist-tie rope formulations, containing either the cotton bollworm, Helicoverpa armigera (Hübner) pheromone or pink bollworm, Pectinophora gossypiella (Saunders) pheromone, or both, in the same rope, were tested in Israel for mating disruption. The success of mating disruption was evaluated by the mating table technique, comparing the percentage of mating of virgin sentinel females in pheromone-treated and control plots. Two variants of this technique were evaluated, one with two mating tables per plot, each containing five to seven females, and the other with six to eight mating tables per plot, with only one female per table. The latter method was more sensitive than the former, particularly at low population densities. Two tests were conducted in 1995 in order to compare a blend of five components of H. armigera pheromone with a blend of two components for mating disruption. The application consisted of 2000 ropes/ha, each with 80 mg pheromone. Evaluation by the two mating table methods showed clearly that the formulation containing two components was superior to the five-component blend for mating disruption, suppressing mating almost completely for 49 days. A new combined formulation, HPROPE, containing 175 mg of the H. armigera two component blend and 65 mg of P. gossypiella pheromone was tested in 1996 for mating disruption of both pests. Application of 625 ropes/ha caused a high level of suppression of mating of H. armigera females for at least 94 days and that of P. gossypiella females for 161 days. The pheromone release rates were c. 625 mg/day/ha for H. armigera and 162 mg/day/ha for P. gossypiella. A ‘long-life’ formulation of P. gossypiella pheromone, PBW rope LR, applied at 125 ropes/ha releasing 137 mg/day/ha achieved complete suppression of mating over 75 days. This release rate of P. gossypiella pheromone was much lower than that currently used in Israel (275 mg/day/ha). The present study indicates that mating of females of two moth pests with different pheromones can be disrupted by one combined formulation.
Evidence for the occurrence of sibling species inEubazusspp. (Hymenoptera: Braconidae), parasitoids ofPissodesspp. weevils (Coleoptera: Curculionidae)
Authors: Kenis M. , Mills N.J. 
Published: July 2009

AbstractComparative studies were made on three presumed sibling species of the genusEubazus, parasitoids of EuropeanPissodesspp. weevils, to clarify their taxonomy and define diagnostic characters. Several populations ofE. semirugosus(Nees),E. robustus(Ratzeburg) andEubazussp. were compared with respect to their morphology (mainly through morphometric analyses), fecundity, isoenzyme patterns and host preference. Crosses were made to assess the genetic and behavioural compatibility of the populations. In addition, the North AmericanE. crassigaster(Provancher), a parasitoid ofPissodes strobi(Peck), was compared toE. semirugosus, a species selected for introduction againstP. strobiin Canada. The ratio of the length of the ovipositor sheath to the fore wing length was the most discriminating morphometric variable, but discriminant analyses including several measurements were needed to completely separate European species. A canonical discriminant function provided a total separation between males ofE. crassigasterandE. semirugosus, but not between females.Eubazus crassigasterandE. semirugosuswere totally separated by the banding pattern of the enzyme phosphogluconate dehydrogenase whereas hexokinase and esterase provided a diagnostic separation betweenEubazussp. andE. robustus. Eubazussp. differed from all the other species by having a greater number of ovarioles and, consequently, a higher potential fecundity. In a two-choice oviposition test,E. semirugosusandEubazussp. showed a significant preference for their natural host,P. castaneusDe Geer andP. piceae(Illiger), respectively. A similar test made with their progenies reared under standard conditions showed that the difference in host preference was genetically fixed. Males and females of different species did not mate readily, in contrast to individuals from the same species. All attempts to interbreedE. robustusandEubazussp. failed, but a few crosses betweenE. semirugosusand the two other European species produced fertile offspring. These observations strongly suggest that the complex ofEubazusspp. parasitoids attackingPissodesspp. in Europe is composed of at least three sibling species, two of which appear to have specialized on distinct host species that occupy exclusive microhabitats.