bluuebunny/crossref_metadata_2025 huggingface dataset:
‘Phytophagous’ thrips are facultative predators of twospotted spider mites (Acari: Tetranychidae) on cotton in Australia
Authors: Wilson L. J. , Bauer L. R. , Walter G.H.
Published: July 2009

Predatory feeding on Tetranychus urticae Koch (Acari: Tetranychidae) populations on cotton by phytophagous thrips, Thrips imaginis Bagnall, T. tabaci Lindeman and Frankliniella schultzei Trybom (Thysanoptera: Thripidae), was investigated in the field and laboratory. Phytophagous thrips are a common early season pest of cotton in Australia, though their true pest status is undefined. In California, the phytophagous thrips (Frankliniella occidentalis (Pergande)) is regarded as an opportunistic predator of mite eggs, their consumption of which increases fitness over a diet of leaf tissue alone. Thrips are among the most abundant of insects on young cotton. If they consume mite eggs, even at relatively low rates, they could have a significant influence on the probability of survival of early season spider mites. Consumption of eggs of T. urticae by thrips was investigated in the laboratory. Second instar F. schultzei consumed more eggs per day (ca. 4 eggs per day) than did second instar T. tabaci or T. imaginis (ca. l egg per day). Consumption by first instar F. schultzei was much lower than for second instars. Adult T. tabaci consumed ca. l egg per day whilst adults of F. schultzei consumed only ca. 0.5 eggs per day, although some individuals of this species did consume substantial numbers of eggs. Larvae of all thrips species showed a type II functional response to prey density. In the field, adults and larvae of T. tabaci and F. schultzei showed a preference for cotton seedlings that were also infested by spider mites. In a glasshouse, larvae of T. tabaci showed a highly significant preference for feeding within mite colonies. In the field, suppression of predators, predominantly T. tabaci and F. schultzei, with a broad spectrum insecticide (dimethoate) contributed to outbreaks of mites occurring earlier than they would have otherwise. The results show that phytophagous thrips eat mite eggs and that they are potentially important predators of spider mites in the field, especially given their abundance on young cotton and preference for inhabiting situations in which mite colonies are found.
The ovarian cycle in Culicoides barbosai Wirth & Blanton and C. furens (Poey) (Diptera, Ceratopogonidae)
Authors: Linley J. R.
Published: July 2009

The ovarian cycle in Culicoides barbosai Wirth & Blanton and C. furens (Poey), two biting midges of considerable importance in Jamaica, was studied in the laboratory. In C. furens, a single blood-meal was sufficient for development of a substantial number of eggs; in C. barbosai, which took a relatively smaller blood-meal, very few eggs were matured (usually between 10 and 20 but sometimes fewer than 10), and some females failed to produce any eggs at all.

A high degree of gonotrophic harmony was observed in C. furens, but in C. barbosai the degree of harmony was low and a large proportion of the ovarian follicles degenerated; these differences may be associated with the relative size of the blood-meals of the two species.

The duration of the gonotrophic cycle (from feeding to the appearance of mature eggs in the ovaries) at 68, 77, 85 and 91°F. was 156, 104, 82 and 72 hr., respectively, in C. barbosai and 102, 59, 42 and 36 hr. in C. furens.

In experiments on the effect of temperature and carbohydrate feeding on egg production, temperature did not influence egg production in C. barbosai, and greater numbers of eggs were not matured by females given access to honey during the period of egg development. However, access to honey did increse the proportion of individuals surviving the period of egg maturation and also the numbers that mastured any eggs at all. Females of C. furens kept at 77°F. matured more eggs than those kept at 91 or 85°F.; access to honey improved survival, but its effects on egg production were inconclusive in these experiments.

Observations indicated that adults of both species are probably in the habit of taking carbohydrate food in nature.

Females of both species may be autogenous, though the proportion of such individuals varied considerably between populations from different breeding sites. Autogenous females of both species emerged from the pupa with ovaries already relatively well developed; in C. barbosai the ovarian follicles were in Stage IIB or III, in C. furens they were in late Stage IIA or IIB. Large numbers of eggs were matured by autogenous females of the former, and the same is probably true of the latter.

The egg stage is apparently of longer duration C. barbosai than in C. furens. At 68, 77, 85 and 91°F., most eggs of C. barbosai hatched on days 12, 6–7, 5–6 and 5, respectively, whereas at the three higher temperatures most eggs of C. furens hatched on days 4, 3 and 2. Percentage fertility varied between individual egg batches of both species.
Measurements by two methods of the susceptibility to DDT and Dieldrin of Glossina palpalis (R.-D.) in Northern Nigeria
Authors: Riordan K.
Published: July 2009

The susceptibilities to DDT and to dieldrin of one-day-old teneral examples of Glossina palpalis (R. -D.), obtained from pupae collected from the field, were measured in the laboratory in Nigeria by two methods, one recommended by the W.H.O. Expert Committee on Insecticides (1963) and the other described by Kernaghan & Johnston (1962).

Pupae were kept in dry sand at a controlled temperature of 78–79°F. and 70–80 per cent. relative humidity until the adult flies emerged, and the latter were then kept individually in 3 × 1 in. glass tubes. All exposures to insecticides were carries out at room temperatures. Five flies were exposed together for one hour in the W.H.O. method, and flies were exposed individually for 1 1/2 minutes in the other method. After exposure, they were kept in a cabinet at 78–79°F. and 60–70 per cent. relative humidity. Mortalities were assessed 8, 24 and 48 hr. after the end of exposure, but only the 24-hr. results are presented. Regression lines and values for LC50’s were calculated by the method of probits

The mortalities amongst untreated flies averaged 5.6 per cent. for males and 5.1 for females, the latter value being insignifiantly affected by the method used. Dieldrin was far more toxic than DDT to both sexes, and females were apparently more susceptible than males to both insecticides; it is suggested that females pick up relatively more of a given deposit because of their greater weight.

The slope of the regression line relating mortality to insecticide concentration was steeper for long exposures than for short ones; it is suggested that this comes about because some insecticide picked up by the flies is lost after they are removed from the treated surface, the loss being relatively greater when greater discussed, and it is concluded that exposure for 1 1/2 minutes is long for satisfactory assessment of susceptibility when continuous contact with the insecticide is ensured (as in the method used for this period), but that exposure for 1 hour, ensuring 100 per cent. mortality at some concentrations, is preferable for detection of resistance. Although mortality from an insecticide may not be completed until 72 hr. after exposure, observations 24 hr. after are considered adequate.

The relative merits of the two methods of testing susceptibility are discussed. It is concluded than the method of Kernaghan & Johnston, which involves less handling and therefore less stimulation of the flies, is the more precise. The impregnated papers available from W.H.O. are a convenient means of exposing flies to known deposits of insecticide.
The effect of temperature on development and hatching of the egg of Blepharidopterus angulatus (Fall.) (Heteroptera, Miridae)
Authors: Muir R. C.
Published: July 2009

Observations on the eggs of the predatory Mirid Blepharidopterus angulatus (Fall.), which plays a part in the control of Panonychus ulmi (Koch) on apple, were carried out in 1963–64. The eggs required chilling at 4.4 or 7.2°C. (40 or 45°F.) for 14–16 weeks to terminate diapause. The reciprocal of the time in days for the first eggs to hatch showed a linear relationship with temperature. The temperature at the threshold of development was found by calculation to be 4.7°C.; 409 day-degress C. were required for the first larvae to hatch and 727 for 50 per cent. of them to hatch. From this information and the daily maximum and minimum temperatures, the expected dates of first hatch at East Malling were calculated for the years 1958–64 and found to agree well with the dates on which the first larvae were observed in the field.
Investigations of the chemical control of insect pests of cotton in central Africa. II.—Tests of insecticides with larvae and adults
Authors: Matthews G. A.
Published: July 2009

Further tests of insecticides, mainly carbaryl, endosulfan, endrin and DDT, for possible use against pests of cotton in Central Africa are described. In laboratory tests in Rhodesia, carbaryl was the most effective against first-instar larvae of Diparopsis castanea Hmps. exposed on leaves, stems and bracts of effective against second-instar larvae of Heliothis armigera (Hb.), to which the insecticides were applied directly, and carbaryl the least.

When adults of Dysdercus intermedius Dist. and D. fasciatus Sign. were caged with treated bolls, carbaryl was the most effective, endrin the next and (against the former sp. only) endosulfan the least. Deposits on leaves from 0.5 per cent. sprays of carbaryl, DDT and endosulfan remained effective in dry conditions for two weeks, but application of 0.05–1.0 in of simulated rain reduced their effectiveness immediately, especially that of carbaryl. The effectiveness of deposits was also reduced by plant growth and was affected by plant habit; on a hairy variety the deposits persisted longer than on a glabrous one, partly because the hairs retained them and partly because they made movement of the larvae more difficult.
Bioassay and histochemical studies of the poisoning and recovery of house-flies (Musca domestica L.) treated with diazinon and diazoxon
Authors: Farnham A. W. , Gregory G. E. , Sawicki R. M.
Published: July 2009

Newly emerged and 3-day-old house-flies (Musca domestica L.) of a diazinin-susceptible and a diazinon-resistant strain were treated topically with diazinon or diazoxon and examined for symptoms of poisoning and recovery at intervals up to 5 hours and at 24 hours after treatment. The effects of the poisons varied with the age and strain of the flies and with the poison used. Most of the flies that became paralysed died, but some recovered, even after appearing to be dead. Of flies treated when newly emerged, more of the resistant than of the susceptible strain recovered from paralysis, and more recovered from diazoxon than from diazinon treatment. Recoveries were fewer amongst flies treated when three days old and occurred in appreciable numbers only amongst those of the resistant strain treated with diazoxon.

Histochemical tests on flies, treated with diazoxon showed a close correlation between inhibition of cholinesterase activity in the thoracic ganglion and the external symptoms of poisoning. Inhibition was slight in apparently unaffected flies, more extensive in severely affected flies, and total or nearly so in completely paralysed flies. Inhibition first appeared at the periphery of the ganglion and spread inwards to the centre. Flies that recovered from paralysis had normal or almost normal cholinesterase activity, partially recovered flies showed activity only in the central parts of the ganglion. Recovery of cholinesterase activity seems to occur from the centre of the ganglion outwards.
On the bionomics and ecology ofHeteronychus licas(Klug) (Coleoptera, Dynastinae), a new pest of sugar-cane in Nigeria
Authors: Taylor T. Ajibola
Published: July 2009

Late in 1962,Heteronychus licas(Klug) was recorded causing damage to sugar-cane for the first time in Nigeria. It had previously been known there only as an inhabitant of grassland and a negligible pest of yams (Dioscoreaspp.). The damage to sugar-cane, which was first noted at an early stage in the development of a large commercial sugar-growing estate (the first in the country) in Nothern Nigeria, resmbles that caused by Lepidopterous stem borers; the young shoots and tillers are eaten away around soil level by the larvae and adults and are eventually killed (‘deadhearts’). The adults sometimes tunnel in the pith of older canes, but seldom kill them. Surveys on the estate in 1963–64 showed that damage by the beetle was becoming increasingly important. In anticipation that this might happen, field and laboratory investigations into the habits and life-historv ofH. licaswere carried out in the same two years, and the initial results are reported.

There is one generation a year. Oviposition took place in moist soil near the bases of cane plants from late October to December. In the laboratory, the average female laid 60–75 eggs over a period of 1–3 weeks, hatching occurred after 9–16 days and the three instars lasted successively 14–19, 15–24 and 20–25 days. Larvae were found in the field from November to March, but occured in large numbers only during January and early February, mostly within a depth of 1 ft. in the soil; only those in the second and third instars fed on the canes. Puation took place in a cell 112–3 ft. below the surface; the prepupal and pupal stages together lasted 23–31 days in the laboratory. In the field, pupae were most numerous in February and March and adults, which began to emerge early in March, reached their greatest numbers between then and May.

Evening catches at a light-source showed thatH. licashad two flight seasons each year, a subsidiary (post-teneral) one in April-June and a main (pre-reproductive) one in October-November, separated by a period of inactivity. Egg laying follows the second, and the adults die. Factors influencing the behaviour of the adults are discussed.

There were marked seasonal fluctuations in the incidence of ‘deadhearts’ caused byH. licas;it was highest in March-June each year, lowest during the period of adult inactivity, and again high during October-November.

Larvae kept together in the laboratory inflicted mutual injuries, mostly ending in death, but the extent to which this occured in nature could not be determined. Five Carabid species were found preying on the larvae in the field, and one on the adults as well. The importance of these and other possible predators and of parasites for the control ofH. licasis discussed.

Measures that could be adopted for control are reviewed the literature.
A new species of Scirtothrips from Kenya attacking tea, with synonymic notes on two related pest species
Authors: Mound L. A.
Published: July 2009

A new species of Scirtothrips found damaging tea in Kenya is described and named S. kenyensis, and a note is given on damage caused by members of this genus. The name Heliothrips minutissimus Bagn. is suppressed as a synonym of Scirtothrips dorsalis Hood, and S. sweetmani Bianchi and S. tilschacki Ananthakrishnan are suppressed as synonyms of S. bispinosus (Bagn.), a combination that is here restored.
A simple technique for applying small measured quantities of insecticides to insects
Authors: MacCuaig R. D. , Watts W. S.
Published: July 2009

An apparatus is described for applying a very small volume (0.1–1.0 μl.) of an insecticidal solution to an insect. It comprises a length of precision-bore glass capillary mounted, with a calibrated scale, in one end of a short tube having at the other end a perforated rubber bulb; the capillary is filled to the required scale mark by applying cotton wool saturated with the liquid to its tip, and the liquid expressed by squeezing the bulb, with the forefinger covering the hole in it. It can be used in conjunction with a calculator consisting of two concentric rotatable discs bearing two pairs of scales, on one of which the insect weight (in g.) is apposed to the per cent, concentration (w/v) of insecticide to be applied, which enables the volume (in μl.) required to yield a given dose (in μl./g.) to be read from the other pair of scales. Both devices have been used successfully in field testing with locusts and other insects.
Descriptions of two new genera and species of Phycitinae associated with Hypsipyla robusta (Moore) on Meliaceae in Nigeria (Lepidoptera, Pyralidae)
Authors: Bradley J. D.
Published: July 2009

Two new genera and species of Phycitinae found with Hypsipyla robusta (Moore) attacking Meliaceae in Nigeria are described. The three genera and species are differentiated, and the genus Hypsipyla is briefly reviewed. Illustrations of the wing venation and wing pattern of the adult male and of the genitalia of both sexes are given for the two species described as new, Catopyla dysorphnaea and Gyroptera robertsi, and also for H. robusta.
A new species of Herpystis Meyrick (Lepidoptera, Tortricidae) on Cuscuta reflexa in West Pakistan
Authors: Bradley J. D.
Published: July 2009

A Tortricid moth belonging to the Olethreutinae, bred from larvae feeding on the parasitic dodder Cuscuta reflexa in West Pakistan, is described as new and is named Herpystis cuscutae sp.n. The species is differentiated from the closely related H. jejuna Meyr., which occurs in India, and also from the two other Indian species of this genus, H. pallidula Meyr. and H. tinctoria Meyr. The status of the three specimens comprising the original type series of H. jejuna is re-evaluated, and one of them is considered to be probably conspecific with H. cuscutae.
The Effect of Climate and Weather on the Numbers of the Red Locust, Nomadacris septemfasciata (Serv.), in the Rukwa Valley Outbreak Area
Authors: Symmons P.
Published: July 2009

An examination of the records from 1930 onwards shows that a very high level of Lake Rukwa is correlated with small numbers of the red locust, Nomadacris septemfasciata (Serv.), in the Rukwa Valley outbreak area in Tanganyika. When the lake level is not very high, the size of the adult locust population (taken as that present in the middle of the dry season) is correlated negatively with the total rainfall of the last but one wet season (broadly, November–May), positively with the size of the preceding parental population (taken as that present at the time of oviposition) and possibly also with the rainfall of the preceding October–December, but not significantly with the date of the drop in temperature that is thought to be associated with the start of ovarian development.

Three tentative explanations of the correlation between adult population and rainfall are offered. First, if the water-table is high because of heavy rain in the previous season, the early rains may make the soil unsuitable for successful egg-laying and incubation; second, after a season of heavy rainfall the grass cover may be particularly dense at the end of the following dry season and the consequent reduction of the oviposition sites may make breeding unsuccessful; third, parental mortality may be high during a dry season following heavy rains. These possibilities are being further investigated.

It is suggested that by using a multiple regression equation incorporating the correlations that have been established, the size of the adult locust population can be forecast in time for the scale of hopper control measures to be appropriately modified and economies thereby achieved.
Some Observations on the fusca Group of Tsetse Flies (Glossina) in the South of Nigeria
Authors: Page W. A.
Published: July 2009

Observations were made on Glossina tabaniformis Westw., G. fusca (Wlk.), G. nigrofusca Newst. and G. medicorum Aust., which all occur near the field station of the West African Institute for Trypanosomiasis Research at Ugbobigha in southern Nigeria. Identification of these species by the use of external characters has not been found possible between the females of G. tabaniformis and G. fusca, but is fairly simple between males of these two species and between both sexes of G. nigrofusca and G. medicorum. A simple key, based on external characters, is given. When necessary, females of G. tabaniformis and G. fusca were separated by dissection. G. tabaniformis, G. fusca and G. nigrofusca usually rest in a vertical position, with the head downwards, at a height of 4–6 ft. above ground (possibly lower for G. nigrofusca), on tree trunks, climber stems, etc., having a diameter of 5 in. or less.

A fly-round was started using a Zebu bull as bait. G. tabaniformis and G. fusca were caught in good numbers, G. tabaniformis forming 83 per cent. of the catch. There appears to be a decrease in population in the late dry season (January and February) in both these species. Females comprised 56 per cent. of the total catch of G. tabaniformis and 47 per cent. of that of G. fusca.

The vegetation of the fly-round, which is typical secondary rain-forest as found in southern Nigeria, was analysed; both G. tabaniformis and G. fusca prefer old forest with an absence of a lower stratum, beneath a continuous middle stratum and good upper stratum, that is to say, where visibility beneath the trees is good. G. nigrofusca comprised only 1·1 per cent. of the catch on the fly-round, although at first it was believed to be common in the area. G. medicorum does not inhabit the main forest belt, but is confined to riverine vegetation and forest islands in savannah.

G. tabaniformis is unlikely to be of economic importance, since the rate of infection with trypanosomes is low (3·7%) and this fly is confined to the forest. G. fusca and G. medicorum are both of economic importance, since their infection rates are high (14·9 and 15·4%, respectively) and they travel out into the savannah grassland. G. nigrofusca has a yet higher infection rate (26·7%), but it is confined to the forest at Ugbobigha; where, as in Ghana, it frequents the savannah, it is potentially dangerous. Females of G. tabaniformis and G. fusca are more heavily infected than males.

Females of G. tabaniformis were examined (by dissection) for pregnancy; 82 per cent. of the females were pregnant and 4·3 per cent. unfertilised. No seasonal fluctuations in the rate were apparent.
Mycophagy as a factor limiting predation of aphids (Hemiptera: Aphididae) by staphylinid beetles (Coleoptera: Staphylinidae) in cereals
Authors: Dennis P. , Wratten S. D. , Sotherton N. W.
Published: July 2009

Previous work demonstrated the potential of the staphylinidsTachyporus hypnorum(Fabricius),T. chrysomelinus(Linnaeus),T. obtusus(Linnaeus) andPhilonthus cognatus(Stephens) to feed on the grain aphid,Sitobion avenae(Fabricius). However, gut dissection and observations of foraging behaviour showed that mycophagy could be a factor influencing the potential ofTachyporusspp. to control aphids. The main fungal material detected in the guts ofTachyporusspp. was spores (conidia) ofErysiphespp. (powdery mildews). In the present study, numbers of conidia (pustules of mildew on leaf-sections) were offered with aphids in food-choice experiments to test how fungal food affected feeding on aphids by these staphylinids. An index of food preference was calculated for each species, sex and for two age classes of larvae, based on the number of conidia and aphids remaining after feeding. Results showed a preference for mildew conidia byT. hypnorum, no preference byT. chrysomelinusandTachyporusspp. larvae and a preference for aphids byT. obtususandP. cognatus(adults and larvae). Food-preferences compared well with dietary composition in recent studies of field collected staphylinids. Futhermore, a functional response was detected to increasing numbers of mildew conidia presented (in mildew only consumption-rate experiments) and to the increase in total food density in food-choice experiments. Mycophagy limited aphid predation and explained the numerical response of staphylinid beetles to areas of cereals with high aphid densities, whilst, in other studies, the proportion of aphids eaten by those beetles did not increase.
Biology of Chrysomya megacephala (Diptera: Calliphoridae) and reduction of losses caused to the salted-dried fish industry in south-east Asia
Authors: Esser J.R.
Published: July 2009

Chrysomya megacephala (Fabricius) is shown to be a principal cause of loss of salted-dried fish in south-east Asia. Field and laboratory work conducted in 1982–1989 was aimed at reducing these losses. Field work at a small–scale fish processing site in Cirebon, West Java, showed that fully gravid C. megacephala females were highly differentially attracted to fish at the salting stage, which means that the salting tanks must have properly designed fly-tight lids to prevent infestation. C. megacephala counts and ovary examinations showed that females with various stages of immature ovaries (stages I–IV) were predominent during the drying stage after the fish had been removed from the salting tanks, with numbers usually greater on the first day of drying than the second. C. megacephala counts were high during the dry season, although numbers fluctuated enormously depending on weather, among other factors. Physically screening fish during the initial drying period effectively controlled infestation, although problems associated with the screen design were identified. In laboratory cultures adult sex ratio was approximately 1:1 and longevity in both sexes, over three generations, ranged from 47 to 55 days (maximum induced longevity, 98 days) at c. 29°C, 30–60% r.h.; under similar conditions, 10% of females had mature (stage V/VI) oocytes after one week, 40% after two weeks and 90% after three weeks. Mean number of ripe oocytes in gravid flies was 221 (range 151–228).
Ovarian ages of tsetse flies (Diptera: Glossinidae) caught from mobile and stationary baits in the presence and absence of humans
Authors: Hargrove J.W.
Published: July 2009

Ovarian ages were obtained for tsetse flies Glossina morsitans morsitans Westwood and G. pallidipes Austen caught in Zimbabwe using a stationary bait ox, an odour-baited trap in the presence or absence of humans, a mobile ox fly-round and a vehicle-mounted electric net. The biggest daily catches were obtained from the electric net and the unacccompanied trap, but while for G. m. morsitans the ratio of the catches from these two methods was 7:1, for G. pallidipes it was 0.7:1. Evening catches were 1.3–5.5 and 2.9–18.8 times higher than morning catches for the two species, respectively; the differences were greater for stationary than for mobile baits. The sample age structures differed significantly (P < 0.05: x2) between methods in six of the ten possible contrasts between pairs of methods in G. m. morsitans and for all ten in G. pallidipes. The differences in age distribution and mean catch levels are attributed to increases in flight activity with age; at each age G. pallidipes is more active than G. m. morsitans. Man's presence in the trapping system reduced catches significantly (P < 0.05: t test) but this effect was small in the youngest and oldest flies. Odour-baited traps are biased in favour of G. pallidipes and, for both species, in favour of older flies; mortalities calculated from age distributions of trap samples therefore underestimate the true value.
Factors determining the peak abundance of Metopolophium dirhodum (Homoptera: Aphididae) on cereals
Authors: Honěk A.
Published: July 2009

From 1986 to 1989, the factors that determined the abundance of Metopolophium dirhodum (Walker) on cereals were studied in western Czechoslovakia. Forty seven sites were selected within cereal fields, mainly of winter wheat. Host plant size and leaf area varied between sites. The maximum abundance of M. dirhodum per tiller varied annually and with host plant stature. The main factor determining maximum abundance was the length of time for which the aphid population grew. M. dirhodum populations differed both in the time of the onset and termination of their growth. On stunted plants population growth started, with little variation, 200 day degrees later than on well developed plants. Within years, nearly all populations ceased growing simultaneously. In years of low or medium aphid abundance it was 40 to 90 day degrees earlier than in aphid outbreak years, and this extension of the population growth was the principal cause of the outbreak. Population growth rates varied slightly with plant quality and differed little between years. They were not important factors determining maximum abundances. 55–75% of the aphids occupied the flag leaves. The lower leaves of well developed plants were more heavily populated than nutritionally and water stressed smaller plants. The population growth rates on particular leaves were related to leaf nitrogen content, but not water content. A relationship for calculating the maximum abundances from a census made during the middle phase of population growth was proposed.
Populations of African black beetle, Heteronychus arator (Coleoptera: Scarabaeidae) in a Mediterranean climate region of Australia
Authors: Matthiessen J.N. , Ridsdill-Smith T.J.
Published: July 2009

Populations of African black beetle, Heteronychus arator (Fabricius), a subterranean pasture-dwelling pest of potatoes, were examined in pastures in geographically separated potato-growing areas covering 3½° of latitude in southwestern Australia. Abundance of all life stages was estimated by taking soil cores and the reproductive state of females was assessed from the stage of their ovarian development. H. arator adults emerged in late summer-early autumn (January–March), ovaries matured slowly during winter and oviposition occurred in spring (September–November). The interval between equivalent population events was about six weeks from the northernmost to the southernmost regions. Fecundity was estimated to be around 12 eggs/female and greatest natural mortality occurred late in the pre-adult development phase.
The absolute efficiency of gypsy moth, Lymantria dispar (Lepidoptera: Lymantriidae), milk-carton pheromone traps
Authors: Taylor R. A. J. , McManus M. L. , Pitts C. W.
Published: July 2009

Catches by gypsy moth (Lymantria dispar (Linnaeus)) ‘milk-carton’ pheromone traps with (+)-disparlure were compared with estimates of the absolute aerial density of gypsy moths obtained using a suction trap of known absolute sampling efficiency. The mean number of male L. dispar caught per pheromone trap per day was found to be proportional to the 2/3 power of the suction trap's estimate of aerial density. We infer that the efficiency of the gypsy moth milk-carton pheromone trap is density-dependent, declining as aerial density increases. The significance of the density-dependent efficiency and the mode of action of attractant traps are discussed, and the problems of designing and building suction traps to standardize pheromone traps for other species are also considered. It is concluded that standardization is only possible when some basic biology is known because pheromone trap parameters are specific to the field behaviour of the species.
A Quantitative Study of a Population of Wheat Bulb Fly, Leptohylemyia coarctata (Fall.), in the Field
Authors: Dobson Ronald M. , Stephenson J. W. , Lofty J. R.
Published: July 2009

During the summer of 1956, a quantitative study of a field population of Wheat Bulb Fly, Leptohylemyia coarctata (Fall.), was carried out at Rothamsted.

The work consisted principally of a study of the development and decline of a population of adult flies. This was supplemented by observations on the populations of the immature stages.

Emergence was investigated by the use of a cage of fine terylene netting, 24 ft. long, 12 ft. wide, and 6 ft. high. This was erected in an infested wheat field shortly before flies were expected to appear, and was searched twice daily, at 10 a.m. and shortly before sunset.

A total of 293 male flies was caught during the 26 days from 24th June to 19th July. Of these, 186 appeared between 1st and 6th July. The highest day's catch was 40 flies on 6th July, by which date (inclusive) about 84 per cent, of the final total had emerged.

A total of 258 female flies was caught during the 35 days from 21st June to 25th July. Of these, about half emerged between 6th and 10th July. The highest day's catch was 37 flies on 8th, by which date (inclusive) 66 per cent, of the final total had emerged.

Population decrease was investigated by the method of marking and recapture. The newly emerged flies caught in the cage were marked with Artist's oil colours and released in the cage. The colour of the mark was changed daily so that the age of marked flies could be ascertained. A search was made for marked flies every three days and their numbers, marks and sex were recorded. From the recapture figures, estimates of the numbers of flies surviving at different times after marking were obtained. Mortality during the first day was very high, but after this numbers decreased at a steady rate. This initial high mortality was believed to be due to marking. The length of life of marked flies which survived this immediate effect was, however, not impaired, therefore the rate of population decrease was estimated from the recapture figures alone, that is, without reference to the numbers originally marked. The half-life of male and female populations was estimated as 7·3 and 11·1 days, respectively.

Application of the estimated rate of population decrease to the observed emergence figures enabled a general picture of the size and structure of the population to be obtained. The predominance of males over females during the early part of the season and the later predominance of females over males were explained.

Observations on the populations of the various stages showed that the mortality between pupation and maturation of adults was high, and that the egg populations inside the cage during the autumn of 1956 was only about 1/7th of that of the previous year. This reduction was not observed outside the cage and may have been due to the survival rate and fecundity of the flies being affected by the experiment. Further work will be necessary before this can be elucidated.
Observations on the Occurrence of Larval Infestations of Wheat Bulb Fly, Leptohylemyia coarctata (Fall.)
Authors: Long D. B.
Published: July 2009

The efiect of the previous crop on the subsequent infestation of winter wheat by the Wheat Bulb Fly, Leptohylemyia coarctata (Fall.), mainly on the clay-loam of Rothamsted Experimental Farm has been investigated for the years 1954 to 1956. By far the highest larval populations followed fallows, the next highest potatoes, which are a low, open cover crop, whilst much lower populations followed the tall crops of beans and wheat, and very small infestations followed the grass mat covers. This confirms the results of previous workers under different agricultural conditions.

Previous applications of dung and straw influenced the infestation following fallow in dry summers but not in a wet year. The effects of other manurial treatments were inconclusive.

An experiment designed to determine the effect of the crop density on oviposition was inconclusive due to the failure to establish an infestation.

Wheat was shown to influence the flight path and to interfere with local egg-laying behaviour, producing a horizontal effect of up to twice its own height.

Apart from the foregoing factors, at Rothamsted, where the wheat fields are well separated, the differences in the level of infestation that were observed could be explained by close proximity or otherwise to a centre of heavy fly infestation.

Reasons are put forward for suggesting that the effect of the previous crop on oviposition may be interpreted in terms of the opportunity existing for contact with the soil rather than as a preference on the part of the fly.
The Effect of Temperature on the Growth Rate and Survival of the Immature Stages ofAëdes aegypti(L.).
Authors: Bar-Zeev Micha
Published: July 2009

The effect of temperature on the growth rate and survival of the immature stages ofAëdes aegypti(L.) was studied by rearing them at each of a series of constant temperatures from 14–38°C. in water to which adequate food (bakers' yeast) was added. Larvae were hatched, by immersing eggs in water, in four successive groups with an interval of six hours between each, and six hours after the last group hatched, and every 24 hours thereafter, those surviving in each group were recorded and transferred to fresh water and food, the exuviae remaining being recorded. The average time at which any given stage was reached was taken as the mid-point of the 6-hr. period within which the number of individuals that had completed the previous stage reached 50 per cent, of the total that finally did so.

The curve relating temperature and time of development from newly hatched larva to adult is hyperbolic, except at the extremes. The later the instar, the lower is the temperature at which growth is most rapid. The threshold of development was between 9° and 10°C., the developmental zero 13.3°C., and the average thermal constant (between 16° and 32°C.) 2,741 degree-hours. The highest and lowest temperatures permitting development from newly hatched larva to adult were 36° and 14°C., respectively. The average durations of the four successive larval stages and the pupal stage, expressed as percentages of the time taken for newly hatched larvae to reach the adult stage, were 14.6, 13.9, 17.5, 33.3 and 20.6, respectively.
Responses of Pests to Fumigation.VII.—The Relation between Fumigation Techniques, Mortality, and the Amount of Hydrogen Cyanide sorbed by Calandra spp.
Authors: Bhambhani H. J. , Blackith R. E.
Published: July 2009

The relation between fumigation techniques, mortality and sorption of fumigant was investigated by two factorial experiments in which adults of Calandra granaria (L.) and C. oryzae (L.) were exposed to hydrogen cyanide at concentrations of 12, 26 or 44 mg. per litre and pressures of 2, 27, 52 and 76 cm. mercury for 30, 60 or 90 min., or at given concentration-time products (36, 72 or 108 mg. hr. per litre), in each of which the time component was 1, 4 or 12 hr., and pressures of 2, 37 and 76 cm. mercury. The methods of fumigation and estimation of sorption and mortality were those used in earlier investigations and the results are shown in a series of graphs.

For both species, sorption of hydrogen cyanide increased as the total pressure was reduced, about three times as much being sorbed, in the first experiment, at a pressure of 2 cm. as at atmospheric pressure, the increase in sorptive capacity being greater in the case of C. oryzae than in that of C. granaria. In the second experiment, sorption by both species, for a given concentration-time product, was greater at a high concentration applied for a short period (1 hr.) than at a lower concentration applied for a long period (12 hr.); in the former conditions, C. granaria consistently sorbed more fumigant than did C. oryzae, in the latter, the reverse was the case, and in intermediate conditions (4 hr. exposure), the amounts sorbed by the two species did not differ materially. This result was inconsistent with that of the first experiment, in which C. oryzae sorbed more than did C. granaria during short exposures (30.90 min.).

These effects on sorptive capacity of differing conditions of fumigation could account for most of the reported departures from the rule that the biological effects of fumigation can be described by the product of the mean concentration of fumigant applied and the period of exposure. Comparison between mortality and sorption at pressures of 27–76 cm. in the first experiment showed, however, that while these were broadly associated, the increased mortality at higher concentrations was greater than would be expected from the associated increase in sorption, and this discrepancy was significantly larger for C. oryzae than for C. granaria.
The Yield ofLasioderma serricorne(F.) (Col., Anobiidae) from a given Quantity of Foodstuff.
Authors: Bull J. O. , Solomon M. E.
Published: July 2009

An experiment was designed to ascertain the maximum yield of adults of the Cigarette Beetle,Lasioderma serricorne(F.) that could be reared from a given quantity of foodstuff. Equal numbers of eggs of this species were added to batches of tubes containing different weights of wheatfeed, and the resulting adults were removed, counted and weighed.

The weights of wheatfeed had been chosen so that in some of the batches of tubes it would not be completely exploited. When emergence of adults was complete, further numbers of eggs, which were calculated to produce approximately the number of larvae necessary to complete the process in each batch of tubes, were then added, and the resulting adults again removed, counted and weighed.

The maximum biomass (wet weight) of adults ofL. serricornewhich could be reared from egg to adult per gramme of wheatfeed at 25°C. and 70 per cent. relative humidity was found to be 0.214 g. (108 to 129 specimens, all more or less undersized, and many with a retarded rate of development, compared with insects given ample food). In addition to the 21 per cent, of the food converted into adult insects, another 27 per cent. by weight of the original foodstuff was lost, presumably as water and carbon dioxide, leaving just over 50 per cent. undigested residue, most of which was faecal matter that would have passed through the insects at least once.

The yield of insects per g. loss of weight of the foodstuff was 0.46 g. (wet weights), which is very close to the corresponding figures calculated from the results of Fraenkel & Blewett forDermestes maculatusDeg.,Tribolium confusumDuv. andEphestia KuehniellaZell. on various foods, but three times as great as the corresponding figure calculated from Richards' results forCalandra granaria(L.) in wheat.

There was evidence suggesting that a truly maximal yield (slightly greater than in these experiments) might be attained by adding an optimal number of eggs to the food at the start, instead of adding a second population to an incompletely exploited food supply.
A Preliminary Survey of the Distribution and Host-specificity of Ticks (Ixodoidea) in the Bechuanaland Protectorate
Authors: Zumpt F.
Published: July 2009

Twenty one species of ticks (Ixodoidea), one of which is represented by two subspecies, are recorded from the Bechuanaland Protectorate. Localities, dates and the hosts are given; general distribution and medical and veterinary importance are discussed under each species.

The shrub desert formations of the Kalahari are shown to be unsuitable habitats for most species of ticks; only a few are able to survive under severe desert conditions.

In medical respects, Ornithodoros moubata (Murr.), as the transmitter of relapsing fever, is the most important tick in the Protectorate. It has been found in the eastern part up to Francistown and in Ngamiland and near Tsane; its further distribution has not yet been established. Larvae and nymphs of various members of the Ixodidae infesting domestic and wild rodents are potential transmitters of tick-bite fever.

Cattle in the eastern area and in Ngamiland were found to be infested by ten species, of which Amblyomma hebraeum Koch, Hyalomma rufipes Koch, H. truncatum Koch, Rhipicephalus appendiculatus Neumann, R. evertsi evertsi Neumann, R. simus simus Koch and Boophilus decoloratus (Koch) are the most important ones, both in respect of the numbers infesting cattle, and of their significance as transmitters of redwater, anaplasmosis, heartwater and sweating sickness.

Sheep, goats, pigs and horses were found to be infested by nine of the species listed above as occurring on cattle.

Dogs were mainly parasitised by Rhipicephalus simus which outnumbered by far the two recognised dog-ticks, Rhipicephalus sanguineus sanguineus (Latr.) and Haemaphysalis leachii leachii (Aud.).

Wild Bovids and zebra are infested by species which also live on domestic ruminants, but the percentage of the different species present varies according to the host and to the locality.

Wild carnivores are infested by the same species as are dogs, but in this group, too, there are differences in the relative abundance of the various tick species.

Small birds are hosts of immature stages of Amblyomma and Hyalomma species. Their importance as carriers for the dispersal of cattle-infesting ticks is noticed.
Enumerating Populations of Adults of the Red Locust, Nomadacris septemfasciata (Serville), in its Outbreak Areas in East and Central Africa
Authors: Scheepers C. C. , Gunn D. L.
Published: July 2009

A method is described of estimating the total numbers and frequency distributions of adults of the Red Locust, Nomadacris septemfasciata (Serv.), in outbreak areas of hundreds of square miles, based upon counting the numbers that fly up in a two-yard strip in front of a moving vehicle. The method has proved itself valuable for indicating both immediate and future requirements for killing the locusts, but it requires refining for some research purposes.

By this method, the importance has been clearly shown of the process of congregation of scattered adult locusts in forming emigrant swarms that could start a plague. The locusts do not congregate but actually disperse just before laying eggs.

The total population in part (189 sq. miles) of the North Rukwa Outbreak Area (a self-contained area of 253 sq. miles) in Tanganyika Territory has been followed for four years. There are indications that a small migrant swarm contains 5–10 million locusts, that a total population in the whole of the North Rukwa Outbreak Area of 20 million locusts is unlikely to yield a migrant swarm, but that 50 million locusts could readily do so.

In 1953, after poor rains, no natural mortality was detected between July and October by the assessment methods described. In 1957, after good rains, natural mortality of 70–90 per cent. was revealed by the same methods, although the dry season was not fully covered by the assessments.
A New European Species of Pachynematus Konow (Hymenoptera, Tenthredinidae) feeding on Spruce (Picea)
Authors: Benson Robert B.
Published: July 2009

Dr. W. Thalenhorst, of the Niedersächsische Forstliche Versuchsanstalt, Göttingen, Germany, sent me some time ago specimens of what he took to be an abnormally dark form of Pachynematus montanus (Zaddach). These had been reared in 1952 from larvae, not at the time distinguished from the larvae of that species and found feeding with them on spruce (Picea abies) in the Harz Mountains in the previous year. Unfortunately the female was smashed in the post and I did not like to describe a new species that would have to be based on only a few males, though I was not able to identify them with any known species. In 1955, however, he reared another female of the same species and from this he tried to obtain eggs but without any success. This female I now have before me. No further specimens have been found.
The Initial Stage of Migration in Salt-marsh Mosquitos
Authors: Nielsen Erik Tetens
Published: July 2009

The departure of the newly emerged adults of the salt-marsh mosquito, Aëdes taeniorhynchus (Wied.) from the breeding sites was studied in Florida. The departures, which are presumed to be the initial stage of the migratory flight, have been observed to take place only in the dark period of the 24 hours, and, the vast majority of individuals being ready to take off at dusk, spontaneous mass departure took place at that time.

Samples of the resting population of mosquitos were taken at intervals before and after the mass departure, and from the departing migrants. The average age of the males in each sample was estimated by the proportion in different stages of hypopygial rotation, from which it is concluded that migratory activity begins when the insects are six or more hours old. The end of the migratory period is not yet known. In all of 21 female departing migrants examined, the ovaries were immature and the spermathecae empty.