bluuebunny/crossref_metadata_2025_split huggingface dataset:
An unconventional use of piperonyl butoxide for managing the cotton whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae)
Authors: Devine G.J. , Denholm I. 
Published: July 2009

AbstractBemisia tabaci (Gennadius) is a pest of global importance which resists many conventional insecticides. Novel strategies for control are required and these may incorporate compounds whose lethal and sublethal effects have gone unremarked. Although most commonly employed as an insecticide synergist, piperonyl butoxide alone was lethal to predominantly second instar nymphs of the cotton whitefly, B. tabaci at LC50s of between 60 and 600 ppm, depending on the strain. Formulated and technical material were similarly toxic and far more so than detergents. Some strains exhibited slight tolerance (c. 3–10 fold) but there was no correlation of this with the presence of known resistance mechanisms or enzyme banding patterns. Residues of piperonyl butoxide alone were toxic to adult B. tabaci at c. 2000 ppm which was similar to the toxicity of paraffin oil. Piperonyl butoxide also increased developmental times among B. tabaci nymphs at doses as low as 10 ppm and exerted a transient effect on oviposition. There was strong evidence that it did not reduce the feeding activity of insects surviving treatment. Such effects offer scope for incorporating this compound into resistance management programmes, especially in conjunction with natural enemies (e.g, parasitoids active specifically against immature hosts).
Impact and oviposition behaviour ofAgeniaspis fuscicollis(Hymenoptera: Encyrtidae), a polyembryonic parasitoid of the apple ermine moth,Yponomeuta malinellus(Lepidoptera: Yponomeutidae)
Authors: Kuhlmann U. , Babendreier D. , Hoffmeister T.S. , Mills N.J. 
Published: July 2009

AbstractThe distribution and extent of parasitism of the apple ermine mothYponomeuta malinellusZeller by the polyembyronic encyrtid parasitoidAgeniaspis fuscicollis(Dalman) were examined in a three year field study and related to oviposition behaviour in the laboratory.Ageniaspis fuscicollisattacks egg batches of its host and kills the final instar larvae, which feed gregariously from within tents. Host population densities in the field were low, from 1.5 to 2.2 tents per 100 leaf clusters, and parasitism increased from 7.8% to 18% over the three year period. Parasitism was independent of host density at the whole tree scale, but at the individual tent scale, the probability of a tent containing parasitized host larvae increased and percent parasitism decreased with the number of host larvae per tent. Observations on the oviposition behaviour ofA. fuscicollisin the laboratory revealed that parasitoids distributed their eggs randomly within host egg batches. On average, they spent almost two hours on an egg batch and laid 44% of their egg load of 132 eggs into the first egg batch visited, leading to a mean of 1.4 eggs laid per host egg through frequent self-superparasitism of hosts. The percentage of eggs receiving one or more ovipositions was independent of the size of an egg batch, contradicting our field observations of inverse density dependence. Factors that might account for the differences in rates of parasitism and attack distributions between laboratory and field data are discussed.
A Comparative Study of the Soil Conditions favoured by certain Melolonthid and Tenebrioned Pests of Tobacco in Southern Rhodesia
Authors: Bünzli G. H. , Büttiker W. W. 
Published: July 2009

An investigation was made to determine the factors governing the distribution pattern of the larvae of certain species of Melolonthids and Tenebrionids; these are known to be serious pests of tobacco plants in Southern Rhodesia.Observations were made on mixed populations of the white grubs, larvae of Anomala exitialis Pér. and Schizonycha profuga Pér. (MELOLONTHINAE), on the one hand, and on those of the false wireworms, larvae of Psammodes similis Pér. and P. scrobicollis (Fhs.) (TENEBRIONIDAE), on the other.It was found that the habitats favoured by white grubs had a higher clay, silt and organic matter content than those favoured by false wireworms. This was indicated by the darker brown colour of the soil; the clay ratio of the soils of the two types of habitat was as 1 to 0·725 and the nitrogen ratio as 1 to 0·524, respectively.Heavy infestations of tobacco fields are associated with 60,000 white grubs or 1,500 false wireworms per acre. The white grubs complete their life-cycle in one year, the larvae obtaining the food requirements necessary for their develop ment in the 4 to 5 months of the wet season. The false wireworms have a two-year life-cycle, the active feeding stages of the larvae being spread over 18 to 21 months, comprising both wet and dry seasons.The infestations by the two classes of insect do not overlap in space to any great extent but are governed by the nature of the soil, the white grubs favouring areas in which the soil has a higher nutrient value and the false wireworms areas where the soil is poorer.Reference is made to parasitisation of white-grub larvae in two areas, where the soil had an abnormally high nitrogen content, by a species of Tiphia in the one area and by entomogenous fungi in the other.False wireworms have not been found to be similarly attacked under field conditions.
The Oviposition and Duration of Life of a small Strain of the Rice Weevil,Calandra oryzae(L.), in Sierra Leone
Authors: Prevett P. F. 
Published: July 2009

A study has been made of the rate of oviposition, on parboiled milled rice, of the small strain of the rice weevil,Calandra oryzae(L.), under normal laboratory conditions of temperature and relative humidity (means 27°C., 80% R.H.) in Sierra Leone, and of the utilisation of grains for oviposition.On the average, a female laid 68 eggs in all, over an oviposition period of 71 days, the peak of egg-laying being reached during the third week. Only 13 per cent, of grains were utilised. Differences between the results obtained and those recorded by previous workers are discussed.The mean length of life of male and female weevils was found to be 113 and 97 days, respectively.
The flight of Culicoides impunctatus Goetghebuer (Diptera, ceratopogonidae) over moorland and its bearing on midge control.
Authors: Kettle D.S. 
Published: July 2009

In the summer of 1958, experiments were conducted in the vicinity of Brunston Muir, Midlothian, 11 miles SE. of Edinburgh, to measure the flight range of Culicoides impunctatus Goetgh. from its breeding site in the direction of the prevailing south-westerly wind. Thirty-six sticky traps were exposed for six weeks from 27th May to 7th July and captured 23,211 specimens of Culicoides, of which 20,105 were of C. impunctatus (7,207 males and 12,898 females).Eleven of the traps were arranged in a line over 1,200 yd. The catch of females did not alter for 400 yd., then decreased to a new level which remained constant from 600 to 1,200 yd. This decrease was associated more with the absence of livestock after 550 yd. than with any density/distance regression. The male distribution was similar to that of the females.Ten more traps stretched over 750 yd. and again no regression was discernible. The female distribution was affected more by the availability of hosts than distance from the breeding site. The male distribution here was different. They appeared to pass less readily through a gap in a narrow belt of woodland than did the females.
Trapping as a means of studying the game tsetse, Glossina pallidipes Aust.
Authors: Morris K. R. S. 
Published: July 2009

In an area of sleeping sickness due to Trypanosoma rhodesiense in Uganda, Morris's ‘ animal ’ traps were used to study the activity and the relations with habitat and hosts of the vector, Glossina pallidipes Aust., a tsetse difficult to sample by conventional fly-round methods.This type of trap was found to give samples both numerically greater and more truly representative of the tsetse population present than did either fly-boys or Chorley's bicycle screen.Black traps showed an over-all superiority to brown traps, greatest during the rains and disappearing in the dry season, and this was related to the tsetse being attracted by the trap as representing a natural host.
Laboratory observations on the life-history and ethology of Mansonia mosquitos
Authors: Gillett J. D. 
Published: July 2009

The rearing of a complete generation of Mansonia (Coquillettidia) aurites (Theo.) is described with notes on the methods used.Variation in the leg ornamentation of the adults forming the progeny of a single egg-raft was found to cover the range usually observed in this species.A plea is made for conformity in the use of terms describing the various kinds of aggregations of eggs.Egg-rafts are discussed, and a tentative key is given to the eggs of six of the Ethiopian species of Coquillettidia, based on egg-raft shape.A modification of the ‘natural’ arrangement is suggested for the Ethiopian species of Coquillettidia, based not only on adult and larval characters, but on oviposition behaviour as judged by egg-raft shape.The possibility of natural interspecific hybridisation is mentioned.The general slowness in many of the life processes found in the genus is put forward as an adaptation to its peculiar mode of life.
Aircraft applications of insecticides in East Africa
Authors: Burnett G. F. , Yeo D. , Miller A. W. D. , White P. J. 
Published: July 2009

SummaryIn the North Block at Chungai, comprising about 11 sq. miles of thorn savannah and thicket in Central Province, Tanganyika, an Auster J5G aircraft was used between July 1959 and March 1960 to apply a 2·5 per cent. solution of dieldrin in oil at the rate of 0·125 gal. per acre in an attempt to eradicate Glossina morsitans Westw. and G. pallidipes Aust. Eight applications were made at approximately four-weekly intervals. Swath width was 55 yd., and the aircraft emitted the insecticide as a coarse aerosol of volume median diameter 50–60μ as it flew in both directions over the block.The operation suffered delays, and three applications were incomplete to varying degrees. Kills of G. morsitans per application appeared to be 85 per cent. or higher, but the final reduction of 99·5 per cent. could theoretically have been attained with consecutive mortalities of only 65 per cent. It is suggested that this discrepancy may be due to the higher lethal dose required by pregnant females. G. pallidipes was also reduced by 99·5 per cent. Numbers of fly were reduced sufficiently for large-scale settlement with cattle, which should complete the work of exterminating the fly.The experiment is compared with that of the previous year in the same block, using γBHC, which reduced fly catches by less than 50 per cent. It is concluded that a combination of reduced swath width, greater volume dosage, more lethal insecticide and smaller lethal drop, together with improved flying technique and the more reliable performance of the disseminating equipment, was responsible for the improved result. It is thought that without delays, interruptions, incomplete applications and reinfestation, even better results would be obtained.This was the cheapest and one of the most successful aerial operations carried out against savannah tsetse. Costs actually over the ground were £301 per sq. mile; incidental costs due to the locality of operations were £66 per sq. mile. There is little chance of reducing the costs of flying directly, but economies are possible by the use of other insecticides or, more probably, by more efficient dispensing equipment.
Studies on the biting habits and medical importance of East African mosquitos in the genus Aëdes. II.—Subgenera Mucidus, Diceromyia, Finlaya and Stegomyia
Authors: Haddow A. J. 
Published: July 2009

The cyclic biting activities of East African mosquitos of the genus Aëdes, belonging to the subgenera Mucidus, Diceromyia, Finlaya and Stegomyia are discussed. The total number of 24-hour catches involved was 448, all in East Africa, of which 401 were made in forest in Uganda.It is pointed out that many species in the subgenera of Aëdes dealt with show arboreal tendencies of varying degree and, while a species may show a preference for some particular level, many of them appear to make daily vertical migrations. Consequently, biting may reach its maximum intensity at different times at different levels. It is also pointed out that the habits of a species may vary from one area to another, and therefore it is often best to discuss a representative series of catches from a productive area, noting such differences as may have been observed elsewhere. It has been found further that, under certain circumstances, a species may fail to show a clear pattern of biting behaviour and the possible reasons for this are discussed.All members of the subgenus Mucidus so far adequately studied are arboreal and nocturnal. In the subgenus Finlaya, A. ingrami Edw. is a mosquito of the forest understorey which bites most freely in the hour before sunset. It makes vertical migrations, however, and the biting cycle at ground-level differs from that in the trees. A. longipalpis (Grünb.) is a diurnal species of the forest canopy. A view formerly put forward by the writer, that the form of the biting cycle in this species could be attributed to different physiological groups biting at different times, can no longer be supported.In the subgenus Stegomyia, A. dendrophilus Edw. and A. apicoargenteus (Theo.) are diurnal species with rather irregular biting cycles, A. dendrophilus
Observations on the ecology of the cotton flea-beetles in the Sudan Gezira and the effect of sowing date on the level of population in cotton
Authors: La Croix E. A. S. 
Published: July 2009

SummaryA series of experiments was undertaken to examine the relative concentration of cotton flea-beetles (Podagrica puncticollis Weise and P. pallida (Jacoby), Halticinae) within cotton fields in the Sudan Gezira in 1954 and 1955. Assessments were carried out on the flea-beetle populations and on the damage done by them, and evidence is produced to show that the use of a damage assessment in the first three weeks of the life of the cotton plant is more satisfactory in a large-scale experiment than beetle counts. The assessment lasted for between three and four weeks after the emergence of the seedling cotton.It appeared that the beetles tended to leave cotton 19 days after sowing. Damage within the cotton field was at first in accord with the sowing differential, but then shifted against this as the flea-beetles moved on to the later-sown cotton as this became more attractive.The peak population of flea-beetles occurred during the last few days of August and the first few of September when the first-sown cotton was 14–18 days old, and this suffered more damage than the later-sown and less attractive cotton. Differences in the level of attack on the four sowings tended to even out, but did not do so completely as the flea-beetle population was declining.
Timing of insecticidal sprays to control the wheat-bulb fly, Leptohylemyia coarctata (Fall.)
Authors: Griffiths D. C. , Scott G. C. 
Published: July 2009

The timing of sprays in relation to the stage of development of wheat plants and larvae of the wheat-bulb fly, Leptohylemyia coarctata (Pall.), was studied in the laboratory and field. The main growth of young wheat plants was of the centre shoot and such plants died when the centre shoot meristems were destroyed. Older plants survived by growth of lateral shoots. Sprays of dimethoate, trichloronate and thionazin applied before the larvae had emerged did not kill many larvae in the soil, and only insecticide that entered the plants was effective. Severely attacked two-leaf plants yielded little, whether sprayed or not, whereas three-leaf plants sprayed in early March gave a worth-while increase in yield: older plants had enough shoots to give moderate yields even when not sprayed.In a large field trial, plants from two sowing dates, 22nd October and 1st November, were both at the late two-leaf stage of growth in late February. Wheat-bulb fly larvae had entered nearly all the shoots but plants from both sowings had buds or small lateral growths hidden beneath the outer leaves. The yields of October-sown plots sprayed on 22nd February, 2nd March, 9th March or 16th March were 28·2, 28·8, 25·5 and 23·2 cwt. grain per acre, respectively, (yield of unsprayed plots = 18.9 cwt./acre) and of November-sown plots were 31·0, 27·5, 17·9 and 14·9 cwt. per acre, respectively, (yield of unsprayed plots = 116 cwt. per acre). Sprays had most effect when applied soon after larvae had entered the plants. Spraying severely-attacked late two-leaf to three-leaf plants gave the greatest benefits because these plants recovered by growth of lateral buds or small lateral shoots.
Effects of larval and pupal environmental factors on biological status of adults at emergence inAedes taeniorhynchus(Wied.)
Authors: Nayar J. K. 
Published: July 2009

Adults ofAedes taeniorhynchus(Wied.) were reared from larvae under five environmental variables—quantity of food, density of larvae, salinity of medium, light regime and temperature—singly and in combination. On emergence these adults were analysed for morphological characteristics, dry body weights, energy reserves and autogeny.The minimal expression of adult characteristics and autogeny was effected by lack of food, crowding of larvae, and higher salinity, singly and in combination, at a constant temperature of 27°C. These three factors in turn showed a distinct relationship with delay in onset and prolongation of pupal ecdysis.The maximal expression of adult characteristics and autogeny was found when 75 to 100 larvae per pan were reared on 2 × - or 4 × -basic ration in 10 to 25 per cent, sea water at 27°C. under alternating 12-hr. light-dark cycles. Above the optimal quantity of food,i.e., 2 × -basic ration, there was almost no enhanced effect on the adult characteristics; in fact, with 4 × - and 8 × -basic ration the morphological characteristics were suppressed. Of the three light regimes, continuous light produced adults that were largest, heaviest, had the most energy reserves and the highest level of autogeny. Adults reared on 4 × -basic ration in ten per cent, sea water under alternating 12-hr. light-dark cycles and at temperatures from 24 to 34°C. showed that even though largest mosquitos were obtained at 24°C, the heaviest mosquitos with maximal lipid and glycogen contents and maximal expression of autogeny were found at 28 and 30°C. Temperature changes during the pupal stage did not affect the adult characteristics.Temperature and light regimes show distinct complex effects on adults at emergence, but the quantity of food, density of larvae and salinity of the rearing medium are more important.
Systates exaptus Mshl. (Col., Curculionidae) and related species as soil pests of maize in Rhodesia
Authors: Rose D. J. W. , Hodgson C. J. 
Published: July 2009

A description is given of the damage caused by the larvae of two weevils, Systates exaptus Mshl. and Mesoleurus dentipes (Mshl.), which are soil pests of germinating maize and other crops in Rhodesia. Information is given on their life-cycles and some features of their biology. The larvae are nearly full grown at the beginning of the dry season, which is passed in an inactive state in the soil. Activity is resumed with the onset of the main rains, and it is at this time that the larvae may cause serious damage by attacking seedlings of maize or other crops growing in infested soil. Factors that encourage local increase of field populations are examined. It is shown that sunn hemp, soya bean and groundnut, all crops with high plant populations, favour the presence of large numbers of weevil larvae in the soil at the beginning of the following season. Growing closely planted maize year after year on the same land has been found to be one of the main causes of serious infestations in farm fields.Results of soil-insecticide trials are given, and these show that larvae are very difficult to control. In the discussion, attention is drawn to similar weevil larvae indigenous to other parts of Africa, which are tolerant of soil insecticides and are also pests under conditions of intensive crop production.Ways are suggested for reducing infestation in the following season. It is shown that properly timed applications of DDT to the maize crop will kill adults and prevent oviposition. Otherwise, infested fields may be left fallow, planted to grass or planted very late in the season.No method of protecting germinating seedlings has been found, but reference is made to a soil-sampling technique that is useful for detecting infested fields before crops are planted.
Relationships between some physical properties of insecticides and their inteinsic and contact toxicities to adult mosquitos (Anopheles stephensi List.)
Authors: Hadaway A. B. , Barlow F 
Published: July 2009

It had been noticed in earlier work that there was a lack of close relationship between the intrinsic and contact toxicities of various compounds to adults of Anopheles stephensi List., the intrinsic toxicities being determined by topical application of solutions and the contact toxicities by exposure to dry deposits. Since the reasons probably lay in the relative rates at which compounds penetrated the cuticle from solution and from the solid state, and since these rates are likely to be differently affected by the physical properties of the compounds, the intrinsic and contact toxicities to A. stephensi of some closely related carbamates and of a miscellaneous group of organophosphorus compounds were determined, together with the solubility in n-hexane and the partition coefficient between n-hexane and water of each, and the results were compared.No definite pattern in the relationship between these physical properties of the compounds and their intrinsic and contact toxicities emerged from consideration of the results. However, there were indications that very low solubility is a limiting factor in the uptake and penetration into mosquitos of a solid insecticide and is associated with low contact toxicity, and that, when solubility is high enough to ensure solution in the wax layer of the cuticle, contact activity is favoured by a low value for the partition coefficient between hexane and water.
A trial use of grass-mat passages in protecting humans from attacks by tsetse flies.
Authors: La Croix E. A. S. 
Published: July 2009

In March 1957, an outbreak of human sleeping sickness was discovered in the South Mamprussi District of northern Ghana. Temporary measures were initiated at a few villages to provide protection, at water-holes on streams, against attack by the two prevalent species of tsetse, Glossina palpalis (R.-D.) and G. tachinoides Westw., until clearings could be made.These measures consisted of grass-mat passages approximately 8 ft. high, extending from about 75 yd. from the stream down to and around the waterhole. At the water-hole, there was a gap of about 1 ft. between mat and water.These passages were found to be successful in excluding tsetse fly. This suggests several points of interest about G. palpalis and G. tachinoides: that at that time of year and in that type of vegetation, they do not rest higher than 8 ft. above ground; that the portions of human anatomy that showed beneath the matting did not attract the fly; and that these species depend on sight for hunting rather than on smell.The cost of this matting was negligible as compared with the cost of routine clearing, and this method of temporary protection was considered successful for its purpose.