bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the Dermestid beetle Trogoderma granarium Everts. VI.—Factors inducing diapause
Authors: Burges H. D. 
Published: July 2009

The facultative larval diapause of the khapra beetle, Trogoderma granarium Everts, is initiated extrinsically by temperature, crowding, and very low or very high humidity. In crowded populations, in tubes of wheat, the proportion of diapause larvae varies from very low (2 to 3 per cent.) in the upper part of the insect's temperature range to 100 per cent, in the lower part. Diapause larvae become more frequent with increasing population density, the frequency becoming noticeable at a density of about ten larvae per gramme of wheat (about 10 times their minimum food requirements). Accumulation of faecal pellets is a factor that induces diapause in crowded conditions. Many larvae that are kept singly enter diapause when fed on old culture food from which pellets have been removed: possibly in the old culture the pellets impart to the food a substance that initiates diapause. The availability of a suitable refuge, in which larvae can cluster, has no consistent effect on the proportion of diapause larvae. Factors that induce diapause also slightly increase the developmental period of non-diapause larvae.In malted barley, more larvae enter diapause than in wheat, probably due to the intensification of crowding by the confinement of larvae to a few malt grains.The relative importance of the factors that induce diapause is discussed. These factors help to explain observations in stores and conflicting results in the literature. The main function of diapause seems to be in assisting the larvae to survive periods of food shortage; diapause may also improve the survival of larvae in a cold winter and synchronise the emergence of adults. Of the factors inducing diapause, accumulation of faecal pellets precedes food shortage and falling temperatures precede the cold of winter, but the role of high and low humidities in this connection is difficult to assess. Diapause larvae play a major part in the dispersal of the species. The diapause of T. granarium is compared with that of other arthropods.
The distribution of insects in stacks of bagged groundnuts in Northern Nigeria
Authors: Prevett P. F. 
Published: July 2009

Decorticated groundnuts (Arachis) are stored in bags in pyramid-shaped stacks in Northern Nigeria over the period November to October. In Kano the dry season extends from October until March and is followed by a short hot season preceding the rainy season, which usually commences during May.The seasonal distribution within such pyramids of the various insect species infesting groundnuts is considered in some detail, with particular reference to the primary pest Tribolium castaneum (Hbst.). This distribution is discussed in relation to temperature and moisture content of the kernels and to the effect on the environment of covering pyramids with tarpaulins, the normal practice for protection during the rainy season. T. castaneum is the only species present on groundnuts initially and throughout the storage season. It is concluded that the elimination, during storage, of other species also present initially, i.e., Cadra cautella (Wlk.), Plodia interpunctella (Hb.), Corcyra cephalonica (Stnt.) and Oryzaephihis mercator (Fauv.), and the ultimate concentration of infestation by T. castaneum within peripheral bags is the result of changes in physical conditions. It would appear that Cryptolestes ferrugineus (Steph.), which was not found until late in the storage season, is a pest of secondary importance.The significance of the results obtained in relation to control measures is discussed, bearing in mind that all but one of the pests considered were found to be present on groundnuts when received at the Kano central storage area from buying stations. It is concluded that a programme of surface spraying of pyramids with insecticides is of little value and recommendations for the introduction of initial fumigation of pyramids have been put forward.
Populations of the leaf-miner Leucoptera meyricki Ghesq. and its parasites in sprayed and unsprayed coffee in Kenya
Authors: Bess Henry A. 
Published: July 2009

Populations of the leaf-miner Leucoptera meyricki Ghesq. and its parasites, of which Zagrammosoma variegatum (Masi), Achrysocharella ritchiei Ferriére and Parahormius leucopterae Nixon were the most abundant, were studied for 40 consecutive weeks during 1960–61 in Kenya, in four experimental blocks of coffee (Coffea arabica), two of which received several applications of parathion sprays and the other two none. Each week eight different trees within each block were covered with a tent, pyrethrum spray was atomised within, and the adult moths and parasites were recovered from the polyethylene sheeting used as a floor to the tent. Fortnightly, counts of leaves, mined and unmined, and collections of leaves with leaf-miner larvae and parasites within them were made. These intensive studies were supplemented with two special spray tests, in which different dosages of insecticides were used, and with collections of leaves made periodically over a rather extensive area in Kenya, from which adult leaf-miners and parasites were reared to gain information on the parasite/host relationships over a wide range of ecological conditions.Parathion used at 1 lb. 20 per cent, wettable powder in either 65 or 80 gal. water per acre appeared to kill all adult leaf-miners and parasites present. Possibly between 50 and 75 per cent, of the leaf-miner larvae, and appreciably fewer of the immature stages of the parasites within the mines, were killed. The sprays apparently had even less effect on the leaf-miner prepupae and pupae and the parasites within the cocoons, which are usually formed in the litter and in crevices in the soil.Leaf-miner populations within the sprayed blocks were somewhat lower than those in the unsprayed blocks, but the fluctuations were remarkably similar. In general, this was also true for the parasites.Assessment of the effects of the sprays on the efficiency of the parasites was made on the basis of the ratios of adult parasites to moths obtained from tented trees and from infested leaf samples held for adult emergence, as well as in terms of percentages of larvae parasitised in the samples dissected. It was found that the sprays killed a greater proportion of the leaf-miner larvae than of parasites within the mines, and thus increased the ratios of living parasites to leaf-miners immediately following the spray applications. During the period from October to January, when the sprays in the Eukera plots were synchronised with the peak populations of the moth, parasitisation was significantly higher in the sprayed plots than in the unsprayed plots. Furthermore, in the special spray tests, where different dosages of parathion and diazinon were used, parasitisation within the surviving populations was higher in the plots that received the higher dosages. These findings suggest that with proper timing of spray applications the efficiency of leaf-miner parasites may be improved.
Studies on Anopheles gambiae Giles and malaria transmission in the Umbugwe area of Tanganyika
Authors: Smith A. 
Published: July 2009

The paper includes a description of studies on Anopheles gambiae Giles in the insecticide-free Umbugwe area of Tanganyika, and the results of dissections of A. gambiae and A. funestus Giles for sporozoite infections.The densities of A. gambiae and A. funestus were assessed in houses by pyrethrum spray catches in 90 houses distributed in ten villages in the Umbugwe area between March 1960 and February 1962. A. gambiae was seasonally abundant, a sharp increase in density being associated with periods of rain. A. funestus type form was scarce in houses throughout the year, although a larval survey showed it to be the most common member of the complex of A. funestus in the area.The average ratio of fed to gravid individuals of A. gambiae was 2·3:1 from June 1960 to November 1961, with peaks reaching 7:1 in March 1960 and 7·5:1 in January 1962. The peaks were attributed to rapid increase in production of adults during the limited period of the rainy seasons that followed very dry conditions.Thirteen per cent, of recently fed individuals of A. gambiae were found in the exit window traps of experimental huts, having attempted to leave the huts on the night of feeding.Two distinct types of huts are commonly found in the area, the tembe, which is large, divided into an average of five rooms by walls that are usually incomplete at the top, and accommodates large numbers of cattle as well as humans; and the banda, which is smaller, divided only into two rooms and seldom housing any domestic animals. Precipitin tests showed that whereas only 20 per cent, of individuals of A. gambiae taken in tembe had fed on man, in banda huts the percentage was 77. It was also shown that there was a dispersal of A. gambiae within a hut shortly after feeding. In a tembe. one-third of the individuals positive for man, and one-quarter of those positive for cattle had moved to rooms other than those in which they had fed.A sporozoite rate of 1·47 per cent, was found among 3,746 specimens of A. gambiae dissected. Of the total number of 55 sporozoite-positive females of A. gambiae, 39 were found among the 424 individuals dissected in February 1962, thereby indicating unusually heavy transmission during the early part of 1962. A. funestus type form appeared to be of virtually no importance in malaria transmission in the Umbugwe area. Transmission by A. gambiae was highly seasonal, for although the percentage of gland-positive specimens was slightly higher in the long dry season than in the rainy season, the much larger mosquito population in the latter led to a higher number of infective bites in the rainy seasons. The highly seasonal transmission by A. gambiae was reflected in the results of examination of blood-films of people attending the Government dispensary.
Aircraft applications of insecticides in East Africa XIV.—Very-low-volume aerosols of dieldrin and isobenzan for the control of Glossina morsitans Westw
Authors: Burnett G. F. , Chadwick P. R. , Miller A. W. D. , Beesley J. S. S. 
Published: July 2009

Two experiments were conducted simultaneously in 1962–63 at Chungai, in central Tanganyika, to test new equipment for disseminating insecticides from aircraft and a new insecticide, isobenzan (Telodrin), in the eradication of Glossina morsitans Westw. and G. pallidipes Aust. The new equipment consisted of an aerosol generator fitted to the exhaust of a Cessna 182E high-wing monoplane, and was used in both experiments. The isobenzan was compared with dieldrin, and the two insecticides were applied at rates inversely proportional to their toxicities to G. morsitans as previously determined in the laboratory.Two blocks of woodland, each 11 sq. miles in area, were treated, one with a 12·3 per cent, solution of dieldrin at the rate of 0·0254 gal. per acre, giving a dosage of 0·5 oz. (14 g.) toxicant per acre, and the other with a 10 per cent, solution of isobenzan at the rate of 0·0124 gal. per acre, giving a dosage of 0·2 oz. (6 g.) per acre. The former block received eight treatments with dieldrin at approximately 3-week intervals, the fourth treatment being incomplete; the latter block received six treatments with isobenzan at intervals ranging from 20 to 45 days. The effects were assessed by means of fly-catches along fixed paths which continued for one year after treatments had ceased.Both species of tsetse fly disappeared from the two blocks before the final treatments took place, and no more were caught until 11 months after spraying ended, when one example of G. morsitans was caught in each block; both were probably immigrants. None was found in the following month, and it is concluded that the flies were exterminated in both blocks. The fact that the blocks were unusually well isolated from sources of reinfestation probably contributed to the success of the operations.The cost per sq. mile was £224 using dieldrin and £190 using isobenzan. These were the basic costs, independent of the locality in which spraying took place. Additional costs were incurred which would vary with local conditions; for the present experiments they were £34 and £30, respectively. It is considered that there is good scope for further reductions in costs, particularly with dieldrin, and that these might make dieldrin economically competitive with isobenzan. Owing to the low fly density in the block treated with isobenzan, the efficacy of this insecticide cannot be regarded as conclusively proved until further experiments have been carried out. It may then merit serious consideration as a toxicant for aerial spraying against tsetse flies.
Axenic culture of the foreign grain beetle,Ahasverus advena(Waltl) (Coleoptera, Silvanidae), and the rôle of fungi in its nutrition
Authors: Hill S. T. 
Published: July 2009

The extent of the dependence of the foreign grain beetle,Ahasverus advena(Waltl), upon moulds in its diet was investigated.Using a simple technique, the insect was cultured axenically at controlled temperature and relative humidity on an autoclaved mixture of rolled oats, wheatfeed and dried yeast. After the mixture was sterilised by exposure to propylene oxide vapour, virtually no larvae completed development on it in the absence of living micro-organisms, and this effect was unchanged by the addition of a mixture of B-vitamins followed by autoclaving. However, when fungi were grown on the food previously sterilised with propylene oxide, it again permitted the complete development of the insect.Autoelaved wheat germ was not a suitable diet forA. advenaunless a small proportion of dried yeast was added before autoclaving. It is concluded that living fungi are not essential in the diet of the insect, but that they may supplement an otherwise inadequate diet.The minimum development time from egg to adult on a complete food at 80 per cent. E.H. and 30°C. varied from 18 to 25 days.
Studies on Bathycoelia thalassina (H.-S.) (Hemiptera; Pentatomidae), the cause of premature ripening of cocoa pods in Ghana
Authors: Lodos N. 
Published: July 2009

Bathycoelia thalassina (H.-S.), of which the developmental stages and life history are described, is responsible for premature ripening of cocoa pods in Ghana. Experiments conducted at Tafo to determine the nature of the damage to pods showed that the insect feeds directly on the beans, and that beans so attacked turn brown and subsequently die: only the empty shell of the bean remains.The saliva of the insect kills any tissue of the pod that it penetrates and within four days the injured areas cease to grow and become yellow, then brown, and finally black.The symptom most characteristic of damage is the change in colour. The pod may become completely yellow, or yellow in the basal or distal half only (usually the latter) or yellow in spots, depending on the size of the pod, the site of attack, and the duration of feeding at each site.The insect usually attacks pods of the Amazon varieties, 10–17 cm. long. The incision made by the stylets is microscopic, and is covered by a jelly-like substance, and no evident lesions develop on the surface as in damage caused by cocoa mirids or coreids.Damage caused by B. thalassina on young pods resembles cherelle wilt of physiological origin, and the two can be distinguished only by slicing the pods, whereupon the former can be recognised by the presence of injured beans.According to the survey of damage caused by B. thalassina in Ghana, this species seems to be an economic pest on some Amazon and hybrid types of cocoa, whereas Amelonado cocoa usually suffers little.
Funnel ants (Aphaenogaster spp., Formicidae) as pasture pests in North Queensland. I.—Ecological background, status and distribution
Authors: Saunders G. W. 
Published: July 2009

In a study of the incidence of funnel ants (Aphaenogaster spp.) on the Atherton and Evelyn Tablelands of northern Queensland in 1959–61, 422 farms were surveyed, totalling over 98,000 acres of pasture, of which 10.8 per cent. proved to be infested with A. pythia Forel. The ants damage the introduced pasture grasses (Paspalum dilatatum and Pennisetum clandestinum) by removing soil from around their roots to from loose mounds, which smother the closely-grazedsward. Inferior species of grass and deep-rooted weeds are thus encouraged and affected areas become useless for dairying.The natural habitat of A. pythia is wet sclerophyll forest which occurs in narrow belts fringing the rain forest and in pockets within it; the rain forest does not harbour the ant, but following its clearance and its replacement by pastures, A. pythia has spread out and colonised the latter. In areas of lower annual rainfall (under 50 in.) occupied dry sclerophyll forest and Eucalyptus woodland, A. pythia is replaced by A. longiceps F. Smith. Improved pastures have not been established here, but in the relatively restricted areas of infestation by this species, the large funnel-shaped orifices of its mounds create a hazard to stock.
Effect of temperature and humidity on the development of tea red spider mite, Oligonychus coffeae (Nietner)
Authors: Das G. M. , Das S. C. 
Published: July 2009

The effects of temperature and humidity on the development of Oligonychus coffeae (Nietner) were studied by exposing the various stages of the mite to air in equilibrium with saturated solutions of appropriate salts in containers within thermostatically controlled cabinets. Adults and early stages were maintained on fresh tea shoots.The pre-oviposition, oviposition and post-oviposition periods of adult females at 75–80% relative varied inversely with temperature, and averaged, respectively, 0.8, 5.9 and 1.4 days at 32° and 2.3, 30.6 and 2.0 days at 20°C. The mean number of eggs laid per female likewise varied inversely with temperature, from 12.0 at 32°C at 32° to 107.3 at 20°C.No eggs hatched when incubated at 34°C., irrespective of humidity, or at 17% R.H., irrespective of temperature. Optimum conditions for incubation (those affording over 90% hatch) were provied by a combination of temperatures and relative humidities within the ranges 20–30°C. and 49–94%. When eggs were exposed daily for five days to temperatures of 37 or 40° for six hours at 72–94% R.H. and then transferred to room conditions (24–32°C., 64–88% R.H.), the percentage of eggs hatching was reduced from 94.7 (room conditions) to about 75 or 5–12, respectively.The mean incubation period of eggs varied from 3.9 days at 32° to 10.8 at 20°C., and the mean duratio of the combined larval and nymphal stages from 4.9 days at 30° to 8.7 at 20°C. At 32°C., larval mortality was very high.
Ticks (Acari: Ixodoidea) in Botswana
Authors: Paine Gordon D. 
Published: July 2009

AbstractIn a survey in 1976–79 in Botswana, more than 14000 adult ticks were collected from cattle and other domestic and wild animals and identified. Larvae and nymphs were also collected but not counted. Comparison with previous records indicates that some species, particularly Amblyomma hebraeum Koch and Boophilus decoloratus (Koch), are becoming more numerous and widespread, probably due to cattle movements and favourable climatic conditions. Haemaphysalis aciculifer Warb. was found for the first time in Botswana. The counts from complete collections of ticks from groups of three cattle are analysed, host-parasite lists are given and the results of a few acaricide resistance tests are recorded.
Chemosterilisation ofGlossina morsitans morsitansWestwood andG. PallidipesAusten (Diptera: Glossinidae) in the field
Authors: House A. P. R. 
Published: July 2009

AbstractWild adults ofGlossina morsitans morsitansWestw. andG. pallidipesAust. were caught in a trap baited with carbon dioxide and acetone near Chimotsi Dam in the Zambezi Valley, Zimbabwe. The design of the trap was such that flies were induced to move into a sterilising chamber, where they were treated with a spray of the chemosterilant metepa, after which they were automatically released back into the environment. Exposure to a spray of 0·2 s duration produced between 94 and 100% sterility, with very low mortality. The sterilising unit, its action and performance are described.
The improvement of traps for tsetse flies (Diptera: Glossinidae)
Authors: Vale G. A. 
Published: July 2009

AbstractBased on previous studies of the trap-orientated behaviour of Diptera, a variety of new traps was designed to maximise the speed and probability of capturing Glossina morsitans morsitans Westw. and G. pallidipes Aust. arriving near traps, and to minimise the probability of capturing other flies. In Zimbabwe, catches were made with these traps in the presence and absence of carbon dioxide and acetone as odour attractants, leading to the identification of a simple trap for which the probability of capturing Glossina spp. was up to twice as great as it was for a standard biconi-cal trap, and for which the probability of capturing other Diptera was very much less than it was for the biconical trap. The probability of capture by the simple trap was 100% for G. pallidipes, 51% for G. m. morsitans, 6% for Stomoxyinae and 1% for non-biting Muscidae. Half the tsetse that arrived near the simple trap were captured within 5 min of arrival. The number of tsetse that contacted simple targets designed to expose flies to insecticide amounted to 32–263% of the catches of a biconical trap. The use of traps and targets for tsetse control, and the procedures for trap improvement, are discussed.
Flight and settling behaviour ofRhopalosiphum Padi(L.) (Hemiptera: Aphididae)
Authors: Wiktelius S. 
Published: July 2009

AbstractAlate exules ofRhopalosiphum padi(L.) were flown in a flight chamber for three different flight times: 1 min, 5 min and 25 min. The rate of climb was recorded continuously during flight. Afterwards, the aphids were forced to land on either wheat or potato and settling behaviour was recorded. The settling response was strengthened with increasing flight time on both plants. The aphids spent more time walking and made more probes on potato than on wheat after 25 min of flight. The rate of climb was the same immediately before landing as immediately after a spontaneous re-take-off, except after a 25-min flight and landing on potato when the rate of climb was significantly higher after re-take-off. Comparison withAphis fabaeScop. from other investigations showed that the change in settling response with flight time was similar for the two species.R. padiseemed less able to discriminate rapidly between host and non-host plants thanA. fabae. It is concluded that its behaviour does not hinderR. padifrom being a vector of stylet-borne potato viruses.
Influence of Scirpophaga incertulas (Lepidoptera: Pyralidae) on deepwater rice
Authors: Islam Zahirul 
Published: July 2009

AbstractThe influence of the lepidopteran stem borer Scirpophaga incertulas (Walker), the most important pest of deepwater rice (Oryza sativa) in south-east Asia, on plant and grain yield was investigated in Bangladesh during 1982–85. Four mechanisms of crop loss were identified: (i) deadhearts at the vegetative stage, (ii) loss of damaged but apparently healthy stems in flood water, (iii) white-heads at the reproductive stage and (iv) the effect of late season stem damage on panicles. A great proportion of damaged stems was not visible and damage symptoms were found to be an unreliable indicator for the assessment of borer activities in the field, and did not represent the actual yield loss. Stem damage had a negative influence on the stem density, with reduced panicle density and grain yield. Stem borer damage also seemed to reduce the elongation ability of the rice stem causing them to rot. Late season stem damage reduced the number of filled grains, mean grain weight and panicle weight and increased grain sterility. These effects were related to severity and position of damage. The average estimated yield loss due to S. incertulas was about 17% which took place during the last 11 weeks (from flood peak to crop maturity) of the deepwater rice season (32 weeks).