Original Articles
The Introduction of Megarhinus Mosquitos into Fiji
- R. W. Paine
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- 10 July 2009, pp. 1-31
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1. In 1927 a suggestion was made by P. A. Buxton to introduce Megarhinus to Samoa and Fiji for the control of Aëdes scutellaris (variegatus), which transmits human filariasis.
2. In 1929, C. E. Pemberton introduced M. inornatus from New Britain into Hawaii, where it has apparently failed to become established.
3. In the same year the writer was sent to Java to obtain parasites for a coconut pest in Fiji; and in 1930 received instructions from the Fiji Government to collect and transport Megarhinus from Java to Fiji.
4. During the latter half of 1930 early stages of Megarhinus splendens—the commonest and most widespread species in Java—were collected from tree-holes, bamboo stumps and tubs at Buitenzorg.
5. Experiments were conducted at Buitenzorg to ascertain how long the larvae could be kept in a healthy condition by restricting their food supply. It was found that they matured normally on a reduced diet after a development lasting as long as two months. The most rapid development from egg to adult was found to take 24 days. Attempts to breed the adults in captivity were unsuccessful.
6. In January 1931, a colony of M. splendens consisting of 283 larvae was taken to Fiji; 45 died or emerged as adults during the voyage of 28 days.
7. On 27th February 1931, 238 M. splendens were landed at Suva.
8. Colonies for distribution to various parts of Fiji were bred in Suva during 1931 and 1932, and by April of the latter year 51 colonies, composed of nearly 3,000 individuals, had been liberated.
9. Megarhinus was bred at Suva by liberating the pupae in barrels kept out of doors. The adults which emerged laid most of their eggs in the barrels in the absence of other breeding-places in the vicinity. The larvae were collected from the barrels when they reached their third instar. They were fed in captivity until they pupated, and then liberated as pupae in colonies sent to various parts of the group.
10. By the end of 1931 Megarhinus had been recovered at six of the colony sites in natural breeding-places, and is now well established. The most favourable type of country in Fiji for Megarhinus to colonise is the swamp land with trees of Inocarpus edulis (“ivi”), which occurs near the coast on many islands.
11. An account is given of the spread of Megarhinus through an Inocarpus swamp on the island of Taveuni, where a survey was made of the Megarhinus and Aëdes content of all the tree-holes within six feet of the ground. M. splendens was present in rather more than 50 per cent, of the holes and Aëdes variegatus in about 40 per cent. The probability is that in this locality Megarhinus has caused a 20 per cent, reduction in the number of tree-holes containing Aëdes during the three months succeeding its liberation.
12. It was found that in most places, in the forest especially, Megarhinus spreads very slowly–undergrowth making an effective barrier to its flight.
13. A. variegatus breeds mostly in tree-holes, tins, holes in rocks, coconut husks, wooden gongs in native villages and crab-holes (the last not yet proved in Fiji). Of these places Megarhinus has so far bred only in tree-holes and tins (very occasionally). It will probably breed in native gongs but unlikely that it will breed in either crab-holes, rock-pools or coconut husks. Therefore at the best it can hardly be expected to reduce the numbers of A. variegatus in Fiji by more than 5 per cent. But even that would justify the trifling expenditure which has been devoted to the project.
14. Studies of the habits and life-cycle of M. splendens made in Java and Fiji revealed the following points of interest:—Incubation period always about 2 days; larval stages, minimum 16 days (food abundant), maximum 134 days (food scarce); pupal stage always about 6 days. The minimum period for a generation is about 30 days.
In spite of the lower average temperature in Fiji very little difference was noted between the rate of development in that country and in Java.
The adults are diurnal in habit. They mate when settled; not on the wing, as do most mosquitos. The eggs are dropped singly on water where they float on the surface film. They are almost round and glossy white. Oviposition continues over several weeks, and is most prolific in sunny weather. The egg capacity was not determined.
Larvae of Megarhinus fed on tadpoles, Tipulid larvae, Chironomus larvae, and all sorts of mosquito larvae. They do not object to feeding on those mosquito larvae whose bodies are very hairy. They are cannibalistic.
15. In May 1933 a small colony of M. inornatus was brought by the writer from Rabaul to Fiji, since it was reported that this species had been found in New Britain breeding in coconut husks. This species is now being bred in Suva, whence, if it survives, it will be distributed to other parts of the group. Its immature stages are of similar duration to those of M. splendens, so that it would seem very unlikely that this species will succeed in reaching maturity in coconut husks in Fiji, complete evaporation of the water taking place too quickly.
M. inornatus is structurally very close to M. splendens, and it is quite possible that the two species will eventually hybridise in Fiji.
The Sugar–Cane Moth Borers in Mauritius
- L. Andre Moutia
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- 10 July 2009, pp. 33-45
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1. The first record of important damage due to borers in Mauritius dates from 1856, the species being the spotted borer, Diatraea venosata, Wlk. From 1856 to 1897, two other species of borers were introduced, the pink borer, Sesamia vuteria, Stoll, and the white borer, Grapholita schistaceana, Snell. From 1897 to 1916, the damage caused by these three borers decreased gradually, so that from 1916 to 1928 these pests were considered by planters as being of minor importance. From 1928 to 1932 an increase in the damage due to the spotted borer was observed nearly all over the island.
2. The spotted borer causes important damage on the coast belt during the dry and cold months, i.e., April to July. The pink borer, distributed all over the island, causes damage of medium importance to young canes; it occurs with intensity during the wet and hot months of the year, i.e., December to April. The white borer is also distributed nearly all over the island but causes damage of relatively slight importance in plantations, with the exception of very rare occasions when it occurs sporadically as a serious pest.
3. The losses due to the pink and white borers vary with the localities and are difficult to estimate. As an average, Rs.6·00 per arpent is incurred for control leasures against these pests.
The spotted borer which attacks mature canes causes losses both in the field and in the factory. The reduction in the field, per arpent, averages 15 per cent. The loss in sugar averages 2.3 per cent., i.e., 16 per cent, of sugar in cane. The gross loss per annum for the whole island is about 1½ million rupees, and the net loss approximately Rs.125,000.
4. The proportion of canes attacked by the spotted borer averages 30 per cent. From estimates made according to the method of Wolcott, in Porto Rico, it was found that the percentage of borers per 100 lb. of cane is 39, as a mean, and the number of borers per acre averages 15,698. The mean percentage of stems attacked by 1 to 5, 6 to 10, and 11 to 15 borers is of 87·6, 10·1 and 2·2 respectively. The proportion of nodes attacked varies between 10 and 25 per cent. approximately.
5. The cane varieties that are heavily attacked by the spotted borer are M.55, M.131, D.109, M.1474, White Tanna, B.H.10/12, R.P.6, D.K.74, D.130 and R.P.8.
6. The various methods of control used in the island for the last 15 to 20 years are discussed. Against the pink and white borers the use of trap plants is recommended as well as the collection of larvae. The burning of trash in the fields is to be avoided.
In the case of the spotted borer the destruction of larvae in the tops to be planted is recommended. A practical method consists in the immersion of the tops in cold water during 72 hours, or in hot water at 50–51°C. for 2 to 2½ hours, or 52°C. for 30 minutes, or in saturated lime-water for eight hours.
7. The breeding of the larval parasites is recommended on estates where larva collecting is practised.
8. The advantages or disadvantages of larva collecting and burning of trash are still under consideration.
Studies of the Willow-Shoot Moth, Depressaria Conterminella, Zell
- Mary Miles, Herbert W. Miles
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- 10 July 2009, pp. 47-53
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A study has been made of the biology of Depressaria conterminella, Zell., the most important willow-shoot moth occurring in commercial willow beds of Lancashire and Cheshire.
The eggs are laid in June-July in bark crevices on the stocks near the level of the soil. Hatching takes place in the following spring, beginning about the time the buds open. The eggs are described.
On hatching the larvae travel to the opening buds. First instar larvae tunnel through the outer leaves into the buds, but larvae in the later stages crawl between the leaves, spinning them together to form a feeding shelter. Larvae have four instars and at the third ecdysis there is a marked colour change. Both larval forms are described. In the course of feeding each larva destroys 3–4 shoots. Infested shoots are illustrated. Pupation takes place in the soil and adults emerge after about three weeks.
The habits of the moths are described. The species is univoltine and no instance of parasitism has so far been observed. A list of other Lepidoptera bred from the shoots of willows is given.
The nature of the crop does not permit of costly control measures. The study of the biology suggested that infestation might be checked by delaying harvesting until after the larvae hatched. In an experiment in the field it was found possible to reduce infestation from over 40 per cent. to under 5 per cent. by this method. Infestation was also reduced by burning waste hay over the rows of willow stocks during the dormant season.
On the Bionomics of a Eulophid (Trichospilus Pupivora, Ferr.) A Natural Enemy of the Coconut Caterpillar (Nephantis Serinopa, Meyr.) in South India
- K. P. Anantanarayanan
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- 10 July 2009, pp. 55-61
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The black-headed palm caterpillar (Nephantis serinopa, Meyr.) has been known to be a serious pest of coconut palms both in Ceylon and South India for many years past, and during the past ten years its appearance on a serious scale along the Malabar coast in South India has been attracting the attention of the Entomological Section of the Madras Agricultural Department. Among the different methods of control, the utilisation of the natural enemies of the pest has been tried to some extent. One of the more important natural enemies found to exert some appreciable influence on this pest was a Eulophid wasp, Trichospilus pupivora, Ferr. As one of the officers of the Entomological Section engaged in the work connected with this coconut pest, the author had opportunities of closely studying this parasite, and in this paper a brief account is attempted of the bionomics of this insect and of some methods employed in breeding it on a large scale.
The Solitary Phase of Schistocerca Gregaria, Forsk., in North-Eastern Kordofan (Anglo-Egyptian Sudan)
- R. C. Maxwell-Darling
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- 10 July 2009, pp. 63-83
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This is an account of work carried out in Kordofan on behalf of the Imperial Institute of Entomology. The period August-September 1931 was occupied with preliminary surveys and observations on hopper bands. From July to September 1932 and from March to July 1933 the ecology of the solitary phase of Schistocerca gregaria was studied at Um Darag ; and in January 1933 a locust survey of the more northern parts was carried out.
The Influence of Temperature on the Activity of Sheep-Blowflies
- A. J. Nicholson
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- 10 July 2009, pp. 85-99
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1. Quantitative methods of recording the activity of blowflies are described.
2. With constant temperatures the greatest activity occurs near the centre of the temperature range, whereas with rising temperature it immediately precedes the upper thermal death-point.
3. Rising temperature causes activity to occur at a lower range of temperatures than does constant temperature.
4. Rising temperature causes the appearance of “distress activity” at high temperatures, but constant temperature does not.
5. For the development of the necessary energy for full crawling and flight activity at the most favourable temperatures, rather long exposure to these temperatures is necessary.
6. Flight and, to a lesser extent, crawling occur in bursts of activity whether the temperature is rising or constant.
7. Differences in the reactions to temperature of the closely related species Lucilia cuprina and L. sericata are very distinct.
8. The curves for general activity and temperature preference correspond to the known distribution of the four species examined.
9. Frequency of regurgitation is definitely associated with high temperature.
10. There are strong indications that the conditions of the experiment were suitable for the flight of L. cuprina but unsuitable for that of the other species examined. This may have been due to the lack of bright sunlight, or to the confined space of the observation-jars.
11. It is shown that activity is a complex phenomenon, and that the character of the results obtained is influenced by the kind of activity examined, by the methods of measurement used, and by the nature of the temperature conditions to which the insects are exposed.
Observations on Phases of the Red-Winged Locust in Northern Rhodesia
- A. P. G. Michelmore, W. Allan
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- 10 July 2009, pp. 101-128
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1. The egg, vermiform larva, and the nymphal stages of ph. gregaria are described. It is shown that six stages occur, or seven instars including the vermiform larva. These stages can be distinguished by (a) the number of antennal joints, (b) the degree of backward prolongation of the pronotum, (c) the differentiation of the terminal abdominal structures. Measurements of the pronotum and femur served to distinguish the stages in material from the same swarm, but the absolute measurements cannot be used to distinguish material from different sources.
2. The colour pattern of ph. dissocians is analysed, and colour changes are indicated as divergences from the gregaria pattern. Forms of ph. dissocians observed in the field are grouped into several types the relationships of which are illustrated, and the environmental factors which produce them are discussed.
3. Hoppers believed to be of ph. congregans could not be distinguished from certain forms of ph. dissocians.
4. Cage experiments in which hoppers were reared under varying degrees of crowding are described. It is strongly indicated that activity which is induced by crowding influences the development of gregaria colouring. The green colouring of dissocians hoppers appears to be associated with high humidity conditions and the presence of green food. Other colours of dissocians hoppers are conditioned by those of the environment.
5. An aberrant pallid type of hopper is described and its origin is ascribed to the effects of parasitism by Nematodes and possibly also by Dipterous larvae.
6. Certain inferences regarding the processes in the formation of the colour pattern are inferred from a consideration of the effects of parasitism and of dissocians producing factors.
7. The colourings of young adults of ph. gregaria a few days after the ultimate moult and of types taken from large swarms in August are described. It is shown that colour changes occur gradually in the field, the conspicuous pattern of light and dark coloration of the young adult being obscured and finally hidden by the development of a bright red pigmentation.
8. The colouring of young adults of ph. dissocians is described. These show a pattern of light and dark coloration similar to that of the young adult of ph. gregaria, from which it is indistinguishable, immediately after the ultimate moult. In ph. transiens no marked colour change takes place throughout the life of the individual except the development of a purple coloration on the hind wings.
9. Factors influencing adult colouring are discussed. Adults crowded in cages and derived from hoppers reared under crowded conditions did not undergo the colour changes observed in the field. Material taken from large swarms in the field and showing some development of swarm colouring were maintained under crowded and uncrowded conditions. The red pigment of the body changed to a dark brown in both cases. Under uncrowded conditions no further change took place except a conspicuous development of purple coloration on the hind wings in all individuals. Under crowded conditions the brown pigment spread, its final distribution resembling that of the red pigment in later swarm types from the field, but the red colouring of the hind wings was developed only to a very slight extent in a few individuals. In the case of individuals isolated completely the swarm colouring was lost entirely.
10. It is inferred that swarm colouring in the adult is associated with crowding and possibly with activity and that development of the red and purple coloration on the hind wings in gregaria and transiens is affected by different factors and possibly differs in composition.
11. Biometrical data obtained from a variety of types is tabulated and discussed. Material varied from types taken from very large and dense swarms to what might be described as “solitaria beginning to congregate.”
12. It is shown that certain measurable characters, especially the relative size of the sexes, the degree of development of the femur in relation to the wing, and the relative length and degree of constriction of the pronotum differ greatly in gregaria and transiens types and may be used to distinguish them.
13. In the case of material from very large and dense swarms and from very small loose swarms no differences in the characters on which the types could readily be distinguished were observed. It may be that these small groups were derived from larger swarms.
14. Interesting aberrations occur in the case of a swarm believed to have been one of the earliest to migrate any considerable distance after the commencement of swarming. The quantity of material was insufficient to permit of very reliable comparison but it would appear that in these forms the pronotum of the female was generally not shortened or constricted to the same extent as in extreme gregaria, although the construction of the pronotum of the male approximated fairly closely to that of more extreme gregaria
List of Chalcid Flies (Hym.) reared in U.S.S.R
- M. Nikol'skaya
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- 10 July 2009, pp. 129-143
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This paper records a number of parasitic and phytophagous species of Chalcididae that have been reared in U.S.S.R. during recent years. The material was partly collected by the author herself, or received for identification from various persons and institutions.
Miscellaneous
Collections Received
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- 10 July 2009, pp. 145-147
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Front matter
BER volume 25 issue 1 Front matter and Errata
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- Published online by Cambridge University Press:
- 10 July 2009, pp. f1-f6
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