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A Review of twenty-five Years of economic Entomology in the Island of Mauritius
- L. Andre Moutia, Raymond Mamet
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- Journal:
- Bulletin of Entomological Research / Volume 36 / Issue 4 / December 1946
- Published online by Cambridge University Press:
- 10 July 2009, pp. 439-472
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The practical results achieved in the past twenty-five years' work on the major insect pest problems of Mauritius are discussed.
The major insect pests studied are the white grubs of sugar-cane, Clemora smithi (= Phytalus smithi) and Oryctes tarandus; the sugar-cane moth borers, Proceras sacchariphagus, Sesamia vuteria, and Argyroploce schistaceana; the coconut scale-insect, Aspidiotus destructor; the pineapple mealybug, Pseudococcus brevipes; the cochineal insects of the prickly pears, Dactylopius tomentosus and D. indicus; fruit-flies; the biting flies, Stomoxys nigra and S. calcitrans; the red ant, Solenopsis geminata; the black ant, Technomyrmex detorquens; and termites.
The actual status of these pests is given in detail. Clemora smithi, which was first recorded in 1911, is still a major pest of sugar-cane in spite of the 43 species of parasites and 2 species of predators introduced to check it. Oryctes tarandus very seldom causes severe damage now to sugar-cane plantations. It is a sporadic pest, and has been definitely held in check since the Scoliid wasp, Scolia oryctophaga, was introduced from Madagascar in 1917.
The status of the three moth borers of sugar-cane and that of their parasites is fully dealt with. Of the five species of parasites introduced from Ceylon and Madagascar in 1938–40 to control Proceras sacchariphagus, only one has so far been recovered and its beneficial effect is very limited. An account is given of experiments on the mass liberation of the egg parasites, Trichogramma australicum and T. evanescens. The results were in both cases deceptive. The spotted borer, P. sacchariphagus, is a major pest of sugar-cane in some localities and further introductions of parasites from other cane-growing countries are recommended.
The coconut scale, Aspidiotus destructor, which, since 1927, threatened all the coconut plantations of the Island, is now under control, owing to the introduction from Ceylon and Java, respectively, of the predacious Coccinellids, Chilocorus nigritus and C. politus. The bionomics of the various parasites and predators of this scale in Mauritius are fully described.
A historical review is given of the introduction of the cochineal insects of prickly pear, Dactylopius indicus and D. tomentosus in the Island. The completely successful eradication of Opuntia tuna and O. monacantha, by these two Coccids is given as a typical example of the biological control of noxious plants by insects.
The pineapple mealybug. Pseudococcus brevipes, which is responsible for wilting disease, is considered to be one of the factors limiting the development of the pineapple industry in Mauritius. Spraying with a diesel-clay emulsion, though checking this pest, is limited in its application. Further introductions of parasites and predators are desirable.
The common white mealybug, Icerya seychellarum, is still a major pest of orchards and ornamental plants in spite of the presence of the local Coccinellid predators, Rodolia chertnesina and Exochomus laeviusculus. Practical control can be achieved by the use of banding grease coupled with the attacks of predators. No local parasite has been recorded in Mauritius.
Six species of Trypetids are recorded. Of these, the flies attacking cucurbitaceous fruits are the most harmful. Experiments with numerous attractants for fruit-flies are mentioned. The only bait showing any success in the control of the Dacus flies is the Mally fruit-fly bait. Parasites have been imported from South Africa and Ceylon without success. Further attempts should be made.
The bionomics and breeding places of the blood-sucking fly, Stomoxys nigra, are described.
The Red Ant, Solenopsis geminata, is a major pest of seedlings in Mauritius. It is now destroyed by the use of a diesel-clay emulsion. Baits containing thallium sulphate have been tried without success.
The rôle of the Black Ant, Technomyrmex detorquens, in preventing development of the Coccinellid predators on Icerya seychellarum is emphasised. Barber's poisoned bait has been found very useful against this household pest.
A review of the species of termites found in Mauritius as well as the various means of control used against them are given. An insecticidal powder containing arsenious oxide has given the best results.
During the last 25–30 years, 64 species of parasites and predators have been imported for the biological control of eight species of insects of major economic importance and of two species of noxious plants.
The results achieved indicate that the introduction of parasites and predators in insular countries like Mauritius should be carried out only after a thorough investigation of the various ecological, biotic and climatic factors existing between the country of exportation and the country of importation.
The rôle of cyclonic disturbance in the fluctuation of the parasite population is mentioned. Scoliid parasites, for instance, are generally scarce after violently disturbed weather and may sometimes remain so for two or three years after the disturbance.
The Search for Parasites of White Grubs (Melolonthids) in Zanzibar, Algeria, Morocco and France
- L. Andre Moutia
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- Journal:
- Bulletin of Entomological Research / Volume 31 / Issue 2 / June 1940
- Published online by Cambridge University Press:
- 10 July 2009, pp. 193-208
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(1) An extensive survey covering a period of 18 months was carried out in Zanzibar, Algeria, Morocco and some parts of France with a view to obtaining parasites of white grubs for furthering the control of Phytalus smithi, Arrow, in Mauritius.
(2) In Zanzibar the results of the survey showed that white grubs are of no great economic importance in clove plantations in this Island. Larvae of several species of white grubs were obtained, viz.: Entyposis impressa, Kolbe, Schizonycha spp., Anomala delagoa, Pèr., etc. ; these larvae are parasitised by the Dexiid fly, Microphthalma disjunctum, Wied. The percentage of parasitism at the time of the survey was from 0·10 to 0·53 per cent. Scoliids were not in great number ; the parasitism amounted to 0·6 per cent. Parasites of adult beetles were obtained on the following insects: Entyposis impressa, Kolbe, Schizonycha spp. and Anomala plebejus, Ol., the parasites being Pexopsis pyrrhaspis, Villen., and an Adapsilia, not yet determined. The parasitism on the above mentioned beetles varied from 1 to 9·7 per cent.
The Sugar-cane Scale, Aulacaspis tegalensis, Zehnt
- L. Andre Moutia
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- Journal:
- Bulletin of Entomological Research / Volume 35 / Issue 1 / April 1944
- Published online by Cambridge University Press:
- 10 July 2009, pp. 69-77
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The sugar-cane scale, Aulacaspis tegalensis, Zehnt., has been known to exist in Mauritius since the year 1899, when de Charmoy recorded it for the first time in the Island.
The species was described by Zehntner in 1898 from Java on sugar-cane, since when little has been recorded of its geographical distribution. In 1921, Ferris recorded it from Formosa. In 1938, D. d'Emmerez de Charmoy, jr., called the attention of the planters of Reunion to the damage caused by this scale on sugarcane, and the author had suspected its presence there many years previously. In Java it was considered of minor importance by Zehntner in 1897. In 1911 Van Deventer drew attention to the damage it caused in Java, and in 1915 van der Goot recorded a serious infestation in the experimental cane fields of the Java Experimental Station. Apart from these records, it has not been reported from other sugar-cane growing countries.
Parasites of the Moth-Borers of Sugar-cane in Mauritius
- L. Andre Moutia, Claude. M. Courtois
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- Journal:
- Bulletin of Entomological Research / Volume 43 / Issue 2 / July 1952
- Published online by Cambridge University Press:
- 10 July 2009, pp. 325-359
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There are three moth-borers of sugar-cane in Mauritius, Proceras sacchariphagus Boj. (Crambid.), Sesamia vuteria (Stoll) (Agrotid.) and Olethreutes schistaceana (Snell.) (Olethreutid.).
The eggs of all three are parasitised by Trichogramma sp. ? australicum Gir., while a second undetermined species of Trichogramma parasitises the eggs of Sesamia and Olethreutes. Sesamia eggs are also parasitised by a Scelionid, Platytelenomus sp. ? hylas Nixon.
The Sugar–Cane Moth Borers in Mauritius
- L. Andre Moutia
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- Journal:
- Bulletin of Entomological Research / Volume 25 / Issue 1 / March 1934
- Published online by Cambridge University Press:
- 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.
Contribution to the Study of some Phytophagous Acarina and their Predators in Mauritius
- L. André Moutia
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- Journal:
- Bulletin of Entomological Research / Volume 49 / Issue 1 / March 1958
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- 10 July 2009, pp. 59-75
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During investigations on the phytophagous mite fauna of Mauritius, of which up to the present five species only had been recorded, 21 species were collected, of which ten species belong to the TETRANYCHIDAE. In addition, nine species, of which the majority are believed to be predacious, were observed.
An annotated list of the species, together with their food-plants, their geographical distribution and the countries from which they might have been introduced into Mauritius, is given.
Of the species of economic importance the following are worthy of mention: — In the TETRANYCHIDAE: Eutetranychus banksi (McG.) on Citrus, Oligonychus biharensis (Hirst) and Oligonychus mangiferus (Rahm. & Sapra) on various fruit trees, including avocado, mango and litchi, Oligonychus sp. (pratensis (Banks) group) on sugar-cane, Tetranychus marianae McG. and Tetranychus sp. (ludeni Zacher group) on many vegetable crops, including bean, egg-plant, tomato, etc. In the ERIOPHYIDAE: Phyllocoptruta oleivora (Ashm.) and Tegonotus sp., which are potential enemies of Citrus and tomato, respectively. In the TENUIPALPIDAE: Brevipalpus phoenicis (Geijskes) has a very wide range of food-plants and its future importance in the cultivation of tea and Citrus are mentioned, whilst Raoiella indica Hirst is an important pest of coconut plantations. In the TARSONEMIDAE: Hemitarsonemus latus (Banks) ranks as an important pest of a large number of economic plants including bean, tea and water-cress.
Only two predatory mites of great economic importance are recorded, viz.:— Typhlodromus caudatus (Berl.) and T. ovalis Evans. The bionomics of the former species are fully described and its relation to Raoiella indica on coconut is discussed. The life-cycle of T. caudatus from egg to adult varies from 4–8 days, in summer to 13–18 days in winter.
Results are given of a survey of the predatory insects associated with the phytophagous mites. The most important predators on Tetranychus spp. are the Coccinellid, Stethorus vinsoni Kapur, and the Cecidomyiid, Feltiella sp. near tetranychi Rübs. The daily mite consumption of these predators is given. Other predators of secondary importance are Oligota pallidicornis Cam. and Scolothrips sp. near indicus Priesn.
The bionomics of T. marianae on tomato and of Raoiella indica on coconut were studied. Duration of the life-cycle of the former species varies from 4–9 days in summer to 15–22 days in winter. Twenty four to 30 generations of this species are estimated to occur in a year. Raoiella has a development period of 18–26 days from egg to adult in summer and of 30–36 days in winter.
A biological study of the predatory insects, Stethorus vinsoni and Feltiella, sp., is given. Their beneficial effect is discussed. These two predators do not exert a control in time to check the build-up of the mite population. Their abundance is directly proportional to the incidence of the mite and the peak is generally only attained when the depredations of the latter have reached a disastrous level.
The various possible factors which have contributed to the sudden increase in the mite population on tomato during the last 6–8 years are discussed. Amongst the important factors are the following: —
(a) Absence of cyclonic disturbances with their heavy rains and violent gales which generally upset considerably the development of the mite population and reduce it to a minimum each year.
(b) Dressing of tomato and other vegetable crops with nitro-phosphatic fertilisers which were not applied until 10 years ago and which, it is thought, may have favoured an increase in the mite population.
(c) The abundance of natural reservoirs of wild food-plants that harbour Tetranychus spp. from which the subsequent spread results in the building up of mite colonies in cultivated areas.
(d) The ineffectiveness of Stethorus vinsoni as a predator on infested tomato plants.