Little is known about phase polymorphism in the red locust, Nomadacris septemfasciata (Serville) in Madagascar, despite its economic importance. Only solitary and transiens forms have been reported from the island earlier, but not the gregarious form. Important recent outbreaks have allowed for the studying of the phase polymorphism under experimental and field conditions. Morphometric differences (pronotum size and shape, and F/C and E/F ratios) were noted among hoppers and adults caged for several generations and at various densities, in a field laboratory. These criteria were later used to study adults collected in different areas between 1996 and 2002, from populations with various densities (<1000 to >25,000 imagos/ha). Morphometric measurements revealed that gregarious red locust populations have existed naturally in Madagascar and that these were erroneously classified as transiens forms. The upper threshold density for the solitary phase was estimated at 5000 adults/ha; beyond this limit, locusts develop either into transiens or into highly gregarious forms. The southern part of the island, known as a red locust outbreak area, has harboured gregarious phases despite previous reports that prevailing ecological conditions are not suitable for its complete phase transformation. Deforestation in the northern part of the island has probably led to new favourable biotopes for serious outbreaks and gregarious populations development.

The activities, working conditions and progress of the International Red Locust Control Service during the mid-1950s are outlined. Research programmes and results are summarised.

The red locust, Nomadacris septemfasciata (Serville) (Orthoptera: Acrididae), is a threat to agricultural productivity in Malawi. The country has a single known red locust outbreak area, the Lake Chilwa flood plains in southern Malawi, in addition to several other areas where the locust occasionally breeds. Activities of the red locust in Malawi during the period 1988 to 1998 are discussed. Four major outbreaks occurred during the period—in 1993, 1995, 1996 and 1997. Control of these outbreaks was conducted by air except for the 1995 outbreak in Mpatsanjoka River Valley which was controlled by spot treatment on the ground. The use of both a helicopter and a fixed-wing aircraft, where the helicopter locates locust swarms and their concentrations and guides the spray aircraft, appears to be the most efficient and effective strategy for controlling locust outbreaks in Malawi.

Austracris guttulosa in northern Australia is similar to Nomadacris septemfasciata in the southern half of Africa in having one generation per year, mainly in tall grass plains that are seasonally flooded by rainfall and flooding rivers. Locusts survive the dry season as adults and after the early rains of the wet season, oviposit in bare areas. Young offspring nymphs hatch out and feed on adjacent short ephemeral grasses while older nymphs and young adults are in taller vegetation. While locusts usually do not breed well outside tall grass plains of the source area, rain is critical to overall population increase of A. guttulosa, allowing egg and nymphal survival in the normally dry open plains south of the source area. When such rain falls, a preventive control programme is instituted, which begins with forecasts of population increase in areas receiving rain for offspring survival; any high populations found are delineated for control. While swarms within the source areas are often not controlled, those further south nearer cropping areas usually are. Austracis guttulosa does not form bands, so control is usually left until the adult stage when swarms form. Current practice involves the use of chemical insecticides, though promising research indicates that the entomopathogenic fungus Metarhizium anisopliae may form part of an integrated pest management programme in the future.

With N. septemfasciata, outbreaks seem to be related to dry periods, but the precise factors leading to outbreaks are not well understood. Until further research that allows accurate forecasting is undertaken, regular monitoring of outbreak areas and control of any bands and swarms that form will be an essential part of any preventive control programme. Both bands and swarms are present for long periods, giving ample opportunity for preventive control particularly in localities where crops are grown near outbreak areas.

The development of a regional control strategy for the red locust, Nomadacris septemfasciata (Serville) began in the 1920s during a period when red, desert and African migratory locust swarms were widespread in Africa. The strategy involved controlling locusts in their permanent breeding areas to prevent swarms escaping over a much larger invasion area and damaging crops and pasture. Mapping and analysis of reports at the Imperial Institute of Entomology in London and field research in the Rukwa and Mweru wa Ntipa areas confirmed the location of two important red locust outbreak areas, and by the mid-1930s implementation of a preventative control strategy became a practical proposition. Regional control against red locusts formally came into being in 1941 under impetus from the Belgian and British Governments and collaborative surveying and control work continued despite the Second World War. Locust swarm activity intensified in the mid 1940s and other outbreak areas were found, raising the profile of the threat red locusts posed to food security. As a result, international collaboration in research, control and information dissemination was formalised in 1945 through the formation of the IRLCO-CSA.

The International Red Locust Control Service (IRLCS) was formally established in 1949 with the primary objective of controlling locusts in their outbreak areas, thereby preventing the recurrence of plagues. The name of IRLCS was subsequently changed in 1970 to the International Red Locust Control Organisation for Central and Southern Africa (IRLCO-CSA), but retained the same objectives. Over the years, IRLCO-CSA has experienced changes in membership and locations of its Headquarters and operational centres. Its principle mandate has remained the same even though it has been modified and rationalised from time to time. The organisation carried out investigations that led to the identification of the red locust outbreak areas and the development of various control technologies. Control methods developed from the original physical ones which were laborious and inefficient; to insecticide dusting and baiting; to the spraying by aircraft. In its history of locust control programmes, IRLCO-CSA has used arsenic compounds, BHC, DNOC, dieldrin and fenitrothion as insecticides. The success that IRLCO-CSA has enjoyed in its 50 years history has been thanks to the cooperation of countries in eastern, central and southern Africa which are vulnerable to attack by the red locust, and the international community.

The outbreak areas of the red locust are seasonally inundated wetland areas supporting a rich biodiversity. The potential for environmental damage from the repeated use of broad-spectrum insecticides for locust control in these ecologically sensitive wetlands is therefore great. This paper describes the first trial of a Metarhizium anisopliae var. acridum (LUBILOSA isolate IMI 330189) mycoinsecticide as an alternative, more environmentally benign, intervention strategy for managing red locust populations in their outbreak areas. Following initial bioassay tests in the laboratory, which gave 90–93% kill of 3rd instar hoppers within 6–9 days, an oil based formulation of aerial conidia was applied at a rate of 5 × 1012 conidia/ha using a motorised ‘Solo’ knapsack sprayer to treat 3rd and 4th instar hopper bands in the Buzi outbreak area near Beira in Mozambique. Caged samples of 3rd instars succumbed quickly with a median time to kill of 3.6–3.9 days and 98–100% kill recorded within 8–9 days. The 4th instars took longer to die, with a median lethal time of 5.9–6.1days and > 90% mortality after 21 days. Mortality in control samples was low with 13–23% mortality after 21 days. During this mortality assessment period mean minimum and maximum air temperatures ranged from 26–34°C and relative humidity ranged from 85–100%. Observations on treated bands in the field showed that the cohesion of the 3rd instar bands broke down within 6 days, while controls still behaved normally. Unfortunately observations on the 4th instar band had to be terminated after 10 days due to heavy flooding. This preliminary field trial demonstrated the feasibility of using a Metarhizium mycoinsecticide, applied through conventional spray equipment, for controlling the red locust in its outbreak areas.

Prospects for the biological control of locusts and grasshoppers have become much brighter during the last ten years thanks to a number of international research projects. This paper examines a number of options, including one that is ready for immediate implementation: the mycoinsecticide, Green Muscle®, based on the fungus Metarhizium anisopliae (flavoviride) var. acridum. It has been registered in South Africa and other African countries are likely to follow during 1999. Trial results on grasshoppers and several locust species have been very encouraging, and preliminary tests on red locusts show potential as well. Recent research on pheromones also points to some interesting possibilities, both when used alone and in combination with a mycoinsecticide. Finally, microsporidian protozoans and rhabditid nematodes show some promise for long-term suppression of red locust populations, but more research and development is needed to demonstrate their potential.

In 1996, many swarms of red locust, Nomadacris septemfasciata (Serville), formed in the Buzi-Gorongosa outbreak area in Mozambique. Some of these swarms migrated and crossed international boundaries, on a scale not seen since the last plague of 1929–1944.

The swarms did not breed in countries that they invaded, namely, Zimbabwe, Zambia, Botswana and South Africa. On the other hand, in Malawi, successful breeding by the swarms resulted in hopper bands. Filial generation outbreaks continued into 1997 in the breeding area, but at a reduced scale.

An analysis is made of the possible causes of the upsurges of 1996 and the likely implications to the preventive control strategy that has been the principle for red locust plague prevention.

There is need for a further comprehensive study of the Buzi-Gorongosa plains so as to understand better the factors that contribute to its high potential as an outbreak area.

Gregarious swarms of red locust, Nomadacris septemfasciata (Serville) capable of causing loss to agriculture originate from specific breeding areas in eastern and central Africa often referred to as outbreak areas. Typically these areas are poorly drained grassland plains that flood during the wet season and then dry out, creating sites for egg laying and stimulating growth of specific types of vegetation necessary for nymphal survival. During 1996, a significant upsurge of red locust occurred throughout central and western Tanzania. Populations also appeared in the Bahi Plains west of Dodoma, an area where significant infestations of red locust had not been recorded since the major plague of 1930–1944. Aerial spraying controlled 13,700 ha of nymphal bands and swarms. The 1996 upsurge could have been caused by a number of contributing factors: a prolonged drought leading to changes in vegetation; possible changes to flood water levels through diversion for irrigation; and either an undetected movement of red locust into the area from outside or localised breeding over several seasons. As a result of this outbreak the Bahi is likely to remain as a possible source of red locust swarms in the future and should be monitored closely.

This paper is a compilation of abstracts of 91 published articles on the red locust, Nomadacris septemfasciata (Serville) for the period 1940–1998. The summaries have been compiled from material held in the library of IRLCO-CSA at Ndola, Zambia and the University of Zambia, Lusaka. The articles deal with different aspects of the biology, ecology and control of the red locust with about equal coverage.

There are 43 identified insect pests of sugar-cane in Mauritius, of which several are important enough to warrant control measures. However, insecticides are not used for this purpose. All the insect pests of sugar-cane are controlled biologically. This includes traditional biological control using parasites or predators, as well as more recent biology-based methods like the use of resistant cane varieties, sex pheromones, etc.

Mauritius has the distinction of being the first country on record to have successfully introduced a natural enemy, namely the Minah bird, specifically to combat a pest—the Red Locust, Nomadacris septemfasciata, in 1792.

Very few of the insect pests in Mauritius are indigenous; most of them are exotic, having been accidentally introduced into the country, one way or the other. Some of the important ones include: spotted stem borer (Chilo sacchariphagus), armoured scale (Aulacaspis tegalensis), white grub (Clemora smithi), white grub (Heteronychus licas), soft scale (Pulvinaria iceyi), armyworm (Leucania loreyi) and pink borer (Sesamia calamistis).

The introduction of various natural enemies from different parts of the world has been made over the years with different degrees of success. In all, there are presently a total of 102 species of parasites and predators controlling 43 species of sugar-cane insect pests.

With sugar-cane spread out over most of the island and representing 90% of all cultivated land, close vigilance over the important pest populations, and swift counter measures as appropriate, is required. This task is being performed efficiently and successfully by the Mauritius Sugar Industry Research Institute.

This paper describes briefly four different locust species that constitute potential widespread danger to agriculture and pasture in the eastern, central and southern Africa region. Particular reference is made to the red locust, Nomadacris septemfasciata Serville which mostly feeds on monocotyledonous plants. Reference is also made to the African migratory locust, Locusta migratoria migratorioides R&F; the brown locust, Locustana pardalina Walker; and the desert locust, Schistocerca gregaria Forskal. There were frequent reports of damage to cereal crops by the red locust during the most recent plague of the 1930's. However, since that time only a few yield loss data are available owing, primarily, to the fact that locust infestations have mostly been irregular and confined within their natural breeding areas, away from crop land. The paper provides general background information that should enable evaluation of locust incidence in the region and assessment of consequent cereal crop production losses.

The ecology of the red locust, Nomadacris septemfasciata Serv. in its outbreak areas plays an important part in the survival of all its developmental stages. Some of the important ecological factors affecting the multiplication and formation of red locust swarms are described briefly. Different methods of controlling the red locust are discussed including ecological, biological and chemical methods. It is concluded that the various control methods play some part in regulating the locust population but at present, when the populations are high, only the chemical method is capable of reducing the population to acceptable levels. The ‘preventive control’ now used to control the red locust is effective and takes advantage of the biology and the ecology of the red locust in the outbreak areas.