The permanent mass rearing of rice stem borer, Chilo zacconius in West Africa; rice stem borer, Chilo suppressalis, in Asia and Europe; and sugar-cane stalk borer, Chilo sacchariphagus, in Asia and Indian Ocean was perfected in the laboratory to enable us multiply some parasites such as Apanteles spp., Goniozus procerae, Tetrastichus spp., Trichospilus spp. or the tacbinids, Diatraophaga striatalis and Lixophaga diatraeae.

The principal difficulties appear during mating of several hosts and parasites, development of pyralid young larvae or when it is necessary to protect reared insects or artificial medium against pathogens.

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.

Pheromones have been successfully used on a large scale for control of pink bollworm, Pectinophora gossypiella, by mating disruption in Egypt and Pakistan using various slow release formulations. Similar formulations are being developed for control of other cotton bollworms, Earias insulana and E. vittella. Small-scale trials are in progress to evaluate pheromone formulations for control of sugar-cane borers, Chilo sacchariphagus and C. auricilius in Mauritius and India, and the tropical warehouse moth, Ephestia camelia, as a pest of stored cocoa in Brazil. Traps baited with the pheromone of the African armyworm, Spodoptera exempta, have been extensively used in Eastern and Southern Africa as the basis of a forecasting system of pest incidence.

Traps baited with the synthetic aggregation pheromone of the larger grain borer, Prostephanus truncatus, have been developed and are in use in E and W Africa for detection and monitoring of this pest of stored grain.