The Control of Coccidae on Coconuts in Seychelles

Abstract

1. The investigation which forms the subject of this paper was commenced in 1936 and closed in 1939. Owing to the low returns from an acre of coconut land it was imperative that control measures should be cheap. Biological methods were therefore employed.2. The soils on which coconuts are planted in Seychelles fall into three main types: (a) beds of coral sand, (b) various types of transported soils, (c) sedentary soils.3. The robustness of the trees was found to be in direct proportion to the quality of the soil. The best trees are located on the deeper alluviums. The limiting factor on the coral sands is often drainage. On the hill-sides the trees deteriorate in proportion to the soil impoverishment and erosion.4. A complex of scale species attack coconuts in Seychelles. None of these presents major problems in other countries, and the better known scales which are pests on this crop in other countries are not found in Seychelles. Four major species are mentioned, two of which are recent introductions to the islands. The life-history and particular requirements of each species are given and their incidence on coconut and their interspecific relationships are discussed.5. In order to combat these scales four species of Coccinellidaewere introduced from East Africa, two of which were predators on Diaspid and two on Lecaniid scales. The life-history, breeding technique and establishment of each is described.