Platynota flavedana Clem. (Lepidoptera, Tortricidae) on Citrus in Jamaica

Abstract

Platynota flavedana Clem. (Lepidoptera, Torticidae), the ‘fruit-dropping caterpillar’ or ‘citrus tortrix’, is an important but sporadic pest of Citrus in Jamaica.Damage is confined to part of the period between April and June, and in a heavy attack large numbers of young Citrus fruits, each bearing a scar or hole in the area shielded by the sepals, are found beneath the trees. At other times of the year the insect is present in the orchards in small numbers only.In the field, the eggs, which are laid in clusters, were found on the leaves of Citrus, the larvae in webbing tunnels, usually beneath the sepals of young fruits but also between leaves drawn together with silk, and the pupae within the webbing. Fertilished females isolated in 3 × l-in. glass subes oviposited readily and continued to do so for rather less than a week. The incubation period of the eggs was 6.5 days. Preliminary experments showed that the young larvae require either new, rapidly growing leaves or young fruits of diameter less than ½ in., and a technique for rearing individual larvae in described. The durations of the larvae and pupal phases were 17–35 and 5–10 days, respectively.In the past, chemical control measures had been attempted when large numbers of small fruits had already fallen. It is suggested that such measures cannot be effective because the hardness of texture, that makes them unsuitable for the development of young larvae. Some evidence is provided of effective control by natural factors, throught to be of a pathogenic nature, and it is recommended that the possibility of biological control should be investigated. The difficulties of fitting biological control into the pattern of routine fungicidal spray-applications is mentioned.It is concluded that a comprehensive investigation of both chemical and biological control is necessary, and it is suggested that in areas where outbreaks of the pest occur at all regulary it would be wise, meanwhile, to apply an insecticide, preferably when the new leaves and flower buds are developing and at latest before completioon of petal-fall.