Observations on the life-history and bionomics ofAnjeerodiplosis peshawarensisMani (Diptera: Cecidomyiidae)

Abstract

Anjeerodiplosis peshawarensisMani is a serious pest in North India of the fruit of the country fig (Ficus carica), which is its only known host. The midges are abundant, hovering under the host tree in the mornings and at dusk, and breed throughout the year, except in the summer from April until the July rains. In this period newly formed fruits are not infested, but in other months scarcely 30 per cent, of the fruits remain free from attack.Eggs are laid in fruits when they one week old, succulent, and of the size of a pea. The eggs are minute, hyaline, unsculptured, oval and pedicellate and occur in bundles of 16. Incubation takes three days in September and March and five days in December and January. In laboratory tests, average viability in January was found to be about 83 per cent.The entire larval period is passed inside the figs, each of which may contain 200–300 larvae. There are four larval instars, which differ in size according to Dyar's law and in morphology. The first-instar larva is devoid of cuticular outgrowths and does not show spiracles; the second and third instars have nine pairs of spiracles and possess characteristic spines, warts and tubercles; the fourth instar develops the sternal spatula. The entire larval period lasts three weeks from the middle of August to October and four weeks in January and February. From the middle of April until the July rains, fourth-instar larvae remain inside the figs. When the larval period is three weeks, the first and second instars together and the third and fourth instars separately last about a week.Full-grown fourth-instar larvae bore out of the fruit and drop to the ground, where they jump for some time with the aid of their sternal spatula. They finally pupate in the soil without forming a cocoon but become covered in a protective case composed of soil particles that adhere to the larval skin. Early fourth-instar larvae, which do not have a sternal spatula, if taken from the fruits, may also successfully pupate, and the pupal period is normal. This period is 10–15 days between July and November and 25–26 days in January and February. It is shortest (10 days) in the rainy season, when both temperature and humidity are high.The pupa is obtect, creamy white and bears poorly developed cephalic horns and bristles, well developed thoracic horns and many spines and cuticular outgrowths. Mortality in the pupal stage is between 15 and 30 per cent.Emergence of the adults invariably occurs in the early hours of the day. Two or three days before emergence, the protective case becomes detached piecemeal. Males emerge before females. The ratio of males to females on the day of emergence is 1:2 between March and December and 2:3 in January and February. Copulation starts soon after emergence and lasts from 60 to 90 seconds.There is considerable overlapping of generations. On the basis of the time required for completion of the life-cycle in different months, it is calculated that seven generations are completed in a year.