FURTHER STUDIES ON POLLINATION ECOLOGY IN FICUS SYCOMORUS II. POCKET FILLING AND EMPTYING BY CERATOSOLEN ARABICUS MAYR

Filling of pockets with pollen by the agaonid wasp Ceratosolen arabicus Mayr (Chalcidoidea, Hymenoptera) was studied in Ficus sycomorus L. at Magadi, Kenya. The phenology of the fig during the male phase (D) was observed in detail and various techniques were devised in order to ensure the normal behaviour of the wasps in spite of the bisection of the fig and the strong illumination necessary for carrying out the observations. It was found that in fig‐halves tightly enclosed with cellophane paper during the second morning of the male phase, the emerging wasps filled their pockets with pollen from anthers previously detached by the male wasps. It was established that the cutting of anthers is a separate, specific action and not merely a byproduct of the tunnelling of the syconial wall that takes place afterwards. In the filling act itself, the role of the combs–rows of stiff bristles along the inner margin of each foreleg coax was established. Pollen was lifted by the arolia of the forelegs from the open anthers to the underside of the thorax and shovelled from there by the coxal combs into the thoracic pockets which gaped widely due to the bending of the body. An analysis of the responses of the wasps to various environmental conditions leads to the conclusion that the size of the cavity is a critical factor in the behaviour of the wasps in the fig of F. sycomorus. The possible role of light for pocket filling in the subdued illumination of the intact fig cavity is discussed.