EGG DISTRIBUTION OF THE FRUIT BORERS CRYPTOPHLEBIA-LEUCOTRETA (MEYRICK) AND CRYPTOPHLEBIA-BATROCHOPA (MEYRICK) (LEPIDOPTERA, TORTRICIDAE) AND THEIR EGG PARASITOID TRICHOGRAMMATOIDEA-CRYPTOPHLEBIAE NAGARAJA (HYMENOPTERA, TRICHOGRAMMATIDAE) IN MACADAMIA TREES IN MALAWI

Field surveys of egg populations of Cryptophlebia leucotreta (Meyrick) , C. batrochopa (Meyrick) and their egg parasitoid Trichogrammntoidea cryptophlebiae Nagaraj were undertaken on macadamia trees at four orch ard sites in Malawi. At three sites, significantly more Cryptophlebia eggs were laid on nuts at the bottom of the canopy. There was a decrea se in the number of eggs with increasing height in the tree at all sit es. Differences between the number of eggs at the middle and top of th e trees were not significant at two sites. Differences in the level of oviposition at the centre and periphery of the canopy were also not s ignificant. Although all sites showed a slight increase in percentage parasitism of Cryptophlebia eggs by T. cryptophlebiae with height in t he tree, none of these increases was statistically significant. At two sites, there was a decrease in the number of viable and dead Cryptoph lebia eggs with increasing height. The differences in the number of li ve, hatched and dead eggs at the centre and periphery of the canopy we re not significant. A higher percentage parasitism did not cause reduc tions in the number of borer-damaged nuts, and there was a weak negati ve correlation between the percentage of mature nuts and the percentag e of borer damage at all of the sites. These findings suggest that mon itoring for pest management decisions should be concentrated at the bo ttom of the tree canopy.