oa African Entomology - Egg distribution of the fruit borers Cryptophlebia leucotreta (Meyrick) and C. 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 Trichogrammatoidea cryptophlebiae Nagaraj were undertaken on macadamia trees at four orchard sites in Malawi. At three sites, significantly more Cryptophlebia eggs were laid on nuts at the bottom of the canopy. There was a decrease in the number of eggs with increasing height in the tree at all sites. Differences between the number of eggs at the middle and top of the trees were not significant at two sites. Differences in the level of oviposition at the centre and periphery of the canopy were also not significant. Although all sites showed a slight increase in percentage parasitism of Cryptophlebia eggs by T. cryptophlebiae with height in the tree, none of these increases was statistically significant. At two sites, there was a decrease in the number of viable and dead Cryptophlebia eggs with increasing height. The differences in the number of live, hatched and dead eggs at the centre and periphery of the canopy were not significant. A higher percentage parasitism did not cause reductions in the number of borer-damaged nuts, and there was a weak negative correlation between the percentage of mature nuts and the percentage of borer damage at all of the sites. These findings suggest that monitoring for pest management decisions should be concentrated at the bottom of the tree canopy.
Article metrics loading...