Browsing by Author "Lyimo, P. J."

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Impact of heteropsylla cubana infestation on Leucaena leucocephala in Morogoro and Tanga regions, Tanzania
(2024) Lyimo, P. J.
Heteropsylla cubana has damaged Leucaena leucocephala in Tanzania since its 1992 outbreak while its impacts remain unclear to date. This study aimed to assess the impact of Heteropsylla cubana on L. leucocephala, a valuable multi-purpose tree in Tanzania. Using the Point Centre Quarter method, the study observed L. leucocephala in Morogoro and Tanga regions to determine the population density of H. cubana, infestation density, and shoot health. Descriptive statistics were used to calculate the frequency and mean population density of H. cubana, infestation density, and shoot health. Analysis of Variance was used to compare the mean population density of H. cubana among different diameter at breast height (dbh) classes and crown parts. The findings show that the population density of eggs of H. cubana differed significantly among crown levels in Morogoro, but not in Tanga. There was no significant difference in nymph and adult population density among crown levels or dbh classes in both regions. The infestation density and shoot damage were slightly higher in Morogoro than in Tanga, but both regions had good shoot health. Farmers can safely plant L. leucocephala without fear of H. cubana, as its population is below injury level in the study areas.
Pest status of leucaena psyllid, Heteropsylla Cubana crawford (Homoptera: Psyllidae) and biological control agents in eastern Tanzania
(Sokoine University of Agriculture, 2016) Lyimo, P. J.
Heteropsylla cubana has caused damaging effects to Leucaena leucocephala in Tanzania since its outbreak in 1992. The major objectives of the study were; to determine population density of H. cubana, mummies of T. leucaena and P. yaseeni, indigenous predators associated with H. cubana, infestation density and shoot health of L. leucocephala resulting from H. cubana attack in Morogoro and Tanga region. The Point Centre Quarter method was employed to select L. leucocephala for observation of H. cubana, mummies, indigenous predators, infestation and shoot health. R and Excel program software were used in data analysis to obtain descriptive statistics of observed data. The mean number of eggs, small nymphs, medium nymphs, large nymphs and adults per 15cm terminal shoot were 14.24, 11.77, 8.78, 4.79 and 2.81 in Morogoro and 11.40, 8.16, 5.80, 3.72 and 2.42 in Tanga respectively. The population density of eggs differ significantly among crown levels (upper, middle and lower) and not significant among dbh classes (1-5 cm, 6-15 cm and >15 cm) in Morogoro. The situation was different in Tanga where there was no significant difference among crown level and dbh classes. The interaction between dbh classes and crown level was not significantly different in both Morogoro and Tanga for eggs population density. The mean number mummies of T. Leucaenae and P. yaseeni were 2.33 and 1.68 in Tanga and 2.64 and 2.1 in Morogoro respectively. The dominant indigenous predators found were spiders followed by ladybird beetles, dragonflies and lacewings for adult and regenerants L. leucocephala. The infestation density and shoot damage were slightly high in Morogoro compared to Tanga for adults and regenerants L. leucocephala. The study has found good shoot health and small injury to L. leucocephala. Farmers are advised to plant L. leucocephala for various usesas psyllid’s population is no longer a problem.