Bio-ecology of false codling moth,Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) within citrus orchards in Kenya and Tanzania

1. False codling moth, Thaumatotibia leucotreta is among the key constraints of the agricultural industry. Little is known about the population dynamics and genetic diversity of this pest in East Africa.
2. The spatial–temporal population dynamics and genetic diversity of false codling moth were evaluated in citrus orchards in Kenya and Tanzania between May 2017 and August 2018 covering two fruiting seasons. The diversity of false codling moth sampled in these orchards and from solanaceous hosts, as well as from specimens received from Uganda, Sudan, and South Africa were assayed using the mitochondrial cytochrome oxidase I gene.
3. A similar spatial–temporal pattern of false codling moth was found in both Kenya and Tanzania, with the most male moths in August 2017 and 2018. In Tanzania, the number of male moths caught at high and mid altitudes did not differ but were significantly higher than those caught at low altitude.
4. A relatively low false codling moth genetic diversity was recorded at the sites where sampling was done in the respective countries as well as between specimens sampled from different host plants.
5. The low false codling moth genetic diversity determined in this trial can be exploited in the management of the pest in the studied countries.

     

Pyrene-degradation potentials of Pseudomonas species isolated from polluted tropical soils

Three Pseudomonas species isolated from oil polluted soils in Lagos, Nigeria were studied for their pyrene degradation potentials. These isolates exhibited broad substrate specificities for hydrocarbon substrates including polycyclic aromatic hydrocarbons, petroleum fractions and chlorobenzoates. All three isolates tolerated salt concentrations of more than 3%. They resisted ampicillin, cenfuroxime, but susceptible to ofloxacin and ciprofloxacin. Pseudomonas sp. strain LP1 exhibited growth rates and pyrene degradation rates of 0.018 h⁻¹ and 0.111 mg l⁻¹ h⁻¹ respectively, while P. aeruginosa strains LP5 and LP6 had corresponding values of 0.024, 0.082 and 0.017, 0.067 respectively. The overall respective percentage removal of pyrene obtained for strains LP1, LP5 and LP6 after a 30-day incubation period were 67.79, 66.61 and 47.09. Resting cell assay revealed that strain LP1 had the highest uptake rate. Strains LP1, LP5, and LP6 also used the ortho-cleavage pathway. Enzyme study confirmed activity of catechol 1,2-dioxygenase in all with values 0.6823, 0.9199, and 0.8344 μmol min⁻¹ mg⁻¹ respectively for LP1, LP3 and LP6. To the best of our knowledge, ours is the first report of pyrene-degraders from the sub-Saharan African environment.