The life history and survival of Neochetina in Lake Victoria basin: Basis for biological weed control
Okeyo Owuor, J.B.
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Using our own experimental data and published data, we review information on the control process of water hyacinth and its status in Lake Victoria basin, Kenya. Experimental results show that the mean fecundity of the two weevils is 290 and 237 eggs per female laid over a period of 16 weeks, with an adult longevity of 98 and 112 days for Neochetina bruchi and N. eichhorniae respectively. There was significant difference between the egg laying capacities of the two weevil species (p=0.002). The survival rate of the two species was significantly different (p<0.05) for all life stages except for larvae to pupa. There was no significant interaction between the species and the method of experimental egg setting (p<0.05). The fecundity of both N. bruchi and N. eichhorniae significantly decreases with time in weeks (t = 4.09; p<0.01 and (t = 3.40.09; p=0.004 respectively). N. bruchi method had a significantly (p<0.05) high larvae to pupa survival percentage (33.8 ± 6.00 for Incision Egg Setting (IES) method as compared to the Free Egg Setting (FES) method (18.7 ± c 2.6). In the case of N. eichhorniae, the percentage survival for IES (25.4 ± 4.6) was also significantly higher (p>0.05) than the FES method (19.7 ± 4.1).On the basis of these results, we review and discuss data on the damage caused by the two weevil species as a basis for large-scale biological control of water hyacinth in Lake Victoria basin.
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