Biological studies of the mottled water hyacinth weevil, Neochetina eichhorniae on the Common water hyacinth Eichhornia crassipes

Abstract

Life parameters of the Mottled water hyacinth weevil Neochetina eichhorniae (Coleoptera: Curculionidae) were studied at 4 temperature (15, 20, 25, 30°c). The host plant was obtained from the Biological Control Studies and Research Centre at the Faculty of Agriculture- University of Damascus. The study was carried out during the 2017 season. The results showed that the Mean generation time GT was (225.9, 57.37, 43.3 and 40.33 days) at previous temperatures respectively, the Net reproductive rate R₀ takes decreasing at high and low temperatures, and the temperature of 30 ° C is the optical degree while the population reproduction at this degree increased well, and the values ​​of R₀ were (0.33, 5.9, 24.7, 39.3) female / female / generation at the previous temperatures respectively, and the Doubling time of the community DT was (82.407, 2.576, 0.464 and 0.271) on the previous consecutive temperatures. The Intrinsic rate of increase (r_m) was 0.0038, 0.269, 1.493, and 2.55 (individual / female / day) at temperatures 15, 20, 25 and 30 ° C. The Lower Developmental Threshold (LDT) for the different stages of the insect was different (9.252, 9.3, 10.4, and 12.3), respectively. The Sum of Effective Temperatures (SET) was 93.457 degrees / day for the egg stage and 384.6 ° / day for Larvae, 256.4 degrees / day for pupa, 714,285 degrees / day for complete insect phase, 769.23 degrees / day for whole generation (from egg to adult).