Rearing Method and Life History of Laboratory Bred African Coffee White Stem Borer, Monochamus Leuconotus (Pascoe) (Coleoptera: Cerambycidae)

Abstract

African coffee white stem borer, Monochamus leuconotus (Pascoe), Cerambycidae, is a major insect pest of coffee that causes yield losses as high as 25%. However, studying biology of Cerambycids is difficult due to the nature of their life cycle, which is mostly spent in the wood. This study aimed at developing and describing a rearing method of M. leuconotus using original artificial diet and its life history in the laboratory. The bioecology information generated will be useful in formulating effective management strategies. To conduct a life table analysis of M. leuconotus, the development and survival of 36 larvae reared on the artificial diet at 25±1°C, 85±5% RH, L:D 12: 12 and the fecundity of 25 adult females kept in pairs in cages with coffee sticks at 27°C and 42% RH were monitored daily. Using this rearing method, the duration of life cycle was reduced to 11 months from 18-24 months reported under field conditions. On average, eggs were 4.28 mm± 0.17 long with a diameter of 1.59± 0.07 mm and took 26±0.87 days to hatch. Seventh instar larvae measured 37.64 ± 1.40 mm long and weighed 0.77 ± 0.06g. Larval stage persisted for 209±12.42 days (7 months). Pupae had a mean length of 23.0 ± 0.43 mm, weighed 0.50 ± 0.02 g and took 23±0.27 days to emerge as adults. The adults on average measured 22.27± 0.27 mm long, weighed 0.49 ± 0.01g and survived for 82± 5.05 days. Survival rate was high at 78, 100 and 92% for larval, pupal and adult stages, respectively. The pre-oviposition period was 35 ±1.69 days on average and the female mean fecundity was 51.84 ± 5.92 eggs. Life table analysis indicated the net reproductive rate (Ro) of 2.60, the intrinsic rate of increase (r) of 0.00315 with population doubling time (Td) of 220.05 day