EIDONOMY AND ECOLOGY OF DACTYLOSTERNUM-ABDOMINALE (COLEOPTERA, HYDROPHILIDAE), A PREDATOR OF THE BANANA WEEVIL COSMOPOLITES-SORDIDUS (COLEOPTERA, CURCULIONIDAE)
Am. Koppenhofer et al., EIDONOMY AND ECOLOGY OF DACTYLOSTERNUM-ABDOMINALE (COLEOPTERA, HYDROPHILIDAE), A PREDATOR OF THE BANANA WEEVIL COSMOPOLITES-SORDIDUS (COLEOPTERA, CURCULIONIDAE), Entomologia generalis, 19(4), 1995, pp. 303-313
Observations on the biology of Dactylosternum abdominale (Fabricius 17
92) were made in W' Kenya in banana plantations. The 3 larval instars
are polyphagous predators in decomposing plant tissues where pupation
occurs. Development from egg to adult [Ig] takes 17-33 days. Ig [Ig] f
eed on the micro-fauna and -flora of decomposing plant tissues, on egg
s and small larvae of insects and the plant tissues. Life-span is appr
oximately 95 +/- 2 days. The sex ratio is 1.16 in favour of the MM. FF
lay on an average 1.7 egg cases per week, each containing 4 eggs. The
pre-oviposition period is 16.6 days, post-oviposition period 3 days.
At unnaturally high population densities fecundity declines. Decomposi
ng plant tissue is more attractive to Ig than fresh plant tissues, and
banana pseudostems more attractive than banana rhizomes. In poorly ma
naged fields and during the rainy seasons population densities are hig
her due to the larger amount of decomposing plant tissue available. Ob
served population densities: 0.5-1.8 Ig/m(2).