Spatial distribution of banana skipper (Erionota thrax L.) (Lepidoptera: Hesperiidae) and its parasitoids in a Cavendish banana plantation, Penang, Malaysia

摘要

Spatial distribution of immatures of the banana skipper (Erionota thrax L.) and their parasitisms from three major parasitoids were studied in a Cavendish banana plantation from April 2004 to December 2004. Infestation levels and parasitism of E. thrax life stages were recorded from bunched plants (BP), flowering plants (FP), preflowered plants (PF), broad leaf followers (BLF) and narrow leaf followers (NLF), as well as on well managed and poorly managed plants. Mean numbers of the immatures and numbers parasitized from the nine blocks in the plantation were fitted to four dispersion indices. Significant numbers of E. thrax immatures and those parasitized by Ooencyrtus erionotae, Cotesia erionotae and Brachymeria albotibialis were recorded from BLF and PF; no eggs were found on BP and FP. Although infestation was higher on well managed plants, only larval parasitism was significantly different. Three of the four indices indicated that eggs and larvae were random while all the indices showed pupae to be clumped. Parasitized eggs and pupae were clumped (4/4 indices) while 3/4 indices revealed a random pattern for parasitized larvae.