PHYSIOLOGICAL AGE-GRADING AND OVARIAN PHYSIOLOGY OF PROSTEPHANUS-TRUNCATUS

The reproductive tracts of male and female Prostephanus truncatus (Hor n) (Coleoptera: Bostrichidae) were described for beetles between emerg ence and 30 days old in order to determine age-grading criteria. Semin al vesicles were bigger among non-mated males than among mated males d ue to accumulation of sperm; no age-specific differences were found fo r male P. truncatus. Ovaries (germarium size, number of follicles and follicle size) were similarly developed for females between 5 and 30 d ays old and did not differ between mated and non-mated females. Starve d females were found to resorb follicles. Yellow body formation was st rongly dependent on age, and was used as an age-grading criterion for female P. truncatus. Females flying off maize cobs and caught with phe romone traps were of varying physiological age and mated, and their ov arian development was suspended. All migrating females were mated, ind icating that lone females may act as colonizers, independently of male s. The applicability of migration theories to P. truncatus and adaptiv e inter-reproductive dispersal as part of its life history strategy ar e discussed.