Determining the age of adults of Stomoxys calcitrans (L.) (Diptera: Muscidae)

Abstract

AbstractA preliminary investigation to find an easily assayable biochemical character, varying reproducibly with age which would give a more accurate assessment of insect age than the best methods then available, had revealed the fluorescent eye pigments, the pteridines, as a promising candidate. Stomoxys calcitrans (L.) was chosen as a model. Double-blind laboratory experiments in which the age post-eclosion of females was predicted from a standard laboratory curve of pteridine accumulation with age post-eclosion, showed the method to be accurate on average to ±1·49 days. Further laboratory experiments defined the relationships between temperature and pteridine accumulation in males and females of S. calcitrans such that the method could be modified for field use. Field observations in the UK indicated that the temperature of adults in the wild is determined by ambient temperature, the number of sunlight hours and the flies' own physiological and/or behavioural capabilities. From this information, equations for the accumulation of pteridines with temperature and age post-eclosion in males and females of S. calcitrans were constructed. To test the accuracy of these equations, approximately 19 600 marked flies of known age were released in a farmyard; 126 females were recaptured over 22 days and 90 males over 19 days. The average errors of predicted age using the pteridine accumulation method were ±190 days for females and ±137 days for males over the life-span of the recaptured insects.