Tagging the Oriental Fruit Moth, Grapholitha molesta (Busck) with Radioactive Phosphorus for Flight and Dispersal Studies

Abstract

AbstractLarge numbers of Oriental fruit moth adults were successfully tagged (500 or more counts per minute) by holding them for 24–48 hr. in cages provided with cotton wicks moistened with a water-solution of P32 at 20 microcuries per millilitre. The addition of sugar to the tagging solution did not increase its effectiveness. Approximately 80% of the total radioactivity of the tagged moths was internal due to ingested liquid and the remainder was on the surface of their bodies; 73% of the total was in and on the abdomen. The loss in radioactivity of tagged moths in 1–6 days was 2.2–4.7 times greater than the theoretical loss due to isotope decay alone. The highest rate of loss occurred during the first day, probably through excretion before the P32 was absorbed from the digestive tract. Egg laying contributed to loss of radioactivity. Though water and liquid bait removed some P32 from tagged moths this did not result in appreciable contamination of other moths trapped in the liquids.Attempts to tag large numbers of moths (400–1000 per cage) for release and recovery experiments were only partially successful as the radioactivities attained by individual moths varied widely at different times and from cage to cage, even under the same environmental conditions. This appeared to be partly due to differences in the feeding behaviour of different batches of moths and it may have been influenced by the conditions under which they were reared.