Marking Bactrocera dorsalis (Diptera Tephritidae) with fluorescent pigments: : effects of pigment colour and concentration

Daylight fluorescent pigment powders are frequently used to self-mark tephritid flies that are released in sterile insect technique programmes and for studies on their population ecology, movement and behaviour. This study was conducted to determine the effects of pigment colour and dose in marking the Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). Six pigment colours (Astral Pink 1, Blaze 5, Stellar Green 8, Lunar Yellow 27, Comet Blue 60 and Invisible Blue 70) were applied to pupae at doses of 0, 2, 4, or 6 g/l. Under laboratory conditions, pigment colour had a small but significant effect on the number of partially emerged and deformed adults; the fewest of these were observed when flies were marked with Astral Pink 1. Pigment concentration, on the other hand, had no effect on adult emergence, partial emergence, deformed adults and mortality on the last day of eclosion. There was no significant effect of pigment colour on adult survival under laboratory and semi-field conditions. Under laboratory conditions, however, there was an effect of pigment concentration on adult survival depending on pigment colour. Visibility under an ultraviolet light and persistence of marks was significantly affected by pigment colour and concentration when observed under laboratory conditions, but not under semi-field conditions. Regardless of colour or dose, pigments used in the study were visible for at least 14 days, but began to fade by 21 days after adult eclosion. To mark B. dorsalis under temperate, warmsummer African conditions, all pigment colours tested in this study may be applied at 2-4 g/l pupae. Recaptures of marked and released flies may be underestimated as the flies age.