Melanic morphs of Batrocera dorsalis, (Hendel) (Diptera: Tephritidae) possess distinct developmental time, weight, wing size and shape

The Scutum of Bactrocera dorsalis individuals shows a high degree of variability in their colouration, which goes from black to brown. Such variation depicts a different level of melanin production in these individuals. Here we asked whether the progeny produced by four melanic morphs of B. dorsalis would present a difference in their developmental time, weight, wing size and shapes. To address this, we followed eggs produced by gravid females of each B. dorsalis melanic morphs by recording their pupation time, emergence time, and larval, pupal and adult weights. Also using the landmark-based geometric morphometric analysis we assessed the variation in wing size and shape of the adults obtained from each parental melanic morphs of B. dorsalis. We found that larvae produced by adults with dark scutum exhibited faster development and weighed more than those produced by adults with brown scutum. At adult stages, individuals from parents with darker and brown scutum had a reduced weight and wing size (length, width, area and centroid size) as compared to those from the parents with moderate melanin production. We also found a significant wing shape variation across the four melanic morphs. Our study shows that melanisation in the scutum of B. dorsalis has a fitness gain in the preimaginal stages of this fly. While in the adult stage, the heavier or the lesser melanin production in the scutum has a fitness cost. This suggests that there is a trade-off between melanin production and other fitness parameters in B. dorsalis which could have implication on its flight and dispersal and consequently, its management.