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