Abstract
Mating compatibility among recently colonized (wildish) populations of Bactrocera dorsalis (Hendel) from different geographic origins in Thailand was assessed through inter-regional mating tests. Outdoor octagonal nylon screen field cages containing single potted mango trees (Mangifera indica L.) were used. Sexual compatibility was determined using the index of sexual isolation (ISI), the male relative performance index (MRPI), and the female relative performance index (FRPI). The ISI values indicated that the northern population of Bactrocera dorsalis from Chiang Mai province was sexually compatible with the southern population of Bactrocera dorsalis (previously Bactrocera papayae) from Nakhon Si Thammarat province. The MRPI values showed that the northern males had a slightly higher tendency to mate than southern males, while the FRPI data reflected that females of both origins participated equally in matings. In all combinations there were no differences between homotypic and heterotypic couples in mating latency. Southern males tended to mate first with southern females, followed by northern males mating with northern females, while the latest matings involved heterotypic couples, in particular northern males mating with southern females. Overall, more couples were collected from higher parts of the field cage and the upper tree canopy, while there were no differences between the origins of flies in terms of elevation of couples within the cage. Laboratory assessments of fecundity showed no differences in the average number of eggs resulting from inter-regional crosses. Development of immature stages was also equal in the two hybrid crosses, with no differences found in the number of pupae produced, percentage pupal recovery, and percent adult emergence. The practical implication of this study is that colony of Bactrocera dorsalis derived from any northern or southern region of Thailand can potentially be used in sterile insect technique programs against this pest.
Highlights
Polyphagous fruit fly species (Diptera: Tephritidae) are considered major threats to many countries as a result of their pest status, widespread distribution, invasive ability and potential impact on market access (Stephens et al 2007)
While Schutze et al (2015a) have synonymized B. papayae with B. dorsalis, as Thai based agricultural researchers we considered it important to carry out local work on diversity in B. dorsalis populations so as to inform local research and policy decisions
Total numbers of mated pairs for the control populations of B. dorsalis were lower for the southern population (SS = 80 pairs) and higher for the northern population (NN = 136 pairs)
Summary
Polyphagous fruit fly species (Diptera: Tephritidae) are considered major threats to many countries as a result of their pest status, widespread distribution, invasive ability and potential impact on market access (Stephens et al 2007). These flies infest a broad range of host plants including fruits and vegetables wherever they occur. Following the taxonomic revision of Drew and Hancock (1994), Bactrocera dorsalis was considered to occur in a broad swath across much of Asia, from the Indian subcontinent and Andaman Islands to southern China, Taiwan, and southeast Asia, extending southwards to central/southern Thailand as far south as the Isthmus of Kra on the Thai/Malay Peninsula, which Drew and Hancock considered its southern limit. Due to the recent synonymization of B. invadens, B. papayae, and B. philippinensis with B. dorsalis by Schutze et al (2015a), the distribution of B. dorsalis extends throughout much of sub-Saharan Africa, across the Indian subcontinent to the southeast Asian Indo/Malay Archipelago, and as far east as New Guinea and the Philippines
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