Reproductive interference between two serious pests,oriental fruit flies <Emphasis Type="Italic">Bactrocera carambolae</Emphasis> and <Emphasis Type="Italic">B. dorsalis</Emphasis> (Diptera: Tephritidae), with very wide but partially overlapping host ranges

Bactrocera carambolae and B. dorsalis (Diptera: Tephritidae) are extremely destructive pests of fruits and vegetables in the Asia-Pacific region. Earlier reports have described that B. carambolae and B. dorsalis, respectively, use mainly star fruit and mango, suggesting a certain level of host partitioning which can be ascribed neither to differences in larval food qualities nor host-specific parasitoid mortality. This study specifically examined reproductive interference (antagonistic sexual interaction) between B. carambolae and B. dorsalis as a potential factor strongly affecting their host partitioning. We observed mating behaviors, especially interspecific courtships and mating, by cohabiting the conspecific and heterospecific pairs together. Consequently, we quantified their effects on the reproductive success of females. Males of both species frequently courted their own females, but they also courted females of other species. Courtship refusal by females was not selective in males of either species. This incomplete discrimination of both sexes led to frequent occurrences of interspecific sexual interactions in both species, but only B. carambolae females showed reduced reproductive success. These results suggest that B. dorsalis, superior in reproductive interference, can occupy high-quality mango, whereas B. carambolae, inferior in reproductive interference, must use low-quality star fruit.     

Simple and on-site DNA purification for LAMP reaction applicable to non-adult tephritid fruit fly (Diptera: Tephiritidae)

Tephritid fruit flies are important pests of fruits and vegetables worldwide, but few studies have examined their ecology and life history in their native range because non-adult individuals of closely related species are morphologically indistinguishable. To identify non-adult individuals collected from host plants, flies examined in earlier studies were painstakingly reared to adulthood. Using Zeugodacus scutellatus Hendel as a model species, this study established a simple DNA extraction and purification method based on loop-mediated isothermal amplification (LAMP) reaction for on-site molecular identification of non-adult fruit flies. The non-adult individual body fluids were sampled using a sterilized toothpick and then diluted in TE buffer and heated for a short time. Alternatively, eggs were crushed in TE buffer using a sterilized toothpick and then heated. After heated buffer was added to the LAMP reaction mixture as template DNA and the mixture was heated for incubation of polymerase, the LAMP reaction detected the amplified DNA of Z. scutellatus. This purification method, characterized by heating after dilution with TE buffer, is simple and rapid. Our purification method, which obviates large centrifuges, thermal cyclers, and other apparatus, provides lower-cost and better on-site molecular identification of non-adult fruit flies than methods described in earlier reports. The LAMP-based molecular identification technique and our purification method are particularly useful for studying quarantined pest organisms that cannot be removed from their native areas.     

Reproductive habitat use,body-size structure and spawning season of Cobitis minamorii minamorii in paddy fields and ditches

We surveyed the reproductive ecology of Cobitis minamorii minamorii in paddy fields and ditches. The spatial distribution of females in the spawning season differed from that in the non-spawning season, even in short ditches. Eggs were collected in both ditches and paddy fields, unlike an earlier study demonstrating that no eggs were collected in ditches. The frequency distributions of standard body lengths of males and females were unimodal and bimodal, respectively. The females with a large standard body length were expected to be gravid with higher probability in May.