Browsing by Author "Carpenter, James E."

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    Mating compatibility and competitiveness between wild and laboratory strains of Eldana saccharina (Lepidoptera : Pyralidae) after radiation treatment
    (Florida Entomological Society, 2016) Mudavanhu, Pride; Addison, Pia; Carpenter, James E.; Conlong, Des E.
    The efficacy of the sterile insect technique (SIT) applied as part of area-wide integrated pest management (AW-IPM) depends on efficient transfer of sperm carrying dominant lethal mutations from sterile males to wild females. Success or failure of this strategy is therefore critically dependent on quality and ability of sterile males to search for and copulate with wild females. The African sugarcane borer, Eldana saccharina Walker (Lepidoptera: Pyralidae) is an economic pest of sugarcane targeted for control in South Africa using an AW-IPM approach with a SIT component. As part of further steps towards development of the technique, levels of mating competitiveness and compatibility were assessed by observing the extent to which individuals from different populations interbreed when confined together under both laboratory and semi-field conditions. Three types of pair-wise competition experiments were conducted: non-irradiated laboratory adults vs. non-irradiated wild adults, irradiated (200 Gy) laboratory adults vs. non-irradiated wild adults, and non-irradiated laboratory adults vs. irradiated (200 Gy) laboratory adults. Data from these tests were used to generate indices for mating performance and measuring sexual compatibility between strains. Irrespective of trial location, wild moths did not discriminate against irradiated or laboratory-reared moths, indicating no negative effects on acceptability for mating due to laboratory rearing or radiation treatment. In general, irradiated males mated significantly more than their wild counterparts regardless of the type of female, which indicated that they were still as competitive as their wild counterparts. The mating indices generated showed no evidence of incipient pre-mating isolation barriers or sexual incompatibility with the wild strain. Data presented in this paper therefore indicate that there is scope for further development of the SIT as an addition to the arsenal of tactics available for AW-IPM of this economic pest.
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    Stable isotope markers differentiate between mass-reared and wild Lepidoptera in sterile insect technique programs
    (Florida Entomological Society, 2016) Hood-Nowotny, Rebecca; Harari, Ally; Seth, Rakesh K.; Wee, Suk Ling; Conlong, Des E.; Suckling, David M.; Woods, Bill; Lebdi-Grissa, Kaouthar; Simmons, Gregory; Carpenter, James E.
    In this study we identified a number of moth (Lepidoptera) species that are potential targets for the sterile insect technique (SIT), and we assessed the feasibility of using stable isotope signatures as markers to distinguish mass-reared from wild moth species. Large natural differences in the isotopic signatures of commercially available sugars render them novel markers for mass-reared insects. Sugar beet (Beta vulgaris L.; Caryophyllales: Amaranthaceae), a C3 plant, has a stable isotopic signature (a measure of the ratio of the stable isotopes 13C:12C) of around −27‰ relative to Vienna Pee Dee Belemnite (VPDB; the international C isotope standard for the stable isotopes, 13C and 12C), and sugarcane (Saccharum spp.; Poales: Poaceae), a C4 plant, has an isotopic signature of around −11‰. Thus by means of such a distinct isotope ratio in the sugar in the diet, mass-reared insects can be easily distinguished from wild insects with a high degree of certainty. It was shown that the method could be extended using a multiple isotope approach, with 15N or a full suite of C, N, S and O isotopes. Intrinsic isotope marking of mass-reared moths proved to be an accurate means of distinguishing wild from mass-reared populations, based on isotopic differences between the wild host plant species and the diets used in mass-rearing, which where possible, had been manipulated to contain the isotopically divergent sugar type. This intrinsic labeling using stable isotopes could be useful in the assessment of the quality of mass-reared moths, because a stable isotope is a marker that does not affect the insect in any detrimental manner.