Search results for "Diamondback moth"
showing 5 items of 15 documents
Mitochondrial Dna Sequence Variation among Geographic Strains of Diamondback Moth (Lepidoptera: Plutellidae)
1997
We examined genetic variation among 6 geographic strains of diamondback moth, Plutella xylostella (L.), using 365 base pairs of the mitochondrial gene encoding cytochrome oxidase I (COI). No sequence variation was detected within 5 of the 6 strains; 1 strain contained 2 haplotypes that differed by a single base substitution (0.27%). Sequence differences between strains of diamondback moth from Hawaii, the Philippines, and Pennsylvania ranged from 0 to 0.82%. With one exception, base pair substitutions among strains resulted in synonymous codons and did not alter amino acid sequence. Genetic divergence between strains of diamondback moth was not correlated with geographic distances between t…
Mode of inheritance and stability of resistance toBacillus thuringiensis varkurstaki in a diamondback moth (Plutella xylostella) population from Mala…
2000
Genetic inheritance of resistance to Bacillus thuringiensis var kurstaki (BTK) was examined in a diamondback moth (Plutella xylostella) population collected from the Melaka region of Malaysia. A BTK-selected sub-population (BTK-SEL) which was more than 100-fold resistant to BTK compared with a susceptible (ROTH) population of P xylostella was used with standard reciprocal crosses and back-crosses between ROTH and BTK-SEL. Logit regression analysis of F 1 reciprocal crosses indicated that BTK resistance was inherited as an incompletely recessive autosomal trait and controlled by a single locus. In contrast, other studies have shown that resistance to Cry1Ac is inherited as an incompletely do…
Inheritance of resistance to aBacillus thuringiensistoxin in a field population of diamondback moth (Plutella xylostella)
1995
Inheritance of resistance to the Bacillus thuringiensis Berl. CryIA(b) crystal protein was studied in Plutella xylostella L. (diamondback moth). A field population 50-fold more resistant to CryIA(b) than a control susceptible strain was used. Dose-mortality curves of the resistant population, the susceptible strain and the F 1 from the two reciprocal crosses were compared. Resistance transmission to the F 1 was dependent on the sex of the resistant progenitor. Sex ratio of the survivors to high doses of CryIA(b) in the F 1 of the two reciprocal crosses did not corroborate the preliminary hypothesis of resistance being due to a recessive sex-linked allele. Since, in a previous work, the loss…
Genetic and Biochemical Characterization of Field-Evolved Resistance to Bacillus thuringiensis Toxin Cry1Ac in the Diamondback Moth, Plutella xyloste…
2004
ABSTRACT The long-term usefulness of Bacillus thuringiensis Cry toxins, either in sprays or in transgenic crops, may be compromised by the evolution of resistance in target insects. Managing the evolution of resistance to B. thuringiensis toxins requires extensive knowledge about the mechanisms, genetics, and ecology of resistance genes. To date, laboratory-selected populations have provided information on the diverse genetics and mechanisms of resistance to B. thuringiensis , highly resistant field populations being rare. However, the selection pressures on field and laboratory populations are very different and may produce resistance genes with distinct characteristics. In order to better…
Lack of cross‐resistance to otherBacillus thuringiensiscrystal proteins in a population ofPlutella xylostellahighly resistant to cryia(b)
1994
Competition experiments were performed with brush border membrane vesicles of diamondback moth larvae using 125I‐labelled CryIA(b) and unlabelled CryIA(a), CryIA(b) and CryIA(c). The results suggested a model with a single binding site for CryIA(b). Heterologous competition showed that CryIA(c) competed as effectively as CryIA(b) for the CryIA(b) binding site, whereas CryIA(a) competed less effectively. Toxicity tests were performed on third instar larvae with trypsin‐activated insecticidal crystal proteins (ICPs) and a commercial formulation of Bacillus thuringiensis (Bt) (Dipel). A laboratory colony was found to be susceptible to all four ICPs tested and to Dipel. CryIA(b), CryIA(c) and C…