Elimination of a Recessive Allele Conferring Resistance to Bacillus thuringiensis from a Heterogeneous Strain of Diamondback Moth (Lepidoptera: Plutellidae)

Yong Biao Liu, Bruce E Tabashnik

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

We devised and tested a procedure for eliminating a recessive allele conferring resistance to Bacillus thuringiensis subsp. kurstaki from a laboratory strain of diamondback moth, Plutella xylostella (L.), composed of resistant and susceptible individuals. We established a homozygous susceptible strain (LAB-PS) from a heterogeneous strain (LAB-P) as follows: We obtained F1 progeny from 7 single-pair families from the heterogeneous strain. Hybrid F2 progeny were produced in 7 mass crosses, each of which involved 10 female F1 progeny from a single-pair family and 10 males from a resistant strain (NO-QA). The hybrid F2 progeny were tested in bioassays with a liquid formulation of B. thuringiensis toxin Cry1Ab at a diagnostic concentration that kills susceptible homozygotes and heterozygotes, but not resistant homozygotes. If the resistance allele occurred in either of the 2 parents that produced a particular F1 family, the hybrid F2 progeny derived from that family were expected to contain at least 25% homozygous resistant individuals that would survive exposure to the diagnostic concentration of Cry1Ab. Conversely, 0% survival of a set of hybrid F2 progeny in the diagnostic bioassay would indicate that the single-pair family from which it was derived was homozygous susceptible. We found 0% survival in 1 set of hybrid F2 progeny and used the F1 single-pair family from which this set was derived to establish a homozygous susceptible strain. Subsequent bioassays showed that diagnostic concentrations of Cry1Ab or Cry1Aa killed 100% of larvae tested from this strain. The LC50 of Cry1Ab at 5 d for the susceptible strain was 7-fold lower than that for the heterogeneous strain. The procedure can be adapted for other insects and other traits, such as resistance to other insecticides.

Original languageEnglish (US)
Pages (from-to)1032-1037
Number of pages6
JournalJournal of Economic Entomology
Volume91
Issue number5
StatePublished - Oct 1998

Fingerprint

Plutellidae
Plutella xylostella
Bacillus thuringiensis
moth
allele
Lepidoptera
alleles
bioassay
bioassays
homozygosity
toxin
insecticide
family
Bacillus thuringiensis subsp. kurstaki
insect
fold
larva
lethal concentration 50
liquid
heterozygosity

Keywords

  • Bacillus thuringiensis
  • Plutella xylostella
  • Resistance
  • Selection for susceptibility

ASJC Scopus subject areas

  • Insect Science

Cite this

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title = "Elimination of a Recessive Allele Conferring Resistance to Bacillus thuringiensis from a Heterogeneous Strain of Diamondback Moth (Lepidoptera: Plutellidae)",
abstract = "We devised and tested a procedure for eliminating a recessive allele conferring resistance to Bacillus thuringiensis subsp. kurstaki from a laboratory strain of diamondback moth, Plutella xylostella (L.), composed of resistant and susceptible individuals. We established a homozygous susceptible strain (LAB-PS) from a heterogeneous strain (LAB-P) as follows: We obtained F1 progeny from 7 single-pair families from the heterogeneous strain. Hybrid F2 progeny were produced in 7 mass crosses, each of which involved 10 female F1 progeny from a single-pair family and 10 males from a resistant strain (NO-QA). The hybrid F2 progeny were tested in bioassays with a liquid formulation of B. thuringiensis toxin Cry1Ab at a diagnostic concentration that kills susceptible homozygotes and heterozygotes, but not resistant homozygotes. If the resistance allele occurred in either of the 2 parents that produced a particular F1 family, the hybrid F2 progeny derived from that family were expected to contain at least 25{\%} homozygous resistant individuals that would survive exposure to the diagnostic concentration of Cry1Ab. Conversely, 0{\%} survival of a set of hybrid F2 progeny in the diagnostic bioassay would indicate that the single-pair family from which it was derived was homozygous susceptible. We found 0{\%} survival in 1 set of hybrid F2 progeny and used the F1 single-pair family from which this set was derived to establish a homozygous susceptible strain. Subsequent bioassays showed that diagnostic concentrations of Cry1Ab or Cry1Aa killed 100{\%} of larvae tested from this strain. The LC50 of Cry1Ab at 5 d for the susceptible strain was 7-fold lower than that for the heterogeneous strain. The procedure can be adapted for other insects and other traits, such as resistance to other insecticides.",
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author = "Liu, {Yong Biao} and Tabashnik, {Bruce E}",
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N2 - We devised and tested a procedure for eliminating a recessive allele conferring resistance to Bacillus thuringiensis subsp. kurstaki from a laboratory strain of diamondback moth, Plutella xylostella (L.), composed of resistant and susceptible individuals. We established a homozygous susceptible strain (LAB-PS) from a heterogeneous strain (LAB-P) as follows: We obtained F1 progeny from 7 single-pair families from the heterogeneous strain. Hybrid F2 progeny were produced in 7 mass crosses, each of which involved 10 female F1 progeny from a single-pair family and 10 males from a resistant strain (NO-QA). The hybrid F2 progeny were tested in bioassays with a liquid formulation of B. thuringiensis toxin Cry1Ab at a diagnostic concentration that kills susceptible homozygotes and heterozygotes, but not resistant homozygotes. If the resistance allele occurred in either of the 2 parents that produced a particular F1 family, the hybrid F2 progeny derived from that family were expected to contain at least 25% homozygous resistant individuals that would survive exposure to the diagnostic concentration of Cry1Ab. Conversely, 0% survival of a set of hybrid F2 progeny in the diagnostic bioassay would indicate that the single-pair family from which it was derived was homozygous susceptible. We found 0% survival in 1 set of hybrid F2 progeny and used the F1 single-pair family from which this set was derived to establish a homozygous susceptible strain. Subsequent bioassays showed that diagnostic concentrations of Cry1Ab or Cry1Aa killed 100% of larvae tested from this strain. The LC50 of Cry1Ab at 5 d for the susceptible strain was 7-fold lower than that for the heterogeneous strain. The procedure can be adapted for other insects and other traits, such as resistance to other insecticides.

AB - We devised and tested a procedure for eliminating a recessive allele conferring resistance to Bacillus thuringiensis subsp. kurstaki from a laboratory strain of diamondback moth, Plutella xylostella (L.), composed of resistant and susceptible individuals. We established a homozygous susceptible strain (LAB-PS) from a heterogeneous strain (LAB-P) as follows: We obtained F1 progeny from 7 single-pair families from the heterogeneous strain. Hybrid F2 progeny were produced in 7 mass crosses, each of which involved 10 female F1 progeny from a single-pair family and 10 males from a resistant strain (NO-QA). The hybrid F2 progeny were tested in bioassays with a liquid formulation of B. thuringiensis toxin Cry1Ab at a diagnostic concentration that kills susceptible homozygotes and heterozygotes, but not resistant homozygotes. If the resistance allele occurred in either of the 2 parents that produced a particular F1 family, the hybrid F2 progeny derived from that family were expected to contain at least 25% homozygous resistant individuals that would survive exposure to the diagnostic concentration of Cry1Ab. Conversely, 0% survival of a set of hybrid F2 progeny in the diagnostic bioassay would indicate that the single-pair family from which it was derived was homozygous susceptible. We found 0% survival in 1 set of hybrid F2 progeny and used the F1 single-pair family from which this set was derived to establish a homozygous susceptible strain. Subsequent bioassays showed that diagnostic concentrations of Cry1Ab or Cry1Aa killed 100% of larvae tested from this strain. The LC50 of Cry1Ab at 5 d for the susceptible strain was 7-fold lower than that for the heterogeneous strain. The procedure can be adapted for other insects and other traits, such as resistance to other insecticides.

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