Related Experiment Video
Updated: Jun 3, 2026

Purification of Biotinylated Cell Surface Proteins from Rhipicephalus microplus Epithelial Gut Cells
Published on: July 23, 2017
Phenotype changes inherited by crossing pyrethroid susceptible and resistant genotypes from the cattle tick
G Aguilar-Tipacamú1, R Rosario-Cruz, Robert J Miller
1FMVZ-UNACH, Camino Ejido Emiliano Zapata Km. 8, Tuxtla Gutiérrez, Chiapas, Mexico.
Abstract:
Dialelic crosses and backcrosses of pyrethroid resistant (RR) and susceptible (SS) Rhipicephalus (Boophilus) microplus tick strains were carried out and the substitution (Phe-Ile) within the sodium channel gene was monitored in order to analyze the effects of the genotype on the pyrethroid resistance phenotype as measured by the larval packet test (LPT). Parental strains: susceptible (SS) and resistant (RR); dialelic crosses: RS (♂RR × ♀SS), and SR (♂SS × ♀RR); and backcrosses: RS × SS, RS × RR, SR × SS and SR × RR were infested on 280 kg calves. Resistance type (monogenic or polygenic) and effective dominance were determined based on the discriminant concentration (DC) for cipermethrine (0.5%), deltamethrine (0.09%) and flumethrine (0.01%). Allele specific PCR (AS-PCR) was used for genotyping, looking at a sodium channel mutation (Phe-Ile substitution). The mortality rates and allele frequency of susceptible and pyrethroid resistant reference strains were 0% mortality and 90% RR alleles for resistant strain, and 100% mortality and 0% RR alleles as measured by the larval packet test (LPT) and allele specific PCR (AS-PCR) respectively. Backcrossed strain SR × RR showed an effective dominance (D(ML)) of 0.605 for cypermethrin, 0.639 for deltamethrin and 0.498 for flumethrin, while survival of backcrosses RS × SS, RS × RR and SR × SS showed a significant tendency to recesivity. Backcrossed strain SR × RR (69.4%) also showed a higher RR genotype frequency with regards to RS × SS (25.5%), RS × RR (36.7%) and SR × SS (32.0%), however, susceptible allele was inherited in general as an incomplete dominant trait. Monogenic inheritance hypothesis was tested and the results showed monogenic inheritance for cypermethrin and flumethrin (P < 0.05) but not for deltamethrin (P > 0.05). However, significant correlation was found between RR genotype and the survival rate for all three pyrethroids used (P < 0.05), suggesting that a single substitution on the sodium channel gene can be responsible for resistance to pyrethroids as a class, due to the high frequency for RR genotypes. Combination with different mutations or metabolic resistance mechanisms cannot be excluded.
More Related Videos
10:59Disclosing Hemolymph Collection and Inoculation of Metarhizium Blastospores into Rhipicephalus Microplus Ticks Towards Invertebrate Pathology Studies
Published on: June 1, 2019
11:44Generation and Multi-phenotypic High-content Screening of Coxiella burnetii Transposon Mutants
Published on: May 13, 2015
Related Concept Videos
Background and Environment Affect Phenotype
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
Epistasis
Test Cross
Rocky Mountain Spotted Fever
Incomplete Dominance
Trihybrid Crosses
Some of Mendel’s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A trihybrid cross is a combination of three individual monohybrid crosses. For example, plant height (tall vs. short), seed shape (round vs. wrinkled), and seed color (yellow vs. green).
The F1 generation plants of a trihybrid cross are heterozygous for all three traits and produce eight gametes. Upon self-fertilization, these gametes have an equal chance to...