Question

Trips, a small insect are unusual in that male. Thrips have only one copy of every gene, whereas female Thrips have two copies of evey gene. The reason for this phenomenon is that males develop from unfertilized eggs. In Thrips, the phenotype for resistance to crypermetrin (insecticide) is dominant over the phenotype for sensitivity to cypermethrin and the phenotype for resistance to imidocloprid (insecticide) is dominant over the phenotype for sensitivity to imidocloprid. If a male Thrip with sensitivity to both crypermethrin and imidocloprid were to mate with a female Thrip that is pure breeding for both resistance to cypermethrin and sensitivity to imidocloprid:

What would the probability that the male will produce an offspring with resistance to both of the insecticides?

How many male offsprings will exhibit sensitivity to both insecticides?

Answer 1

Male has only one copy of all the genes where as female has two copies for each gene. Male is produced from the unfertilized eggs. The cross ---

male-- ci x CCii---female

The probability of the offspring being resistant to both insecticides is 0. Because male has  recessive alleles for both genes. Female homozygous for both alleles . Resistant to cypermethrin  (dominant allele) ,sensitive to imidocloprid which is recessive allele. So the offspring being dominant (resistant )for both genes is nil.

All offspring will be resistant to cypermethrin and sensitive to Imidocloprid.

Male is formed from unfertilized eggs, so male offspring do not exhibit sensitivity to both insecticides. They will be resistant to cypermethrin and sensitive to imidocloprid.