Alternate Methods of Reproduction

Jacob Nikodym Author

07/19/2022 Added

14 Plays

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This video describes examples of pests that utilize alternative methods of reproduction.

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[00:00:07.800]This video will discuss alternative reproductive
[00:00:11.100]strategies utilized by some pest species, and their
[00:00:15.300]impacts on the development of resistance to pesticides
[00:00:18.600]by those species.
[00:00:21.720]Understanding the inheritance of genes is important
[00:00:25.290]when determining resistance management strategies.
[00:00:28.620]It is also important to know the differences between
[00:00:31.710]inheritance in sexually reproducing, compared to
[00:00:34.860]asexually reproducing populations.
[00:00:37.800]In sexual reproduction, genes from a male and a female
[00:00:41.460]parent combine to form the genome of the offspring.
[00:00:45.360]However, in asexual reproduction, only one parent is
[00:00:48.930]required, and the offspring is a genetic clone of the parent
[00:00:53.340]with all of the same genes.
[00:00:55.560]This type of reproduction occurs in many species
[00:00:58.620]of bacteria and fungi, as well as several species of
[00:01:02.400]insects and other arthropods.
[00:01:06.060]Asexual reproduction can lead to levels of pesticide
[00:01:10.170]resistance in a population increasing very quickly,
[00:01:13.800]because one resistant individual can produce
[00:01:16.680]a large number of offspring with the same resistant
[00:01:20.160]genotype without susceptible alleles potentially being
[00:01:23.790]reintroduced through recombination.
[00:01:27.060]However, this reproductive strategy limits the genetic
[00:01:30.570]diversity of a population because genetic recombination
[00:01:34.530]does not occur.
[00:01:37.050]Some insects, like Aphids, spend most of their year
[00:01:40.980]reproducing asexually, but undergo
[00:01:43.740]a single sexual generation normally in the fall.
[00:01:47.970]This reproductive system provides the benefit of
[00:01:51.330]genetic diversity that results from genetic recombination
[00:01:55.470]during the sexual generation, but it also allows for
[00:01:59.340]a rapid increase in beneficial alleles through
[00:02:02.490]the asexual generations.
[00:02:05.670]Another unusual method of reproduction that leads to
[00:02:09.180]resistance in a population growing quickly
[00:02:12.420]can be seen in Two-Spotted Spider Mites.
[00:02:15.810]This species has what is called arrhenotokus reproduction,
[00:02:21.330]in which the males are haploid, and only have one copy
[00:02:25.140]of each gene, rather than two copies, diploid,
[00:02:29.130]like the females and most other organisms.
[00:02:32.910]This means that resistant males cannot carry
[00:02:36.780]susceptible alleles.
[00:02:38.550]So when selection pressure is applied, only those who
[00:02:42.180]are resistant will survive, eliminating the susceptible
[00:02:45.840]alleles from the males in the population.
[00:02:49.620]The surviving males then mate with surviving females in
[00:02:53.460]the population guaranteeing that the offspring will have
[00:02:57.900]at least one resistant allele, as shown by
[00:03:01.710]the Punnett squares here.
[00:03:03.990]These mites also have very short lifespans and produce
[00:03:08.430]many generations with large numbers of offspring
[00:03:11.970]each generation, thus the frequency of resistant alleles
[00:03:16.410]in the population is able to increase very quickly.
[00:03:20.850]The Two-Spotted Spider Mite is considered the most
[00:03:24.180]resistant arthropod to pesticides with resistance
[00:03:27.960]demonstrated to 92 pesticide active ingredients.

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Alternate Methods of Reproduction

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