Selfish DNA as a method of pest control

The inheritance of most genes is tightly controlled, governed by the rules of mendelian inheritance if nuclear or uniparental inheritance if cytoplasmic. A few notable genes and cytoplasmic genomes have escaped this regulation. Such genes may spread by increasing their own rate of transmission despite reducing host fitness and may be regarded as ‘selfish’. Their population genetics are described and it appears they may impose a significant genetic load on the host population. Modern molecular techniques may enable similar loads to be imposed on pest species either by transferring selfish genes between species, or by linking deleterious genes to a selfish locus. Alternatively, ‘modifier’ genes that eliminate the virulent, or disease vectorial capacity, of the pest population may be introduced by linkage to a selfish locus. Selfish elements present in multiple copies may be preferable to single-copy elements as the former are capable of a larger reduction in host fitness. The practical application of these agents depends on five factors: (i) the rate of ‘reversion’ to a non-selfish form; (ii) the evolution of host repressor systems; (iii) their effect on host fitness, which determines their rate of invasion; (iv) the mechanism regulating host population size in the field; and (v) their ease of manipulation in the laboratory. The first two factors are the most uncertain in most systems, but should be amenable to experimental analysis. It is proposed that the development of such techniques may result in powerful new methods of population control which may be applied to both agricultural pests and disease vectors.

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Mitogenomic analysis of diversity of key whitefly pests in Kenya and its implication to their sustainable management

Scientific Reports ◽

10.1038/s41598-021-85902-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Fathiya M. Khamis ◽

Fidelis L. O. Ombura ◽

Inusa J. Ajene ◽

Komivi S. Akutse ◽

Sevgan Subramanian ◽

...

Keyword(s):

Sustainable Management ◽

Management Strategies ◽

Spatial Models ◽

Abundant Species ◽

Plant Viruses ◽

Pest Species ◽

Agricultural Pests ◽

Protein Coding ◽

Aleyrodes Proletella ◽

Aleurodicus Dispersus

AbstractWhiteflies (Hemiptera: Aleyrodidae) are devastating agricultural pests of economic importance vectoring pathogenic plant viruses. Knowledge on their diversity and distribution in Kenya is scanty, limiting development of effective sustainable management strategies. The present study is aimed at identifying whitefly pest species present in Kenya across different agroecological zones and establish predictive models for the most abundant species in Africa. Whiteflies were sampled in Kenya from key crops known to be severely infested and identified using 16S rRNA markers and complete mitochondrial genomes. Four whitefly species were identified: Aleyrodes proletella, Aleurodicus dispersus, Bemisia afer and Trialeurodesvaporariorum, the latter being the most dominant species across all the agroecology. The assembly of complete mitogenomes and comparative analysis of all 13 protein coding genes confirmed the identities of the four species. Furthermore, prediction spatial models indicated high climatic suitability of T. vaporariorum in Africa, Europe, Central America, parts of Southern America, parts of Australia, New Zealand and Asia. Consequently, our findings provide information to guide biosecurity agencies on protocols to be adopted for precise identification of pest whitefly species in Kenya to serve as an early warning tool against T. vaporariorum invasion into unaffected areas and guide appropriate decision-making on their management.

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THE SEARCH FOR MATING-TYPE-LIMITED GENES IN THE HOMOTHALLIC ALGA CHLAMYDOMONAS MONOICA

Genetics ◽

10.1093/genetics/113.3.601 ◽

1986 ◽

Vol 113 (3) ◽

pp. 601-619

Author(s):

Karen P VanWinkle-Swift ◽

Jang-Hee Hahn

Keyword(s):

Mating Type ◽

Resistance Mutation ◽

Mendelian Inheritance ◽

Sexual Cycle ◽

Uniparental Inheritance ◽

Cell Type ◽

Erythromycin Resistance ◽

Type Locus ◽

Heterothallic Species ◽

Chlamydomonas Monoica

ABSTRACT The non-Mendelian erythromycin resistance mutation ery-u1 shows bidirectional uniparental inheritance in crosses between homothallic ery-u1 and ery-u1 + strains of Chlamydomonas monoica. This inheritance pattern supports a general model for homothallism invoking intrastrain differentiation into opposite compatible mating types and, further, suggests that non-Mendelian inheritance is under mating-type (mt) control in C. monoica as in heterothallic species. However, the identification of genes expressed or required by one gametic cell type, but not the other, is essential to verify the existence of a regulatory mating-type locus in C. monoica and to understand its role in cell differentiation and sexual development. By screening for a shift from bidirectional to unidirectional transmission of the non-Mendelian ery-u1 marker, a mutant with an apparent mating-type-limited sexual cycle defect was obtained. The responsible mutation, mtl-1, causes a 1000-fold reduction in zygospore germination in populations homozygous for the mutant allele and, approximately, a 50% reduction in germination for heterozygous (mtl-1/mtl-1 +) zygospores. By next screening for strains unable to yield any viable zygospores in a cross to mtl-1, a second putative mating-type-limited mutant, mtl-2, was obtained. The mtl-2 strain, although self-sterile, mates efficiently with mtl-2 + strains and shows a unidirectional uniparental pattern of inheritance for the ery-u1 cytoplasmic marker, similar to that observed for crosses involving mtl-1. Genetic analysis indicates that mtl-1 and mtl-2 define unique unlinked Mendelian loci and that the sexual cycle defects of reduced germination (mtl-1) or self-sterility (mtl-2) cosegregate with the effect on ery-u1 cytoplasmic gene transmission. By analogy to C. reinhardtii, the mtl-1 and mtl-2 phenotypes can be explained if the expression of these gene loci is limited to the mt + gametic cell type, or if the wild-type alleles at these loci are required for the normal formation and/or functioning of mt + gametes only.

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Capturing the transcription factor interactome in response to sub-lethal insecticide exposure

10.1101/2020.11.26.399691 ◽

2020 ◽

Author(s):

Victoria A Ingham ◽

Sara Elg ◽

Sanjay C Nagi ◽

Frank Dondelinger

Keyword(s):

Transcription Factors ◽

Time Course ◽

Lethal Dose ◽

Resistance Mechanisms ◽

Dynamic Bayesian Networks ◽

Disease Vectors ◽

Anopheles Coluzzii ◽

Pest Species ◽

Agricultural Pests ◽

Insecticide Exposure

AbstractThe increasing levels of pesticide resistance in agricultural pests and disease vectors represents a threat to both food security and global health. As insecticide resistance intensity strengthens and spreads, the likelihood of a pest encountering a sub-lethal dose of pesticide dramatically increases. Here, we apply dynamic Bayesian networks to a transcriptome time-course generated using sub-lethal pyrethroid exposure on a highly resistant Anopheles coluzzii population. The model accounts for circadian rhythm and ageing effects allowing high confidence identification of transcription factors with key roles in pesticide response. The associations generated by this model show high concordance with lab-based validation and identifies 44 transcription factors regulating insecticide-responsive transcripts. We identify six key regulators, with each displaying differing enrichment terms, demonstrating the complexity of pesticide response. The considerable overlap of resistance mechanisms in agricultural pests and disease vectors strongly suggests that these findings are relevant in a wide variety of pest species.

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An updated global COI barcode reference data set for Fall Armyworm (Spodoptera frugiperda) and first record of this species in Bhutan

10.1101/2020.05.17.100883 ◽

2020 ◽

Author(s):

Kiran Mahat ◽

Andrew Mitchell ◽

Tshelthrim Zangpo

Keyword(s):

Spodoptera Frugiperda ◽

Reference Data ◽

Dna Barcode ◽

Fall Armyworm ◽

First Record ◽

Molecular Techniques ◽

Data Sets ◽

Pest Species ◽

Maize Crop ◽

Data Set

AbstractWe report the first detection of Fall Armyworm (FAW), Spodoptera frugiperda (Smith, 1797), in Bhutan. FAW feeds on more than 300 plant species and is a serious pest of many. It has been spreading through Africa since 2016 and Asia since 2018. In Bhutan, this species was first detected in maize fields in the western part of the country in September 2019 and subsequently found infesting maize crop in southern parts of the country in December 2019 and April 2020. Using morphological and molecular techniques the presence of the first invading populations of S. frugiperda in Bhutan is confirmed through this study. We present an updated reference DNA barcode data set for FAW comprising 374 sequences, which can be used to reliably identify this serious pest species, and discuss some of the reasons why such compiled reference data sets are necessary, despite the publicly availability of the underlying data. We also report on a second armyworm species, the Northern Armyworm, Mythimna separata (Walker, 1865), in rice, maize and other crops in eighteen districts of Bhutan.

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DNA-DNA Hybridization, Phylogenetic Reconstruction and the Fossil Record

Short Courses in Paleontology ◽

10.1017/s2475263000000684 ◽

1988 ◽

Vol 1 ◽

pp. 75-88 ◽

Cited By ~ 1

Author(s):

Charles R. Marshall

Keyword(s):

Dna Hybridization ◽

Nuclear Dna ◽

Phylogenetic Reconstruction ◽

Cost Effective ◽

Single Copy ◽

Molecular Techniques ◽

Phylogenetic Information ◽

Molecular Approaches ◽

Molecular Characters ◽

Rates Of Molecular Evolution

In 1962 Zuckerkandl & Pauling suggested that the amino acid sequence of proteins might evolve in a clock-like fashion and thus may be useful for phylogenetic reconstruction. Since then, many different molecular approaches to phylogenetic reconstruction have been proposed (Wilson et al., 1977). Enthusiasm for the clock hypothesis was dampened by the discovery that rates of molecular evolution for many macromolecules have been highly variable through time (Romero-Herrera et al., 1979). However, the contribution of molecular characters to the study of phylogeny is not necessarily dependent on the notion of a molecular clock and molecular approaches continue to be an important source of phylogenetic information. One of the more powerful and cost-effective molecular techniques for phylogenetic purposes is DNA-DNA hybridization, which measures the single-copy nuclear DNA sequence divergences between species.

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Theoretical basis for the use of pathogens as biological control agents of pest species

Parasitology ◽

10.1017/s0031182000053592 ◽

1982 ◽

Vol 84 (4) ◽

pp. 3-33 ◽

Cited By ~ 50

Author(s):

R. M. Anderson

Keyword(s):

Population Growth ◽

Mathematical Models ◽

Horizontal Transmission ◽

Host Density ◽

Host Population ◽

Pest Species ◽

Population Abundance ◽

Pest Population ◽

Insect Pathogen ◽

Cyclic Changes

SUMMARYThe population dynamics of insect–pathogen interactions are examined with the aid of simple mathematical models. Three concepts of central importance to the interpretation of population behaviour are discussed, namely the ability of the pathogen to persist within its host population, the ability to regulate and depress host population abundance, and the ability to induce non-seasonal cyclic changes in host density. The selection of pathogen species or strains to depress pest population growth is discussed and the optimal characteristics are shown to be intermediate pathogencity combined with an ability to reduce infected host reproduction, high transmission efficiency, including elements of vertical as well as horizontal transmission stages. When the pathogen plays a significant role in the regulation of host population growth, it is argued that many insect–pathogen interactions will exhibit non-seasonal oscilations in host and pathogen abundance. Mathematical models are used to explore the patterns of population behaviour that result from the continual introduction of a pathogen into a target pest population. It is shown that there exists a critical introdution rate, above which the eradication of the pest is theoretically possible. Significant reductions in pest population abundance will not occur until the introduction rate approaches this critical value, whereupon the oscillatory behaviour of the interaction between host and pathogen population will be suppressed.A general dicussion is given of the problems arising from the combined use of chemical agents and pathogens for the control of pest species, and the evolutionary pressures acting on host and pathogen populations.

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Inheritance and resistance to insects in CryIA(c) transgenic cabbage

Chinese Journal of Agricultural Biotechnology ◽

10.1017/s1479236207001258 ◽

2007 ◽

Vol 4 (1) ◽

pp. 57-61

Author(s):

Li Han-Xia ◽

Yin Ruo-He ◽

Lu Ya-Chun ◽

Zhang Yu-Yang ◽

Zhang Jun-Hong

Keyword(s):

Diamondback Moth ◽

Dominant Gene ◽

Single Copy ◽

Mendelian Inheritance ◽

Kanamycin Resistance ◽

Pcr Analysis ◽

Regenerated Plants ◽

Resistance To Insects ◽

Bt Gene ◽

Polymerase Chain

AbstractUsing hypocotyl segments of aseptic seedlings of cabbage (Brassica oleracea var. capitata) as explants, regenerated plants with kanamycin resistance were obtained mediated by Agrobacterium tumefaciens (strain LBA4404). The transformed plants with the CryIA(c) (Bt) gene were confirmed by Southern blotting analysis, indicating the integration of the transgene into the cabbage genome. The majority of the transgenic plants had only a single copy of the inserted CryIA(c) gene. Leaf section bioassays showed that resistance against larvae of diamondback moth in CryIA(c) transgenic cabbage was significantly enhanced. The inheritance patterns of the transgene in T1 offspring of transgenic cabbage were investigated using polymerase chain reaction (PCR) analysis and a kanamycin resistance test on the leaves of young seedlings. The results showed that dominant gene loci, CryIA(c) or neomycin phosphotransferase gene (NPTII), followed Mendelian inheritance, with a ratio of 3:1 segregation in T1 populations.

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Odonata: Who They Are and What They Have Done for Us Lately: Classification and Ecosystem Services of Dragonflies

Insects ◽

10.3390/insects10030062 ◽

2019 ◽

Vol 10 (3) ◽

pp. 62 ◽

Cited By ~ 11

Author(s):

Michael May

Keyword(s):

Ecosystem Services ◽

Aquatic Ecosystems ◽

Insect Flight ◽

Economic Importance ◽

Molecular Techniques ◽

Disease Vectors ◽

Agricultural Pests ◽

Top Predators ◽

New Information ◽

And Control

Odonata (dragonflies and damselflies) are well-known but often poorly understood insects. Their phylogeny and classification have proved difficult to understand but, through use of modern morphological and molecular techniques, is becoming better understood and is discussed here. Although not considered to be of high economic importance, they do provide esthetic/spiritual benefits to humans, and may have some impact as predators of disease vectors and agricultural pests. In addition, their larvae are very important as intermediate or top predators in many aquatic ecosystems. More recently, they have been the objects of study that have yielded new information on the mechanics and control of insect flight.

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Antisense RNA inhibition of the putative vacuolar H(+)-ATPase proteolipid of Dictyostelium reduces intracellular Ca2+ transport and cell viability

Journal of Cell Science ◽

10.1242/jcs.109.2.489 ◽

1996 ◽

Vol 109 (2) ◽

pp. 489-497 ◽

Cited By ~ 2

Author(s):

Y. Xie ◽

M.B. Coukell ◽

Z. Gombos

Keyword(s):

Atpase Activity ◽

Cell Viability ◽

Antisense Rna ◽

Single Copy ◽

Protein Product ◽

Molecular Techniques ◽

Contractile Vacuole ◽

Endogenous Gene ◽

Wild Type Phenotype ◽

High Amino Acid

Transport of Ca2+ via a P-type pump into the contractile vacuole of Dictyostelium discoideum appears to be facilitated by vacuolar proton (V-H+) ATPase activity. To investigate the involvement of the V-H(+)-ATPase in this process using molecular techniques, we cloned a cDNA (vatP) encoding the putative proteolipid subunit of this enzyme. The deduced protein product of this cDNA is composed of 196 amino acids with a calculated M(r) of 20,148 and the primary structure exhibits high amino acid sequence identity with V-H(+)-ATPase proteolipids from other organisms. vatP is a single-copy gene and it produces one approximately 900 nt transcript at relatively constant levels during growth and development. Attempts to disrupt the endogenous gene using vatP cDNA were unsuccessful. But, expression of vatP antisense RNA reduced the levels of vatP message and V-H(+)-ATPase activity by 50% or more. These antisense strains grew and developed slowly, especially under acidic conditions, and the cells seemed to have difficulty forming acidic vesicles. During prolonged cultivation, all of the antisense strains either reverted to a wild-type phenotype or died. Thus in Dictyostelium, unlike yeast, the V-H(+)-ATPase seems to be indispensable for cell viability. When different antisense strains were analyzed for Ca2+ uptake by the contractile vacuole, they all accumulated less Ca2+ than control transformants. These results are consistent with earlier pharmacological studies which suggested that the V-H(+)-ATPase functions in intracellular Ca2+ transport in this organism.

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Developmentally Regulated Chromosome Fragmentation Linked to Imprecise Elimination of Repeated Sequences in Paramecia

Eukaryotic Cell ◽

10.1128/ec.2.5.1076-1090.2003 ◽

2003 ◽

Vol 2 (5) ◽

pp. 1076-1090 ◽

Cited By ~ 58

Author(s):

Anne Le Mouël ◽

Alain Butler ◽

François Caron ◽

Eric Meyer

Keyword(s):

De Novo ◽

Germ Line ◽

Single Copy ◽

Mendelian Inheritance ◽

Direct Repeats ◽

Developmentally Regulated ◽

Chromosome Fragmentation ◽

Dna Elimination ◽

Flanking Sequences ◽

Identical Cell

ABSTRACT The chromosomes of ciliates are fragmented at reproducible sites during the development of the polyploid somatic macronucleus, but the mechanisms involved appear to be quite diverse in different species. In Paramecium aurelia, the process is imprecise and results in de novo telomere addition at locally heterogeneous positions. To search for possible determinants of chromosome fragmentation, we have studied an ∼21-kb fragmentation region from the germ line genome of P. primaurelia. The mapping and sequencing of alternative macronuclear versions of the region show that two distinct multicopy elements, a minisatellite and a degenerate transposon copy, are eliminated by an imprecise mechanism leading either to chromosome fragmentation and the formation of new telomeres or to the rejoining of flanking sequences. Heterogeneous internal deletions occur between short direct repeats containing TA dinucleotides. The complex rearrangement patterns produced vary slightly among genetically identical cell lines, show non-Mendelian inheritance during sexual reproduction, and can be experimentally modified by transformation of the maternal macronucleus with homologous sequences. These results suggest that chromosome fragmentation in Paramecium is the consequence of imprecise DNA elimination events that are distinct from the precise excision of single-copy internal eliminated sequences and that target multicopy germ line sequences by homology-dependent epigenetic mechanisms.

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