Biology subjects

Belgaidi, Z.

Publications and source records attributed to Belgaidi, Z..

4 recordsLinked to original sources

bioRxiv2024

Transcriptomic response to pyrethroid treatment in closely related bed bug strains varying in resistance

The common bed bug, Cimex lectularius, is one of the main human parasites. The world-wide resurgence of this pest is mainly due to globalization, and the spread of insecticide resistance. A few studies have compared the transcriptomes of susceptible and resistant strains. However, these studies usually relied on strains originating fromdistant locations, possibly explaining their extended candidate gene lists. Here, we compared the transcriptomes of two strains originating from the same location and showing low overall genetic differentiation (FST =0.018) but varying in their susceptibility to pyrethroids, before and after insecticide exposure. In sharp contrast with previous studies, only 24 genes showing constitutive differential expression between the strainswere identified. Interestingly, most of the genes with increased expression in the resistant strain encoded cuticular proteins. However, those changes were not associated with significant difference in cuticular thickness, suggesting that they might be involved in qualitative changes in the cuticle. In contrast, insecticide exposure induced the expression of a multitude of genes, mostly involved in detoxification. Finally, our set of transcriptome candidate loci showed little overlap with a set of loci strongly genetically differentiated in a previous study using the same strains. Several hypothesis explaining this discrepancy are discussed.

evolutionary biology↗

bioRxiv2023

Insect population dynamics under Wolbachia-induced cytoplasmic incompatibility: puzzle more than buzz in Drosophila suzukii

In theory, the introduction of individuals infected with an incompatible strain of Wolbachia pipientis into a recipient host population should result in the symbiont invasion and reproductive failures caused by cytoplasmic incompatibility (CI). Modelling studies combining Wolbachia invasion and host population dynamics show that these two processes could interact to cause a transient population decline and, in some conditions, extinction. However, these effects could be sensitive to density dependence, with the Allee effect increasing the probability of extinction, and competition reducing the demographic impact of CI. We tested these predictions with laboratory experiments in the fruit fly Drosophila suzukii and the transinfected Wolbachia strain wTei. Surprisingly, the introduction of wTei into D. suzukii populations at carrying capacity did not result in the expected wTei invasion and transient population decline. In parallel, we found no Allee effect but strong negative density dependence. From these results, we propose that competition interacts in an antagonistic way with Wolbachia-induced cytoplasmic incompatibility on insect population dynamics. If future models and data support this hypothesis, pest management strategies using Wolbachia-induced CI should target populations with negligible competition but a potential Allee effect, for instance at the beginning of the reproductive season.

ecology↗

bioRxiv2022

Larval density in the invasive Drosophila suzukii: immediate and delayed effects on life-history traits

The immediate and delayed effects of density are key in determining population dynamics, since they can positively or negatively affect the fitness of individuals. These effects have great relevance for polyphagous insects for which immature stages develop within a single site of finite feeding resources. Drosophila suzukii is a crop pest that induces severe economic losses for agricultural production, however little is known about the effects of density on its life-history traits. In the present study, we (i) investigated the egg distribution resulting from females egg-laying strategy and (ii) tested the immediate and delayed effects of larval density on emergence rate, development time, sex ratio of offspring, fecundity and adult size (a range of 1 to 50 larvae was used). We showed that most of fruits contain several eggs and aggregate of eggs of high density can be found in some fruits. This high density has no immediate effects on the emergence rate, but has effect on larval developmental time. This trait was involved in a trade-off with adult life-history traits: the larval development was reduced as larval density increased, but smaller and less fertile adults were produced. Our results should help to better understand the population dynamics of this species and to develop more successful control programs.

ecology↗

bioRxiv2021

Analyses of symbiotic bacterial communities in the plant pest Bemisia tabaci reveal high prevalence of Hemipteriphilus asiaticus on the African continent

AO_SCPLOWBSTRACTC_SCPLOWMicrobial symbionts are widespread in insects and some of them have been associated to adaptive changes. Primary symbionts (P-symbionts) have a nutritional role that allows their hosts to feed on unbalanced diets (plant sap, wood, blood). Most of them have undergone genome reduction, but their genomes still retain genes involved in pathways that are necessary to synthesize the nutrients that their hosts need. However, in some P-symbionts, essential pathways are incomplete and secondary symbionts (S-symbionts) are required to complete parts of their degenerated functions. The P-symbiont of the phloem sap-feeder Bemisia tabaci, Candidatus Portiera aleyrodidarium, lacks genes involved in the synthesis of vitamins, cofactors, and also of some essential amino-acids. Seven S-symbionts have been detected in the B. tabaci species complex. Phenotypic and genomic analyses have revealed various effects, from reproductive manipulation to fitness benefits, notably some of them have complementary metabolic capabilities to Candidatus Portiera aleyrodidarium, suggesting that their presence may be obligatory. In order to get the full picture of the symbiotic community of this pest, we investigated, through metabarcoding approaches, the symbiont content of individuals from Burkina Faso, a West African country where B. tabaci induces severe crop damage. While no new putative B. tabaci S-symbiont was identified, Candidatus Hemipteriphilus asiaticus, a symbiont only described in B. tabaci populations from Asia, was detected for the first time on this continent. Phylogenetic analyses however reveal that it is a different strain than the reference found in Asia. Specific diagnostic PCRs showed a high prevalence of these S-symbionts and especially of Candidatus Hemipteriphilus asiaticus in different genetic groups. These results suggest that Candidatus Hemipteriphilus asiaticus may affect the biology of B. tabaci and provide fitness advantage in some B. tabaci populations.

evolutionary biology↗