Biology subjects

Friend, L. A.

Publications and source records attributed to Friend, L. A..

4 recordsLinked to original sources

bioRxiv2024

Female fruit flies use social cues to make egg clustering decisions

BackgroundThe ability to respond plastically to environmental variation is a key determinant of fitness. Females may use cues to strategically place their eggs, for example adjusting the number or location of eggs according to whether other females are present, driving the dynamics of local competition or cooperation. The expression of plasticity in egg laying patterns within individual patches, i.e., in contact clusters or not, represents an additional, under-researched and potentially important opportunity for fitness gains. Clustered eggs might benefit from increased protection or defence, and clustering could facilitate cooperative feeding. However, increased clustering is also expected to increase the risk of over-exploitation through direct competition. These potential benefits and costs likely covary with the number of individuals present, hence egg clustering behaviour within resource patches should be socially responsive. We investigate this new topic using the fruit fly Drosophila melanogaster. ResultsOur mathematical model, parameterised by data, verified that females cluster their eggs non-randomly, and increase clustering as group size increases. We also showed that, as the density of adult females increased, females laid more eggs, laid them faster, and laid more eggs in clusters. Females also preferred to place eggs within existing clusters. Most egg clusters were of mixed maternity. ConclusionsCollectively, the results reveal that females actively express plasticity in egg clustering according to social environment cues and prefer to lay in clusters of mixed maternity, despite the potential for increased competition. These findings are consistent with egg clustering plasticity being selected due to public goods-related benefits.

animal behavior and cognition↗

bioRxiv2024

Female oviposition decisions are influenced by the microbial environment

In ovipositing animals, egg placement decisions can be key determinants of offspring survival. One oviposition strategy reported across taxa is egg clustering, whereby a female lays multiple eggs next to one another or next to the eggs of other females. The fitness benefits of egg clustering, especially in mixed maternity clusters, are unknown. In some species, mothers provision eggs with diffusible defence compounds, such as antimicrobials, raising the possibility of public good benefits arising from egg clustering. Here we report that Drosophila melanogaster females frequently lay eggs in mixed maternity clusters. We tested two hypotheses for potential drivers of this oviposition behaviour: (i) the microbial environment affects fecundity and egg placement in groups of D. melanogaster females; (ii) D. melanogaster eggs exhibit antimicrobial activity. The results partially supported the first hypothesis. Females exposed to environmental microbes that naturally colonised the oviposition substrates in the absence of antimicrobial preservatives reduced their levels of fecundity but did not significantly alter egg clustering. In contrast, the presence of commensal (fly-associated) microbes did not affect oviposition. The second hypothesis was not supported. There was no evidence of antimicrobial activity, either in whole eggs or in soluble surface material extracted from them. In conclusion, while there was no evidence that oviposition decisions are shaped by the opportunity to share antimicrobials, there is evidence that the microbial environment provides cues that females use to make sophisticated decisions on fecundity and egg placement.

evolutionary biology↗

bioRxiv2021

Characterisation of the symbionts in the Mediterranean fruitfly gut

Symbioses between bacteria and their insect hosts can range from very loose associations through to obligate interdependence. While fundamental evolutionary insights have been gained from the in-depth study of obligate mutualisms, there is increasing interest in the evolutionary potential of flexible symbiotic associations between hosts and their gut microbiomes. Understanding relationships between microbes and hosts also offers the potential for exploitation for insect control. Here, we investigate the gut microbiome of a global agricultural pest, the Mediterranean fruitfly (Ceratitis capitata). We used 16S rRNA profiling to compare the gut microbiomes of laboratory and wild strains raised on different diets and from flies collected from various natural plant hosts. The results showed that medfly guts harbour a fairly simple microbiome, primarily determined by the larval diet in both wild and laboratory flies. However, regardless of the laboratory diet or natural plant host on which flies were raised, Klebsiella spp dominated the medfly microbiomes and resisted removal by antibiotic treatment. We sequenced the genome of the dominant putative Klebsiella spp (designated Medkleb) isolated from the gut of the Toliman wild type fruitfly strain. Genome-wide ANI analysis placed Medkleb within the K. oxytoca / michiganensis group. Molecular, sequence and phenotypic analyses supported its identity as K. oxytoca. Medkleb has a genome size (5 825 435 bp) which is 1.6 standard deviations smaller than the mean genome size of free-living Klebsiella spp, and lacks some genes involved in environmental sensing. Moreover, the Medkleb genome contains at least two recently acquired unique genomic islands as well as genes that encode pectinolytic enzymes capable of degrading plant cell walls. This may be advantageous given that the medfly diet includes unripe fruits containing high proportions of pectin. These results suggest that the medfly harbours a commensal gut bacterium that may have developed a mutualistic association with its host and provide nutritional benefits.

evolutionary biology↗

bioRxiv2016

Vertically transmitted rhabdoviruses are found across three insect families and have dynamic interactions with their hosts

A small number of free-living viruses have been found to be obligately vertically transmitted, but it remains uncertain how widespread vertically transmitted viruses are and how quickly they can spread through host populations. Recent metagenomic studies have found several insects to be infected with sigma viruses (Rhabdoviridae). Here, we report that sigma viruses that infect Mediterranean fruit flies (Ceratitis capitata), Drosophila immigrans, and speckled wood butterflies (Pararge aegeria) are all vertically transmitted. We find patterns of vertical transmission that are consistent with those seen in Drosophila sigma viruses, with high rates of maternal transmission, and lower rates of paternal transmission. This mode of transmission allows them to spread rapidly in populations, and using viral sequence data we found the viruses in D. immigrans and C. capitata had both recently swept through host populations. The viruses were common in nature, with mean prevalences of 12% in C. capitata, 38% in D. immigrans and 74% in P. aegeria. We conclude that vertically transmitted rhabdoviruses may be widespread in insects, and that these viruses can have dynamic interactions with their hosts.

evolutionary biology↗