Probiotics as a Beneficial Modulator of Gut Microbiota and Environmental Stress for Sustainable Mass-Reared <em>Ceratitis capitata</em>

The Mediterranean fruit fly Ceratitis capitata (medfly) is a major pest throughout the world and one of the most destructive. Several strategies for controlling this pest have been proposed, including the sterile insect technique (SIT). The SIT’s effectiveness against the medfly is well documented. Sterile medflies, on the other hand, can perform poorly. Reduced mating compatibility and mating competitiveness in the field may be caused by genetic and symbiotic differences between natural and laboratory medfly populations. Probiotic gut symbionts have been shown to facilitate control strategies and improve male medfly fitness. They are equally effective in the live and inactivated forms when administered to medfly adults or larvae. They have been shown to modulate a large set of inducible effector molecules including antimicrobial peptides (AMP) and stress-responsive proteins. The selection procedures of probiotics for their use in the medfly rearing process are reviewed, and other pathways for selection are proposed based on recent in silico studies. This chapter summarizes the most relevant evidence from scientific literature regarding potential applications of probiotics in medfly as an innovative tool for biocontrol, while also shedding light on the spectrum of symbiotic relationships in medfly that may serve as a powerful symbiotic integrative control approach

Global patterns in genomic diversity underpinning the evolution of insecticide resistance in the aphid crop pest Myzus persicae

Abstract: The aphid Myzus persicae is a destructive agricultural pest that displays an exceptional ability to develop resistance to both natural and synthetic insecticides. To investigate the evolution of resistance in this species we generated a chromosome-scale genome assembly and living panel of >110 fully sequenced globally sampled clonal lines. Our analyses reveal a remarkable diversity of resistance mutations segregating in global populations of M. persicae. We show that the emergence and spread of these mechanisms is influenced by host–plant associations, uncovering the widespread co‐option of a host-plant adaptation that also offers resistance against synthetic insecticides. We identify both the repeated evolution of independent resistance mutations at the same locus, and multiple instances of the evolution of novel resistance mechanisms against key insecticides. Our findings provide fundamental insights into the genomic responses of global insect populations to strong selective forces, and hold practical relevance for the control of pests and parasites.Peer reviewedFinal Published versio

The relative density of cDNA amplicons of <i>Cecropin</i> gene expression (Log₂ transformed fold) in infected post-mating <i>Ceratitis capitata</i> males and females compared to virgin ones.

<p>Each bar shows mean ± SE. Different symbols correspond to a significant difference, (*) for the females (F) and (#) for the males (M), (Multivariate analysis, MANOVA).</p

Effect of mating status and infection by injection with <i>Providencia rettgeri</i> on male and female <i>Ceratitis capitata</i> mortality.

<p>Virgin infected flies are flies from experiment “Infection by injection”. Each bar shows mean percentage± SE. Different symbols correspond to a significant difference (LSD test) for the males (*) and (#) for females.</p

Effect of <i>Providencia rettgeri</i> (suspension at 1 and 2%) on egg to pupae recovery.

<p>Control corresponds to non infected eggs. Male represent brown pupae and Female represent white pupae. Each bar shows mean percentage ± SE.</p

Evaluation of <i>Providencia rettgeri</i> pathogenicity against laboratory Mediterranean fruit fly strain (<i>Ceratitis capitata</i>)

<div><p>The Mediterranean fruit fly (medfly) <i>Ceratitis capitata</i> (Wiedemann) (Diptera: Tephritidae), is often referred to as the most severe agricultural pest. Its biological control is mainly through the Sterile Insect Technique (SIT). Colonization, mass-rearing conditions and the irradiation process impact the competitiveness of sterile males and disrupt symbiotic associations by favoring some bacterial species and suppressing others. Levels of <i>Providencia</i> species have been shown to fluctuate considerably in the gut of the medfly laboratory strain Vienna 8 under irradiation, increasing by up to 22%. This study aimed to determine the pathogenicity of <i>Providencia rettgeri</i> isolated from the gut of laboratory Vienna 8 medfly strains by examining the effects of 1) two different treatment doses on egg-hatching and development and 2) two infection methodologies (ingestion and injection) of male and female adults according to their mating status. Treatment of eggs with <i>P</i>. <i>rettgeri</i> (2%) significantly decreased the mean egg to pupae recovery rate. Our data showed significant high mortality in flies with both injection and ingestion after 24 hours without any effect of sex. Microbial counts demonstrated that the bacteria could proliferate and replicate in adult flies. There was a significant sex-dependent effect after infection, with mortality decreasing significantly for males more than females. <i>Providencia rettgeri</i> can be considered as a potential pathogen of <i>C</i>. <i>capitata</i>. Mating protected males and females against infection by <i>P</i>. <i>rettgeri</i> by triggering an immune response leading to double the levels of <i>Cecropin</i> being secreted compared to infected virgin adults, thus reducing the virulence of the bacteria.</p></div

Expression of 7 immune genes in <i>Ceratitis capitata</i> inoculated with <i>P</i>. <i>lilacinum</i> for the times analyzed (0h, 24h, 72h, and 144h).

The bottom and top “whiskers” represent minimum and maximum values, respectively. The thick line bisecting the box represents the median. The bottom and top of the box represent the 25th and 75th percentiles, respectively. Asterisks indicate a significant difference (* pS1 Data.</p

Average amounts of lipid, glycogen, and sugar in infected larvae (red) and non-infected larvae (blue) of <i>Ceratitis capitata</i>.

Error bars indicate the standard error. (*) indicates a significant difference between columns (P<0.05).</p