BACKGROUND: Leishmaniasis is a group of neglected vector-borne diseases transmitted by phlebotomine sand flies. Leishmania parasites must overcome various defenses in the sand fly midgut, including the insects's immune response. Insect immunity is regulated by the ecdysone hormone, which binds to its nuclear receptor (EcR) and activates the transcription of genes involved in insect immunity. However, the role of ecdysone in sand fly immunity has never been studied. Phlebotomus perniciosus is a natural vector of Leishmania infantum; here, we manipulated its neuroendocrine system using azadirachtin (Aza), a natural compound known to affect ecdysone synthesis. METHODS: Phlebotomus perniciosus larvae and adult females were fed on food containing either Aza alone or Aza plus ecdysone, and the effects on mortality and ecdysis were evaluated. Genes related to ecdysone signaling and immunity were identified in P. perniciosus, and the expression of antimicrobial peptides (AMPs), EcR, the ecdysone-induced genes Eip74EF and Eip75B, and the transcription factor serpent were analyzed using quantitative polymerase chain reaction (PCR). RESULTS: Aza treatment inhibited molting of first-instar (L1) larvae to L2, with only 10% of larvae molting compared to 95% in the control group. Serpent and Eip74EF, attacin, defensin 1, and defensin 2 genes were downregulated by Aza treatment in larvae. Similarly, Aza-treated adult females also presented suppression of ecdysone signaling-related genes and the AMPs attacin and defensin 2. Notably, all gene repression caused by Aza was reversed by adding ecdysone concomitantly with Aza to the larval or female food, indicating that these genes are effective markers for ecdysone repression. CONCLUSIONS: These results highlight the critical role of ecdysone in regulating the development and immunity of P. perniciosus, which potentially could interfere with Leishmania infection.
- Klíčová slova
- Phlebotomus perniciosus, Antimicrobial peptides, Azadirachtin, Ecdysone,
- MeSH
- antimikrobiální peptidy genetika farmakologie MeSH
- ekdyson * MeSH
- hmyz - vektory účinky léků genetika parazitologie imunologie MeSH
- hmyzí proteiny genetika metabolismus MeSH
- larva * účinky léků imunologie genetika MeSH
- limoniny * farmakologie MeSH
- Phlebotomus * účinky léků genetika parazitologie imunologie MeSH
- shazování tělního pokryvu účinky léků MeSH
- signální transdukce * účinky léků MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- antimikrobiální peptidy MeSH
- azadirachtin MeSH Prohlížeč
- ekdyson * MeSH
- hmyzí proteiny MeSH
- limoniny * MeSH
Synthetic chemical pesticides can enhance crop yields but also have undesired effects. Alternative 'botanical insecticides' may also have non-target effects on pollinators and biocontrol services. Employing action thresholds (ATs) can reduce pesticide (whether synthetic or botanical) use compared to fixed-interval applications. Here the azadirachtin-based botanical formulation NeemAzal and a neem seed extract (NSE) were evaluated in field spraying trials alongside commonly-used synthetics (Voliam Flexi [chlorentraniliprole plus thiamethoxam] and imidacloprid) in developing ATs for the regular and cosmopolitan cauliflower pests Brevicoryne brassicae, Plutella xylostella and Spodoptera litura. We considered the size of the S. litura larvae infesting the crop in order to derive ATs. ATs per plant were higher for NeemAzal (0.55 larvae for P. xylostella and 3 larvae for large-sized S. litura) than for Voliam Flexi (0.30 larvae for P. xylostella and 0.80 larvae for S. litura) but were similar for B. brassicae (50 individuals). Higher ATs when using azadirachtin were associated with the diverse modes of action of botanicals, for instance NeemAzal and NSE deterred oviposition of S. litura. Although the exact values of ATs are likely to have regional limits, our approach can be applied for determining ATs against common lepidopteran and aphid pests in many other vegetable crop agro-ecosystems.
- MeSH
- Brassica * MeSH
- druhová specificita MeSH
- dusíkaté sloučeniny farmakologie MeSH
- glyceridy farmakologie MeSH
- insekticidy chemická syntéza farmakologie MeSH
- larva účinky léků MeSH
- limoniny farmakologie MeSH
- mšice účinky léků MeSH
- můry účinky léků růst a vývoj MeSH
- neonikotinoidy farmakologie MeSH
- ovum účinky léků MeSH
- roční období MeSH
- terpeny farmakologie MeSH
- thiamethoxam farmakologie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Indie MeSH
- Názvy látek
- azadirachtin MeSH Prohlížeč
- dusíkaté sloučeniny MeSH
- glyceridy MeSH
- imidacloprid MeSH Prohlížeč
- insekticidy MeSH
- limoniny MeSH
- neem oil MeSH Prohlížeč
- neonikotinoidy MeSH
- terpeny MeSH
- thiamethoxam MeSH
