10: Bs & Bti

Hello! During week 10, the majority of the time was spent designing and putting together a draft presentation for practice presentations with my advisor. I did additional research  on the bacteria that are used in microbial larvicides, typically used for malaria control. 

Bacillus thuringiensis israelensis, the gram-positive, soil-dwelling bacteria, is used predominantly against mosquito larvae, particularly those of the Anopheles species that transmit malaria. Bti produces protein crystals during sporulation (spore formation), which produce a potent toxin called cry toxins. These toxins kill larval midgut cells by causing an osmotic shock leading to cell lysis, which is when the cell membrane is destroyed to release genetic material of some sort or the organelles within the cell. When mosquito larvae ingest Bti spores or Cry toxins while feeding, the toxins specifically bind to receptors in the larval gut lining, allowing for selective larvicidal action. Bs, or Lysinibacillus sphaericus joins Bti as a gram-positive bacteria breaking down mosquito larvae. Bs also relies on spores for its larvicidal activity. These spores germinate in the mosquito larval gut. After germination, it releases a combination of insecticidal proteins that damage the larval gut lining and kills the larvae. Bs shows effectiveness against a broader range of mosquito species compared to Bti. This complementary action makes it a very valuable addition to vector control strategies. A limitation of the effectiveness of these larvicides is that their success depends on proper application to ensure optimal reach and impact on mosquito breeding sites.

Thanks for reading this week’s blog! This blog was just mentioning the progress I’ve made in terms of research, but working on the presentation and report will take most of my time from now on. I likely won’t be doing much more research on these control methods other than to fill in gaps and make final conclusions, but that’s saved for my report. Next week is the final time I’ll be making progress, I’ll have finished my report (hopefully), and begin working on final edits. See you next week!