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Monday 18 May 2020

Close Encounter With The Mango Pulp Weevil (19 May 2020)

I harvested 2 mangoes from the garden and was looking forward to eating the mangoes. When I cut into one of the mangoes, I was disappointed to find that it was attacked by the Mango Pulp Weevil (Sternochetus frigidus), rendering the mango inedible. 

Nevertheless, to make the best of the situation, I decided to extract the weevil larvae and use them to do a post since Singapore is still on the stay-home circuit breaker measure to fight the Covid-19 pandemic. I have intentionally not have any photographs of the attacked mango as it was not a pretty sight, and it took away my appetite for mangoes.

When a Mango Pulp Weevil come across a ripening mango, possibly attracted by the fragrance emitted from the ripening mango, it would lay eggs on the surface of the mango. When the eggs hatched, it will burrow into the mango and start eating the mango pulp. As the larvae feast on the juicy pulp, they also excreted waste. When they were about to pupae, they made use of the excreted waste to form pupa chambers. Inside the pupa chambers, the larvae will turn into pupae and later develop into adult weevils. 

Back to the mango. There were many pupa chambers in the mango but I only managed to extract 6 pupae from it. Here are the extracted pupae.  





To keep the pupae for further observations, I decided to make an artificial pupa chamber using a piece of used flower arrangement foam by poking a ballpoint pen into the foam.



I then placed the pupae into the holes with them vertically placed with head at the top.



After which I covered the pupae with a piece of acrylic to prevent the hatched weevils from flying away.



After a few days, the weevils started to emerge. The first one to hatch was the one at the top right corner. The bottom middle one also looked almost ready to emerge.






It was an interesting few days watching the pupae transforming to weevil, but it was something that I would rather not have as they took away the pleasure of me enjoying one of my favorite fruit.