Robert N. Malek Profile picture
Apr 13, 2022 9 tweets 5 min read Read on X
A few words on how this spray is generated and why the #beetle is not harmed in the process:

Hydroquinone and hydrogen peroxide are secreted by specialized glands and stored in a tank. Other glands produce catalyst enzymes such as catalases and peroxidases. 1/7 Image
When the contents of the two glands are mixed, oxygen forms and in turn reacts with hydroquinone to convert it to benzoquinone. Pressure due to the buildup of oxygen then causes the hot mixture of water and benzoquinone to be expelled. 2/7 Image
The explosion chamber is made of a mixture of chitin, proteins and waxes, which protect the beetle’s soft interior from the chemical mix, the high temperatures and the pressure. To withstand the #explosive force, the blast consists of a series of micro-pulses. 3/7
Why the beetle ejects its defensive spray in pulses as opposed to one, dramatic blast? First of all, the attack can be sustained for a longer period of time and has a wider range. Also, the beetle's body can cope with multiple smaller forces better than one greater force. 4/7
The beetle aims accurately at its own body parts, in response to attack. Grab one of the beetle’s lower leg segments, and the boiling spray will be directed exactly at that segment, even if the entire abdomen must be twisted to point the nozzle in the right direction. 5/7
This ability is thought to have #evolved as a defense against #ants, which can attack from any direction. 6/7 Image
The beetle's cuticle is not harmed by these pulses thanks to the same mixture of chitin, proteins and waxes that make up the explosion chamber.
#chemical_warfare #defense_mechanism #insects
Dean et al. 1990:
Arndt et al. 2015:


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More from @MalekRobert

Feb 28, 2021
The fall armyworm (FAW), Spodoptera frugiperda is an invasive insect pest that is native to south America. It is spreading across the world and was recently reported in neighboring Syria. Why is this a big deal?
@Ibrakhim_Aya @MouhanedD @souhad_16 @TSerhal…
Via natural flight and through the movement of infested goods, this pest has now spread to the US, to most African countries, to south east Asia and Australia, wreacking havoc along the way.
In its larval stage, it can cause significant damage to crops. It prefers maize, but can feed on more than 80 additional species of plants, including rice, sorghum, millet, sugarcane, vegetable crops and cotton.
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May 31, 2020
When planning on starting your small garden, certain simple measures may turn out to be beneficial on the long run.
Let's go through some of them 👇

@Ibrakhim_Aya @MouhanedD @souhad_16
Design you soil beds in a way that permits an ease of access and maintenance. Whether you're using raised beds or direct soil cropping, keep in mind that you will have to walk through them for inspection, pruning, harvesting...
A balanced irrigation is essential. Over-watering is harmful to the plant and puts it at risk of infection by fungal diseases. Under-watering stresses the plant and reduces yield. While a drip irrigation system is very efficient, a DIY plastic bottle system is muuuch cheaper.
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May 15, 2020
We are supposed to preserve our natural biodiversity, especially that which concerns natural enemies of insects that are harmful to our crops, oak trees and pine groves.
But when an insect becomes a public nuisance and invades people's houses, dealing with it becomes tricky.
Calosoma beetles feed on the pine processionary moth (دودة الصندل) and on the gypsy moth which causes severe defoliation of oak forests. In the early 1900s Calosoma beetles were mass released to control the above-mentioned pests in Minnesota and in other places.
Under certain environmental conditions, their numbers increase dramatically and they start causing public annoyance as we're seeing in the Bekaa.
Read 8 tweets
Mar 19, 2020
As Nadine pointed out, ToBRFV (Tomato brown rugose fruit virus) is indeed an emerging disease that threatens the Lebanese tomato cultivation, both greenhouse and field grown tomatoes.
It has already been reported in neighboring countries such as Jordan, Turkey and Italy, all countries with which we have strong commercial links, especially with regard to agricultural products and produce (seeds, plants, fruits and vegetables...)
It is only a matter of time before it's incidence is reported in Lebanon. When it comes to emerging pests and diseases, Lebanese researchers in Universities and in LARI usually learn of their presence, inform authorities (MoA), whose advice is usually to sweep it under the rug
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