True or False? Tobacco Beetle

[El Presidente]

 

I came across this today. 

 

"The larvae of the tobacco beetle can survive in temperatures as low as 12°C (54°F)"

 

True or False?   

[LizardGizmo]

I remember seeing a photo on FOH showing 100% mortality on a larvae was somewhere around 5ºC/41ºF after 14 days. A larvae that was acclimated at 15ºC for 3 months could survive at 5ºC/41ºF for 60+ days.

Burned in my brain and now I freeze like crazy...

Edit: Found it. Credit to @bpegler11

[JohnS]

The confusion, with this question for our members, may be as a result of knowing of the optimal conditions for hatched, adult beetles. Very different to the survival conditions of larvae.

[BossHogg]

I couldn't say. I've never had that issue... knock on Spanish cedar 😄.  Hopefully I'll never have to as well, since I only buy from here 👍 

[Corylax18]

I think the larvae can survive down close to 40F. I couldnt find it, but I'm sure someone has a link to the Japanese tobacco institute's document on the subject. Its "the bible" on cigar freezing in my opinion. They were more concerned about cigarette tobacco, but the species is the same. 

[NSXCIGAR]

Larvae aren't what's important. In fact I've not heard any claims that low temps including freezing kill larvae, only that they become dormant.

Once they hatch and are active they're tunneling out very quickly. What's important is killing laid eggs while preventing newly laid eggs from hatching. Freezing cracks laid eggs and temps below 60° prevent newly laid eggs from hatching. 

[Corylax18]

I found the study, the abstract is copied below. It states 15c was "tolerant" and describes the number of hours they can live at various dropping levels of temp. 

Time-temperature-mortality relationships for egg, larval, pupal, and adult stages of the cigarette beetle, Lasioderma serricorne were investigated to determine disinfesting conditions for stored tobacco. Susceptibility to low temperatures changed according to the developmental stage. Eggs were most susceptible to low temperatures that were higher than −5°C. Larvae acquired cold tolerance during exposure to 15°C for 1 mo. These acclimated larvae were the most tolerant of all. LT₉₉ values of acclimated larvae were calculated as 7.2 h at −15°C, 23.7 h at −10°C, 376 h at −5°C, 1,140 h at 0°C, and 1,880 h at 5°C. As the most susceptible stage, egg susceptibility to moderately low temperatures (16–20°C) was specifically examined. At 20°C, most eggs (>80%) normally hatched within 4 wk, but all eggs died within 6 wk at temperatures less than 18°C. This fact indicates that the reproductive cycle can be blocked at temperatures less than 18°C, and that tobacco stored in such conditions will never become infested, even if eggs are deposited by invading adults. Consequently, if the tobacco temperature is reduced to 5°C for 3 mo in winter and is subsequently maintained below 18°C throughout the rest of the year, tobacco can become and remain pest-free without any chemical control.

https://www.jstage.jst.go.jp/article/aez/41/1/41_1_87/_article

[jakebarnes]

Have we ever determined how long beetle eggs will stay active? Years?

[Glass Half Full]

These are the charts I've kept as my guide from FOH postings in the past (and inspired my freezing just out of an abundance of caution):

[Corylax18]

I use the same method, but I skip the fridge. If you notice in the above chart, larvae that have been "acclimated" to lower temps (like spending a day in the fridge would do) actually live for twice as long, or more, than if they were tossed straight in the freezer. Its pretty easy for my to keep my place cool and dry though, if you live in a hot/humid environment, you may want to be more cautious of condensation when you remove the cigars from the freezer/fridge. 

[El Presidente]

True it is 

19 minutes ago, jakebarnes said:

Have we ever determined how long beetle eggs will stay active? Years?

That is my question for tomorrow 

[Rhinoww]

@Corylax18 makes a good point re acclimating in fridge. I have some farm rolls arriving soon. Straight in the freezer they will go. Depending on ambient air humidity when they come out they may go to the fridge or straight to Coolidor after the walk from the garage deep freeze to the basement storage. 

[PrairieSmoke]

I've always skipped the fridge step and never had an issue. 🤷‍♂️

[NSXCIGAR]

On 4/4/2023 at 6:52 PM, jakebarnes said:

Have we ever determined how long beetle eggs will stay active? Years?

Addendum to Rob's thread from today the answer is best estimated that at 15°C eggs will likely die within 6 weeks. Just above 15°C they will probably die but they could also hatch (conflicting research). rH conditions can obviously play a part when dealing with temps at or just above 15°C, but at 15°C there seems to be an effective 100% mortality rate at all humidity levels given enough time.