How long can a tobacco beetle egg remain dormant at 12C / 54F ?

[El Presidente]

You freeze all your cigars and then throw then into your humidor that you run cold at 12C/54F.  You had one recently rolled farm cigar gifted to you at a herf, it looked fine but to unknown to you three tobacco beetle eggs lay in the filler. 

Under ideal conditions, eggs will hatch within 7 days. 

Under these conditions.....how long can the eggs remain dormant yet viable? 

 

[NSXCIGAR]

https://www.coresta.org/sites/default/files/abstracts/Tobacco_Science_1976_20-50_p._165-166_ISSN.0082-4523.pdf

Percent of egg hatch at 15.6”C for eggs laid by females reared on whole wheat flour and tobacco medium was 1.0% and 1.1% respectively;

So at 15.6C (60.08F) you have a hatch rate of 1%. It's safe to say that egg hatch is statistically unlikely below that temp with rH at 67% which was the control for that study. Obviously at 12C it's even less likely, as in nigh impossible to get a hatch.

As far as abolute lifespan of a laid, unhatched Lasioderma egg I'm having trouble finding that information. 

[El Presidente]

7 minutes ago, NSXCIGAR said:

 

Percent of egg hatch at 15.6”C for eggs laid by females reared on whole wheat flour and tobacco medium was 1.0% and 1.1% respectively;

 

For the sake of the exercise.......these were raised 100% on Cohiba Robusto and esplendido. They had a reason to hatch 

[El Presidente]

18 minutes ago, NSXCIGAR said:

https://www.coresta.org/sites/default/files/abstracts/Tobacco_Science_1976_20-50_p._165-166_ISSN.0082-4523.pdf

Percent of egg hatch at 15.6”C for eggs laid by females reared on whole wheat flour and tobacco medium was 1.0% and 1.1% respectively;

So at 15.6C (60.08F) you have a hatch rate of 1%. It's safe to say that egg hatch is statistically unlikely below that temp with rH at 67% which was the control for that study. Obviously at 12C it's even less likely, as in nigh impossible to get a hatch.

As far as abolute lifespan of a laid, unhatched Lasioderma egg I'm having trouble finding that information. 

Just to be clear. 

The question wasn't about "hatch rate" a temp. It is about dormancy/ viability. 

Assume a situation where the cigars are removed from that temp after say 6 months  and put into a humidor at 20 Centigrade. 

are those eggs live/viable?

[ATGroom]

At one point I tried breeding beetles... I wanted some high quality macro pictures for CCW etc.😜

This was in 2021. I had received a few boxes of 2019 stock from Cuba that had been sitting in a closed LCDH with no power for a couple of years and arrived full of holes. 

I put them in a tub, kept them warm and humid for a few months, unrolling one once in a while to check for larvae or anything. Nothing ever hatched.

 

According to this (https://www.cubancigarwebsite.com/cigar-pests.pdf), 6 weeks for 100% mortality at 16°C, so at 12°C would be less.

 

2 minutes ago, El Presidente said:

Assume a situation where the cigars are removed from that temp after say 6 months  and put into a humidor at 20 Centigrade. 

are those eggs live/viable?

So no, not even close.

[NSXCIGAR]

4 minutes ago, El Presidente said:

Assume a situation where the cigars are removed from that temp after say 6 months  and put into a humidor at 20 Centigrade. 

are those eggs live/viable?

That's what I'm trying to find. I actually don't know if it's been studied. We know below 15C they'll likely remain dormant but for how long is the question. 

[El Presidente]

.

https://www.cubancigarwebsite.com/cigar-pests.pdf

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. Key words:

Low temperature; tobacco; warehouse; cigarette beetle; Lasioderma serricorne

[JohnnyO]

In my experience most bugs lose their "buzzability" below 70 F (21 C). Beetles thrive in 80F (26 C) weather if they are for extended periods of time. At 18 C they don't have a chance, its the 26 C + that is a concern. I had no scientific training for these conclusions. In Cuba it is common for 90F + 85RH in the summer months. John

[NSXCIGAR]

2 hours ago, ATGroom said:

6 weeks for 100% mortality at 16°C,

This pretty much acknowledges the drastic difference in findings of the Fletcher & Long paper from the coresta link I posted. I think that alone casts some serious doubt about the conclusions of both of these studies.

...but not with those of Fletcher and Long (1976). The latter reported that ca. 1% at 15.6°C  and ca. 60% at 18.3°C hatched, respectively, in 23–30 d and in 17–25 d. This discrepancy may result from those studies’ different experimental procedures, the accuracy of temperature control and measurement, and the insect strains used. 

About all that can be concluded (using the most conservative figures from both studies) is that below 15C eggs will likely die within 6 weeks. There doesn't seem to be any info in Imai & Harada on rH at the moderate temps to compare to Fletcher & Long. Given the stark contrast in results there seems to have been major differences in testing environments or other variables. 

[Fuzz]

Question, are these Cuban or NC tobacco beetles?

 

[NSXCIGAR]

1 hour ago, Fuzz said:

Question, are these Cuban or NC tobacco beetles?

I don't think beetles are that discerning. They are often referred to as cigarette beetles so I think they're pretty open-minded. 

According to the notes in the Imai & Harada paper different strains of Lasioderma serricorne may have some variation that affects mortality but the "tobacco beetle" is always Lasioderma serricorne. 

[GVan]

Very cool subject (Pun intended )!!!  Thanks for all the info.