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Any thoughts on why a group of healthy appearing crickets would suddenly start dying-off in droves? Any insight will be greatly appreciated.
Any symptoms such as red bellies or you notice them lying on their backs twitching as they are dying? How's the humidity and what are you feeding them?
Andrew, haven't noticed any red bellies but I'll check for that tonight. I'm finding them dead upside down and right side up, and darker than normal, plus the smell they give off after dying is putrid. Humidity is low, maybe 20-25% and they're fed ground dog/cat food with vegetables and fruit on occasion. This particular group are the offspring (4th generation) from adult crickets bought back in early September. Once the mass die-off begins there seems to be no way of stopping it. I've been struggling with this problem on and off for 15 years.
Hi JButera, -
"Diseases in insects produced for food and feed", (2015) by Eilenberg, Cappelloza & Nielsen-Leroux, Vlak & Jensen originally published in Journal of Insects as Food and Feed 1(2) is available as free full pdf via ResearchGate.
It discusses the well known densovirus (AdDNV) that afflicts Acheta domestics house crickets & that there are other viruses like iridovirus (CrIV). As per pg. 92 of original text,
where goes on to explain non-replicating viruses "... can be transformed to an infective state ...."
Authors sent a questionnaire to insect producers & found "... for the house cricket ... several diseases ... virus ... in particular ...." In Section 6 they discuss prevention/control & in sub-section 3 advise segregation of some stock & preventing sub-populations mixing until assure no disease cross contamination.
As for viral incidents "... latency ... triggering active infection ... unpredictable. Thus in sub-section 4 authors recommend "...regular intervals ..." of new breeders introduced into old stock - with careful segregation of those sub-populations.
Since you mention 15 years of periodic die offs it seems likely, to me (unless current die-off due to food contaminated somehow with other vectors report mentions, or simply die-off from food on which "Bt" natural insecticide used), that at some point a latent virus appeared in your general population. This scenario, in theory, involves a segment of the population that did not die which non-the-less served as a carrier of a virus; &/or introduction into the colony of a new latent virus carrier.
Cited report Figure 3 has, among others, an image of the double strand DNA irido-viridae (like CrIV) & Baculo-viridae. Figure 2 image "G" shows an example of virus taking over insect cell DNA for replicating itself.
If you look at Table 2 can see 4 distinct kinds of viruses that have plagued silk worm producers. Figure 4 shows how honeybees over the last 50+ years have encountered assorted viruses. Which may be an indication captive cricket producers also have more than just one version of the AdDNV or the CrIV viruses around.
Acheta domesticus densovirus (AdDV) causes slow growth & those that die (from septicemia) lie on their back paralyzed. According to Weissman, et al. (2012) AdDV is not limited to Acheta domestics; see "Billions and billions sold: pet feeder crickets, commercial cricket farms, an epizootic densovirus and government regulations makes a potential disaster"; available on-line as free full pdf from csun.edu
The AdDV related Acheta domestics mini Ambidensovirus has been noted since 2013. Thai cricket farmers have fought with Cricket iridovirus (CrIV) , which afflicts Acheta domestics, Gryllus bimaculatus, G. campestre & G. assimilis.
Cricket Paralysis virus (CrPV) has plagued lab colonies of Teleogryllus oceanicus & T. commodes, but also has been found in Acheta domesticus. Another concern is the Acheta domestics Volvovirus (AdVVV) & it's related AdVVV-IAF.
Gryllus bimaculatus nudivirus affects G. bimaculatus. This nudi-virus shares 21 of it's key genes with baculo-viridae.
Iridovirus are somewhat easier to diagnose than others because an insect under heavy viral load actually appears lavender/turquoise iridescent.
The way to deal with viral risks is to keep breeding operation separate from the herd reared for market. The introduction of a virus can occur by everything from field collected food to cannibalism.
Acheta domestics are prone to parasitic, bacterial & fungal impacts, which can stress their immune system in a way that latent virus can activate. Other viral inductor stresses include over crowding, unbalanced diet, high temperature & high relative humidity. There exists the possibility that genes coding protein of a virus capsid can mutate & this too allows latency to become virulent.
Note: not edited for auto-correct errors, I have got to go now
Thank you again, gringojay. Andrew, is this what you meant by red bellies?