Darkling Beetles in poultry houses

There is a serious under appreciation for the severity by which darkling beetles (Alphitobius diaperinus) imperil the poultry industry.  Egg, broiler, and turkey producers are coming to the realization that darkling beetles in many areas of the United States are the greatest vector for transmitting avian diseases. 

For many years there was an on-going whimsical debate among poultry producers as to whether darkling beetles were a benefit or a detriment to poultry units.  The supporters of cohabiting the beetles thought beetles would eat enough fly maggots in the manure to justify the existence and in eating manure would dry up the manure.  Some producers even purchased beetles by the thousands to augment their supply.  Detractors on the other hand knew the beetles gradually devoured insulation and wood construction.  The subject provided fodder for convivial discussion among poultry producers. 

Research over the past 3 decades has been demonstrating the severity of beetles for transmitting virtually every disease that threatens the poultry industry.  Darkling beetles have been demonstrated to be a serious vector in the industry.  Just as in the swine industry where the danger of disease transmission was not appreciated until rats and mice were trapped in and around swine facilities and blood titers were measured to most all transmissible swine diseases, the poultry industry has under estimated the darkling beetle in compromising biosecurity and disease transmission.

Now we have that same evidence that cohabiting darkling beetles carry pathogenic microorganisms that cohabit within beetles. The first report of disease transmission involving the darkling beetle was by Eidson (1966) who described induction of tumors associated with Mareks disease by inoculating chicks with suspensions of homogenized beetles.  (Calibeo, 2002)

Building management practices also have confounded the degree of biosecurity sustained in poultry units depending on clean-out procedures. Thoroughness of clean out varies from total cleaning of the entire building followed by sanitizers to achieve a pristine unit to the opposite extreme of partial cleaning where some manure is deliberately retained in the building for the express purpose of providing an existing starting microbial culture.   That starting culture may likely contain beetles and pathogens as well.  

Darkling beetles have a reputation for traversing considerable miles whether between buildings or from site of manure spreading to other premises.  Savage (1992) reported that darkling beetles may travel more than a mile per day.  This was clearly experienced by the residents of La Rue, Ohio that were inundated by darkling beetles that purportedly traveled from the site of manure spreading into the homes of La Rue, as reported by the Wall Street Journal (Miller 1997). This generated a law suit for $25 million by the residents (Miller 1997).

The research community has been building a library of research results over the past 40 plus years that clearly documents that the darkling beetle is a continuing threat to the microbial well-being of the poultry industry and possibly the greatest vector to biosecurity of poultry that extends from viruses through bacteria and fungi. Despins and Axtel (1995) reported that feed conversion and weight gain of broilers and turkey poults decreases due to the consumption of the adult and larval beetles.

Darkling beetles have been shown to harbor and transmit avian leucosis, (Eidson et.al. 1965), Mareks disease virus (Eidson 1966), avian reovirus (De Las Casa, E. et.al. 1973) and fowl pox virus and Newcastle disease virus (De Las Casa, E. et.al. 1976).   McAllister et.al. (1995) isolated infectious bursal disease virus (IBDV) from blood and throughout the digestive tract of the beetles.  Chickens fed darkling beetles from farms testing positive for IBDV developed symptoms of IBDV.   Goodwin and Waltman (1996) collected at least 75 darkling beetles from each of 7 farms known to harbor large populations of beetles.  On 5 of the 7 farms the beetles tested positive for IBDV.  On 3 of the 7 farms the beetles tested positive for reovirus.

Despins and Axtell (1994) demonstrated that darkling beetles harbor turkey enterovirus and rotavirus.  Watson et. al. (2000) reported that turkey poults fed beetle homogenates infected with turkey coronavirus (TCV) and TCV contaminated materials would show clinical signs associated with TCV including 50% mortality.

Ou (2010) extensively studied Infectious Laryngotracheitis Virus (ILTV) in beetles and their larvae collected from commercial broiler farms,  diagnosed with a vaccinal ILTV outbreak.  ILTV DNA remained on the surface of darkling beetles for at least 42 days after the ILTV farm outbreak.  The work by Ou (2010) adds ILTV to the avian diseases demonstrating that darkling beetles, and their larvae can carry ILTV and may transmit it to susceptible chickens.

A vast number of bacteria genera have been shown to be harbored by darkling beetles and transmitted to different genera of poultry.  This evidence also began to appear in the 1960''''s.

De Las Casa, E, et.al. (1968) reported the infection and recovery of Salmonella typhimurium and Escherichia coli from within darkling beetles.   De Las Casa, E. (1972) conducted an extensive study of turkey brooder units over a 2 year period in which darkling beetles were captured, surface disinfected, macerated, and cultured in selected media. Micrococcus spp, Streptococcus spp, and Bacillus subtilis were the most common gram-positive  bacteria, while Escherichia spp dominated the gram negative bacteria and Salmonella was present in a smaller number of units.  Aspergillus flavus was the most prominent fungi within the beetles in 25 % of the samples. 

Harein et.al. (1970) collected adult darkling beetles from the litter of poultry brooder houses over a 2 year period.  Over a thousand adult beetles were individually surface disinfected, macerated and cultured for Escherichia coli and Salmonella spp detection.  Five species of Salmonella were found within the beetles.  Forty-eight serotypes of E. coli were recovered from within 251 beetles, 26 of which were known as pathogens for man and animals.

McAllister et.al. (1994)  fed 1 larval or adult beetle inoculatedwith Salmonella Typhimurium, to chicks and tested for colonization inthe chicks by cloacal swabs 24 and 48 h after gavage. They foundthat 90% of chicks fed 1 larval beetle,and 70% chicks fed 1 adult beetle had  positive cloacal swabs within 24 hr.

Roche et.al. (2009) fed 4 beetles that had been exposed to Salmonella typhimurium per chick.  These chicks served as challenged broilers at 1 to 2 per pen with either 5 or 10 pen mates. From 20 to 40% of the pen mates tested positive for cecal presence of Salmonella.  

Goodwin and Waltman (1996) studied bacteria present in darkling beetles in 7 broiler chicken houses from which 75 adult darkling beetles were captured from each unit. The beetle homogenates plated on appropriate media were extremely rich in aerobes (10⁶ ), coliforms (10⁴ ) and Streptococcus (10⁶ ).  Clostridia were present, but at a lower CFU/ ml.  

Strothers et.al. (2005)  found that the lesser mealworm (darkling beetles) could acquire, harbor, and transmit viable Campylobacter jejuni to chickens that consumed beetles. Ninety percent of the birds that consumed a single adult or larval beetle became Campylobacter-positive, whereas 100% of the birds that consumed 10 adults or larvae became positive.

Goodwin and Waltman (1996) also demonstrated the presence of Eimeria in the beetle homogenate collected from 7 broiler farms.  The beetle homogenate tested positive for coccidia on 6 of the 7 farms.

Finally the darkling beetle is considered to be more than a vector for transmission of disease causing organisms.  The darkling beetle inflicts physical damage on chickens and turkeys.  Beetles in thirst will attack chickens by biting birds and chewing on the skin in part to obtain liquid, but also blood.  (Savage 1992).  The lady in La Rue, Ohio (Miller 1997) that was awakened to find a darkling beetle crawling in her ear would agree with this assessment by Savage (1992).

This is but a sampling of the research findings that have been published in the past 30 + years.  It certainly documents the economical and biological impact on the poultry industry whether for meat or eggs.  Virtually every Conclusion Section of the research reports points out that the darkling beetle is a serious vector for diseases within the poultry industry.

Probably the research that convinced more poultry and swine producers, the value of including disinfecting facilities prior to entry of animals into food production animal facilities was conducted by Scott 1963 (University of Illinois) in which a disinfecting step was introduced following cleanup/wash/up.

The research demonstrated the immediate value of disinfecting facilities. Prior to instituting disinfection there was practically a linear decrease in 7 day chick gain with each passing group  However, following disinfection there was a sizeable increase in gain by the next set of chicks. 

The problem is that most disinfectants can only be used in the absence of animals,  most assuredly not in the presence of food-producing animals.  Most disinfectants are carcinogenic and/or may create tissue residue. In most cases the animals can not be returned to the rooms in less than 24 hours because of concerns for tissue residue. This time allows the disinfectants to decompose to avoid harm to the animals. Of course, with the break down of disinfectants they are no longer destructive to microbes. As described earlier in swine farrowing units, this initial kill of microbes provides protection until the first sow defecates. From that point forward the microbial level starts to increase and continues to build under  such management until the pigs are weaned. 

Whether it be darkling beetles or the many microbial pathogens, a prophylactic management program is critical to biosecurity.  Whether for meat or egg production it is critical to suppress and kill resident microbes from viruses up through bacteria, fungi, protozoa and insect and parasite larvae.  As shown by Scott (1963) disinfectants are quite beneficial in the cleaning process between groups of poultry or pigs. What has been lacking is a prophylactic program that will continue to suppress these microbial genera plus larval stages of insects and parasites and that is safe when dusted on all surfaces including animals  throughout the animal growth cycle or the entire egg laying cycle.

Hospital research is addressing  nosocomial diseases world wide to counter the critical contracting and loss of life world wide to diseases from hospital visits.  In spite of all the disinfectants used in hospitals, the US Center for Disease Control and Prevention(2009)estimates that in the US alone we have 2 million people contract diseases annually from going to a hospital and over 90,000 die annually from these infections.  The most sustained protection against infections are being provided by using contact materials made from specific mineral elements (Keevil 2008  and Harmon 2011) that have been shown to be extremely effective against a broad spectrum of viruses, bacteria and fungi.  Sagripanti (1992, 1993) at FDA (Food and Drug Administration) demonstrated the efficacy of both iron and copper against multiple viruses.  Sagripanti reported that these 2 elements were "comparable to the activity of the recommended disinfectants: formaldehyde, peroxide, and chlorine".  Keevil et.al. (2009)  have shown that copper has capability to eradicate the H1N1 virus.   Zinc is extremely effective against multiple bacterial genera including Salmonella enteritidis, that is creating such concern in the egg industry (Jin et.al, 2009).  MRSA (Methicillin Resistant Staphylococcus Aureus) that is the scourge of hospitals is quite susceptible to copper in various alloy forms (Noyce and Keevil 2004 and Keevil et. al. 2005).  Faundez et.al. (2004) reported a linear pick up of 2 mg of copper by 100 gm meat samples over a 50 minute time period and a 6 log reduction in Salmonella enterica on copper plates compared to stainless steel plates.

The fungi, Aspergillus niger (Keevil et.al. 2007) and Candida albicans (Zeelie and McCarthy 1997) have been shown to be eradicated by zinc and copper. 

The efficacy of Disrupt, a dry mineral based prophylactic powder, has been demonstrated against a broad spectrum of pathogens encountered in food-animal production.

Research that led to the development of Disrupt Environmental Prophylactic powder, paralleled the hospital research that also fights frequent infusion of microbes.  While hospitals are reconfiguring to use more copper, zinc and iron in place of stainless steel surfaces, the Disrupt Environmental Prophylactic powder is used to provide a programmed dusting of all surfaces in food-animal production units using the same mineral elements.  The mineral elements in Disrupt retain anti-microbial actions without breakdown, quite in contrast to the essential decomposition of most disinfectants for safety reasons for human and animal health .  Disrupt is dusted weekly typically at 1 lb per 100 sq ft in animal units with animals present to sustain action against microbes (Harmon 2010).   Disrupt also is effective against the larval stages of insects such as Darkling beetles and flies as well as parasites such as coccida.

Poultry and swine producers have reported an extensive list of benefits from the programmed use of Disrupt. These include:

          Reduced infectious diseases                            Reduced breast blisters on turkeys                                        

          Reduced diarrhea incidence                             Reduced environmental ammonia

          Reduced respiratory infections                         Reduced employee respiratory complaints

          Reduced pig shoulder and joint infections        Increased manure nitrogen analysis

          Reduced greasy pig incidence                         Reduced fly, gnat, and beetle problems

          Reduced umbilical hernias                               Reduced mold growth

The Disrupt Environmental Prophylactic powder also improves the environmental air quality within rooms by greatly reducing ammonia levels within animal units.  This is demonstrated clearly in poultry units where there is greatly reduced ammonia in air samples, but concomitant increases in nitrogen retained in the accumulated solid manure beneath the birds, such that manure analysis records reflects these increases.  Disrupt serves to abate odors by trapping and chemically binding odorous materials and also serves as an effective desiccant through the hygroscopic action of the calcine carrier.