Ig-Nobel Prize Winners – Entomology

The brilliant thing about the Ig-nobel prizes is that they celebrate scientific research that can be applied to all walks of life.

The Entomology prize winners for 2021 is a great example of this – recognising the research that has led to a new method of cockroach control on submarines.

This research fundamentally changed the procedure for dealing with cockroach infestations on American submarines, solving personnel welfare concerns while being more economically viable.

A Quick Reminder – What are the Ig-Nobel Prizes?   

If you have read any of our previous articles on the subject of the Ig-Nobel Prizes – you can skip this section! If, however, you have never heard of this award ceremony then keep reading for a quick introduction.  

The Ig Nobel Prizes were set up to honour those people and projects that make people laugh, then think. The prizes are handed out for the weird, the imaginative, the unusual – anything that can spur people’s interest in science, medicine or technology.  

Usually, the ceremony is held every September as a gala-type event in Harvard University’s Sanders Theatre. Unfortunately, in a Covid blighted world this was not possible so the entire event was streamed online.   

It is possible to watch the full event for free by clicking here.  Previous ceremonies have had the prizes presented to recipients by Nobel Laureates in front of the massed 1100 spectators. Thousands more watch along online.   

The Entomology Prize  

The team that won the entomology prize is from the United States of America (John Mulrennan Jr., Roger Grothaus, Charles Hammond, and Jay Lamdin) for their research study ‘A new method of cockroach control on submarines’. The winners were handed their prize by a previous Chemistry Nobel laureate, Frances Arnold, at the time stamp of 1:04:30.

The Entomology Prize – Background 

It is understood from the introduction of the research paper (with references to many other papers) that cockroaches have been present as pests on ships since the days of sailing ships. They have continued to be present as a pest aboard modern day naval vessels too. Specifically, the control of the German Cockroach (Blatella germanica) aboard U.S Navy ships and submarines presents a serious challenge to be overcome.

Enter U.S Navy Entomologists…

The uniqueness of the issue in a submarine setting comes from the capability of the vessel to be a closed system, which in some instances re-uses the same air after purification. This procedure makes it impossible to use most residual insecticides that will continue to produce toxic vapours following application.

Control of cockroaches on nuclear submarines has been accomplished historically by either fumigation (carboxide) and application of Kepone or propoxur bait. For diesel submarines, the main methods are fumigation (carboxide), application of Kepone or propoxur bait, or a residual spray of 3% malathion emulsion. For the 3% malathion emulsion, this has been limited to 15% or less of the total area of any compartment, during treatment the submarine must remain at the surface and must be ventilated for at least 24 hours following treatment.

Carboxide fumigation does indeed control cockroaches effectively – but this does not make it the perfect solution. It is seen to be a dangerous, expensive, and time-consuming practice that must be carried out by highly trained personnel.

There has been no uniform recommendation for cockroach control on all types of submarine in the U.S Navy that is inexpensive, save, and effective. This incredibly interesting fact prompted an investigation by the Disease Vector Ecology and Control Centre (DVECC) into the possibility of using Dichlorvos in an aerosol formula in conjunction with propoxur bait for cockroach control.

A Brief Explanation of the Methodology 

For the purpose of this article the methodology of this research paper have been simplified, with parts omitted. If you would like to read the full paper (which we recommend you do), you can find a link here: https://academic.oup.com/jee/article/64/5/1196/2210530

For the research, eight submarines were treated with commercially prepared 6.5% dichlorvos. In order to fully prepare the submarines for treatment, all of the cabinets, drawers, and void spaces were opened wherever possible and all ventilation shut off.

Both treatment and pre-treatment surveys were accomplished at the same time, with one man beginning at each end of the submarine. The cockroaches were flushed with a 2-oz dispenser of 2.7”/pyrethrin and 6.3”/0 piperonyl butoxide prior to the dichlorvos release. Treatment was completed and the men exited, with the procedure allowing the team to survey and treat in one operation.  

The cockroaches flushed from their places of shelter made them increasingly vulnerable to the dichlorvos treatment, with the solution being directed into the various harborages in each compartment. Once sufficient material was released (relative to the space involved) and the lights secured then the procedure was repeated in the next compartment of the submarine.

The submarines were kept sealed and darkened for 2 hours before being ventilated, which allowed the crew to reboard. Following ventilation, dead cockroaches were counted as a measure of initial kill.

The Results

For the purpose of this article the findings of the research paper have been simplified, with parts omitted. If you would like to read the full paper (which we recommend you do), you can find a link here: https://academic.oup.com/jee/article/64/5/1196/2210530

The dichlorvos treatment resulted in a 97-100% control of German cockroach on all submarines after 24 hours. The data obtained from this research also further demonstrated the imperative need for thorough treatment of all void spaces within submarine compartments. Although the control was obtained in all other areas on submarine H, fifty cockroaches were found during a post-treatment survey within a void space. This undermined and reduced the overall control effectiveness.

In terms of human safety, previous studies by others on toxicity found no reduction in cholinesterase level of workers exposed to concentrations of dichlorvos which ranged from 0.29 to 2.3 jLg/litre for 16 days, and a single hour exposure to 6.9µg/litre showed no effect on cholinesterase level too. The obtained dichlorvos levels show that the submarine crew can reboard the submarine after a 1-hour ventilation with no expected safety risks. After a 43-hour period, there is certainly no hazard to the crew.

However, as the hatching of cockroach eggs was not affected by the dichlorvos treatment, to achieve total eradication of cockroaches then submarines would need to be retreated again after 2 weeks. This would allow enough time for all eggs to hatch, and then be destroyed.

The results table included from the study holds important comparative information between dichlorvos and carboxide control methods. The dichlorvos control method is shown to not only be the safest, but also the most effective and economical method on all types of submarines.

Figure 1 – Comparison of Carboxide and Dichlorvos control methods