Methods in Anopheles Research - MR4

Chapter 1 : Insectary Operation1.2 Cleanliness and General MaintenancePage 2 of 8some or all of these can be employed in any laboratory. The consistent, combined use of these isessential.Chemicals including bleach, gases and solventsChlorine bleach (sodium hypochlorite) is commonly used to sterilize plastic containers, countertops, andfloors. Ethanol also has some sterilization effect on bacteria and fungi, but be careful not to exposemosquitoes directly to ethanol as it will kill them instantly. Hydrogen peroxide is another common anduseful chemical that is compatible with many materials for sterilization purposes. Finally, ethylene oxidesterilization can be useful if facilities are available.Cold temperatures including freezing and refrigerationUnless special precautions are taken to protect the organisms, freezing will kill many microbes. Eventhose that will survive cold/freezing to some extent may be reduced in number or their growth-ratediminished. Both larval and adult diets should be stored in a refrigerator or freezer.DesiccationExtremely low humidity, especially in combination with elevated heat, reduces the abundance of manymicrobes. Therefore, plastic rearing containers and other equipment dried and stored in a dry place arelikely to harbor fewer microbes than those dried and stored inside a humid insectary. Drying ovensprovide low humidity and high heat and are useful for sanitizing equipment that cannot withstandautoclaving.DetergentsHand-washing with soap is more effective than just using water since detergents break down cellmembranes and kill microbes in the process. Similarly, detergents will kill microbes and loosen microbialfood sources such as grease and dirt in the insectary better thanwater alone. While excessive detergent residues might also killmosquitoes, surfaces that are cleaned with detergents andrinsed thoroughly will harbor fewer microbes. If you are in doubtabout the toxicity of a detergent, perform a simple doseresponse mortality test with L1s using realistic concentrationsthat might exist as when containers are not completely rinsed.FiltrationUltra-filtration will remove fungi and bacteria from solutions.However, this method is usually only useful for small volumes ofsolutions due to the cost.HeatHeat-treatment via autoclaving is standard for total sterilization.Therefore equipment should be selected with this in mind. Asmentioned above, drying ovens reduce microbes and may becompatible with equipment that cannot be autoclaved. Briefimmersion in hot water is a measure that provides some benefit,and it can be made available in even the most basic insectaries.Irradiation: gamma, X-ray, UV, photonsMany types of irradiation educe the abundance of microbes. AtFigure 1.2.1. Any household water-heatingpot designed for kitchens can work well inthe insectary for sanitizing equipment.Immersing equipment between usesaddresses two problems simultaneously: Itwill clean instruments to protect thetransfer of infection and will also kill anylarvae/pupae that were accidentally leftbehind on the tool.first glance, such methods as listed might not appear to be appropriate for an insectary. However, theymight be used in the ventilation system (UV) or for sanitizing rearing containers. UV rays from sunshinewill even kill some microbes.