Add IPM to the list of things I didn’t know before coming to Penn State. IPM stands for Integrated Pest Management, which means what it sounds like – it’s a strategy in agricultural systems that integrates several methods of insect pest control to manage crop damage. For a recent journal club meeting, we covered this paper: “Lessons from Agriculture for the Sustainable Management of Malaria Vectors” (Thomas et al 2012), which describes ways mosquitologists can learn from IPM to control mosquito-borne diseases.
Currently we control mosquitoes in the same way agricultural pests were controlled before the IPM movement in the 1960s: massive sprays with pesticides (kill ‘em all!). IPM practices are not perfect, but they have been moving away from sole reliance on chemicals. Pesticides are expensive, damage the environment and create resistant insect populations. Luckily, several innovative ways of controlling mosquito-borne disease have been proposed instead of mass killing them. Some of these methods have been quite futuristic (the mosquito laser gun!), but are impractical from many standpoints.
More realistic approaches have been proposed, including using microorganisms that only infect insects, like fungus. Other have included genetically modified mosquitoes that have sterile offspring or using natural bacteria, like Wolbachia, to render them unable to transmit viruses.
One interesting bit I gleaned from our discussion was that graduate students who are conducting agricultural research were shocked to find out that we don’t regularly use IPM methods to control mosquitoes. For mosquito and disease control, a strategy called integrated vector management (IVM) has been described, but not widely used (A vector is any bug that transmits disease – like mosquitoes, flies and ticks). According to the World Health Organization (WHO), “IVM is a rational decision-making process for the optimal use of resources for vector control. The approach seeks to improve the efficacy, cost-effectiveness, ecological soundness and sustainability of disease-vector control.” The WHO has compiled an IVM handbook to serve as a guide and framework for people who are developing control programs. However, this handbook came out in 2012 and we are a long way from widespread use of these integrated methods. In fact, if you google IVM, anything related to integrated vector management doesn’t show up until several pages later.
So, why don’t we use IVM? We discussed several obstacles to overcome if we are to use IVM, but of course others have described additional obstacles as well.
(1) Developing IVM programs are complicated. Often, when there is a public health threat in a country, town, etc there isn’t just one disease or one mosquito we’re trying to control.
(2) More money should be diverted to research areas that would benefit IVM programs. Currently, most funding directed at infectious disease goes into development of drugs and vaccines. The problem is that drugs eventually lose efficacy (due to pathogen resistance) and good vaccines are a long way off. In malaria funding alone, more than 60% of the $500,000,000+ in funding is directed at drugs and vaccines. Less than 30% of funding goes into basic mosquito research, which would be the basis for any IVM program. We don’t know much about what mosquitoes do when they’re not biting people. How often do they feed on sugar and where? Where do they relax during the day? What eats them? We need more studies that research what mosquitoes do.
(3) Lack of experience with developing integrated strategies. Mosquitologists could greatly benefit from learning about integrated management strategies from agricultural scientists. This seems like a no-brainer, but there are next to no collaborations and cross-talk between these disciplines. The disciplines first appear to have no overlap, but improving human health involves both better food/nutrition, as well as decreasing mosquito-borne disease. How can we facilitate collaborations? There already exist some systems in which ag scientists and mosquito scientists could collaborate. For example, rice in many countries is grown in field plots flooded with water and this agricultural practice has been shown to increase mosquito densities. I would enjoy hearing any other ideas!