Well. That was the headline. But in truth I suspect this is not just a Durban phenomenon.
I've noticed increasing pest problems as a trend for many years. My observations and the reports that led to the story in the first place are, however, anecdotal. I'm not aware of a particular study that has scientifically measured and tracked this. Some of it is good news. Some a bit of a challenge. There are a number of contributing factors.
Long lasting pesticides have steadily been removed from the market. DDT, Dieldrin, Aldrin and Chlordane in particular had renowned long-lasting effects. In older areas where properties have been treated at some time in the past, there was/is some residual effect that is still gradually wearing off. Bit by bit, these products are losing their effect to the point where insect populations have an ever-increasing potential to grow.
Globally, there has been a steady trend towards pesticides with ever-shorter persistence. The ideal pesticide does its job and then breaks down to something harmless. This is good for the environment, but increases the frequency of application to manage pest populations as compared to the older more persistent products. In residential situations and on average, we are using shorter life products, but not increasing the frequency of treatments.
A similar trend to pesticide persistence is also being seen in pesticide safety. We want safer, more environmentally friendly products. This is largely achieved with products that have less overall toxicity, although there are still some exceptions. Some insecticides do have a high insecticidal effect but are very safe for mammals.
However, in general terms, we are using less toxic products. To achieve the same result as the older products requires more technical skill. Not only are we seeing do-it-yourself enthusiasts failing to work on increased skills and understanding (no real surprise there), we see some of this amongst older pest management professionals who are either too set in their ways, or too proud to recognise the need to update their skills and knowledge.
It should be noted that poor application of a milder, safer product can actually aggravate pest populations over the medium term. Nature tends to defend itself. With ants in particular, failure to get sufficient active ingredient to the nest, the ultimate source of the problem, will lead to increased worker production, more reproductives and budding - a phenomenon where the colony splits to form multiple colonies. These are defense mechanisms against a high forager loss rate, but where the colony is not being eliminated.
Poor application of milder products also increases the potential for the development of resistance to the pesticide.
Improved pest species targeting.
Products and techniques are reducing the effect of pesticide application on non-target species. As example, the old way of treating for cockroaches also went a long way to reducing ant problems. Modern treatment methods can be highly effective against cockroaches whilst having a near-zero impact on ants.
Continued improvements in chitin inhibitors in particular hold out the potential of targeting particular species - there are already products that are pretty specific down to the family level.
Suburbia has expanding massively, growing into areas without a history of pest management, at least not the types that affect homeowners.
Inner city decay.
This is applicable to particularly older high density living structures. They weren't designed that well from a pest management point of view in the first place. There was no need as the older products could manage the associated pest problems. The situation is aggravated by a noticeable drop in sanitation standards and aging plumbing which introduces water and accumulated organic matter.
What may be deemed a suitable pesticide in a particular situation is something of a balancing act. In very simple terms, you have to balance the harm the pest is doing against the harm the pesticide may cause. This means that many pesticides are not relevant in some highly influential areas such as Europe or North America, but extremely relevant elsewhere, particularly tropical zones.
Western nations have had a series of reviews as to what pesticides are relevant to them. The discontinuation of a particular product in these nations has a considerable impact on global perception of the product and, perhaps more critically, production viability. Manufacture of some products have been discontinued globally based on decisions made in the western nations.
Climate change will have an effect. Tracking long term changes in insect behaviour could prove a useful indicator. However, whilst we need to keep an eye on this as it would impact pest management practices, I don't consider the effects of global warming as a major contributor to the general observed trend.
There are two particular contributing factors to this.
New generation products are the result of improved (and costly) applied science. New products are very expensive to develop, leading to ever more expensive available products as cheaper, old generation products are discontinued.
Add the increasing need for high technical skill and a regulatory environment that is increasingly requiring application by pest management professionals only, and the cost to client is escalating. This is not a major issue in areas with residents having high disposable incomes, but for areas with low disposable income, pest management is a pretty low priority against more pressing demands such as food, shelter, clothing and (dare I say it) cell phones.