Pest control
The use of chemical pest control is documented as early as 2500 B.C., where Ancient Sumerians used sulfur compounds to kill insects, and it is still used to this day to tackle mites and fungus in farms.6 Although HLK has not been around for 4,500 years, it has been involved in protecting inventions relating to pest control for much of its 175-year history. Way back in 1894, HLK (or Haseltine, Lake & Co., as our firm was known back then) assisted in the filing of a patent to a candle for burning sulfur. While sulfur’s sustained use over thousands of years demonstrates its effectiveness as a pesticide, it does not come without drawbacks, such as its negative impact on beneficial insects, contribution to the formation of acid rain and gasses which are harmful to human health, and not least the smell – I definitely wouldn’t want to light a sulfur candle in my flat…!

Front page of GB189404195, a patent to a candle for burning sulfur, filed in 1894 by Henry Harris Lake of Haseltine, Lake & Co.

Schematic diagrams of the sulfur burning candle in GB189404195.
Thankfully, there have been a number of developments in pest control over the last 175 years and HLK has been involved in obtaining patent protection for some of these inventions, including GB669823 (an improved rosin amine pest control composition), GB716643 (a method of producing the insecticide hydrogen phosphide), and GB1395129 (insecticidal phenols).
However, not all advancements have proved beneficial. The influential book “Silent Spring” by Rachel Carson documents the negative effects humans have on the natural world, in particular through the indiscriminate use of pesticides.11 A notorious example of this is the now banned dichloro-diphenyl-trichloroethane (DDT), a pesticide which, after widespread indiscriminate use, was found to persist in the environment, accumulate in the food chain, and harm both animal and human health. This is one of many instances where pesticide use has had ecological and environmental consequences.
Recent developments in pest control
The agricultural sector is therefore searching for new strategies to combat pests which do not have a detrimental impact on our planet. The use of RNA interference (RNAi) technology to control pests is one such promising approach.12 RNAi is a naturally occurring cellular defence system mediated by double-stranded RNA (dsRNA) which can be exploited to supress the expression of genes essential for an insect’s growth or reproduction. As RNAi is sequence-specific, the delivery of RNA sequences tailored to a particular insect can selectively kill the pest in an agricultural setting without undesired adverse ecological effects. Nevertheless, the delivery of RNA is often thwarted by limited cellular uptake and chemical or enzymatic degradation of the nucleotide sequence. To fully exploit the capabilities of this emerging technology, further developments are required.