Latest News from BPCA

12 May 2021

The science of smell: exploiting bed bug biology with pheromones

PEST CONTROL | PPC103 MAY 2021

Dr Laura Tugwell and Dr Victor Brugman, from Vecotech Ltd, track their innovation journey from scientific question to commercial product.

Insights are shared into the technical processes and cutting-edge chemical ecology techniques behind the development of their new, research-led bed bug lure, BugScentsTM.

the-science-of-smell-main-image

SPEED VIEW:

  • >50% of bed bug infestationsgo unnoticed
  • Understanding the bed bug life cycle and their navigation cues enables us to manipulate them for monitoring and control
  • Pheromones are chemical cues emitted by an insect to change the behaviour of another
  • Live bed bugs were subjected to behavioural experiments to understand how different compounds in pheromones affect them
  • As with any pheromone-baited trap, chemicals are added to a matrix placed in the trap.

The problem with bed bugs

Bed bugs (Cimex lectularius, Hemiptera: Cimicidae) are a serious economic threat to the hospitality industry, and their detection and control remain challenges to pest professionals in many settings.

Preventing bed bug infestations is key to avoid expensive eradication costs. This can be achieved through effective bed bug monitoring to detect infestations early, helping to verify treatment success and check for re-infestation.

Factors including widespread resistance to commonly used insecticides and, pre-pandemic at least, increased international and domestic travel, have contributed to a global rise in infestations.

At the local level, the ability of the bugs to spread rapidly (estimates suggest bed bugs can travel up to one metre per minute), evade detection and survive long periods between blood-feeds mean infestations can easily be overlooked.

As a result, more than 50% of infestations can go unnoticed. This is exacerbated by the ability of the bed bugs to hide almost anywhere within the complex ‘geography’ of a property.

This means they can move and re-infest between neighbouring units, adding further challenges in multiple-occupancy settings in particular.

Bed bugs are therefore well adapted for urban co-habitation with humans and their natural behaviour presents us with numerous barriers to their control. However, it is this natural behaviour that also presents us with opportunities.

By understanding each step in the bed bug life cycle and the cues used by them to navigate their environment, we can begin to manipulate them for the benefit of monitoring and control. It is this exploitable biology that forms the basis of Vecotech Ltd’s innovation, the BugScents™ bed bug lure.

Its patented formulation mimics the smell of a bed bug aggregation and causes bed bugs to move towards the lure and into the trap in which it is deployed, providing enhanced detection of even low-level infestations.

Exploiting bed bug biology

Bed bugs, in common with other insects, are highly sensitive to their environment. Through a system of receptor mechanisms, bed bugs can detect and process a variety of cues from their environment and other bed bugs.

These cues are then translated to changes in behaviour which include feeding, mating and avoiding danger.​

Pheromones are chemical cues emitted by one insect which then causes a behavioural change in another. For bed bugs specifically, pheromones can cause them to form aggregations whereby the bugs group together in refuges.

Even subtle differences in the chemical composition of ​these pheromones can influence how another bed bug will respond. Across the spectrum of insect pests, supplementing monitoring traps with pheromone attractants has been shown to boost both the sensitivity and specificity of detection.

The natural tendency of bed bugs to aggregate together in favourable refuges has long been recognised, yet at the start of the BugScents™ innovation journey some twelve years ago, very little was known about the aggregation pheromone that facilitated this behaviour.

Uncovering the chemical composition of the aggregation pheromone could provide the vital tools needed to enhance existing monitoring systems. So, which chemicals within this pheromone odour are responsible for this aggregation response?

Scientific innovation and development

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World-leading experts in medical entomology and chemical ecology at the London School of Hygiene and Tropical Medicine (LSHTM) and Rothamsted Research have spent over a decade answering this important question.

The team began to investigate the characteristics of an established bed bug infestation that will be familiar to many: faecal stains, presence of shed cuticles and the unique odour.

Initial experiments revealed that filter paper previously exposed to bed bugs and containing these hallmarks of infestation was more attractive to bed bugs than their clean filter paper counterparts. All bed bugs behaved in this way regardless of sex, life stage, or if they had fed or not.

With the attractive role of the faecal and cuticle matter established, the next step was to find out the specific chemical compounds causing this behavioural response. To achieve this, the chemicals from the bed bug exposed filters papers were extracted and collected using specialist air purifying equipment in a process called air entrainment.

 

Initial experiments revealed that filter paper previously exposed to bed bugs and containing these hallmarks of infestation was more attractive to bed bugs than their clean filter paper counterparts. All bed bugs behaved in this way regardless of sex, life stage, or if they had fed or not.

 

Firstly, clean (charcoal-purified) air is passed over the bed bug exposed filter paper in a sealed chamber. Any volatile chemicals drawn into the air stream are captured onto a porous material and then washed off, generating a liquid chemical mixture.

The compounds in this extract are then separated and identified based on their relative chemical properties using gas chromatography and coupled gas chromatography-mass spectrometry methods.

Next, the identity of those compounds causing a physiological response in bed bugs was determined. When an insect responds to a chemical cue like a pheromone, the antennae generate a small electrical signal. By attaching electrodes to the insect’s antenna, a complete electrical circuit is created.

In this process, called electroantennography (EAG), bed bugs are exposed to the compounds within the extracted chemical mixture. If receptors in the antennae respond to a compound, an electrical response is recorded.

Using this innovative technique over twenty different electrophysiologically active compounds were identified. But the influence of each of these compounds is not equal. Some compounds will be produced in greater quantities, or play a relatively more important role in the attractive response.

The number of compounds is also a key commercial consideration; formulation stability and performance must be balanced by product cost targets. Furthermore, EAG only tells us the insect is responding to a compound, not whether it is attractive or repellent to the insect.

To address this, an extensive series of behavioural experiments were carried out using live bed bugs. These tests involved sequentially screening out compounds of less significance on the aggregation response.

The search was narrowed down and eventually left just two compounds from the aggregation pheromone which dramatically, and consistently, induced the aggregation behaviour.

Optimal doses of these two key aggregation compounds were defined, and a unique and innovative blend​ was synthesised. This scientific discovery was patented allowing for its application in bed bug monitoring enhancement.

Applying research to provide a solution

At this stage, Vecotech Ltd took over the product development reins. As the first spin-out company from LSHTM we are ideally positioned to accelerate the development of promising novel research through to application.

Supported by a prestigious Innovate UK grant, Vecotech embarked on a research and development pathway encompassing the latest in chemical ecology, insect behaviour and materials science.

With target end-user features firmly in mind, the innovative formulation was further refined. As with any pheromone-baited trap, chemicals are added (impregnated) into a matrix which is then placed in the trap.

At Vecotech, several candidate matrices and associated chemical impregnation methods were evaluated. The efficacy and stability of these were tested through a series of scaled behavioural experiments exploring the bugs’ responses to cues.

At Vecotech, several candidate matrices and associated chemical impregnation methods were evaluated. The efficacy and stability of these were tested through a series of scaled behavioural experiments exploring the bugs’ responses to cues.

These were conducted across increasingly larger distances and in more complex environments, including our ‘baited bedrooms’ which allow the bugs to wander freely, mimicking a natural setting.

The result is BugScents™, a long-lasting lure impregnated into a biodegradable matrix, effective at attracting bed bugs even in low-level infestations. BugScents™ is sealed within a protective foil sachet which can be stored at room temperature for at least two years.

It has been designed with compatibility in mind and can be used with a wide range of trap types including pitfall-style and sticky traps. When opened and placed inside a trap, the impregnated material will continue to release the active compounds for up to three months.

The development of this product is all the more remarkable for having taken place during the Covid-19 pandemic and all of the challenges this has brought to businesses. The Vecotech team has embraced the challenge and, in collaboration with UK-based partners, is pleased to have brought a new product to the market.

Benefits of BugScents™ to PCPs

The BugScents™ technology has been developed to provide an effective, long-lasting, and environmentally friendly solution to detecting bugs before an infestation becomes established.

Pest control professionals are now able to enhance their bed bug monitoring devices allowing for the rapid detection of early-stage infestations.

The BugScents™ lure can be used with a monitoring trap as part of regular pest control activities to:

  • Confirm the presence of a bed bug infestation
  • Verify the success of treatment
  • Monitor for re-infestation following treatment
  • Enable long-term monitoring of high-risk properties.
Want to learn more?

Take a look at the new BugScents™ website.

bugscents.com

Source: PPC103

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