Nattaro Scout™ Bed Bug Pheromone Lure & Trap

Bed bugs, for long a forgotten nuisance, have reappeared. The detection and eradication of them have become a million dollar industry. Bed bugs are well protected from watery solutions of pesticides by a waxy outer cuticle (shell) and they easily become resistant to pesticides as unlike cockroaches and other crawling insects Bed Bugs do not wash themselves. It is therefore unlikely a bed bug will injest a chemical pesticide.  Approximately ten weeks after infestation a bed bug population change from linear to exponential growth. To detect an infestation before this point is crucial for a successful treatment. Our aim is to develop a monitoring system that detect bed bugs at low densities, partly substituting costly ocular inspections and a system that can evaluate the efficacy of a treatment. 

We collected and analysed emissions from bed bug colonies with headspace, enfleurage and GC-MS methods. Bed Bug attraction in test arenas to the pheromones resulted in a solution of five chemicals, which, applied in traps, were presented together with control traps and tested in mesocosm. Pheroemission decreased with time, but was easily detectable after six days. Ten bed bugs (4 females, 6 males) were released at start, after 24 and 72 hrs and retrieved after 24, 72 and 144 hours, respectively. Scent baited pherotraps caught 37, 38 and 37 % of the introduced bed bugs during the first, second and third period, respectively and caught significantly more bed bugs than unscented control traps (p=2 x 10-16). 

Figure 1. Arena tests, each with ten bed bugs, of the mixture abefg against water controls. The activity was video recorded for 30 minutes.Each time a bed bug went under the rim of the glass over a scent or a control vial it was scored. At the end of the 30 minute period the position of each bed bug in the arena was scored as the bugs were removed. The difference is small between the score during the 30 minute period and at the end of the period indicating that the bed bugs make a choice and then usually stay in that position the remaining time. (Of ten bed bugs, 1.3 ± 1.24 (average ± S. D.) females and 2.3 ± 2.27 males did not make any choice).

The attraction of bed bugs to this synthetic mixture was then tested in a seminatural environment established in mesocosm that contained wooden skirting boards and clothing which are favourite materials for bed bugs to hide in or under. Ten bed bugs, four females and six males, were released into a mesocosm with two traps one with the synthetic scent bait (pherotrap) and the other with control bait. The proportion of females to males reflects that found in natural populations. The bed bugs were scored at three positions: pherotrap, control trap and outside of either trap at the end of each period. The pherotrap caught statistically significant more bed bugs than the control trap (p=2 x 10-16) (Fig 2). There were no differences between the sexes caught in the trap but significantly more males were left in the mesocosm compared to either sex in the pherotrap (p<0.05).

The life length of the scented bait lasted the whole test period. Although the emission decreased about 40 fold from when the bait was loaded into the traps (3147 ng/hr) and until the experiment ended 144 hours later (75 ng/hr, Fig. 3) it still attracted bed bugs during the third period.

The effect of exposure time was tested for the first period by extending the duration to 48 hrs (0-48 hrs). The pherotrap caught significantly more bed bugs during the longer exposure (p=0.05) (Table 1 and Fig. 4). This highlights the traps efficiency as the bed bugs aggregate in the mesocosm but are then attracted from their initial aggregation towards the pherotrap after the first 24 hrs.

The scented pherotraps displayed a strong hit-rate for all three periods as well as the extended first period (Fig 5). Few control traps caught more than one or two bed bugs, whereas the probability of capturing 2 to 4 bed bugs was higher in the scented trap

Figure 3.Figure 3. Longevity of the synthetic scent mixture in pherotraps. GC-MS analysis of head space from the scent mixture (ng h-1) in pherotraps at the start and/or end of the three periods (0-24, 24-72 and 72-144 hrs). The scent mixture was still easily detectable after 144 hours at the end of the experiment.