When a cockroach finds a good source of food, it’s believed to communicate the information with other cockroaches. This is just one reason why product manufacturers such as Ensystex develop highly palatable baits. 

It might come as a total surprise, but cockroaches have been shown to ‘recommend’ good food sources to other cockroaches by ‘talking to each other’, according to a study by Dr Mathieu Lihoreau and Dr Colette Rivault.1

It is well known that the German cockroach (Blattella germanica) is a gregarious species that lives in mixed- family aggregates. These usually consist of equal numbers of males and females, with a typical mix of 60% nymphs and 40% adults.

Under low population densities, cockroaches forage independently, using a combination of their knowledge of their home range and food odours to exploit food sources. However, under high population densities, they often feed on the same food sources to form feeding aggregates, returning to a communal harbourage after each expedition. The question is how and why?

The research by Dr Lihoreau and Dr Rivault suggests that feeding cockroaches release an odour (as yet to be identified) that attracts additional cockroaches to the feeding site to form a feeding aggregation. It appears the odour is only detected over a short distance, meaning that the mechanism does not help individual cockroaches discover a food source, but once discovered it makes it more attractive for them to feed at that food source. What is the benefit of this behaviour?

Mathematical modelling suggests group foraging may be a less than optimal strategy when large numbers of cockroaches are present, due to the increased competition. However, this may be offset by the benfit that group feeding offers an anti-predation strategy, increasing an individual’s chance of escaping threats. Also, since aggregates usually consist of different developmental stages, there may be bene ts to early instar nymphs, as adults and late instar nymphs have greater ability to process foods, making nutrients available to these younger cockroaches.

More particularly, it might allow cockroaches to share essential information about available food sources which, in urban environments, are typically unpredictable. The authors of the study suggest we may be observing an ‘honest message’, that guarantees the quality and/or quantity of the food, allowing foragers to increase their speed of detection of quality food sources. Omnivorous cockroaches have to mix their diet from foods that vary greatly in nutritional value, so this may allow them to better balance their nutritional intake.

Steve Broadbent, regional director of Ensystex, believes that Zenithor Gel Cockroach Bait is one food source that cockroaches will be certain to ‘talk’ to each other about, due to its ‘Synergised high-consumption bait technology’.

Zenithor Gel Cockroach Bait

Zenithor employs a unique range of natural sensory attractants to draw the cockroaches to the bait, together with carefully selected feeding stimulants to induce feeding and promote increased consumption. The amount of bait eaten at a single feed is very important in a control program since it determines the speed of kill and protects against resistance.

“Zenithor’s ‘Synergised high-consumption bait technology’ is further enhanced through our ‘Viral excretion transfer’ technology, to provide improved control of all cockroach life-stages,” Mr Broadbent added. “The gel bait includes an emetic to ensure the intoxicated cockroaches contaminate their harbourages with toxicant-enriched vomitus and faeces to create the most potent transfer effect possible.

“This advances the transfer of the toxicant to the more sedentary life-stages, specifically early instar nymphs that do not venture far for their food resources.”

Mr Broadbent further explained, “A key to unlocking the success of our innovative gel formulation was the selection of the (S)-isomer of indoxacarb as the active constituent. Zenithor Gel Cockroach Bait provides a stable gel with a moist, viscous presentation at all times, that does not run, even on vertical surfaces.”

1 Lihoreau M, Rivault C (2011). Local Enhancement Promotes Cockroach Feeding Aggregations. PLOS ONE 6(7): e22048. doi:10.1371/journal. pone.0022048.