Cockroaches: an endless problem
Edition 8 technical note on cockroaches: a never-ending problem, with a focus on diagnosis, prevention and criteria applicable to professional pest management.
A few days ago we finished the ninth “Theoretical-practical course on Urban, Domestic and Industrial pests” that we taught with the Bromatologist María José Quercetti at the Faculty of Agrarian Sciences of the U. N. de Cuyo, in Mendoza, 23 interested parties attended it. During the event, we were drawn to the problems that several of the attendees currently face in achieving good control of Blatella germánica. This situation is a
constant over time and leads me to think about the possible causes of this serious difficulty that makes one imagine supercockroaches resistant to the most aggressive treatments attempted for their control. The questions raised by Pest Management Professionals are basically oriented towards chemical control. They claim to use mixtures of different active ingredients and gels, even mixtures with insect growth regulators or IGRs, performing weekly or biweekly treatments.
We can consider that there are several known tools that are not used or that are used poorly. In any case, there are factors specific to the place to be treated that determine a greater or lesser level of difficulty in carrying out a good treatment. Let's look at this aspect a little: Structures that have undergone frequent modifications, maintenance work carried out without considering the behavior of cockroaches, situations that mean a large supply of shelters
for cockroaches. Furthermore, it is common for cooks or waiters to use aerosols when they see a cockroach, favoring pyrethroid resistance processes or nullifying the effectiveness of the gels they use.
would have been applied. It is undeniable that many reinfestations are due to the entry of new cockroaches hidden in supplies (cardboard boxes, egg trays, bakery, beer and soda containers, vegetables, etc.). The work schedule is another important determining factor of the good outcome of the Pest Management Professional's work. When the pest control service has to be carried out at night, you must wait until the kitchen work has finished, which depends on the presence of customers. In this circumstance, the waiters already want to leave and pressure the Pest Management Professional to carry out his task quickly to the detriment of the results. Returning to the tools available for good cockroach control, we see that applications of products diluted in water are made with sprayers (backpacks) that are not calibrated and their real performance is not known. In a test that we carried out during the course we compared the work of four operators, three of them applied an amount of water equivalent to doses lower than those recommended (- 24.5%, -16.6%, -15%) and one with higher doses (+ 3.76%). This shows us that in most cases we work with doses lower than those recommended, which favors the appearance of resistance or the work is simply ineffective due to using insufficient doses. The use of vacuum cleaners accompanied by the application of gel and the sealing of cracks is an effective task that requires sufficient time, but operators must perform their task in a few minutes and cannot implement this technique adequately. Another common aspect that results in treatment failure is forgetting the habit of gravid females of Blatella germánica by which they remain in their shelters for a long time and thus escape spraying. We must also not forget that the places where they find refuge are usually made up of absorbent materials: brick, wood, gaps in walls and structures, so the sprayed product should be a Concentrated or Floable Suspension formulation, microencapsulated or wettable powder, however, emulsifiable formulations are mostly used that are absorbed into the treated materials and thus the product is not available.
for the plague. Then, a few days after the best spraying, reinfestations occur from those thread cockroaches that escape treatment. It is then appropriate to review the work strategies considering the conditions of the infested site, not only the active ingredients but also the formulations to be used, the operating times and the schedule of execution of the task, the use of calibrated equipment provided with a device that allows working at a constant pressure (manometer) to be able to apply correct doses, and the incorporation of vacuum cleaners, gel and the sealing of cracks not as part of cockroach control, but as part of an Integrated Cockroach Management Program.