Trap-N-Vac

Even with the promotion of integrated pest management programs for the German cockroach, the pest control industry has generally relied on the use of chemically based synthetic insecticides as the main control technique.

Cockroaches are behaviorally, physiologically, and genetically adaptable, and it is unlikely that a single approach to their control will be effective through time; it takes a combination of approaches to reduce German cockroach populations below levels where they are considered pests. Currently, there is significant interest in the control of German cockroaches without the use of residual sprays and surprisingly, many consumers are inquiring about the feasibility of controlling the German cockroach with nonchemical strategies or by using low-impact insecticide techniques.

Sticky traps are primarily used as sampling, detection and monitoring tools. However, there has been an interest in the use of sticky traps as control tools. Traps have been advocated as an alternative to chemical methodologies and their use has increased with the implementation of IPM programs. Recent articles have reported on the use of vacuum cleaners for direct physical removal of cockroaches. However, quantitative data regarding the potential benefits from the use of traps and vacuum cleaners for cockroach control, alone or in conjunction with other methods, were lacking.

The research documentation which follows is the result of a two-pronged study carried out in the past two years. First, the research was designed to provide quantitative data on the effectiveness of seven types of commercially available sticky traps in reducing German cockroach populations. The study was also conducted to determine the effectiveness of nonchemical techniques (trapping and vacuuming) compared with low-impact insecticide applications (flushing and vacuuming, baiting) and residual sprays, in controlling German cockroach populations in heavily infested apartments.

EVALUATION OF STICKY TRAPS.Seven sticky traps were evaluated separately in 1-square-meter Plexiglas boxes. Cockroaches were provided with a harborage unit positioned in the center of the arenas, which provided 250 square centimeters of horizontal surface space. The harborage unit consisted of a stack of five masonite panels separated by 5 millimeter spaces. A water vial was placed at one corner of the arena and a nontoxic rodent block (as a food source) was placed on the opposite side. Two traps of each type (see Figure 1) were placed in the remaining opposite corners of the box and were kept there for 14 days. Cockroach populations were established in boxes by releasing 160 cockroaches (30 small nymphs, 30 nymphs, 20 one-week-old gravid females, 40 females, and 40 males) into the boxes. The cockroaches were allowed two days to establish within the harborage before the traps were introduced. Each treatment was replicated three times. The trap catch was recorded after one, three, seven, 10 and 14 days.

It was found that the percentages of cumulative trap catch in the seven sticky traps varied significantly at all sampling periods. The seven sticky traps caught from 5% to 47% of the cockroaches during the first 24 hours of trapping, with the greatest percentage of trapped cockroaches being in the Victor Large Pheromone trap, followed by Lo-Line. Trap catches increased gradually over time and, by the end of the test, 18% to 87% of the cockroaches were caught, with greatest percentages recorded from Victor Large Pheromone traps and Lo-Line traps. The high trap catch in the Victor Pheromone trap and Victor Large Pheromone trap is likely due to the presence of aggregation pheromones on the ceiling of both traps and the presence of a food attractant in the center of the large Victor traps. The lower number of cockroaches caught on larger traps was probably due to sub-optimal trap design and quality of sticky materials. When efficacy of traps was further compared by the number of cockroaches trapped per square centimeter, the Victor Pheromone trap and the Victor Large Pheromone trap caught higher numbers of cockroaches than other larger traps.

The ability of the trap to catch large numbers of cockroaches is important if control is desired. Trap efficacy in reducing cockroach populations is likely dependent on a number of factors such as trap design (number, location and size of openings on the sides and top of the traps), trap placement near infested sites and food sources, the ability of a trap to hold and attract cockroaches (quality of sticky materials and the presence of attractants), cockroach exploratory behavior during foraging, and cockroach learning through contact with sticky materials. Field trials to support this laboratory research are needed to determine the effectiveness of these traps in reducing cockroach populations.

EVALUATION OF TRAPPING, VACUUMING. Field tests were conducted May through July of 1995 and June through August of 1996 in a multi-family housing complex. Five different treatment programs (trapping, vac-uuming, flushing and vacuuming, spraying, and baiting) were conducted in 1995. Three treatment programs (baiting, trapping, spraying) were conducted in 1996.

To estimate cockroach populations in each apartment before treatments, one Lo-Line sticky trap was placed for one night each week (for a four-week monitoring period in 1995 and for an eight-week period in 1996) in each of the following locations: the cabinet under the kitchen sink, the cabinet above the sink, under or adjacent to the stove, under and behind the refrigerator, adjacent to the utility area, and on the floor behind the bathroom toilet. In order for an apartment to be included in the test as an observation unit, the six traps had to catch a total number of at least 12 cockroaches. After the initial treatments, six Lo-Line traps were set out and checked weekly to monitor cockroach populations, determine trap catch reductions, and eventually determine the success of each treatment.

Spray treatments were made using a 1-gallon B&G compressed air sprayer. In 1995, applications of Empire 20 were made at Day 1 at the rate of 1.3 fluid ounces per gallon of water (0.2% chlorpyrifos). In 1996, applications of Suspend SC were made at the rate of 1.5 fluid ounces per gallon of water (0.06% deltamethrin). Treatments were directed into cracks and crevices and, in addition, all obvious harborages (along and behind baseboards; beneath and behind sinks, stoves, refrigerators, and cabinets) were treated. About 0.75 to 1.0 liter of spray dilution was applied to each test apartment.

Baiting treatments were made using Siege gel bait (2% hydramethylnon) in 1995 and using Knockdown Pheromone Boric Acid consumer bait stations (46.994% boric acid and 0.004% aggregation pheromone) in 1996. Siege applications, using the Xactadose Precision Baiting System, were regulated at 150 mg per placement; and 100 placements were made (15 grams of gel bait per apartment). Placements were distributed only throughout the kitchen (85 placements) and the bathroom (15 placements).

Twelve Knockdown bait stations were placed in each apartment and left in place for eight weeks in 1996. Bait stations were placed in the cabinets under the kitchen sink (2), the cabinets above the sink (2), under and adjacent to the stove (2), under or behind the refrigerator (3), under or adjacent to the utility area (2), and on the floor behind the bathroom toilet (1).

Vacuuming treatments were made using the backpack vacuum model of the lil’ Hummer (Figure 2). Cockroach harborage areas were vacuumed on Day 1 and again seven days later. Because the use of a vacuum cleaner or repellent flushing pyrethroids (or both) can alter the distribution of cockroaches, a follow-up treatment was made at Day 7. All cockroaches picked up by the vacuum cleaner were counted.

In the flushing-and-vacuuming treatment, vacuuming was combined with the use of a flushing agent at Day 1 and Day 7. Because German cockroaches are able to hide in cracks and crevices and may withstand the suction of the vacuum cleaner in certain harborage sites, the PT 565 Pyrethrin Insect Fogger was applied in areas where visible inspection was limited (under the refrigerator; splash boards; behind cabinets and stoves). This flushing agent forced the cockroaches to enter open areas within two to three minutes after application, where they could be vacuumed. Vacuuming was discontinued when no cockroaches were observed.

In the trapping treatments, individual Victor Roach Pheromone traps, separated at the perforations, were used. Traps were placed at Day 1 in 12 locations (the same as for the Knockdown bait stations) in each apartment and left in place for four weeks in 1995 and eight weeks in 1996 to obtain the total trap catch. All filled, missing or wet traps were replaced weekly.

In the 1995 testing period, the average number of cockroaches trapped before treatments ranged from 26 to 52 per trap (Table 1, page 54). These numbers were not significantly different, indicating that the infestations in these apartments assigned to each treatment were similar. Populations were reduced by more than 50% one week after treatments.

All treatments provided an acceptable level (>70%) of cockroach reductions at the end of the four-week test, with the greatest reduction occurring after the application of Siege gel bait (82%). There were no significant differences among the treatments at the end of the test; therefore, all treatments were equally effective at reducing German cockroach infestations.

Empire spray showed only 47% reduction in trap catch at three weeks after treatment. Therefore, a second spray treatment was made. The unacceptable population reduction (<50%) may be related to not having enough residual solution put in the apartment under the extreme conditions of the apartments.

A significant difference in the amount of time spent vacuuming between the vacuuming and flushing-and-vacuuming treatments was observed at the initial treatments on Day 1 (17 and 32 minutes, respectively), but no difference was found at the follow-up treatments on Day 7 (10 and 16 minutes, respectively). At the initial treatments, 29 and 77 cockroaches per vacuum bag were found for the two treatments, respectively, but there was no significant difference in these means. At the follow-up treatments, difference in the number of cockroaches vacuumed was observed with averages of seven and 33 for the two treatments, respectively. The number of egg cases collected at Day 1 doubled with flushing and was 10 times more than in vacuuming alone at Day 7.

In 1996, the average numbers of cockroaches before treatments (Table 2) were not significantly different, indicating that the infestations in these apartments assigned to each treatment were similar. All treatments provided an acceptable level (>70%) of cockroach reductions six weeks after treatment. Knockdown bait, Victor traps, and Suspend spray caused population reductions of 85%, 81%, and 69%, respectively, at the end of the eight-week tests.

Vacuuming treatment alone significantly reduces cockroach populations to a low level but does not eliminate cockroaches because there is no residual. The remaining cockroach populations tend to rebound in three or four weeks. Vacuuming should be directed into cracks and wall voids, sides of cabinets, behind baseboards, and potential harborage in appliances and furniture. In addition to the physical removal of cockroaches, vacuum cleaning removes food sources, cast skins, and fecal materials from inaccessible sites, and always adds stress to cockroaches and places them at greater risk to the effects of insecticides and other control tactics.

The flushing-and-vacuuming technique is very useful in a control program where high numbers of cockroaches are present. Also, hard-to-reach gravid females are more vulnerable to being caught by the flushing-and-vacuuming technique than by other methods. Gravid females are more important than males and nymphs from the standpoint of long-term population reduction.

The use of sticky traps and vacuum cleaners reduced cockroach populations in infested apartments to levels comparable to those obtained through the use of insecticides alone. Public perception is an important factor in determining the value of these nonchemical control strategies. Whenever new techniques and technologies are developed, it is important to ensure public acceptance and development of proper safety procedures. It is also important to reduce the application of unnecessary pesticides to achieve acceptable, cost-effective cockroach control. Additional field testing should be conducted using nonchemical control techniques, in conjunction with low-impact pesticide techniques, to develop the strategies for using these technologies in an integrated pest management system in infested residences.

Walid Kaakeh is the manager of Sponsored Product Research Program at the Center for Urban & Industrial Pest Management, Purdue University. Gary Bennett, the coordinator at the Center for Urban & Industrial Pest Management, is also a professor at Purdue.