mega-catch outcatches mosquito magnet

Mega-Catch™ outcatches Mosquito Magnet Pro and Mosquito Magnet Residential

Large Cage and Field Comparison Tests of Mega-Catch™ and Mosquito Magnet™ Traps

Daniel L. Kline, PhD
Research Entomologist
USDA-ARS, CMAVE
1600 SW 23rd Drive
Gainesville, FL 32608, USA
dkline@gainesville.usda.ufl.edu

Abstract

The relative efficacy of various configurations of the Mega-Catch™ and Mosquito Magnet™ mosquito traps were evaluated at three study sites: a large outdoor screen cage, a suburban residential backyard and a wildlife refuge. Laboratory reared Aedes aegypti, Culex quinquefasciatus and Ochlerotatus taeniorhynchus were used in the large cage studies. In these studies CO2 -baited Mega-Catch™ traps caught nearly 2x as many Ae. aegypti and nearly equal numbers of the other two species as the Mosquito Magnet™ Pro trap. The Mega-Catch™ trap without CO2 caught several hundred less Ae. aegypti and only about 0.25x as many Oc. taeniorhynchus as the CO2 -baited configuration. Studies conducted in a suburban residential backyard indicated that the Mega-Catch™ trap, whether baited with CO2 or not, caught a larger variety of mosquitoes than the Mosquito Magnet™ Pro; without CO2 it caught about the same quantity of mosquitoes as the Pro; with CO2 it caught ca. 3x as many mosquitoes as the Pro. In the wildlife refuge several configurations of the Mega-Catch™ trap were compared to the Mosquito Magnet™ Pro and Residential models. The CO2 baited configurations of the Mega Catch™ traps (dry and wet collection methods) caught many more mosquitoes than either the Pro or Residential traps. Mixed results were obtained in comparative trials with the no CO2 configurations. The Residential unit was the least effective in trapping mosquitoes in these trials. With the exception of the wet CO 2-baited configuration, the Pro and Residential units caught more Culicoides spp biting midges.

Introduction

In the last five years there has been increased activity in the private sector to produce more efficient traps for collecting adult mosquitoes. This activity has been triggered by the public's interest in controlling mosquitoes in their own backyards without using chemical insecticides. Two companies which have produced traps to fill this marketing niche are Envirosafe Technologies N.Z. Ltd., of Auckland, New Zealand, and American Biophysics of East Greenwich, Rhode Island, USA.

According to Envirosafe's published literature, their trap, the Mega-Catch™, utilizes slow gas release technology which is designed to release carbon dioxide at an exponentially decaying (negative) rate over fixed intervals to produce a concentration gradient in the attractant enriched air plume emanating from the lower part of the trap. The Mega-Catch™ uses food grade CO2gas from an aluminum cylinder. The Mega-Catch™ also incorporates electronically controlled diode lighting which produces intermittent light at selected oscillating frequencies. The model of Mega-Catch™ used in the trials described in this report also utilized a UV light.

Two models of American Biophysics Mosquito Magnet™ trap were used in these studies, the Pro and Residential. Both models are powered by a 20-lb propane tank. The use of propane to produce CO2gas is one of the major differences in the two companies approach in how they present various mosquito attractants. The CO2is produced and released at a relatively constant rate by the Mosquito Magnets™™. According to American Biophysics' literature both models use a patented counterflow technology, which enables the traps to emit a plume of CO2, heat, octenol attractant and moisture, while simultaneously vacuuming the biting insects into a net where they dehydrate and die. The manufacturer claims the Pro model offers coverage up to 1 acre whereas the Residential model offers coverage up to 2 acre. The Pro model has stainless steel construction as opposed to the Residential model's plastic construction. The Pro unit also has a larger capacity vacuum than the Residential model.

Methods and Materials

Three test sites were used: (1) A large outdoor screen cage at the USDA-ARS, CMAVE location in Gainesville, Florida; (2) a wooded residential lot in northwest Gainesville; and (3) The Lower Suwannee Wildlife Refuge, near Cedar Key, Florida.

Large cage studies. The cage screened with mosquito mesh netting is 9.2 m wide x 18.3 m long x 4.9 m high on the sides and 6.1 m high at the peak. It is used to determine the relative efficiency (i.e., what proportion of released mosquitoes are recaptured) of different trapping methods. Natural grass, weeds, wild flowers and shrubs were allowed to grow inside the cage to provide resting and nectar sites for introduced mosquitoes. This simulated a natural outdoor environment. Each trap night ca. 1000 3- to 4-day old laboratory reared female mosquitoes were introduced into the cage ca. 90 minutes before sunset. In these studies Aedes aegypti were used each night; Ochlerotatus taeniorhynchus was used when available and Culex quinquefasciatus was used on one occasion. Mosquitoes were released at the north end of the cage.

Landing (biting attempts) counts were made the day after release (ca. 90 minutes after sunrise) and trap collections were made immediately after the landing counts were made. Landing counts were made at 3 stations along a transect which extended from the southwest corner to the northeast corner of the cage. Sampling stations were these 2 corners and the mid-point of the transect which was the center of the cage. At each station a 6 minute biting count was made. This cage was used for four nights of competitive tests between the Mega-Catch™ and Mosquito Magnet™ Pro (without octenol) traps placed ca. 2 m apart at the south end of the cage in late June-early July 2001. The cage was also used to evaluate the efficiency of the Mega-Catch™ trap alone; for five nights the Mega-Catch™ was operated with CO2+ lights using the dry (net) capture system; 1 night the trap was operated with CO2+ lights and the wet (collector container with liquid) capture system.

In late summer 2001, 2 additional large screen cages (same size and dimensions as the original cage) were built and became available for testing. These cages were landscaped differently than the original cage. Plants were of the type found at typical residential locations and were arranged to simulate a typical suburban backyard. Four additional nights of testing were conducted during which a Mega-Catch™ trap was placed into each new cage. In one cage CO2+ lights were used and in the other cage only lights (no CO2) were used. The treatments were alternated between the cages each night. The black net capture system was used for all trials.

Northwest Gainesville Studies. This study site was located in a suburban residential neighborhood near a fresh water swamp/water management area. Vegetation was consistent with a freshwater swamp. The specific backyard used was that of the author of this report (DLK). Approximately, 32 different species of mosquitoes are caught at this location during the course of a typical year. The studies conducted at this site consisted mainly of paired comparisons between the Mega-Catch™ and the Mosquito Magnet™ Pro. Two trap stations were set up in the backyard at the woodland/lawn interface, ca. 150 feet apart. Traps were rotated nightly between the two sites. Mainline electricity was used to operate the Mega-Catch™ trap. For nine trap nights the paired trap comparisons consisted of a Mega-Catch™ trap with CO2+ lights and a Mosquito Magnet™ Pro (no octenol).

Lower Suwannee Wildlife Refuge. The Lower Suwannee Wildlife Refuge is located on the west coast of Florida near Cedar Key. It consists of ca. 23,000 acres of protected natural ecosystems. Both freshwater and brackish water habitats are found within the refuge. Since the freshwater habitats were similar to those found at the northwest Gainesville study site, these studies were conducted near the brackish water habitats (salt marsh areas). The prominent mosquito species found at this site was the black salt marsh mosquito, Ochlerotatus taeniorhynchus. Culicoides spp. biting midges are also prolific at this site and cause extreme annoyance to both nearby residents and tourists during visits to the refuge.

Initial studies were conducted to compare the Mega-Catch™ trap with CO2(dry and wet capture methods) with the Mosquito Magnet™ Pro. Since mainline electricity was unavailable, the Mega-Catch™ traps were powered by deep cycle marine batteries. Traps were set up ca. 100 feet apart at a site known as Cabin Site, a wooded area adjacent to a salt marsh. This site and several trapping stations, established along a trail, which transected the southern end of the salt marsh, were utilized. Since very few specimens were obtained during the first few days (we were in the middle of a prolonged drought and thus few mosquitoes were being produced along this trail), subsequent studies were concentrated at the Cabin Site.

For three nights the Mega-Catch™ trap was compared to both models of the Mosquito Magnet™. The first night the Mega-Catch™ wet capture method was used. On the second night the Mega-Catch™ was operated without CO2and specimens were captured using a fine mesh net. The third night the Mega-Catch™ was operated with CO2and the fine mesh net was again used.

Results

Large Cage Studies

Mega-Catch™ vs Mosquito Magnet™ Pro Competitive Tests.
In the competitive tests (Table 1) the Mega-Catch™ trap averaged capturing almost twice as many Aedes aegypti as the Mosquito MagnetTM Pro. In the one test with Ochlerotatus taenioryhnchus the Mosquito Magnet™ Pro captured slightly more (470 to 436) mosquitoes than the Mega-Catch™ trap. In the one test with Culex quinquefasciatus the Mega-Catch™ trap caught slightly more (353 to 316) mosquitoes than the Pro.

 

Mega-Catch™ Alone Efficacy Tests.

In the tests (Table 2) to evaluate the efficiency of the Mega-Catch™ trap used alone, for the five nights when the trap was operated with CO 2+ lights, using the net capture system, an average of 732 female Ae. aegypti were captured each night; the one night the wet capture method was used, 409 female Ae. aegypti were captured. A limited number of Oc. taeniorhynchus were available for release on 2 nights when the net capture system was used. On the first night 580 of 750 (77.3%) Oc. taeniorhynchus released were recaptured. On the second night 126 of 250 (50.4%) released were recaptured.

Mega-Catch™ CO2vs No CO2Tests.

In the studies (Table 3) comparing Mega-Catch™ baited with CO2versus no CO2, the CO2baited traps captured 722.5/trap night Ae. aegypti compared to 521.8/trap night for the no CO2trap. The CO2baited trap captured 437.3/trap night Oc. taeniorhynchus compared to 98.0/trap night for the no CO2trap.

Northwest Gainesville Studies.

During the course of this study 23 species (Table 4) of mosquitoes were captured: Ochlerotatus atlanticus (OcA), Oc. dupreei (OcD), Oc. infirmatus (OcI), Oc. canadensis (OcC), Oc. fulvus-pallens (OcFP), Oc. mitchellae (OcMi), Oc. triseriatus (OcTri), Aedes albopictus (AeAl), Ae. vexans (AeV), Anopheles crucians (AnCr), An. punctipennis (AnP), An. quadrimaculatus (AnQ), Culex erraticus (CxE), Cx. nigripalpus (CxN), Cx. salinarius (CxS), Cx. quinquefasciatus (CxQ), Culiseta melanura (CsM), Psorophora columbiae (PsC), Ps. ciliata (PsCi), Ps. ferox (PsF), Ps. howardi (PsH), Coquillettidia perturbans (CqP) and Uranotaenia sapphirina (UrS). The Mega-Catch™ trap caught at least one specimen of each species. No Oc. mitchellae, Ps. columbiae, Ps. ciliata, or Ur. sapphirina were captured by the Mosquito Magnet™ Pro. In terms of total mosquitoes caught, the Mosquito Magnet™ Pro caught 507 compared to 480 for the Mega-Catch™ trap operated without CO2. This was 101.4/trap night for the Pro compared to 96.0/trap night for the Mega-Catch™. However, when the Mega-Catch™ used CO2it caught 3769 (418.7/trap night) compared to 1230 (136.7/trap night) mosquitoes for the Pro.

Lower Suwannee Wildlife Refuge.

Data are summarized in Tables 5 and 6. In the initial studies both the Mega-Catch™ (wet and dry) traps with CO2caught at least 3 times as many mosquitoes as the Pro traps. The wet Mega-Catch™ trap caught more biting midges than the Pro traps, but both Pro traps caught more biting midges than the dry Mega-Catch™ traps with the regular net. The Mega-Catch™ trap with CO2and the fine mesh net (Table 5) did as well as the Mosquito Magnet™ Pro, but not as well as the Residential model for capturing biting midges.

At the Cabin Site, trap comparisons were done between both models of the Mosquito Magnet™ and the Mega-Catch™ trap. The wet collection Mega-Catch™ trap baited with CO2did well for both mosquitoes and biting midges. Over a 2 day period this configuration collected 7.9x and 38.2x as many mosquitoes as the Pro and Residential models, respectively. It caught nearly as many biting midges as the Pro model and 5x as many biting midges as the Residential model.

In the one night comparison of the 3 trap types when the dry collection Mega-Catch™ trap with no CO2was used, the Mega-Catch™ caught 2.3x and 18.2x more mosquitoes, respectively, than the Pro and Residential models. However, both Mosquito Magnet™ models caught ca. 27x more biting midges.

In the one night comparison of the 3 trap types when the dry collection Mega-Catch™ (fine mesh net) was used, the Mega-Catch™ caught 24.6x and 147.3x more mosquitoes than the Pro and Residential models, respectively. In contrast, the Pro and Residential models caught 2.9x and 22.5x more biting midges than this configuration of Mega-Catch™ trap.

Discussion and Conclusions

In published studies (Burkett et al. 2001, Kline 2002) the Mosquito Magnet™ Pro has proven to be one of the most effective commercially available traps for capturing mosquitoes and biting midges. The studies included in this report were my first opportunity to evaluate the efficacy of the Mega-Catch™ trap. In most cases, whether baited with CO2or not, it caught more mosquitoes than either model of Mosquito Magnet™.

In the large cage trials, in which the CO2baited Mega-Catch™ trap and the Mosquito Magnet™ Pro were in direct competition in the same cage, the Mega-Catch™ captured almost twice as many Ae. aegypti as the Pro. In the one test with Oc. taeniorhynchus, however, the Pro caught slightly more mosquitoes than the Mega-Catch™ trap. The opposite occurred in the one test with Cx. quinquefasciatus. More direct competition studies between these two trap types are needed with a greater diversity of species. Based on the performance of the Mega-Catch™ trap without CO2, when tested alone in the cage, it would be very interesting to conduct direct competition between this configuration and the Pro trap in future cage studies. I would like to conduct such studies because my initial thought was that the difference in "drawing power" of the two traps was the quantity and CO2release technology. The Mega-Catch™ releases almost twice as much CO2as the Pro model. This thinking has been modified based on the results obtained in field studies and the fall 2001 large cage studies conducted with the Mega-Catch™ traps with and without CO2.

The bottom line was that the CO2baited trap configuration did better than its unbaited counterpart, but the latter still caught very large numbers of mosquitoes. More field studies against a diversity of natural mosquito populations need to be conducted with these two configurations of Mega-Catch™. The northwest Gainesville studies indicate that the relative effectiveness of the Mega-Catch™ (baited with CO2or not) compared to the Mosquito Magnet™ Pro depends on which mosquito species are present. Mega-Catch™ collections were greatly reduced in the absence of CO2, but it still caught a good diversity of mosquito species. In fact even without CO2, the Mega-Catch™ did as well as the Pro for most species. Exceptions were Oc. triseriatus, Ae. albopictus, Cx. salinarius and Ps. ferox. With CO2the Mega-Catch™ trap still did better than the Pro for all mosquito species collected except Ae. albopictus.

The Mosquito Magnet™ Residential model did not do as well as the Pro model for capturing mosquitoes. Overall both Mosquito Magnet™ models appear to do a better job of capturing Culicoides biting midges than the Mega-Catch™. An exception may be when the Mega-Catch™ wet collection method was used. More studies comparing the wet and dry (regular net and fine net) collections methods of the Mega-Catch™ need to be conducted.

Literature Cited

Burkett, D.A., W.J. Lee, K.W. Lee, H.C. Kim, H.I. Lee, J.S. Lee, E.H. Shin, R.A. Wirtz, H.W. Cho, D.M. Claborn, R.E. Coleman and T.A. Klein. 2001. Light, carbon dioxide, and octenol-baited mosquito trap and host-seeking activity evaluations for mosquitoes in a malarious area of the Republic of Korea. Journal of the American Mosquito Control Association, 17(3): 196-205.

Kline, D.L. 2002. Evaluations of various models of propane-powered mosquito traps. Journal of Vector Ecology, 27(1):1-7 (in press).

Dr. Dan Kline. A brief CV.

Dr. Dan Kline received his Ph.D. from North Carolina State University in 1975 and has worked as a Research Entomologist at the USDA Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, Florida, since 1978. Research accomplishments include the development of (1) innovative surveillance technologies for mosquitoes and biting midges (sand flies) that use newly isolated or synthesized chemical attractants and remote sensing data; (2) novel control technologies (e.g., removal trapping) for adult mosquitoes and biting midges; (3) larval control strategies for intertidal zone biting midge species that utilize conventional insecticides and insect growth regulators (IGRs), as well biological control agents; and (4) in-depth ecological studies of mosquitoes and biting midges. In the past few years a major emphasis has been placed on the use of combinations of semiochemicals and traps/targets to manage biting midge and mosquito populations, and on development of new and improved traps and attractants.