Five light traps including 2 standard traps (New Jersey light trap and CDC light trap) and 3 new light traps (UV light trap, black light trap, and yellow fluorescent light trap) were evaluated for the collection of mosquitoes and non-target insects in northeast Florida from Sep to Oct 2013. In the evaluation of light traps without a chemical lure, the black light and CDC light traps collected large numbers of mosquitoes, and the ratios of mosquitoes to non-target insects were 1:7.5 and 1:8.9, respectively. In the evaluation of the 5 light traps, each baited either with octenol or with BG-Lure, the black light and CDC light traps collected larger numbers of mosquitoes than the other 3 types of traps. The ratios of mosquitoes to non-target insects were 1:2.8 and 1:6.7 for black light traps baited with octenol and BG-Lure, respectively, and 1:1.5 and 1:5.2 for CDC traps baited with octenol and BG-Lure, respectively. The results indicated that the black light trap was the best of the new traps evaluated based on its mosquito capture capabilities, while collecting the least non-target insects. Use of black light traps will benefit mosquito population surveillance by increasing the capture of insects of medical and veterinary importance.
Mosquito traps play a vital role in monitoring mosquito populations and mosquito-borne diseases (Kline 2006). Through surveillance programs, mosquito trap efficacy has been used as justification for implementation and intervention of control measures. The New Jersey light trap, developed in the 1920s, became the “gold standard” trap used in mosquito surveillance (Reinert 1989). Since the invention of the New Jersey light trap, many mosquito traps have been developed and tested for mosquito surveillance (Moore et al 2001; Ritchie et al. 2008). Currently, the most popular of the developed traps, the CDC light trap, incorporates light and a secondary mosquito attractant, such as CO2, to increase the number of mosquitoes captured (Newhouse et al. 1966). To enhance mosquito collection numbers, other secondary mosquito attractants, such as octenol (Takken & Kline 1989) or BGLure, have been used. Although there are many publications comparing the use of CDC light traps and other types of traps (Kline 2006), the literature focus is solely on the number of mosquitoes and mosquito species captured rather than on the non-target insects recovered in traps. Although the ability of a trap to capture mosquitoes is obviously critical, it is also important to consider capturing the smallest possible numbers of non-target insects.
Barrier spraying of vegetation with insecticides or attractive toxic sugar baits (ATSB) recently has been adapted for the operational con trol of adult mosquitoes in golf courses, parks, and schools (Qualls et al. 2012, 2013, 2014; Xue et al. 2013). Concern about the impact of broadcast applications of insecticides to vegetation that is used by a great diversity of non-target organisms has gained the attention of scientists and residents. CDC light traps have been used to demonstrate barrier spray effectiveness. However, one might ask: Which light traps without secondary attractants are most suitable for collecting target mosquitoes without collecting many non-target insects?
The purpose of the present study was to evaluate the performance of 5 light traps including 3 new mosquito light traps with and without attractants (octenol and BG-Lure) to capture great numbers of target mosquitoes and small numbers of non-target insects such as butterflies, moths, beetles, and flies.
Materials and Methods
This study was conducted from 1 Sep to 30 Oct 2013 in the residential and agricultural farmland of Elkton in St. John County, northeast Florida. The performance of 5 light traps fitted with and without 1 of 2 attractants was evaluated. The traps were (1) CDC light trap (John W. Hock Company, Gainesville, Florida), (2) New Jersey light trap (John W. Hock Company, Gainesville, Florida), (3) black light mosquito trap (a small “U”-shaped light bar with a light wavelength of 365 nm and with the sucking fan in the bottom of the trap; PestNetChina Co., Ltd, Shanghai, China), (4) yellow fluorescent light trap (a large circular fluorescent light bar around a large yellow light bulb in the center with a yellow light wavelength of 570 nm, with the sucking fan under the light bulb; PestNetChina Co., Ltd, Shanghai, China), and (5) UV light trap (model: MSTRS-Talent; UV light bar with a dimension of 190 mm L ´ 63 mm W ´ 32 mm H and a light wavelength of 325 nm) modified from the CDC light trap and supplied by J. W. Zhu (Iowa State University, Ames, Iowa). The 2 attractants were octenol (BioSensory, Willimantic, Connecticut) and BG-Lure (BioGents, Regensburg, Germany). Trap performance was evaluated first without a secondary attractant, and then with the secondary attracts, octenol or BG-Lure, individually incorporated into the traps.
Each light trap was suspended 1.5 m above the ground. Traps were positioned linearly at a single location with a minimum distance of 20 m between trap sites. To eliminate site effects, traps were rotated between each site each day for 5 d, creating a 5 ´ 5 Latin Square design, providing 5 trap periods per trap model and 25 trap periods per experiment. This design was repeated for another 5 d period with the inclusion of octenol and BG-Lure, tested separately. Insects were removed from the traps every 24 h and stored in a -20 °C freezer before being identified and counted. Mosquitoes were identified to species, whereas non-target insects were identified to order and confirmed by staff at the Division of Plant Industry, Florida Department of Agriculture and Consumer Services, Gainesville, Florida.
Collection data were log(n+1) transformed, and the numbers of mosquitoes and non-target insects collected were subjected to Latin Square Analysis of Variance (Snedecor & Cochran 1989). The model effects were trap type and sampling site. A significance F-test (P < 0.05) for a model effect was followed by a Least Significant Difference (LSD) post-hoc test to separate trap collection means. The mean numbers of mosquitoes and non-target insects collected by 5 different traps were subjected to Fisher's t-test (SAS Institute 2001). The ratios of total number of mosquitoes captured to total number of non-target insects captured were used to compare the efficacy of 5 light traps against targeted mosquitoes and non-target insects.
Mean numbers (± SD) of all mosquitoes captured by 5 different types of light traps with or without attractants in northeast Florida.
NUMBERS OF MOSQUITOES CAPTURED
Twenty-five trap periods (5 traps operated over 5 d) yielded 261 mosquitoes without the use of attractant, and 677 or 290 mosquitoes with the addition of either octenol or BG-Lure, respectively. Mosquito species captured included Anopheles crucians Wiedemann, Aedes atlanticus Dyar and Knab, An. quadrimaculatus Say, Coquillettidia perturbans Walker, Culiseta melanura Coquillett, Culex erraticus Dyar and Knab, Cx. nigripalpus Theobald, Psorophora columbiae Dyar and Knab, and Uranotaenia sapphirina Osten Sacken regardless of attractant. Anopheles crucians was the dominant species and comprised 81.0% of mosquitoes captured.
There were significant differences in the mean numbers of mosquitoes caught between traps without attractant (F = 15.13, df = 4, P < 0.01), with octenol (F = 14.51, df = 4, P < 0.01), and with BG-Lure (F = 32.52, df = 4, P < 0.0001). The relative ranking of the different trap types with respect to