Efficiency of Malaise traps and colored pan traps for collecting flower visiting insects from three forested ecosystems

Pan and Malaise traps have been used widely to sample insect abundance and diversity, but no studies have compared their performance for sampling pollinators in forested ecosystems. Malaise trap design and color of pan traps are important parameters that influence insect pollinator catches. We compared pan trap (blue, yellow, white, and red) and Malaise trap catches from forests in three physiographic provinces (Piedmont, Coastal Plain, and Blue Ridge) of the southeastern United States. Similarities in trap performance between sites were observed with blue pan traps being most effective overall. Our results showed that various pollinator groups preferred certain pan trap colors and that adding color to Malaise traps influenced insect pollinator catches. However, pan traps generally caught more pollinators than Malaise traps. Because of their low cost and simplicity, using several colors of pan traps is an effective way to sample relative abundance and species richness of flower-visiting insects.     

瓢虫的趋光性反应研究

以六斑月瓢虫Menochilus sexmaculata Fabricius和狭臀瓢虫Coccinella transversalis Fabricius为例,研究了瓢虫对不同光质(波长)的趋光性反应。在室内分别测定了六斑月瓢虫和狭臀瓢虫对5种发光二极管(LED)光波的趋性,以及在田间挂板(佳多)测定了瓢虫对色板的选择趋性。室内测定结果表明,瓢虫对黄色和白色LED光波的选择趋性显著高于与其它颜色;田间挂板试验表明,黄色对瓢虫的诱杀作用最强。综合分析,黄色对瓢虫有强烈的吸引作用,建议在使用黄板进行田间监测和防治时应考虑对天敌瓢虫的诱杀作用。     

Are pan traps colors complementary to sample community of potential pollinator insects?

The global initiatives of monitoring and conserving pollinators require worldwide assessments with comparable data sets collected through standardized methods. The use of pan traps is a passive method widely applied to sample flower visitors, standing out for its simplicity. Despite its wide use to sample pollinator diversity, the influence of color on trap efficiency is not well understood. The available studies are particularly scarce in the tropics and have generated divergent results. The main goal of the present study was to assess whether blue, yellow and white pan traps are complementary to sample Hymenoptera community. For this, we placed 49 sample units of blue, white and yellow pan traps in agricultural and natural (savanna-like) areas in Chapada Diamantina, Bahia, Brazil. We found that the species richness from blue and yellow pan traps were not significantly different, but both were significantly greater than the species richness from white pan traps. However, bees were significantly more attracted to the blue pan traps and wasps to the yellow ones; thus, color attractiveness was group-specific. Pan traps of different color showed low species composition overlap with 61 % of species collected exclusively in one of the three pan trap colors, and the species composition in the blue traps differed consistently from that in the traps of the other colors. In the article we discuss the implication of the results and defend the combined use of pan traps with different colors as a solution for the differential variable sample bias.     

Assessing bee (Hymenoptera: Apoidea) diversity of an Illinois restored tallgrass prairie: methodology and conservation considerations

Bee species diversity and the effectiveness of four sampling methods were investigated in a west-central Illinois restored tallgrass prairie. Bees were sampled using malaise traps, ground-level pan traps, elevated pan traps, and vane traps. A total of 4,622 bees representing 31 genera and 111 species were collected. Malaise traps collected the greatest number of bees and species, and ground-level pan traps the least. Among the pan traps and vane traps, blue-colored traps collected the greatest abundance and species richness, and yellow traps the least. Chao1 estimator and rarefaction analyses showed that substantial increases in sample sizes would be necessary to achieve asymptotic species richness levels, particularly if ground-level pan traps alone were used. Elevated pan traps and vane traps collected relatively similar species composition. Different colored pan traps at the same height collected more similar species composition than did those at different heights, but species composition of blue ground-level pan traps was relatively similar to elevated pan traps, regardless of color. Indicator species analysis revealed 22 species that were significantly associated with a specific trap type, and 11 species that were associated with a particular pan trap color/elevation. Results of this study show that elevated traps can increase the effectiveness of bee surveys in tallgrass prairie, and that a combination of trap types gives a more complete picture of the bee fauna than does a single survey method. These results should be considered along with cost, ease of use, and goals when planning and designing bee inventories.     

Evaluation of yellow sticky traps for monitoring the population of thrips (Thysanoptera) in a mango orchard

Populations of several thrips species were estimated using yellow sticky traps in an orchard planted with mango, Mangifera indica L. during the dry and wet seasons beginning in late 2008-2009 on Penang Island, Malaysia. To determine the efficacy of using sticky traps to monitor thrips populations, we compared weekly population estimates on yellow sticky traps with thrips population sizes that were determined (using a CO(2) method) directly from mango panicles. Dispersal distance and direction of thrips movement out of the orchard also were studied using yellow sticky traps placed at three distances from the edge of the orchard in four cardinal directions facing into the orchard. The number of thrips associated with the mango panicles was found to be correlated with the number of thrips collected using the sticky trap method. The number of thrips captured by the traps decreased with increasing distance from the mango orchard in all directions. Density of thrips leaving the orchard was related to the surrounding vegetation. Our results demonstrate that sticky traps have the potential to satisfactorily estimate thrips populations in mango orchards and thus they can be effectively employed as a useful tactic for sampling thrips.     

6种颜色粘虫板对春季菜地昆虫的诱集效应

为筛选对春季蔬菜害虫具有较好诱集效果的粘虫板,促进蔬菜害虫绿色防控技术的研究与推广,采用红色、黄色、绿色、蓝色、白色和黑色6种颜色的市售粘虫板对菜地昆虫进行诱集试验.结果显示,粘虫板诱集的害虫以尖眼蕈蚊Bradysia minpleuroti、小菜蛾Plutella xylostella、端大蓟马Megalurothrips distalis和黄蓟马Thrips flavus为优势种;黄曲条跳甲Phyllotreta striolata、南美斑潜蝇Liriomyza huidobrensis、灰地种蝇Delia platura、棉蚜Aphis gossypii、小绿叶蝉Empoasca flavescens、菜粉蝶Pieris rapae为常见种.试验中蓝色粘虫板诱集的灰地种蝇的数量显著高于其它处理组(P<0.05);黄色粘虫板诱集的南美斑潜蝇、棉蚜、小绿叶蝉的数量显著高于其它处理组(P<0.05);蓝色和白色粘虫板诱集的端大蓟马、黄蓟马的数量显著高于其它处理组(P<0.05);蓝色粘虫板诱集到的尖眼蕈蚊的数量显著低于其它处理组(P<0.05).各种颜色粘虫板诱集昆虫的益害比较低,诱集益虫总数仅占诱集昆虫总数的1.64％,表明该时段使用粘虫板防治菜地害虫,对益虫伤害较小,对保护利用天敌昆虫具有重要意义.本研究结果为科学使用粘虫板防治菜地害虫提供理论依据.     

Comparison of adult corn rootworm (Coleoptera: Chrysomelidae) sampling methods

Studies were conducted in Kansas corn and soybean fields during 1997 to compare various sampling methods, traps, and trap components for capturing three species of adult corn rootworms: western (Diabrotica virgifera virgifera Leconte), southern (D. undecimpunctata howardi Barber), and northern (D. barberi Smith & Lawrence). Lure constituents affected the species of beetle attracted to the trap. Traps with a lure containing 4-methoxycinnamaldehyde attracted more western corn rootworms, those with a lure containing eugenol were more attractive to northern corn rootworms, and those containing trans-cinnamaldehyde were most attractive to southern corn rootworms. Multigard sticky traps caught more beetles than did Pherocon AM sticky traps. In corn, a newly designed lure trap caught more beetles than did sticky traps on most occasions. Also, lure-baited sticky traps caught more beetles than did nonbaited sticky traps. Varying the color of the lure trap bottom did not affect the number caught. In soybeans, the new lure traps captured more beetles than did the nonbaited Multigard or Pherocon AM sticky traps. Results of this study suggest the new lure trap may provide a more accurate assessment of corn rootworm populations than traditional monitoring techniques and may be more esthetically pleasing to growers and consultants.     

缨小蜂对颜色的选择性和粘卡技术的应用研究

本文比较了7种颜色的粘卡,在茭白田中对飞虱天敌缨小蜂（Anagrus spp.）的诱捕能力,结果表明,黄色粘卡对缨小蜂的诱捕量显著高于其它颜色的粘卡。缨小蜂对颜色的嗜好顺序为黄色＞蓝色＞蓝绿色＞绿色＞白色＞红色＞黑色。黄色粘卡在离地面40cm、70cm、100cm、130cm和160cm5个高度上,以70cm和100cm高度捕获的缨小蜂最多。黄色粘卡对缨小蜂的诱捕量在东、南、西、北四个方向差异不显著。一天中的不同时间段里,黄色粘卡所诱捕到的缨小蜂量以上午6：00至9：00最多。     

An alternative sampling technique for cucumber beetles (Coleoptera: Chrysomelidae) and diurnal beetle activity on muskmelon

Field studies were conducted to investigate the effectiveness of yellow sticky traps as an alternative sampling technique for striped, Acalymma vittatum (F.), and spotted, Diabrotica undecimpunctata howardi Barber, cucumber beetles (Coleoptera: Chrysomelidae) and the diurnal beetle activity on muskmelon, Cucumis melo L., near Vincennes, IN, in 2003 and 2004. The experimental design included six replications of seven 20-m-long rows each of muskmelon with 1.5 m between rows. On each sampling date, two yellow sticky traps were placed randomly between rows in each replication. One sticky trap was placed vertically with the lower edge even with the top of the canopy, whereas the other trap was placed horizontally, even with the top of the canopy. After traps were placed in the field, number of beetles on plants was counted in situ from 0800 to 1600 hours at 2-h intervals the next day. After 48 h in the field, the number of cucumber beetles adhering on traps was counted. Analyses of variance and Tukey's multiple comparison procedure were used to compare the densities of beetles among sampling times, and regression analyses were applied to correlate the numbers of beetles on traps and the numbers of in situ counts. Results show that both species of cucumber beetles were most active from 1200 to 1400 hours, and 20 beetles on the vertically positioned sticky trap were equivalent to one beetle per plant in the field. The application of the sampling technique and scouting time for cucumber beetle management are discussed.     

Colour-coded sampling: the pan trap colour preferences of oligolectic and nonoligolectic bees associated with a vernal pool plant

1. Pan traps or water traps have been used widely to sample agricultural insect pests, but no formal studies have assessed the utility of these traps as sampling devices for bees. 2. Coloured pan traps, used as flower models, can efficiently and selectively sample an oligolectic bee, Andrena (Hesperandrena) limnanthis, and other bees associated with white-flowered Limnanthes douglasii rosea. 3. Females and males of A. limnanthis unexpectedly exhibit different colour preferences. Females are strongly attracted to white and blue traps, but discriminate against yellow traps. Males prefer white traps over blue and yellow traps. Consequently, blue traps are selective for females only, while white traps are selective for both sexes. 4. Non-A. limnanthis bees were caught in significantly greater numbers in yellow than in blue or white traps. These bees included generalists, as well as specialists that are oligolectic on mostly yellow-flowered species. 5. Colour of traps had a significant effect on the numbers of A. limnanthis females and males, and non-A. limnanthis bees caught in traps. These results indicate that quantitative sampling of bees by pan trap methods can be highly sensitive to trap colour.