Field testing of different chemical combinations as odour baits for trapping wild mosquitoes in The Gambia

Odour baited traps have potential use in population surveillance of insect vectors of disease, and in some cases for vector population reduction. Established attractants for human host-seeking mosquitoes include a combination of CO(2) with L-lactic acid and ammonia, on top of which additional candidate compounds are being tested. In this field study in rural Gambia, using Latin square experiments with thorough randomization and replication, we tested nine different leading candidate combinations of chemical odorants for attractiveness to wild mosquitoes including anthropophilic malaria vectors, using modified Mosquito Magnet-X (MM-X) counterflow traps outside experimental huts containing male human sleepers. Highest catches of female mosquitoes, particularly of An. gambiae s.l. and Mansonia species, were obtained by incorporation of tetradecanoic acid. As additional carboxylic acids did not increase the trap catches further, this 'reference blend' (tetradecanoic acid with L-lactic acid, ammonia and CO(2)) was used in subsequent experiments. MM-X traps with this blend caught similar numbers of An. gambiae s.l. and slightly more Mansonia and Culex mosquitoes than a standard CDC light trap, and these numbers were not significantly affected by the presence or absence of human sleepers in the huts. Experiments with CO(2) produced from overnight yeast cultures showed that this organic source was effective in enabling trap attractiveness for all mosquito species, although at a slightly lower efficiency than obtained with use of CO(2) gas cylinders. Although further studies are needed to discover additional chemicals that increase attractiveness, as well as to optimise trap design and CO(2) source for broader practical use, the odour-baited traps described here are safe and effective for sampling host-seeking mosquitoes outdoors and can be incorporated into studies of malaria vector ecology.     

Evaluation of commercial and field‐expedient baited traps for house flies,Musca domestica L. (Diptera: Muscidae)

A comparison of nine commercial baited fly traps on Florida dairy farms demonstrated that Terminator traps collected significantly more (13,323/trap) house flies (Musca domestica L.) than the others tested. Final Flight, Fly Magnet, and FliesBeGone traps collected intermediate numbers of flies (834‐2,166), and relatively few were caught with ISCA, Advantage, Fermone Big Boy, Squeeze & Snap, or OakStump traps (<300). Terminator traps collected about twice as many flies (799.8/trap) as FliesBeGone traps (343.8) when each trap was baited with its respective attractant, but when the attractants were switched between the two trap types, collections were significantly lower (77‐108) than was observed with traps baited with their respective attractant. Solutions of molasses were significantly more attractive to house flies than honey, maple syrup, or jaggery (date palm sugar). Field‐expedient traps constructed from discarded PET water bottles were much less effective than commercial traps, but painting the tops of such traps with black spray paint resulted in a six‐fold increase in trap capture.     

A sex pheromone‐baited trapping system for management of sweetpotato weevil,Cylas formicarius (Coleoptera: Brentidae)

A potent male attractant of sweetpotato weevil helps in monitoring and control of sweetpotato weevil in many production areas around the world. At present, it has not been used in Malaysia. Cost of the components of a trapping system is a major constraint in the adoption of male lure‐baited trapping by growers in Malaysia. Seven field trapping experiments were conducted from February 2013 to November 2015 as part of an effort to develop a simple, easy to construct, cost‐effective and efficient sex pheromone‐baited trap acceptable for use by farmers in Malaysia for monitoring and control of sweetpotato weevil (Cylas formicarius Fabricius). Overall, sweetpotato weevil trap catch was significantly affected by the number of windows in the trap, the killing agent used in the trap and the position of the trap relative to sweetpotato foliage, while trap size and trap colour did not significantly affect trap catch. Trap catch was best in plastic pole traps made from polyethylene terephthalate, with four window opening to facilitate weevil entry, with detergent solution as a killing agent and with the trap positioned from 0 to 40 cm above the crop canopy level. In a comparison study with commercial trap designs, sex pheromone‐baited plastic pole traps caught 60%–78% more weevils than were caught in sex pheromone‐baited delta traps, wing traps or unitraps. Optimization of trap characteristics is important for improving the performance of pheromone‐baited traps for use in population monitoring or mass‐trapping efforts to minimize crop damage by sweetpotato weevil infestation.     

Synthetic host volatiles increase efficacy of trap cropping for management of Colorado potato beetle, Leptinotarsa decemlineata (Say)

Abstract 1 The attractiveness of pitfall traps baited with a synthetic host volatile attractant to colonizing adult Colorado potato beetle, Leptinotarsa decemlineata (Say) was evaluated in a field setting. 2 Significantly more postdiapause, colonizing adult L. decemlineata were captured in baited than unbaited pitfall traps. 3 The potential for this synthetic kairomone to enhance the efficacy of trap cropping as a management tool was evaluated by comparing conventionally managed plots with like‐sized plots bordered by either attractant‐treated trap crop or untreated trap crop. 4 More postdiapause, colonizing adults, egg masses and small larvae were present in attractant‐treated trap crops than in untreated trap crops. 5 There were no significant differences in egg mass and small larvae densities between plots bordered by attractant‐treated trap crops and conventionally managed plots, but there were significantly fewer large larvae and adult beetles in conventionally managed plots. 6 Plant canopy area of conventionally managed plots was significantly greater than in plots bordered by either type of trap crop. 7 Yields for conventionally managed plots and plots bordered by attractant‐treated trap crops did not differ, and less insecticide (44%) was applied to plots bordered by attractant‐treated trap crops.     

A carbon dioxide, heat and chemical lure trap for the bedbug, Cimex lectularius

Abstract A trap for the collection of bedbugs, Cimex lectularius Linnaeus (Hemiptera: Cimicidae), is described. The trap was baited with CO₂ (50–400 mL/min), heat (37.2–42.2 °C) and a chemical lure comprised of 33.0 μg proprionic acid, 0.33 μg butyric acid, 0.33 μg valeric acid, 100 μg octenol and 100 μg L‐lactic acid, impregnated into a gel. Laboratory studies, conducted in a square arena measuring 183 cm on each side, showed that traps with and without baits captured adult bedbugs, but traps with CO₂ emissions of 50–400 mL/min caught significantly (P < 0.05) more bedbugs than traps without CO_2. In an infested unoccupied apartment, traps with heat and with or without the chemical lure were tested without CO₂ on 29 trap‐days and with CO₂ on 9 trap‐days. The numbers of bedbugs captured were 656 and 5898 in traps without and with CO₂, respectively. The numbers of bedbugs of all development stages captured were significantly greater in traps with CO₂ (χ² = 15 942, d.f. = 1, P < 10^?9). A non‐parametric two‐way analysis of variance evaluation of six different traps with or without CO₂, heat or a chemical lure monitored over 19 trap‐days in an infested apartment showed that trap type was highly significant (n = 2833 bedbugs collected) (P < 10^?7). The trap with CO₂, heat and a chemical lure captured more bedbugs than the other traps, but only caught significantly more fourth and fifth instar nymphs than all other traps. Otherwise, the catches in this trap did not differ significantly from those caught by traps that contained CO₂ and heat only. The total numbers of bedbugs collected for each trapping date (pooling all six traps) followed an exponential decline over the trapping period. This type of trap, which caught bedbugs in unoccupied apartments with and without furniture, and in an occupied apartment, may have utility in studying the ecology of bedbugs, in detecting bedbug infestations and in reducing numbers of bites by trapping host‐seeking bedbugs.     

Improving monitoring tools for spotted wing drosophila,Drosophila suzukii

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) were trapped in the field using colored plastic sphere traps coated with insect Tangle‐trap. Red and black spheres captured significantly more D. suzukii than white spheres. Translucent deli‐cup traps deployed in cherry orchards and baited with yeast, the Alpha Scents lure, or the Scentry lure captured significantly more flies than the Trécé lure and Suzukii bait; all attractants had poor selectivity for D. suzukii. No‐choice evaluations of attractants conducted in field cages corroborated the cherry orchard field study, though translucent deli‐cup traps provisioned with the yeast bait captured significantly more flies than those baited with the Alpha Scents lure. Red sphere traps baited with the Scentry lure captured 3–6× more flies than the deli‐cup trap baited with the same lure, and 3–4× more flies than the deli‐cup trap baited with yeast bait, demonstrating that a trap integrating both visual and olfactory cues is a superior tool for monitoring D. suzukii. Moreover, this simple sticky, dry trap design requires far less labor and maintenance than does a liquid‐based deli‐cup trap.     

Monitoring oriental fruit moth (Lepidoptera: Tortricidae) with the Ajar bait trap in orchards under mating disruption

Studies in Oregon, California, Pennsylvania and Italy evaluated the relative performance of the Ajar trap compared with several other traps for the capture of Grapholita molesta (Busck), in pome and stone fruit orchards treated with sex pheromone dispensers for mating disruption. The Ajar is a delta‐shaped trap with a screened jar filled with an aqueous terpinyl acetate plus brown sugar bait solution (TAS) that opens inside the trap and is surrounded by a sticky liner. The TAS‐baited Ajar trap was evaluated with and without the addition of a sex pheromone lure and compared with a delta trap baited with a sex pheromone lure and a bucket trap filled with the TAS bait. Although the Ajar trap had a 90% lower evaporation of the TAS bait than the bucket trap, both of them caught similar numbers in the majority of the field tests of both sexes of G. molesta. The addition of the sex pheromone lure did not increase moth catches by the TAS‐baited Ajar trap. The TAS‐baited Ajar trap caught significantly greater numbers of moths than the sex pheromone‐baited delta trap in 18 of the 20 orchards. Few hymenopterans were caught in orange TAS‐baited Ajar traps, but the catch of flies and other moths relative to the target pest remained high. Flight tunnel and field tests evaluated the effect of several screen designs on the catches of G. molesta and non‐target species. All exclusion devices significantly reduced the catch of larger moths. However, designs that did not reduce the catch of male G. molesta did not reduce the catch of muscid flies. Exclusion devices with openings <7.0 mm significantly reduced the catch of female G. molesta. The addition of (E)‐β‐farnesene, (E)‐β‐ocimene or butyl hexanoate septa lures to TAS‐baited Ajar traps significantly increased total moth catch. The addition of (E)‐β‐ocimene also significantly increased female moth catch.     

Serum levels of luteinizing hormone, prolactin, estradiol and progesterone in laying and nonlaying mallards (Anas platyrhynchos)

Temporal changes of circulating serum hormones were measured to compare the reproductive endocrinology of laying and nonlaying mallards. In this study all sixteen control mallards left with their mates laid eggs, while only one of sixteen mallards stressed by daily movement into new pens, laid eggs. Serum levels of luteinizing hormone (LH), prolactin, estradiol, and progesterone were significantly lower (P less than 0.05) in stressed nonlaying mallards than in laying mallards over the 7-week period. Within 1 week of the rotation treatment, LH concentrations in stressed mallards averaged (means +/- SEM) 2.72 +/- 0.19 ng/ml and were significantly lower (P less than 0.05) than LH levels in the controls (3.62 +/- 0.18 ng/ml). After 7 weeks, injections of luteinizing hormone releasing hormone (LHRH) induced a greater change in circulating LH levels in stressed mallards (2.1 +/- 0.3 ng/ml) than in breeding control mallards (0.9 +/- 0.2 ng/ml). These data demonstrate that the lack of reproduction in stressed mallards was associated with LHRH-sensitive pituitary pools of LH, despite their low concentrations of serum LH. These data suggest that the block in reproduction is a failure of the hypothalamus to produce or release releasing hormones. The serum hormone levels of the control mallards varied temporally with stages in the nesting cycle. LH levels increased with the onset of nesting activity, and showed marked fluctuations during the laying period. LH levels fell at the onset of incubation but increased after loss of clutch. Estradiol levels were highest prior to the laying of the first egg and their peak coincided with the initial nest building behavior of the females. Progesterone levels increased sharply with the laying of the 2nd-4th eggs, decreased sharply with the laying of the 6th egg, and then increased slightly at the end of the nesting cycle. Prolactin levels were initially low but gradually increased with laying and incubation activity, declined with loss of clutch, and increased again with renesting activity. Prolactin levels in the stressed mallards also increased (P less than 0.01) over the 7-week period, but significantly less (P less than 0.05) than in layers.     

Laboratory and field testing of bednet traps for mosquito (Diptera: Culicidae) sampling in West Java,Indonesia

Surveillance of medically important mosquitoes is critical to determine the risk of mosquito‐borne disease transmission. The purpose of this research was to test self‐supporting, exposure‐free bednet traps to survey mosquitoes. In the laboratory we tested human‐baited and unbaited CDC light trap/cot bednet (CDCBN) combinations against three types of traps: the Mbita Trap (MIBITA), a Tent Trap (TENT), and a modified Townes style Malaise trap (TSM). In the laboratory, 16 runs comparing MBITA, TSM, and TENT to the CDCBN were conducted for a total of 48 runs of the experiment using 13,600 mosquitoes. The TENT trap collected significantly more mosquitoes than the CDCBN. The CDCBN collected significantly more than the MBITA and there was no difference between the TSM and the CDCBN. Two field trials were conducted in Cibuntu, Sukabumi, West Java, Indonesia. The first test compared human‐baited and unbaited CDCBN, TENT, and TSM traps during six nights over two consecutive weeks per month from January, 2007 to September, 2007 for a total of 54 trapnights. A total of 8,474 mosquitoes representing 33 species were collected using the six trapping methods. The TENT‐baited trap collected significantly more mosquitoes than both the CDCBN and the TSM. The second field trial was a comparison of the baited and unbaited TENT and CDCBN traps and Human Landing Collections (HLCs). The trial was carried out from January, 2008 to May, 2008 for a total of 30 trap nights. A total of 11,923 mosquitoes were collected representing 24 species. Human Landing Collections captured significantly more mosquitoes than either the TENT or the CDCBN. The baited and unbaited TENT collected significantly more mosquitoes than the CDCBN. The TENT trap was found to be an effective, light‐weight substitute for the CDC light‐trap, bednet combination in the field and should be considered for use in surveys of mosquito‐borne diseases such as malaria, arboviruses, and filariasis.     

Monitoring oriental fruit moth and codling moth (Lepidoptera: Tortricidae) with combinations of pheromones and kairomones

Experiments were conducted in North and South America during 2012–2013 to evaluate the use of lure combinations of sex pheromones (PH), host plant volatiles (HPVs) and food baits in traps to capture the oriental fruit moth, Grapholita molesta (Busck), and codling moth, Cydia pomonella (L.), in pome and stone fruit orchards treated with sex pheromones. The combination of the sex pheromone of both species (PH combo lure) significantly increased G. molesta and marginally decreased C. pomonella captures as compared with captures of each species with either of their sex pheromones alone. The addition of a HPV combination lure [(E,Z)‐2,4‐ethyl decadienoate plus (E)‐β‐ocimene] or acetic acid used alone or together did not significantly increase the catch of either species in traps with the PH combo lure. The Ajar trap baited with terpinyl acetate and brown sugar (TAS bait) caught significantly more G. molesta than the delta trap baited with PH combo plus acetic acid in California during 2012. The addition of a PH combo lure to an Ajar trap significantly increased catches of G. molesta compared to the use of the TAS bait or PH combo lure alone in 2013. Female G. molesta were caught in TAS‐baited Ajar traps at similar levels with or without the use of additional lures. Ajar traps baited with the TAS bait alone or with (E)‐β‐ocimene and/or PH combo lures caught significantly fewer C. pomonella than delta traps with sex pheromone alone. Ajar traps with 6.4‐mm screened flaps caught similar numbers of total and female G. molesta as similarly baited open Ajar traps, and with a significant reduction in the catch of non‐targets. Broader testing of HPV and PH combo lures for G. molesta in either delta or screened or open Ajar traps is warranted.     

Monitoring oriental fruit moth (Lepidoptera: Tortricidae) with sticky traps baited with terpinyl acetate and sex pheromone

Studies in Argentina and Chile during 2010–2011 evaluated a new trap (Ajar) for monitoring the oriental fruit moth, Grapholita molesta (Busck). The Ajar trap was delta‐shaped with a jar filled with a terpinyl acetate plus brown sugar bait attached to the bottom centre of the trap. The screened lid of the jar was inserted inside the trap, and moths were caught on a sticky insert surrounding the lid. The Ajar trap was evaluated with and without the addition of a sex pheromone lure and compared with delta traps left unbaited or baited with a sex pheromone lure and a bucket trap filled with the same liquid bait. Studies were conducted in a sex pheromone‐treated orchard in Argentina and an untreated orchard in Chile. In Chile, the Ajar trap without the sex pheromone lure caught significantly fewer males, females and total moths than the bucket trap, and fewer males and more females than the sex pheromone‐baited delta trap. Total moth catch did not differ between the Ajar trap without a sex pheromone lure and the sex pheromone‐baited trap. Adding a sex pheromone lure to the Ajar trap significantly increased total moth catches to levels not different from those in the bucket trap. However, the Ajar trap with the sex pheromone lure caught significantly more males and fewer females than the bucket trap. In Argentina, the Ajar trap with or without the addition of a sex pheromone lure caught similar numbers of both sexes and total moths as the bucket trap. The sex pheromone‐baited delta trap caught <4% of the number of moths as these three traps. The bucket trap in both studies caught significantly more non‐targets than the delta and Ajar traps. Moth catches in the Ajar trap declined significantly after 2–3 weeks when the bait was not replaced.     

Improved monitoring of female codling moth (Lepidoptera: Tortricidae) with pear ester plus acetic acid in sex pheromone-treated orchards

The performance of clear delta traps baited with 3.0 mg of pear ester, ethyl (E,Z)-2,4-decadienoate, and 5.0 ml of acetic acid in separate lures was compared with orange delta traps baited with a single lure containing 3.0 mg of both pear ester and the sex pheromone, (E,E)-8,10-dodecadien-1-ol (codlemone) for codling moth, Cydia pomonella (L.), in apple, Malus domestica (Borkhausen). Residual analyses and field tests demonstrated that both the pear ester and acetic acid lures were effective for at least 8 wk. The two trap-lure combinations caught a similar number of total moths in an orchard treated with sex pheromone dispensers during short-term trials in 2008. However, the mean catch of female moths was significantly higher and male moths significantly lower in clear traps baited with pear ester and acetic acid versus orange traps baited with pear ester and codlemone. Season-long studies were conducted with these two trap-lure combinations in orchards treated with (n = 6) and without (n = 7) sex pheromone dispensers during 2009. The two trap-lure combinations caught similar numbers of moths in dispenser-treated orchards. In contrast, total catch was significantly higher (>2-fold) in the orange compared with the clear traps in untreated orchards. The clear caught >6-fold more females than the orange trap in both types of orchards. These studies suggest that deploying clear delta traps baited with pear ester and acetic acid can be an effective monitoring tool for female codling moth and an alternative to codlemone-baited traps in sex pheromone-treated orchards.     

Effect of trap type, trap position, time of year, and beetle density on captures of the redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae)

The exotic redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), and its fungal symbiont Raffaellea lauricola Harrington, Fraedrich, and Aghayeva are responsible for widespread redbay, Persea borbonia (L.) Spreng., mortality in the southern United States. Effective traps and lures are needed to monitor spread of the beetle and for early detection at ports-of-entry, so we conducted a series of experiments to find the best trap design, color, lure, and trap position for detection of X. glabratus. The best trap and lure combination was then tested at seven sites varying in beetle abundance and at one site throughout the year to see how season and beetle population affected performance. Manuka oil proved to be the most effective lure tested, particularly when considering cost and availability. Traps baited with manuka oil lures releasing 5 mg/d caught as many beetles as those baited with lures releasing 200 mg/d. Distributing manuka oil lures from the top to the bottom of eight-unit funnel traps resulted in similar numbers of X. glabratus as a single lure in the middle. Trap color had little effect on captures in sticky traps or cross-vane traps. Funnel traps caught twice as many beetles as cross-vane traps and three times as many as sticky traps but mean catch per trap was not significantly different. When comparing height, traps 1.5 m above the ground captured 85% of the beetles collected but a few were caught at each height up to 15 m. Funnel trap captures exhibited a strong linear relationship (r2 = 0.79) with X. glabratus attack density and they performed well throughout the year. Catching beetles at low densities is important to port of entry monitoring programs where early detection of infestations is essential. Our trials show that multiple funnel traps baited with a single manuka oil lure were effective for capturing X. glabratus even when no infested trees were visible in the area.     

Niche overlap and interspecific association between Chilo partellus and Chilo orichalcociliellus on the Kenya coast

The use of felt traps to estimate oviposition by the cabbage root fly, Delia radicum (L.), and turnip root fly, Delia floralis (Fall.), was compared with soil sampling at seven localities between 1992 and 1994 in Denmark and Norway. In all, 281 comparisons were made, based on 6800 samples. In 4.6% of these comparisons no eggs were found by either method. In 16% of the comparisons, 2.0±0.41 (±S.E.) eggs were found per soil sample and no eggs were found in felt traps, whereas in 0.7% of the comparisons 0.10±0.03 eggs were found per felt trap and no eggs in soil samples. When eggs were found using both methods, the ratio between soil sampling and felt traps varied from 13.1±3.2 when the egg laying rate was very low to 1.8±0.2 at high egg laying rates. Regression analysis showed significant correlation between felt trap catches and soil sampling (P<0.001), whereas locality did not influence felt trap efficiency (P=0.096). The influence of the physical conditions of felt traps, i.e., whether they were clean and dry, were analysed in a single year. Tentative action thresholds for control measures against cabbage root flies and turnip root flies were developed for cauliflower, Brassica oleracea, convar. botrytis (L.) Alef., var. botrytis, based on data from the literature and the present results.     

Influence of trap type, trap colour, and trapping location on the capture of the pine moth, Thaumetopoea pityocampa

Studies were conducted to evaluate the effect of type, location, and colour of traps baited with 1 mg of the sex pheromone (Z)‐13‐hexadecen‐11‐ynyl acetate in polyethylene vials on the capture of the pine processionary moth, Thaumetopoea pityocampa (Denis & Schiffermüller) (Lepidoptera: Thaumetopoeidae), males. The experiments were carried out during two flight seasons in 2002 and 2003 at a low elevation Mediterranean pine forest on the hill of Goritsa (Magnesia, Thessaly, Central Greece). The hill is covered by approximately 120 ha of pines, among which Pinus brutia Ten. (Pinaceae) is predominant with Pinus halepensis Mill. (Pinaceae) as second most common species. Among the commercially available trap types used, the Delta and Pherocon II captured significantly more males than the Funnel trap. Furthermore, pine density had a significant effect on trap type and trap colour catches. Delta traps caught significantly more adults than the other two trap types in the low density pine stand, while in the medium and high‐density pine stands no significant differences were noted between Delta and Pherocon II traps. In addition, trap colour performance varied according to pine density; white‐ and yellow‐coloured traps caught significantly more males than the other two trap colours in the high‐density stand. The first adults were captured in traps during May, and traps continued to capture adults in low numbers (< two individuals per trap) until mid‐June. A period of 3–4 weeks of no trap captures followed until mid‐July, when captures restarted, at low numbers. The peak of T. pityocampa flight was observed during late August–September.     

Monitoring plum curculio, Conotrachelus nenuphar (Coleoptera: Curculionidae), populations in apple and peach orchards in the mid-Atlantic

We evaluated responses of plum curculio, Conotrachelus nenuphar (Herbst), to four trap types in commercial and unsprayed apple and peach orchards. Trap types included black pyramid and clear Plexiglas panel traps deployed outside the orchard 2 m from the border row, and branch-mimicking cylinder and trunk-mounted screen traps attached to trees in the border row. Bait treatments evaluated in conjunction with each trap type included the synthetic fruit volatile benzaldehyde, the aggregation pheromone grandisoic acid (GA), benzaldehyde in combination with GA, and an unbaited control treatment. In commercial apple orchards, significantly more plum curculio were captured in traps baited with benzaldehyde + GA compared with traps baited with other treatments. Furthermore, significantly more plum curculio were captured by screen traps baited with benzaldehyde + GA compared with unbaited control traps. Significantly more plum curculio were captured by screen traps compared with other trap types in an unsprayed apple orchard. Very few captures were recorded in commercial peach orchards. Dissections of trapped females indicate that bivoltine populations are present in the mid-Atlantic. In general, correlations between timing and amount of trap captures and timing and amount of fruit injury inflicted concurrently or 1 wk after trap captures were very weak for all trap types and bait combinations. Our results agree with previous studies in the northeastern United States in which trap captures are increased by presence of semiochemical baits but fail to serve as reliable tools to determine need for and timing of insecticide application against plum curculio.     

Odour-baited traps influence thrips capture in proximal unbaited traps in the field

Two field experiments examined the distance over which an attractant odour of a volatile chemical could influence thrips capture in proximal traps that were without the odour. In each experiment a star‐shaped array of water traps consisted of a centre trap with or without an odour surrounded by odourless traps at 0.5, 1, 2, 5, and 10 m in eight equally spaced radial arms 45° apart. Experiments ran for 47 h (centre trap: ethyl nicotinate) or 7 h (centre trap: ethyl isonicotinate). Each had four replicates. With ethyl nicotinate, more thrips were trapped in the centre‐baited traps than in the unbaited centre traps (63×, 7×, 98× and 200× for total thrips, Thrips tabaci Lindeman ♀, and Thrips obscuratus Crawford ♀and ♂, respectively) (Thysanoptera: Thripidae). More total thrips and T. tabaci♀ were trapped in the centre traps baited with ethyl isonicotinate than in unbaited centre traps (21× for both). For ethyl nicotinate, numbers of T. obscuratus in unbaited traps downwind from the baited centre trap declined by 50% within 0.4 m (♀) and 2 m (♂) and by 95% within 3 m (both ♀ and ♂) based on model predictions. For ethyl isonicotinate, numbers of T. tabaci in unbaited traps downwind from the baited centre trap declined by 50% within 1.3 m and by 95% within 10 m based on model predictions. Wind direction was an important factor in the degree and direction of thrips capture with the highest thrips capture downwind from the centre trap with odour. There was no increase in numbers of T. tabaci in any traps without odour in the ethyl nicotinate‐centred array. Differences in trapping patterns between thrips species and odours indicated that there were thrips species–odour specific interactions. Experiments examining differences between traps with and without a thrips attractant odour need to be designed very carefully to ensure meaningful results especially in enclosed and/or low‐wind indoor situations.     

Small‐plot studies comparing pheromone and juice baits for mass‐trapping invasive Synanthedon myopaeformis in Canada

Recent introduction of Synanthedon myopaeformis (Borkhausen) (Lepidoptera: Sesiidae) into organic apple‐growing areas of Canada has stimulated research on semiochemical‐based management of this European pest. Replicated, small‐plot (0.16 ha) experiments were conducted to compare sex pheromone, 3Z,13Z‐octadecadienyl acetate (10 mg), Concord grape juice (300 ml), or their combination, as mass‐trapping lures at trap densities equivalent to 12.5, 25, 50, and 100 traps ha^?1. Total numbers of male and female moths removed from test plots increased significantly with trap density in all juice‐based mass‐trapping experiments. In pheromone mass‐trapping experiments, however, total catches of males did not increase significantly as trap densities were increased and catches appeared to plateau with 25–50 traps ha^?1. With pheromone‐based mass‐trapping, significantly fewer males were caught in pheromone‐baited assessment traps at the centre of each mass‐trapping plot than in identical traps in untreated plots. This reduction is indicative of significant trap interference or trap ‘shut‐down’. Increasing the density of juice‐based mass‐trapping had no effect on catches of male or female moths in juice‐baited assessment traps, indicating a short range of attraction and lack of interference between juice traps. Pheromone‐ and juice‐based mass trapping removed similar numbers of males at each trap density tested, respectively, but summed catches of males and females were greatest with juice baits. Combining pheromone and juice into a single mass‐trapping treatment (50 traps ha^?1) did not significantly increase catches of males or females relative to either treatment alone. If a practical bisexual mass‐trapping system is going to be developed for S. myopaeformis, then identification of volatile kairomones in Concord grape juice may be useful.     

Effects of Chromium Propionate on Egg Production,Egg Quality,Plasma Biochemical Parameters,and Egg Chromium Deposition in Late-Phase Laying Hens

This study was conducted to investigate the effects of chromium propionate on egg production, egg quality, plasma biochemical parameters and egg chromium deposition in late-phase laying hens. Four hundred thirty-two 60-weeks old laying hens were divided into four groups of 108 birds per group according to egg production. The dietary treatments consisted of the basal diet adding with 0, 200, 400, and 600 μg/kg chromium as chromium propionate. All laying hens were given feed and water ad libitum for 8 weeks. The addition of 400 μg/kg Cr as chromium propionate increased egg production (P?<?0.01) during the later 4 weeks, but decreased albumen height, yolk color score, and Haugh unit of eggs. Six hundred micrograms per kilogram Cr as chromium propionate supplementation improved shell thickness (P?<?0.05). 200 μg/kg Cr as chromium propionate supplementation decreased the uric acid concentration by 31 % (P?<?0.05). However, supplemental Cr did not affect the egg chromium deposition of hens (P?>?0.05). These data indicated that feeding of late-phase laying hens with chromium propionate could improve egg production, increase eggshell thickness, but do not result in abnormal levels of chromium deposition in eggs.     

Factors affecting captures of male citrus leafminer, Phyllocnistis citrella Stainton, in pheromone-baited traps

The citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), is an important world‐wide pest of citrus. Larval mining within leaf flush impacts yield and predisposes trees to infection by citrus canker, Xanthomonas axonopodis pv. citri. The present series of studies sought to identify factors affecting male P. citrella catch in pheromone‐baited traps with the intent of developing effective monitoring. A commercially available pheromone lure (Citralure, ISCA Technologies, Riverside, CA, USA) was highly effective in attracting male P. citrella to traps. Pherocon VI Delta (Trécé Inc., Adair, OK, USA) traps baited with a Citralure captured more male P. citrella than identically baited Pherocon IC Wing traps (Trécé Inc.). The superiority of the Delta‐style trap was found to be due to a 3 cm long closing latch that likely prevents males from flying directly through the trap without capture. Within canopies of mature citrus trees (approximately 3.5 m high), traps at mid‐canopy height (2.0 m) captured more males than traps placed higher (3.5 m) or lower (0.6 m). On the canopy perimeter and in between canopies, traps near ground level (0.6 m height) captured more males than traps at 2.0 and 3.5 m heights. Male catch was greater within the tree canopy or on the canopy perimeter than 2.0 away from the canopy. Traps deployed in trees on the edge of groves captured more males than traps placed 120 and 240 m away from the grove edge and within the grove interior. In non‐pheromone‐treated grove plots, the optimal dosage for catching males was between 0.1 and 1.0 mg of the 3 : 1 blend of (Z,Z,E)‐7,11,13‐hexadecatrienal and (Z,Z)‐7,11‐hexadecadienal; however, in pheromone‐treated plots a higher 10.0 mg dosage lure was most effective. Male catch in pheromone‐baited traps exhibited a diel rhythm with most males captured during scotophase (22:00–23:00 h) and no males captured during photophase.