An Efficient Alternative to the CDC Gravid Trap for Southern House Mosquito (Diptera: Culicidae) Surveillance

West Nile virus (WNV) is the most prevalent arbovirus found throughout the United States. Surveillance of surface breeding Culex vectors involved in WNV transmission is primarily conducted using CDC Gravid traps. However, anecdotal claims from mosquito abatement districts in Louisiana assert that other trap types may be more suited to WNV surveillance. To test the validity of these assertions, we conducted a series of trapping trials and WNV surveillance over 3 yr to compare the efficacy of multiple trap types. First, we compared the CDC Gravid trap, CO2-baited New Standard Miniature Blacklight traps, and CO2-baited CDC light traps with either an incandescent light, a red light, or no light. We found that the CDC Gravid trap and CO2-baited no-light CDC Light trap collected the most mosquitoes. Second, we conducted additional, long-term trapping and WNV surveillance to compare these two trap types. We found that CO2-baited no-light CDC traps collected more of the local WNV vector, Culex quinquefasciatus (Say, Diptera, Culicidae), and detected WNV with greater sensitivity. Finally, we conducted trapping to compare the physiological states of Cx. quinquefasciatus and diversity of collected mosquitoes. CO2-baited no-light CDC light traps collected more unfed Cx. quinquefasciatus while Gravid traps collected more blooded Cx. quinquefasciatus; both traps collected the same number of gravid Cx. quinquefasciatus. Additionally, we found that CO2-baited no-light CDC light traps collected a larger diversity of mosquito species than Gravid traps.

(3S,6E)-nerolidol-mediated rendezvous of Cyclocephala paraguayensis beetles in bottle gourd flowers

Cyclocephalini beetles of the genus Cyclocephala (Coleoptera: Melolonthidae: Dynastinae) use flowers of some plants as food, shelter, and mating sites. However, little is known about floral scent chemistry involved in this interaction. Here we show that a sesquiterpene alcohol mediates attraction of Cyclocephala paraguayensis Arrow, on bottle gourd flowers, Lagenaria siceraria (Cucurbitaceae). Both males and females started to aggregate on the flowers at twilight; after that, mating began and remained for the entire night. GC-FID/EAD analysis of the L. siceraria floral scent collected in the field revealed that only the major constituent of the airborne volatiles elicited electroantennographic responses on male and female antennae of C. paraguayensis. This compound was identified as (3S,6E)-nerolidol, which was tested in two field trapping trials in Brazil. In the first bioassay, traps baited with nerolidol (mix of isomers) captured significantly more adult C. paraguayensis than control traps. In the second field trial, catches in traps baited with a mixture of isomers or enantiopure nerolidol were significantly higher than captures in control traps, but the treatments did not differ significantly. Analysis from the gut content of adult C. paraguayensis showed the presence of pollen, suggesting that they also use bottle gourd flowers for their nourishment. Taken together, these results suggest that (3S,6E)-nerolidol plays an essential role in the reproductive behavior of C. paraguayensis by eliciting aggregation, mating, and feeding.

Please come again: attractive bait augments recapture rates of capture-naïve snowshoe hares

ContextCapture–recapture sampling is one of the most commonly used methods for monitoring population demographics and is needed in a wide variety of studies where repeat sampling of individuals is desired. Although studies employing capture–recapture methods often assume unbiased sampling, it is well established that inherent capture biases can occur with these methods, including those related to baits. Reducing sources of sampling bias and augmenting recapture reliability is necessary for capture-dependent studies. However, few studies have examined the efficacy of baits on individuals with variable capture experience. AimsTo investigate the use of an attractant-augmented bait in enhancing capture–recapture probabilities for snowshoe hares (Lepus americanus). MethodsTo examine the efficacy of different attractant-augmented bait types, a variety of baits were created, with bait preference tested on a captive hare. Because a strawberry jam-based bait was preferentially consumed (in comparison with other tested baits), the effectiveness of this attractant in enhancing capture–recapture rates was subsequently examined in wild hares, using paired live-trapping field trials (n=6 trials). ResultsLive-trapping trials showed that although overall hare capture rates were not affected by the use of a jam-based bait, recaptures were 33.1% higher in capture-naïve individuals exposed to our attractant. This was not the case for hares with prior capture experience; such hares had an equal likelihood of being recaptured regardless of the bait type used. ConclusionsThe tested attractant improved recapture rates of capture-naïve hares. ImplicationsStudies relying on high recapture rates should use methods that maximise recapture rates wherever possible, including the use of baits that may augment recaptures in capture-naïve animals.

Comparative efficacy of mass trapping and attract-and-kill technique in the control of medfly (Ceratitis capitata, Wiedemann) in Central Moroccan peach orchards

To develop eco-friendly alternative control strategies for medfly, mass trapping trials were conducted in the central Morocco during the crop season 2016. Two control methods, mass trapping and the attract-and-kill technique were compared for the control of medfly on two peach varieties (?Rome Star? and ?Ryan Sun?) in Sefou district. For mass trapping, 62 traps/1.23 ha of MagnetTMMed type baited with ammonium acetate, trimethylamine, putrescine and 0.01 g of deltamethrin were installed on both varieties. In plots testing the attract-and-kill technique, treatments with malathion in mixture with protein hydrolyzate were applied to straw tufts attached to branches of the same varieties whenever 1 fly was caught on a Trimedlure trap installed at the center of each plot. The results showed that the number of flies captured by mass trapping reached 508 and 489 adults on ?Rome Star? and ?Ryan Sun?, respectively. The average number varied from 1 to 3 adults/trap/day, depending on the date of capture and the variety, and females accounted for 62-100% of total caught flies. In plots protected by the attract-and-kill technique, and taking into account the threshold adopted by the farm, 11 and 15 treatments were carried out respectively on the ?Ryan Sun? and ?Rome Star? varieties. Overall, infestation rates in plots did not exceed 0.3% before or at harvest with mass trapping versus 0.9% with the attract-and-kill technique. On fruit dropped on the ground, the infestation rate did not exceed 4% in mass trapping, compared to 11.5% in the chemically treated plots. Mass trapping was therefore proved to be an effective and eco-friendly tool for managing medfly on peach fruit.

Fishing directly selects on growth rate via behaviour: implications of growth-selection that is independent of size

Size-selective harvest of fish and crustacean populations has reduced stock numbers, and led to reduced growth rates and earlier maturation. In contrast to the focus on size-selective effects of harvest, here, we test the hypothesis that fishing may select on life-history traits (here, growth rate) via behaviour, even in the absence of size selection. If true, then traditional size-limits used to protect segments of a population cannot fully protect fast growers, because at any given size, fast-growers will be more vulnerable owing to bolder behaviour. We repeatedly measured individual behaviour and growth of 86 crayfish and found that fast-growing individuals were consistently bold and voracious over time, and were subsequently more likely to be harvested in single- and group-trapping trials. In addition, there was some indication that sex had independent effects on behaviour and trappability, whereby females tended to be less active, shyer, slower-growing and less likely to be harvested, but not all these effects were significant. This study represents, to our knowledge, the first across-individual support for this hypothesis, and suggests that behaviour is an important mechanism for fishing selectivity that could potentially lead to evolution of reduced intrinsic growth rates.

Comparative performance of traps for the Mediterranean fruit fly Ceratitis capitata Wiedemann (Diptera: Tephritidae) baited with female-targeted or male-targeted lures

Results of trapping trials in Italy confirmed that the non-sticky CSALOMON® VARs+ funnel trap was highly efficient for the capture of Mediterranean fruit fly (Ceratitis capitata Wiedemann) (Diptera: Tephritidae), when baited with either male-targeted (trimedlure), or synthetic female-targeted (ammonium carbonate, ammonium acetate, trimethylamine, putrescine) baits. Trimedlure-baited traps caught ten times more flies (all males), than traps with synthetic female-targeted lures (which cauught predominantly females). Although less efficient, traps with the female-targeted lures had the significant advantage over trimedlure that they attracted predominantly females, so in cases when for control or experimental purposes the capture of female flies is more informative (i.e. timing of egg-laying, fertility and fecundity studies, etc.), these lures would be the best choice. The present results suggested that putrescine could be left out from female-targeted lure combinations without dramatic change in activity.

Cameraria gaultheriella and C. lobatiella attracted in Canada to (E,Z)-8,10-tetradecadienal, the sex pheromone of the European C. ohridella

Field trapping trials showed that Cameraria gaultheriella Walsingham and C. lobatiella Opler and Davis (Lepidoptera: Gracillariidae) were attracted in significant numbers in British Columbia, Canada, to sticky traps baited with 10 µg of (E,Z)-8,10-tetradecadienal (E8Z10-14Ald), the sex pheromone of the European horse chestnut leafminer, C. ohridella Deschka and Dimic. There was perfect specificity in captures at habitats located only about 8 km apart from each other: C. gaultheriella was captured exclusively at a humid habitat covered by the shrub salal, Gaultheria shallon Pursh (Ericaceae), whereas C. lobatiella was trapped at an arid location with Garry oak trees, Quercus garryana Dougl. (Fagaceae). Seasonal flight patterns of these two Canadian Cameraria species, as monitored by pheromone traps, indicated differences in their respective flight periods. The possibility of additional cryptic components in the respective pheromones of these three Cameraria species attracted to E8Z10-14Ald is discussed.