Comparing the Powers of the Wald-Wolfowitz and Kolmogorov-Smirnov Tests

The Wald-Wolfowitz test and the Kolmogorov-Smirnov test are two well-known tests which can be used to test for differences between two population distributions, where these distributions could differ in means, variances or shapes. This paper compares the simulated power of the Wald-Wolfowitz test to that of the Kolmogorov-Smirnov test in several situations. Differences in location only, differences in variance only, and differences in both location and variance are considered. In most cases, equal sample sizes of 10 and 20 are used.     

Year‐round spatial movements and trophic ecology of Trindade Petrels (Pterodroma arminjoniana)

Trindade Petrels (Pterodroma arminjoniana) are vulnerable gadfly petrels that breed on the remote Trindade Island, located ~1100 km off the Brazilian coast. Little is known about their spatial ecology, and their trophic ecology has only been described for the breeding season. We tagged four Trindade Petrels with global location sensing loggers (GLS) from October 2013 to November 2014 and sampled the blood and feathers (innermost primary and the eighth secondary) of 14 individuals to evaluate their year‐round spatial and isotopic ecology. We examined individual distributions, habitat use and suitability, activity, and isotopic values during the breeding, migration, and non‐breeding periods. Trindade Petrels used areas in the southwest Atlantic Ocean (between 10°N and 50°S in latitude) during the breeding season. They migrated through pelagic waters of the tropical Atlantic to the northwest Atlantic, where they spent the non‐breeding season. Trindade Petrels used mostly tropical to subtropical waters in areas of intermediate to high wind speeds and low marine productivity. Individuals spent more time foraging at night than during the day. During the breeding season, birds in northerly areas had higher carbon‐13 values, and birds that used more pelagic areas foraged on prey at a higher trophic level (higher nitrogen‐15 values) than those in more southern and coastal areas. Isotopic values during the breeding, migration, and non‐breeding periods differed, possibly due to differences among individuals in their at‐sea distribution throughout the year. We confirmed the non‐breeding distribution of Trindade Petrels, which was previously known only from vessel sightings and stranded birds. Our results also suggest a strong temporal segregation in the at‐sea distribution and trophic ecology between two groups of individuals, which might indicate the existence of two separate breeding populations.     

Does previous experience enhance foraging on a particular host in a polyphagous frugivore?

Prior oviposition or feeding experience with a host plant has been proposed to improve foraging efficiency for polyphagous insect herbivores. Many laboratory-based experiments have attributed certain modified behavioural responses, such as an improved ability to locate a host, as evidence for the benefits of learning. However, few studies have considered the negative ramifications of learning, particularly under field conditions rather than laboratory conditions. In the current study, using the polyphagous fruit fly Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), we explore both the positive and negative consequences of modified host selection resulting from prior oviposition experience. In field cage experiments, prior oviposition experience on a given host increased the selection of that host despite its abundance and its suitability for offspring development. For example, in a field cage that contained significantly more blueberry (poor larval host) than guava (good larval host), prior experience on guava resulted in more flies selecting and accepting guava than did naïve flies (a presumed positive foraging outcome). However, the opposite also held, that prior experience on blueberry led to increased blueberry use, even when guava was more abundant. In unrestrained flies, prior experience dramatically improved recapture rate with flies locating the training fruit. The results highlight the potential benefits of learning, but also identify that learning can be a disadvantage if prior experience on a poor host leads to flies repeatedly using that host over a more suitable host.     

The role of 1-octen-3-ol as a host-odour attractant for the biting midge, Culicoides impunctatus Goetghebuer, and interactions of 1-octen-3-ol with a volatile pheromone produced by parous female midges

Abstract. 1-octen-3-ol, a component of the body odour of ruminants, is demonstrated to be an attractant for host-seeking, parous female Culicoides impunctatus Goetghebuer (Diptera, Ceratopogonidae).This compound was electrophysiologically and behaviourally active and, in the field, released at 0.11 ± 0.01 mg/day, increased female C.impunctatus catches over a seven-day period compared with control catches.When 1-octen-3-ol was combined either with live female midges or an extract of female midges in an electroantennogram assay, additive effects were recorded.Behaviourally, the same combination resulted in both enhanced attraction and repellency, depending on concentration.Attraction was recorded mainly when sub-threshold concentrations of the separate components were combined.The potential of such a combination as an effective field bait is discussed.