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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2004.07.017 Byline: Mitchell B. Baker Abstract: Habitat quality, and the levels of habitat variables that are associated with good habitat, can vary between years. Therefore, animals that are able to adjust their habitat selectivity should enjoy higher fitness. I examined the use of experience in habitat selection during natal dispersal in Hemilepistus reaumuri, a monogamous, semelparous desert isopod. Young from the previous year emerge in the spring and walk from a few to over one thousand metres before establishing burrows or settling in already established burrows. Isopods were held in outdoor pens for 7-day priming treatments, then moved to new pens and tested for settling 4 days later. Perceived habitat quality was defined as the fraction of isopods settling in each pen during its use in the 7-day priming treatments. Settling was tested as a function of the change in perceived quality isopods experienced. Settling was significantly positively correlated with change in perceived quality, suggesting that experience is used to prime habitat selection during dispersal, and that the effects of experience last at least a few days in desert isopods. Time of year also had a significant positive effect on settling. The effect of change in perceived quality was stronger than the effect of perceived quality in the final pen. If changes in habitat are used to calibrate settling decisions, longer dispersal distances may be needed to allow for habitats to be compared. Use of experience to regulate settling may also affect the population dispersal response to habitat change. Author Affiliation: Animal Behavior Graduate Group, University of California at Davis , U.S.A. Mitrani Department for Desert Ecology, Ben Gurion University of the Negev, Sde Boqer, Israel Article Note: (miscellaneous) MS. number: A9705 more...

BACKGROUND: Organic pest management eschews synthetic pesticides and insecticide resistance is rarely studied in organically managed systems. Spinosad is a biologically based insecticide used widely by both organic and conventional growers. Colorado potato beetle, Leptinotarsa decemlineata, is infamous for its ability to evolve resistance to insecticides. Spinosad resistance was surveyed in conventionally managed fields in eastern New York in 2006. In response to grower reports of spinosad failure on two organic farms in 2009, resistance to spinosad was assayed in both conventionally and organically managed fields the following year, and growers were surveyed for their prior spinosad use. RESULTS: In 2006, spinosad resistance measured as median lethal dose (LD50) varied 9.8‐fold among the eight conventional fields sampled and a laboratory susceptible strain. In 2010, the resistance ratios of LD50 values relative to a laboratory susceptible strain ranged from 17.5 to 40.6 in conventionally managed fields, and from 128.7 to 5750.3 in organically managed fields, a dramatic increase from 2006 with higher resistance ratios in organically managed fields. Organic growers reported much heavier use of spinosad in the years prior to 2010. CONCLUSION: This is the first report of high‐level resistance to spinosad in Coleopterans. Selection strength due to number of years used and number of applications per season appear to have been the primary factors driving the evolution of resistance to spinosad, highlighting the need for resistance management in organic production, where fewer alternative active ingredients for resistance management are available. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR] more...

Eastern New York State is frequently the site of Colorado potato beetle (Leptinotarsa decemlineata , Say) populations with the highest observed levels of insecticide resistance to a range of active ingredients. The dominance of a resistant phenotype will affect its rate of increase and the potential for management. On organic farms on Long Island, L. decemlineata evolved high levels of resistance to spinosad in a short period of time and that resistance has spread across the eastern part of the Island. Resistance has also emerged in other parts of the country as well. To clarify the level of dominance or recessiveness of spinosad resistance in different parts of the United States and how resistance differs in separate beetle populations, we sampled in 2010 beetle populations from Maine, Michigan, and Long Island. In addition, a highly resistant Long Island population was assessed in 2012. All populations were hybridized with a laboratory-susceptible strain to determine dominance. None of the populations sampled in 2010 were significantly different from additive resistance, but the Long Island population sampled in 2012 was not significantly different from fully recessive. Recessive inheritance of high-level resistance may help manage its increase. [ABSTRACT FROM AUTHOR] more...