Does insecticide application in a winter oilseed rape field influence the abundance of pollen beetle <i>Meligethes aeneus</i>
 in nearby ornamental flowers and vegetables?

Ahmed, Nur; Englund, Jan‐Eric; Johansson, Eva; Åhman, Inger

doi:10.1002/ps.3492

Cited by 3 publications

(2 citation statements)

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“…The negative influence of non-crop habitats on abundance of overwintered beetles could also represent a weaker dilution effect, as they would also spillover to these areas. Pollen beetles respond not only to volatiles emitted by oilseed rape but also to the odour of several plant species, including rye (Secale cereale L.) (Ruther and Thiemann 1997), and are often found in wild flowers (Ahmed et al 2013;Honěk et al 2013). Additionally, almost the same number of overwintered beetles (2012) was collected in oilseed rape and in non-crop areas, and even more were found in other crops.…”

Section: Landscape Components and Overwintered Pollen Beetlesmentioning

confidence: 99%

Using multi-level generalized path analysis to understand herbivore and parasitoid dynamics in changing landscapes

2015

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Context In patchy environments, such as agricultural landscapes, both spatial and temporal scales of habitat heterogeneity can affect population dynamics and trophic interactions. As a result of crop rotation, landscapes and local resource availability may change dramatically within and between years. Objectives We used a tritrophic interaction constituted by pollen beetles, their host plant oilseed rape, and their parasitoids, as a model system to investigate how the effect of landscape composition on insect abundance changes with time and whether system dynamics showed carry-over effects of previous years. We employ path analysis models that allow us to study whole networks of hypotheses rather than univariate cause-effect relationships. Methods We exposed pan traps in a 5 9 5 grid design within 10 landscapes in June 2011 (after oilseed rape flowering) and May 2012 (at peak oilseed rape flowering). Additionally, we assessed parasitism rates of pollen beetle larvae in May 2011 and measured changes in landscape composition. ResultsThe effect of the oilseed rape proportion on beetle abundance changed with time from negative (during flowering) to positive (after flowering). Parasitism had a negative effect on the number of newly emerged pollen beetles, but only in landscapes with a low proportion of oilseed rape. Interestingly, our path analysis showed that landscape composition affected herbivore abundance 1 or 2 years later, mediated by changes in parasitism. Conclusions Our results suggest that plant-herbivore-parasitoid interactions in dynamic agricultural landscapes can show interannual carry-over effects, as they are affected by landscape composition and topdown effects in previous years.

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Section: Landscape Components and Overwintered Pollen Beetlesmentioning

confidence: 99%