[MAIPC] steep decline in pollinators this summer?

[Muth, Norris (MUTH)]

Are there any citizen science or otherwise public data sets that could help? I could imagine teasing the information out of iNaturalist – but that would take some doing if you wanted it to be a reliable indicator of the hypothesized trend.

Here in Central PA I had very low numbers of pollinators in spring and early summer (e.g. button bushes that were empty that had been swarmed in previous years). Things picked up a bit and seemed more like recent years by mid-summer. No cicada or SLF spraying up here (or there shouldn’t have been).


—

Norris Z. Muth, Ph.D.

he/him

Professor of Biology, Juniata College

muthlab.org<http://muthlab.org/>

From: Stephen Hiltner<mailto:stevehiltner at gmail.com>
Sent: Monday, August 23, 2021 4:31 PM
To: MAIPC Listserve<mailto:maipc at lists.maipc.org>
Subject: [MAIPC] steep decline in pollinators this summer?

This may not be exactly on topic, but I'd like to check in with the group about others' observations of pollinators this summer. My observations are very local, in Princeton, NJ, but I have paid pretty close attention to pollinators on the classic summer wildflowers, which we have planted in abundance, and though I noticed declines over the past two years, this year there's been a disturbing absence. Though I've seen quite a few bumblebees, particularly on our wild senna, the number and variety of bees and wasps is way down. As an example, blue-winged wasps were common in previous years, but only a few seen this year. Our clustered mountain mint was covered with pollinators last year, with 4-6 tiger swallowtails at a time among a host of other insects, but even the swallowtails are rare now. Boneset, usually a magnet for insect action, is essentially empty. It's like hosting a party and no one shows up. Strangely numerous are baldfaced hornets and European hornets, which are often the first insects I see as I approach one of our plantings. These are not interested in nectar, but are instead predatory on other insects. It's not clear if they are more numerous or more obvious given the lack of other insects. There has also been a reduction in mosquitoes this year, mentioned by several people I've spoken with.

Others I've asked thus far have also noticed reductions in pollinators. One suggested that homeowners are spraying more insecticides, due to the 17 year cicada brood and the lanternfly invasion. I wonder if the warm winters mess with dormancy, and if the heavy and numerous rains are flooding out ground nesting insects, particularly given our dense piedmont soils. Could the cicada's myriad channels be reducing standing water that breeds mosquitoes, but also allowing the soil to become more quickly penetrated by rainwater, which could increase flooding of ground nesters? That hornets are numerous could point to rain as an issue, giving an advantage to insects that nest above ground, and leading to increasing predation on any pollinators that survive other challenges. I have never seen a hornet catch another insect and carry it away, however, though it may happen so fast that it goes unnoticed.

Please let me know what you've been seeing, whether it be good news or bad.

Steve
PrincetonNatureNotes.org<http://princetonnaturenotes.org/>



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