[PCA] Pollinator Abundance in Semiarid Pastures as Affected by Forage Species - native plants attract greatest number of pollinators

[De Angelis, Patricia]

By Krishna B. Bhandari, C. P. Westa, S. D. Longing, C. P. Brown, P. E.
Green and E. Barkowsky
Crop Science, September 2018

ABSTRACT:
The semiarid Texas High Plains has a declining water supply for irrigated
crop production because of unsustainable pumping from the Ogallala aquifer.
Conversion of land from annual crops to limited-irrigated perennial forages
is an option for profitable land use. ‘WW-B.Dahl’ old world bluestem
[Bothriochloa bladhii (Retz) S.T. Blake, OWB] is a well-adapted grass known
for deterring some soil-dwelling insects, but effects of OWB on insect
pollinators are unknown. The aim of this study was to determine whether
adapted forage types (species or mixtures) affected insect pollinator
abundance in pastures. Foraging insects were collected using bee bowls and
compared among OWB alone, OWB mixed with alfalfa (Medicago sativa L.),
alfalfa, and a native grass mix. Twenty-one families from four orders of
insects were recovered over 3 yr. Sweat bee (Hymenoptera: Halictidae) was
the most abundant family, with 59% of the total number of insects
collected. Honey bees (Hymenoptera: Apidae) constituted an additional 17%
of the total number of insects collected, with hover flies (Diptera:
Syrphidae) and skippers (Lepidoptera: Hesperiidae) found in lesser
abundances. Interactions between forage type and years restricted
consistent forage-type effects. In general, the lowest abundances of
foraging insects were commonly found in OWB growing alone, especially of
the native, ground-nesting sweat bee, whereas greater abundances were more
commonly found in native grass and alfalfa pastures. Widespread adoption of
WW-B.Dahl OWB may reduce local numbers of foraging insects in the Texas
High Plains, which could negatively affect pollinators in managed
grasslands.

Link to article:
https://dl.sciencesocieties.org/publications/cs/articles/58/6/2665
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