Long term sampling reveals previously unobserved trends in predatory coccinellid populations in an agricultural landscape.

Predatory coccinellids (ladybeetles) are important providers of biocontrol services in numerous ecosystems. Each growing season since 1989, coccinellid populations have been monitored weekly in a variety of habitats at the Kellogg Biological Station in southwestern Michigan. Coccinellid captures were recorded from main site treatments (maize, soybean, wheat, alfalfa, poplar, and early successional vegetation) and adjacent unmanaged forest plots (coniferous, deciduous and successional forest).  This poster explores population trends, habitat use, and seasonality of four of the fourteen most commonly observed species from this survey. Adalia bipunctata, a native species, has been in rapid decline since the initiation of this survey. Until 1999, it was most commonly observed in poplar stands, but since 2000, it has only been observed in conifer forests, and has not been observed at KBS since 2008. Coleomegilla maculata, an omnivourous native coccinellid, is variable in net abundance, but general population trends appear to be stable over the duration of the observation period. This species is much more abundant in maize plots, likely due to a dietary preference for maize pollen. Coccinella septempunctata, an introduced species, exhibits wide variation in abundance, but abundance of this species appears to be cyclical, with a 4-5 year period of oscillation. Harmonia axyridis, another introduced species, first appeared in 1995, slowly increased in abundance until 2000, and then, since 2001, has undergone repeated cyclical abundance related to populations of soybean aphid.