Coccinellids in the KBS LTER Landscape
Long Term Ecological Research sites (LTER) were founded in 1980 by the NSF. The goal is to support more long term studies to find larger patterns and create extensive databases of baseline information for different environments. Kellogg Biological Station’s (KBS) LTER is one of 26 in the US but is the only agroecology site. The LTER ladybeetle study was started in 1989 by Dr. Stuart Gage and has since continued as a main site baseline study. The study tracks populations of nine key coccinellid species with the purpose of monitoring interactions between populations but has also been used for identifying novel species in the environment. Two species of non-native ladybeetles (Coccinella septempunctata, Harmonia axyridis) and six species of native ladybeetles (Coleomegilla maculata, Cycloneda munda, Hippodamia parenthesis, Chilocorus stigmata, Coccinella trifasciata, and Hippodamia glacialis) are monitored in habitats ranging from woodland to highly managed agricultural fields. In 2005, Hippodamia variegata was observed for the first time and added to the study the following year. Propylea quatuordecimpunctata was added to the study in 2007 after the first observation in 2006.
Coccinella septempunctata: C7 is one of the most abundant species in the LTER and also an exotic. Farmers often purchase and release C7 for aphid control. The species was present from the beginning of the study.
Harmonia axyridis: HAXY is also one of the most abundant species in the LTER and again an exotic. HAXY was first observed in the LTER in 1994 but saw a dramatic increase in population in 2000, the first year the soybean aphid, Aphis glycines, arrived in Michigan. Subsequent years have shown a possible relationship between soybean aphid. HAXY also appears to have a deleterious effect on CMAC.
Coleomagilla maculata: CMAC is the most abundant native species of coccinellid in the LTER. It focuses mainly in crops for resources and often overwinters in forest litter and usually first appears on dandelion in May.
Hippodamia variegata: This species was first observed in the LTER in 2005. HVAR was released by USDA/APHIS/PPQ in 1988 for the biocontrol of the Russian wheat aphid along with C7 and PQUA. The population did not establish in the Western United States but did in the Northeast and has been moving west.
Propylea quatuordecimpunctata: This species was first observed in the LTER in 2006. It was also released in 1988 by USDA/APHIS/PPQ for the biocontrol of the Russian wheat aphid. PQUA’s population establishment and pattern of movement through the US follows closely to that of HVAR.
- C. septempunctata has remained consistent with a cyclic rise and fall in population.
- C. maculata’s population declined and remained lower starting in 2000 coinciding with the arrival of the soybean aphid and subsequent rise in population of H. axyridis.
- H. axyridis saw a rise in population beginning in the mid 1990’s and even further after the arrival of the soybean aphid in 2000.
- H.axyridis shows a clear positive relationship with soybean aphid, exhibiting a classic predator-prey interaction curve. When soybean aphid’s population peaks in one year, the coccinellid’s population almost invariably peaks the following year.
- As compared to earlier years, C.maculata’s population has suffered a decline in overall abundance and magnitude in population fluctuation as a result of the negative impact of the increase in H. axyridis.