Trap height affects capture of lady beetles (Coleoptera: Coccinellidae) in pecan orchards

Authors: Cottrell, Ted

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2016
Publication Date: 2/17/2017
Citation: Cottrell, T.E. 2017. Trap height affects capture of lady beetles (Coleoptera: Coccinellidae) in pecan orchards. Environmental Entomology. 46(2):343-352.

Interpretive Summary: There is little information concerning the occurrence of lady beetles at different heights within tall trees. A number of studies have been done in orchards and forests but very few of them have examined the occurrence of lady beetles high in tree canopies. The objective of this study was to determine the abundance of different lady beetle species at different heights in mature pecan orchards with tall trees. From spring through late fall during 2013 and 2014, yellow pyramidal Tedders traps were suspended in the pecan canopy at 6.1 and 12.2 m, in addition to being placed on the ground (0 m). The exotic multicolored Asian lady beetle and the sevenspotted lady beetle accounted for a high percentage of trapped lady beetles during this study. Except for Olla v-nigrum, low numbers of native species (Hippodamia convergens, Coleomegilla maculata, Cycloneda munda, Scymnus spp. and Hyperaspis spp.) were captured. However, significantly more were captured in ground traps instead of in canopy traps with the exception of O. v-nigrum. Similar to most native species, significantly more of the sevenspotted lady beetle were captured in ground traps than canopy traps. This contrasts sharply with the multicolored Asian lady beetle that was similarly abundant at all trap heights. The ability to exploit resources from the orchard floor to the tops of pecan trees may be an underestimated factor helping to explain the invasiveness of the multicolored Asian lady beetle.

Technical Abstract: There is scarce information regarding the vertical stratification of predaceous Coccinellidae in tall trees. Although numerous studies have been done in orchards and forests, very few studies have assessed the occurrence of predaceous Coccinellidae high in tree canopies. The objective of this study was to examine the abundance of Coccinellidae at different heights in mature pecan orchards with tall trees. From spring through late fall during 2013 and 2014, yellow pyramidal Tedders traps were suspended in the pecan canopy at 6.1 and 12.2 m, in addition to being placed on the ground (0 m). The exotic species Harmonia axyridis and Coccinella septempunctata accounted for a high percentage of trap capture during this study. Except for Olla v-nigrum, low numbers of native species (Hippodamia convergens, Coleomegilla maculata, Cycloneda munda, Scymnus spp. and Hyperaspis spp.) were captured. However, significantly more were captured in ground traps rather than in canopy traps with the exception of O. v-nigrum. Similar to most native species, significantly more C. septempunctata were captured in ground traps than canopy traps. This contrasts sharply with H. axyridis captured similarly at all trap heights. The ability to exploit resources across vertical strata, unlike many intraguild predators, may be an underestimated factor helping to explain the invasiveness of H. axyridis.