A procedure for pinpointing cannibalism, intraguild predation, and life stage-specific feeding events

Authors: Hagler, James; Casey, Miles; Machtley, Scott

Submitted to: BioControl
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/19/2020
Publication Date: 6/5/2020
Citation: Hagler, J.R., Casey, S.R., Machtley, S.A. 2020. A procedure for pinpointing cannibalism, intraguild predation, and life stage-specific feeding events. Biocontrol. 65:297-304. https://doi.org/10.1007/s10526-020-10005-2.
DOI: https://doi.org/10.1007/s10526-020-10005-2

Interpretive Summary: Insect “predators” often feed on other predator species. This phenomenon is known as intraguild predation (IGP). Also, some “predators” are cannibalistic. Obviously, predators that frequently engage in cannibalistic or IGP feeding activity are not very useful biological control agents for insect pest species. ARS scientists at Maricopa, AZ developed a clever method for examining both IGP and cannibalism on a well-known predator, the green lacewing. The method entailed tagging young (third instar) and old (fifth instar) lacewing larvae with rabbit IgG and chicken IgY proteins, respectively. The uniquely marked lacewings were then introduced into caged arenas containing a cotton plant and an assemblage of predators. The predators in each arena were recaptured and their gut contents were examined for the presence of rabbit IgG- and chicken IgY-marked lacewing remnants by protein-specific immunological assays. The predator gut analyses detected one cannibalism event (a fifth instar ate a third instar) and 15 and eight IGP feeding events on third and fifth instar lacewings, respectively. This proof-of-concept study shows that this technique can be useful tool for pinpointing cannibalism and life stage-specific predation events.

Technical Abstract: A predator gut analysis technique is described that can simultaneously pinpoint predation events which are life stage-specific, intraspecies-specific (cannibalism) and interspecies-specific (intraguild). The third and fifth larval life stages of green lacewing, Chrysoperla carnea Stephens s.l. (Neuroptera: Chrysopidae), were marked with rabbit IgG and chicken IgY, respectively. The uniquely marked lacewing life stages were then introduced into caged arenas (n = 59 caged experimental units) containing a cotton plant and an assemblage of predators. The predators in each arena were recaptured after 6 h and their gut contents were examined for the presence of rabbit IgG- and chicken IgY-marked lacewing remnants by an anti-rabbit and anti-chicken enzyme-linked immunosorbent assay (ELISA), respectively. The predator gut ELISAs detected one cannibalism event and 15 and eight intraguild predation (IGP) events on third and fifth instar lacewings, respectively. This proof-of-concept study shows that the prey immunomarking technique, when combined with field cage methods, can be useful for pinpointing cannibalism and life stage-specific predation events.