Pharmacophagy in green lacewings (Neuroptera: Chrysopidae: Chrysopa spp.)?
- Published
- Accepted
- Subject Areas
- Agricultural Science, Biochemistry, Ecology, Entomology
- Keywords
- Neuroptera, Chrysopidae, Chrysopa, green lacewings, pheromone, sequestration, pharmacophagy, iridodial, predator, aphid
- Copyright
- © 2015 Aldrich et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
- Cite this article
- 2015. Pharmacophagy in green lacewings (Neuroptera: Chrysopidae: Chrysopa spp.)? PeerJ PrePrints 3:e1311v1 https://doi.org/10.7287/peerj.preprints.1311v1
Abstract
Green lacewings (Neuroptera: Chrysopidae) are voracious predators of aphids and other small, soft-bodied insects and mites. Earlier, we identified the first lacewing pheromone from field-collected males of the goldeneyed lacewing, Chrysopa oculata Say; (1R,2S,5R,8R)-iridodial is released from thousands of microscopic dermal glands on the abdominal sternum of males, along with comparable amounts of nonanal, nonanol and nonanoic acid. Iridodial-baited traps attract C. oculata and other Chrysopa spp. males into traps, while females come to the vicinity of, but do not usually enter baited traps. Despite their healthy appearance, normal fertility and usual amounts of C9 compounds, laboratory-reared C. oculata males do not produce iridodial. However, we observed that goldeneyed lacewing males caught alive in iridodial-baited traps sometimes try to eat the lure, and in Asia Chrysopa spp. males reportedly eat the native plant, Actinidia polygama (Siebold & Zucc.) Maxim. (Actinidiaceae) to obtain the iridoid, neomatatabiol. These observations prompted us to investigate why laboratory-reared Chrysopa green lacewings do not produce iridodial. Lacewing adult males fed various monoterpenes reduced carbonyls to alcohols and saturated double bonds, but did not convert these compounds to iridodial. Males fed the bicyclic iridoid aphid pheromone component, (4aS,7S,7aR)-nepetalactone, converted ~75% to dihydronepetalactone, but did not produce iridodial; however, wild C. oculata males collected in May often contained traces of dihydronepetalactone. On the other hand, adult males fed the second common aphid pheromone component, (1R,4aS,7S,7aR)-nepetalactol, converted this compound to iridodial. In California the peak late-season attraction of green lacewings to nepetalactol (the lactone is unattractive) occurs at least a month earlier than the peak in aphid oviparae (the pheromone producing morph of aphids), consistent with the hypothesis that Chrysopa males feed on oviparae to obtain nepetalactol as a precursor to iridodial. Adult males from laboratory-reared C. oculata larvae fed nepetalactol failed to produce iridodial, and wild C. oculata males collected early in the spring produce less iridodial than males collected later in the season. Therefore, we further hypothesize that Asian Chrysopa eat A. polygama to obtain iridoid precursors in order to make their pheromone, and that other iridoid-producing plants elsewhere in the world must be similarly usurped by male Chrysopa species to sequester pheromone precursors. Whether or not sequestration of iridodial precursors from oviparae and/or iridoid-containing plants is truly the explanation for lack of pheromone in laboratory-reared Chrysopa awaits further research .
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Structures of Chrysopa semiochemicals:
1: (1R,2S,5R,8R)-iridodial, 2: (1R,4S,4aR,7S,7aR)-dihydronepetalactol, 3: (4aS,7S,7aR)-nepetalactone, 4: dihydronepetalactone, 5: (1R,4S,4aR,7S,7aR)-dihydronepetalactol, 6: (1R,4R,4aR,7S,7aR[i])dihydronepetalactol
GC and MS data of abdominal cu?cular extracts from Chrysopa oculata males a) & b) collected 28 May, 2009, sweeping vetch, Beltsville, MD
(4 = dihydronepetalactone; column = 30m HP-‐5; conditions described in text)
GC‐MS data for dihydronepetalactone (4), 2 July 2014
Analyzed on an HP 6890N GC coupled in series with an HP 5973 mass selective detector using a 30m DB-5 capillary column (250 μm x 0.25 μm film thickness; Agilent Technologies, Wilmington, DE, USA), 50 °C for 5 min, to 280 °C at 10 °C/min, hold 3 min.