Method for Continuously Rearing Coccinella Lady Beetles (Coleoptera: Coccinellidae)

ABSTRACT

Coccinella novemnotata L., the ninespotted lady beetle, and Coccinella transversoguttata richardsoni Brown, the transverse lady beetle, are predatory species whose abundance has declined significantly over the last few decades in North America. An ex situ system for continuously rearing these two beetles is described here to aid conservation efforts and facilitate studies aimed at determining factors in their decline and possible recovery. All rearing of lady beetles was conducted in the laboratory at or near room temperatures and 16:8 L:D photoperiod. The two coccinellid species were each reared separately, and different life stages were handled independently. Eggs were collected every 1 to 2 d and placed in holding containers, and individual clutches were transferred to cages with prey when their eggs began to hatch. Neonate larvae were fed live bird cherry-oat aphids [Rhopalosiphum padi (L.)] for 3 to 4 d, and second instars were trans-ferred to different cages and fed live pea aphids [Acyrthosiphon pisum (Harris)]. Third and fourth instars were also fed pea aphids, but reared individually in small cups to preclude cannibalism. Upon pupation, individuals were collectively trans-ferred to fresh cups and placed in a different container for the duration of pupation. Newly emerged adults were collected within containers about 2 d after eclosion. Adults were housed in cages stocked with live pea aphids, supplemental food, and rumpled paper towels as oviposition substrate. Over 80% of egg clutches were deposited by beetles on rumpled paper towels versus other surfaces within cages, and incidence of cannibalism of egg clutches was greatly reduced on rumpled paper towels. Techniques for successful rearing of these two coccinellids and future research regarding adaptations to fur-ther optimize their rearing methods are discussed.

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