Cornicle secretions of Uroleucon nigrotuberculatum (Homoptera: Aphididae) as the last bullet against lady beetle larvae

Abstract

Aphids have evolved various defense strategies against natural enemies, including secretions from their cornicles. We assessed the defensive function of cornicle secretions by the goldenrod aphid, Uroleucon nigrotuberculatum (Olive), against larvae of the lady beetles Coccinella septempunctata bruckii Mulsant and Propylea japonica (Thunberg) (Coleoptera: Coccinellidae). The aphid secreted red droplets from its cornicles when attacked by the larvae. Two‐thirds of the C. septempunctata bruckii larvae and 46.7% of the P. japonica larvae that preyed on the aphids died before reaching the pre‐pupal stage. The secretions caused molting failure when smeared on the larvae's heads or glued to the larvae's mouthparts, killing 56.7% of C. septempunctata bruckii larvae and 36.7% of P. japonica larvae. Second instar larvae were affected most. About 40% of third and fourth instar larvae of C. septempunctata bruckii vomited soon after ingesting the aphids. In the field, up to 40% of first and second instar larvae were smeared with red secretions. Our results show that these cornicle secretions are an effective and active defense against earlier instars of coccinellid larvae.

Aphelinus nigritus‐induced transgenerational fecundity compensation in parasitized Melanaphis sorghi

“…Chemically, some aphids produce cornicle secretions bearing alarm pheromones that alert conspecifics of impending danger (Vandermoten et al, 2012). Cornicle secretions can also coat the rostrum and mouthparts of certain predators, preventing them from moulting or feeding (Barry & Ohno, 2016). While first‐line responses can be successful, they are often bypassed by some aphid parasitoids.…”

“…Cornicle secretions can also coat the rostrum and mouthparts of certain predators, preventing them from moulting or feeding (Barry & Ohno, 2016). While first-line responses can be successful, they are often bypassed by some aphid parasitoids.…”

Cornicle secretions byAphis fabae(Hemiptera: Aphididae) result in age-dependent costs and improved host suitability forLysiphlebus fabarum(Marshall) (Hymenoptera: Braconidae)

“…Aphid cornicle secretions are composed largely of triglycerides and function as a fast-drying liquid wax with strongly adhesive properties (Callow et al , 1973), although more recent analyses have revealed greater chemical complexity (Alfaress et al , 2016). Droplets of cornicle secretion can permanently seal the mouthparts of smaller predators or otherwise ensnare them (Butler & O'Neil, 2006; Barry & Ohno, 2016), foul parasitoid antennae and force wasps to engage in an extended period of grooming, and even result in parasitoid death when wasps become permanently stuck to the aphid (Rasekh et al , 2010 a ). However, the secretion of cornicle droplets can result in various fitness costs for the aphid.…”