Effectiveness of tiger moth (Lepidoptera, Arctiidae) chemical defenses against an insectivorous bat (Eptesicus fuscus)

Abstract

Adult tiger moths exhibit a wide range of palatabilities to the insectivorous big brown bat Eptesicus fuscus. Much of this variation is due to plant allelochemics ingested and sequestered from their larval food. By using a comparative approach involving 15 species from six tribes and two subfamilies of the Arctiidae we have shown that tiger moths feeding on cardiac glycoside-containing plants often contain highly effective natural feeding deterrents.Feeding on pyrrolizidine alkaloid-containing plants is also an effective deterrent to predation by bats but less so than feeding on plants rich in cardiac glycosides. Moths feeding on plants containing iridoid glycosides and/or moths likely to contain biogenic amines were the least deterrent. By manipulating the diet of several tiger moth species we were able to adjust their degree of palatability and link it to the levels of cardiac glycosides or pyrrolizidine alkaloids in their food. We argue that intense selective pressure provided by vertebrate predators including bats has driven the tiger moths to sequester more and more potent deterrents against them and to acquire a suite of morphology characteristics and behaviors that advertise their noxious taste.

Tempo and mode of antibat ultrasound production and sonar jamming in the diverse hawkmoth radiation

“…Many tiger moths are chemically defended and they use sounds to warn bats of their toxins (12,13,40). Hawkmoths do not appear to sequester plant toxins in their adult tissues (41), are known to be palatable to birds (42), and we have confirmed they are palatable to bats (Table S1).…”

Evolution of Homospermidine Synthase in the Convolvulaceae: A Story of Gene Duplication, Gene Loss, and Periods of Various Selection Pressures

“…They are characterized by a nitrogen-containing bicyclic ring system, the necine base, which is esterified with one or more necic acids. Because of the observed feeding deterrence, PAs are regarded as part of the chemical defense of plants (Dreyer et al, 1985;Singer and Stireman, 2003;Hristov and Conner, 2005;Siciliano et al, 2005;Reinhard et al, 2009). PAs occur in several unrelated angiosperm families, one of which is the Convolvulaceae (Hartmann and Witte, 1995;Langel et al, 2011).…”

Sonar jamming in the field: effectiveness and behavior of a unique prey defense

“…Depending on whether a species is chemically defended and the amount of sound it produces, moth clicks serve as acoustic aposematic (Hristov and Conner, 2005a;Hristov and Conner, 2005b;Ratcliffe and Fullard, 2005), mimetic (Barber and Conner, 2007;Barber et al, 2009) or sonar-jamming signals (Corcoran et al, 2009;Corcoran et al, 2010;Corcoran et al, 2011;Conner and Corcoran, 2012). In some cases these defenses may be combined; for example, a small degree of sonar jamming may enhance bat learning of aposematic signals (Ratcliffe and Fullard, 2005).…”