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  • 1
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    Dietary specialization influences the efficacy of larval tortoise beetle shield defenses (2005)
    Springer
    Details
    Publication Date: 2005-07-03
    Print ISSN: 0029-8549
    Electronic ISSN: 1432-1939
    Topics: Biology
    Published by Springer
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    PAPER CURRENT
  • 2
    Electronic Resource
    Electronic Resource
    The shield defense of the sumac flea beetle, Blepharida rhois (Chrysomelidae: Alticinae) (1998)
    Springer
    Chemoecology 8 (1998), S. 25-32 
    Details
    ISSN: 1423-0445
    Keywords: Key words. fecal shield - predation - Blepharida rhois - Rhus glabra - tannins - phytol - hexadecanoic acid - Alticinae - chemical defense - sumac
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary. Both adults and larvae of the sumac flea beetle, Blepharida rhois (Forster), are dietary specialists that feed on smooth sumac, Rhus glabra, on Long Island, NY. Instead of discarding their feces, B. rhois larvae retain it on their backs to form fecal 'shields'. We observed that ants attacking shielded larvae retreated and groomed vigorously, indicating the possible presence of chemical deterrents. To examine whether shields were chemical rather physical barriers against predation, we employed a generalist ant predator as a bioassay. Shields of larvae reared on R. glabra thwarted ants while larvae that had their shields removed were readily taken. Moreover, larvae reared on a substitute diet of lettuce were defenseless. However, protection was restored after their lettuce-derived shields were replaced with shields obtained from larvae reared on R. glabra. We then extracted and fractionated shields in order to locate active deterrents. To determine whether larvae synthesized defensive compounds or obtained them from the host, leaves were also analyzed and compared to the chemicals found in shields. The shield defense was a mixture of three fatty acids, a suite of tannins, their metabolites and phytol. All shield compounds or their precursors were obtained entirely from the host plant. Pure standards of shield compounds were found to be deterrent when assayed. This is one of the first instances of an insect using a mixture of primary and secondary substances for defense against predators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00001800
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  • 3
    Electronic Resource
    Electronic Resource
    Proximate Mechanisms of Sexual Selection in the Firefly Photinus pyralis (Coleoptera: Lampyridae) (1998)
    Springer
    Journal of insect behavior 11 (1998), S. 191-207 
    Details
    ISSN: 1572-8889
    Keywords: firefly ; Photinus pyralis ; Photinus macdermotti ; sexual selection ; mate competition ; flash behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Male competition in courtships of the firefly Photinus pyralis is intense. Morphometric analysis revealed that male size is variable, possibly exhibiting alternative body plans. We examined the outcomes of courtships to determine the proximate mechanisms of selection that may have led to male allometry. Two distinct selective events exist within mate competition: (1) searching and (2) scramble competition. Although many courtships failed, those without rivals were shorter and successful males spent less time in the “mate-guarding” position than when several males were in competition. Winners outflashed rivals, but flash dialogs occurred at similar frequencies across rival densities, indicating that females require some quantum of information before mating. Female flash preference was examined in choice tests to evaluate female discrimination ability. Females preferred flashes of greater intensity and precedence. This suggests that flash “synchronization” is a competitive display rather than a cooperative behavior to maintain female responsiveness. Selection for male size was density dependent: females preferred large males in searching, while small males were favored in scrambles. Simulated scrambles showed that small males have superior locomotor abilities, allowing them to reach the female rapidly. Comparison with a species lacking scrambles, P. macdermotti, revealed that selection in P. pyralis is disruptive, targeting traits alternately, and may have led to the evolution of higher allometric ratios in a species with direct male competition. Both male competition and female choice are important determinants of the outcome of P. pyralis courtships.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021091806472
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  • 4
    Electronic Resource
    Electronic Resource
    Flash behavior of femalePhoturis versicolor fireflies (Coleoptera: Lampyridae) in simulated courtship and predatory dialogues (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 843-858 
    Details
    ISSN: 1572-8889
    Keywords: firefly ; entrainment ; insect communication ; Coleoptera ; aggressive mimicry ; bioluminescence ; Lampyridae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract FemalePhoturis versicolor fireflies attempt to capture males by responding to heterospecific flash patterns. A mating-dependent switch occurs which affects response timing and frequency of female flashes. We examined the switch using females of known age, mating status, and flash experience to assess how accurate mimicry is, what factors influence it, and what mechanism produces it. Presentations of simulated male flash patterns before and after mating revealed elements of an entrainment mechanism controlling female responsiveness. Unmated females preferentially answered conspecific patterns with variable latencies, averaging 1 s. Mating induced changes in both response frequency and response latency: Females answered heterospecific patterns more frequently, and latencies elicited by conspecific patterns shifted away from the unmated range. Heterogeneity in mean and variance of response latency among individuals indicates that females do not share a discrete reply to a given pattern. Little correspondence exists between latencies of sympatric species andP. versicolor females, suggesting that the flash response mechanism produces entriainment to any rhythmic pattern, not a one-to-one matching between prey and predator latencies. Different selective scenarios underlie strict mimicry versus entrainment mimicry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01997130
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  • 5
    Electronic Resource
    Electronic Resource
    Shield Defense of a Larval Tortoise Beetle (1999)
    Springer
    Journal of chemical ecology 25 (1999), S. 549-566 
    Details
    ISSN: 1573-1561
    Keywords: Plagiometriona clavata ; Lema trilinea ; Solanum ; steroidal glycoalkaloid ; phytol ; saponin ; fatty acid ; fecal shield ; larval defense ; Chrysomelidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Larvae of the folivorous tortoise beetle, Plagiometriona clavata, carry shields formed from feces and exuviae above their bodies. We used an ecologically relevant predatory ant, Formica subsericea, in a bioassay to determine if shields functioned as simple barriers, as previous studies indicated, or whether they were chemical defenses. Shields were necessary for larval survival; shield removal rendered larvae vulnerable. Shields produced by larvae reared on a substitute diet failed to provide protection. Solvent-leached shields also failed to deter ants, indicating the shield had a host-derived chemical component likely located in the feces, not in the exuviae. Solanum dulcamara, the larval host plant, contained free phytol, steroidal glycoalkaloids, and saponins. Shields contained partially deglycosylated metabolites of host steroidal glycoalkaloids and saponins, a suite of fatty acids, and derivatives of phytol, which together formed a deterrent barrier against ant attack. We compared the mobile shield of P. clavata to the stationary shield of another S. dulcamara-feeding leaf beetle, Lema trilinea. Both larval shield defenses were formed from a very similar array of host-derived compounds with deterrent properties. We concluded that convergent patterns of limited chemical transformation and selective incorporation of particular deterrent metabolites in shield defenses of two unrelated taxa represented responses to selection from invertebrate predators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020905920952
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  • 6
    Electronic Resource
    Electronic Resource
    Larval Beetles Form a Defense from Recycled Host-Plant Chemicals Discharged as Fecal Wastes (1998)
    Springer
    Journal of chemical ecology 24 (1998), S. 765-785 
    Details
    ISSN: 1573-1561
    Keywords: Lema trilinea ; Solanum dulcamara ; Neolema sexpunctata ; steroidal glycoalkaloid ; larval defense ; fecal shield ; Chrysomelidae ; phytol ; palmitic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Larvae of the leaf-feeding beetles Neolema sexpunctata and Lema trilinea carry feces on their backs that form shields. We used the generalist predatory ant, Formica subsericea, in a bioassay to determine whether shields were a physical barrier or functioned as a chemical defense. Fecal shields protected both species against ant attack. Larvae of both species reared on lettuce produced fecal shields that failed to deter ants. Commelina communis, N. sexpunctata's host, lacks noxious secondary compounds but is rich in phytol and fatty acids, metabolites of which become incorporated into the fecal defense. In contrast, the host plant of L. trilinea, Solanum dulcamara, contains steroidal glycoalkaloids and saponins, whose partially deglycosylated metabolites, together with fatty acids, appear in Lema feces. Both beetle species make modifications to host-derived precursors before incorporating the metabolites into shields. Synthetic chemicals identified as shield metabolites were deterrent when applied to baits. This study provides experimental evidence that herbivorous beetles form a chemical defense by the elimination of both primary and secondary host-derived compounds. The use of host-derived compounds in waste-based defenses may be a more widely employed strategy than was hitherto recognized, especially in instances where host plants lack elaborate secondary compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022382931766
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