Varying degree of physiological integration among host instars and their endoparasitoid affects stress-induced mortality

Rieta Gols, Vera I.D. Ros, Paul J. Ode, Dhaval Vyas, Jeffrey A. Harvey

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)

Abstract

In natural populations of insect herbivores, genetic differentiation is likely to occur due to variation in host plant utilization and selection by the local community of organisms with which they interact. In parasitoids, engaging in intimate associations with their host during immature development, local variation may exist in host quality for parasitoid development. We compared the development of a gregarious endoparasitoid, Cotesia glomerata L. (Hymenoptera: Braconidae), collected in The Netherlands, in three strains and three caterpillar instars (L1–L3) of its main host, Pieris brassicae L. (Lepidoptera: Pieridae). Hosts had been collected in The Netherlands and France, and were reared in the laboratory for one generation. We also used an established Dutch laboratory strain that had not been exposed to parasitoids for at least 24 generations. Parasitoid survival to adulthood was inversely correlated with host instar at parasitism. Adult parasitoid body mass was largest when hosts were parasitized as L1 and smallest when hosts were parasitized as L3, whereas egg-to-adult development time was quickest on L3 hosts and slowest on L1 hosts. Higher survival and faster development of C. glomerata on French L2 hosts also showed that there is variation in host-instar-related suitability. Many L2 and most L3 caterpillars that were parasitized exhibited signs of pathogen infection and perished within a few days of parasitism, whereas this never happened when hosts were parasitized as L1 or in non-parasitized control caterpillars. Our results reveal that, irrespective of the host strain, L1 hosts are optimally synchronized with C. glomerata development. By contrast, the high precocious mortality of L3 larvae may be due to stress-induced regulation by the parasitoid in order to ‘force’ its developmental program into synchrony with the developing parasitoid larvae. Our results underscore a potentially important role played by pathogens in mediating herbivore–parasitoid interactions that are host-instar-dependent in their expression.

LanguageEnglish
Pages424-432
JournalEntomologia Experimentalis et Applicata
Volume167
Issue number5
Early online date28 Feb 2019
DOIs
Publication statusPublished - May 2019

Fingerprint

instars
mortality
parasitoid
Cotesia glomerata
caterpillar
insect larvae
parasitism
parasitoids
herbivore
Netherlands
herbivores
pathogen
host quality
larva
host strains
Pieris brassicae
Pieridae
adult development
pathogens
larvae

Keywords

  • Braconidae
  • Cotesia glomerata
  • host regulation
  • Hymenoptera
  • insect herbivores
  • Lepidoptera
  • multitrophic interactions
  • parasitoids
  • pathogens
  • Pieridae
  • Pieris brassicae

Cite this

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title = "Varying degree of physiological integration among host instars and their endoparasitoid affects stress-induced mortality",
abstract = "In natural populations of insect herbivores, genetic differentiation is likely to occur due to variation in host plant utilization and selection by the local community of organisms with which they interact. In parasitoids, engaging in intimate associations with their host during immature development, local variation may exist in host quality for parasitoid development. We compared the development of a gregarious endoparasitoid, Cotesia glomerata L. (Hymenoptera: Braconidae), collected in The Netherlands, in three strains and three caterpillar instars (L1–L3) of its main host, Pieris brassicae L. (Lepidoptera: Pieridae). Hosts had been collected in The Netherlands and France, and were reared in the laboratory for one generation. We also used an established Dutch laboratory strain that had not been exposed to parasitoids for at least 24 generations. Parasitoid survival to adulthood was inversely correlated with host instar at parasitism. Adult parasitoid body mass was largest when hosts were parasitized as L1 and smallest when hosts were parasitized as L3, whereas egg-to-adult development time was quickest on L3 hosts and slowest on L1 hosts. Higher survival and faster development of C. glomerata on French L2 hosts also showed that there is variation in host-instar-related suitability. Many L2 and most L3 caterpillars that were parasitized exhibited signs of pathogen infection and perished within a few days of parasitism, whereas this never happened when hosts were parasitized as L1 or in non-parasitized control caterpillars. Our results reveal that, irrespective of the host strain, L1 hosts are optimally synchronized with C. glomerata development. By contrast, the high precocious mortality of L3 larvae may be due to stress-induced regulation by the parasitoid in order to ‘force’ its developmental program into synchrony with the developing parasitoid larvae. Our results underscore a potentially important role played by pathogens in mediating herbivore–parasitoid interactions that are host-instar-dependent in their expression.",
keywords = "Braconidae, Cotesia glomerata, host regulation, Hymenoptera, insect herbivores, Lepidoptera, multitrophic interactions, parasitoids, pathogens, Pieridae, Pieris brassicae",
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Varying degree of physiological integration among host instars and their endoparasitoid affects stress-induced mortality. / Gols, Rieta; Ros, Vera I.D.; Ode, Paul J.; Vyas, Dhaval; Harvey, Jeffrey A.

In: Entomologia Experimentalis et Applicata, Vol. 167, No. 5, 05.2019, p. 424-432.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Varying degree of physiological integration among host instars and their endoparasitoid affects stress-induced mortality

AU - Gols, Rieta

AU - Ros, Vera I.D.

AU - Ode, Paul J.

AU - Vyas, Dhaval

AU - Harvey, Jeffrey A.

PY - 2019/5

Y1 - 2019/5

N2 - In natural populations of insect herbivores, genetic differentiation is likely to occur due to variation in host plant utilization and selection by the local community of organisms with which they interact. In parasitoids, engaging in intimate associations with their host during immature development, local variation may exist in host quality for parasitoid development. We compared the development of a gregarious endoparasitoid, Cotesia glomerata L. (Hymenoptera: Braconidae), collected in The Netherlands, in three strains and three caterpillar instars (L1–L3) of its main host, Pieris brassicae L. (Lepidoptera: Pieridae). Hosts had been collected in The Netherlands and France, and were reared in the laboratory for one generation. We also used an established Dutch laboratory strain that had not been exposed to parasitoids for at least 24 generations. Parasitoid survival to adulthood was inversely correlated with host instar at parasitism. Adult parasitoid body mass was largest when hosts were parasitized as L1 and smallest when hosts were parasitized as L3, whereas egg-to-adult development time was quickest on L3 hosts and slowest on L1 hosts. Higher survival and faster development of C. glomerata on French L2 hosts also showed that there is variation in host-instar-related suitability. Many L2 and most L3 caterpillars that were parasitized exhibited signs of pathogen infection and perished within a few days of parasitism, whereas this never happened when hosts were parasitized as L1 or in non-parasitized control caterpillars. Our results reveal that, irrespective of the host strain, L1 hosts are optimally synchronized with C. glomerata development. By contrast, the high precocious mortality of L3 larvae may be due to stress-induced regulation by the parasitoid in order to ‘force’ its developmental program into synchrony with the developing parasitoid larvae. Our results underscore a potentially important role played by pathogens in mediating herbivore–parasitoid interactions that are host-instar-dependent in their expression.

AB - In natural populations of insect herbivores, genetic differentiation is likely to occur due to variation in host plant utilization and selection by the local community of organisms with which they interact. In parasitoids, engaging in intimate associations with their host during immature development, local variation may exist in host quality for parasitoid development. We compared the development of a gregarious endoparasitoid, Cotesia glomerata L. (Hymenoptera: Braconidae), collected in The Netherlands, in three strains and three caterpillar instars (L1–L3) of its main host, Pieris brassicae L. (Lepidoptera: Pieridae). Hosts had been collected in The Netherlands and France, and were reared in the laboratory for one generation. We also used an established Dutch laboratory strain that had not been exposed to parasitoids for at least 24 generations. Parasitoid survival to adulthood was inversely correlated with host instar at parasitism. Adult parasitoid body mass was largest when hosts were parasitized as L1 and smallest when hosts were parasitized as L3, whereas egg-to-adult development time was quickest on L3 hosts and slowest on L1 hosts. Higher survival and faster development of C. glomerata on French L2 hosts also showed that there is variation in host-instar-related suitability. Many L2 and most L3 caterpillars that were parasitized exhibited signs of pathogen infection and perished within a few days of parasitism, whereas this never happened when hosts were parasitized as L1 or in non-parasitized control caterpillars. Our results reveal that, irrespective of the host strain, L1 hosts are optimally synchronized with C. glomerata development. By contrast, the high precocious mortality of L3 larvae may be due to stress-induced regulation by the parasitoid in order to ‘force’ its developmental program into synchrony with the developing parasitoid larvae. Our results underscore a potentially important role played by pathogens in mediating herbivore–parasitoid interactions that are host-instar-dependent in their expression.

KW - Braconidae

KW - Cotesia glomerata

KW - host regulation

KW - Hymenoptera

KW - insect herbivores

KW - Lepidoptera

KW - multitrophic interactions

KW - parasitoids

KW - pathogens

KW - Pieridae

KW - Pieris brassicae

U2 - 10.1111/eea.12765

DO - 10.1111/eea.12765

M3 - Article

VL - 167

SP - 424

EP - 432

JO - Entomologia Experimentalis et Applicata

T2 - Entomologia Experimentalis et Applicata

JF - Entomologia Experimentalis et Applicata

SN - 0013-8703

IS - 5

ER -