Development and oviposition strategies in two congeneric gregarious larval-pupal endoparasitoids of the seven-spot ladybird, Coccinella septempunctata

Minghui Fei, Haowu Hu, Rieta Gols, Shengnan Liu, Xiaolin Wan, Baoping Li*, Jeffrey A. Harvey

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Aphids are serious pests of many crops in agroecosystems and their biological control is focused on enhancing the performance of specialized natural enemies of aphids such as parasitoid wasps and predators like ladybirds. However, ladybirds are often attacked by their own parasitoids in the fourth trophic level that can negatively affect ladybird performance and, hence, their effectiveness as control agents. The biology and ecology of these parasitoids has been less well explored. This study compared various life-history traits in two closely related parasitoids of the seven-spot ladybird, Coccinella septempunctata (Coleoptera: Coccinellidae): Oomyzus scaposus and O. spiraculus (Hymenoptera: Eulophidae), which naturally co-occur in eastern China and are facultatively gregarious koinobiont larval-pupal endoparasitoids of ladybird beetles. They can oviposit and develop in all four larval instars of their hosts but kill and emerge from the pupae. Both parasitoids did not have a clear oviposition preference for any host instar, but oviposition duration tended to increase in first to third instar hosts. Moreover, oviposition time was significantly longer for O. spiraculus than for O. scaposus. Adult eclosion from parasitized hosts (ranging between 35 and 45%) and sex ratios (85–90% female) were similar in both species and did not differ among host instars. Brood sizes were similar in both species but tended to increase in first to third instar hosts. Egg-to-adult development time was shorter and the eclosing adults of O. scaposus were heavier than those of O. spiraculus. In both species, development time decreased with host instar at parasitism, but instar-specific effects on biomass differed between the two species: heavier O. scaposus adults developed from second and third instar hosts, whereas biomass of for O. spiraculus tended to decrease with instar at parasitism. In both species, females were significantly larger than males. Our results show that expression of some of the life-history traits vary depending on which instar is parasitized, but do not point at a specific instar optimal for each of the parasitoids. Moreover, despite being closely related, there is some variability in the expression of life-history traits in both parasitoids.

Original languageEnglish
Article number104756
Pages (from-to)1-6
Number of pages6
JournalBiological Control
Volume163
Early online date18 Aug 2021
DOIs
Publication statusPublished - Nov 2021

Bibliographical note

Funding Information:
The authors thank Haitian Song for valuable suggestions for the experiments. Funding for this study was provided by National Natural Science Foundation of China (NSFC; 31800355 ), the Natural Science Foundation of Jiangsu Province of China ( BK20180547 ), and Undergraduate Innovation and Entrepreneurship Training Program of Jiangsu Province of China ( 201910307099Y ).

Publisher Copyright:
© 2021 Elsevier Inc.

Keywords

  • Biological control
  • Fourth trophic level
  • Host quality
  • Host size
  • Oomyzus scaposus
  • Oomyzus spiraculus

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