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The effect of sublethal neogregarine infections in the spruce needleminer, Epinotia tedella (Lepidoptera: Tortricidae)
Author(s) -
MÜNSTERSWENDSEN M.
Publication year - 1991
Publication title -
ecological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.865
H-Index - 81
eISSN - 1365-2311
pISSN - 0307-6946
DOI - 10.1111/j.1365-2311.1991.tb00211.x
Subject(s) - biology , tortricidae , lepidoptera genitalia , fertility , host (biology) , parasitoid , population , larva , population density , population cycle , insect , pupa , zoology , botany , ecology , demography , predation , sociology
.1 A hitherto unknown factor causing cyclic reduction in population fertility of Epirzotia tedella (Cl.) was identified as sublethal infections of the neogregarine Mattesia sp. 2 Infection probably takes place when larvae enter hibernation, but does not develop into spore production until the formation of pupae and adult moths. 3 At the individual level, the sublethal neogregarine infection causes a slight delay in adult emergence, a decreased adult lifespan, a suppression of egg development, and thus a reduction in fertility. 4 At the population level, fertility reduction has a delayed density dependent component and, through correlation, Mattesia is assumed to be causative. Since fertility reduction is a key‐factor in E.tedella, Mattesia may even be a dominant factor in the dynamics of this species. 5 Mattesia infections were found in no other dominant insect species at the locations, and consequently the interaction between E.tedella and Mattesia sp. seems to be specific. Such delayed density dependent interaction can create host oscillations, as seen in many forest insects. However, host‐parasitoid interaction alone leads to oscillations with the observed period of 6–8 years length, and the neogregarine infections apparently act in parallel with the parasitoids and enhance the amplitude of the oscillations.