Modeling Climatic Influences on Three Parasitoids of Low-Density Spruce Budworm Populations. Part 3: Actia interrupta (Diptera: Tachinidae)

Abstract

This article is the third and last of a series of models developed to investigate the impact of climate on the spatiotemporal biology of parasitoids. After two earlier papers investigating Tranosema rostrale and Meteorus trachynotus, this last article concerns the tachinid fly Actia interrupta (Diptera: Tachinidae). An individual-based model of the seasonal biology of A. interrupta was developed to determine the impact of climate on its interactions with two of its hosts, the spruce budworm Choristoneura fumiferana (Lepidoptera: Tortricidae) and the obliquebanded leafroller C. rosaceana in eastern North America. The model is based on the developmental responses of ‘the parasitoid’s successive life stages and the ovipositional response of adult females to temperature. It was found that the number of generations this parasitoid undergoes each year varies geographically from two to four, and that its potential growth rate, as dictated by synchrony with larvae of its overwintering host C. rosaceana, is highly patterned geographically and topographically as a result of phenological matching with larvae of obliquebanded leafroller entering diapause in late summer.

Density‐dependence and competition between Tranosema rostrale and Elachertus cacoeciae, two parasitoids of the spruce budworm

“…Early in this study (1987–1994), most parasitism on sentinel spruce budworm larvae was caused by species other than T. rostrale or E. cacoeciae (grey area in Figure 2A, B), in particular Meteorus trachynotus Viereck (Hymenoptera: Braconidae) and Actia interrupta Curran (Diptera: Tachinidae) (Régnière et al., 2021a,b). In the 27 subsequent years, T. rostrale and E. cacoeciae were the overwhelming causes of sentinel mortality, with combined parasitism rates ranging from 50 to 95%.…”

Changes in Population Densities and Species Richness of Pollinators in the Carpathian Basin during the Last 50 Years (Hymenoptera, Diptera, Lepidoptera)

“…The most important effect is the optimization of the synchronicity between the presence of the host and the parasitoid's egg-laying time: an optimally developed host animal larva should be available at the time of reproduction. Climatic conditions can improve this, but they can also shift it in an unfavorable direction [116], which could also be the reason for the fluctuation shown in Tables 12 and 13. For Bombyliidae, Boesi et al [117] provide a good explanation for their increased reproduction: bee flies (Diptera: Bombyliidae) have a virtually cosmopolitan distribution and are commonly found in warm arid to semiarid habitats, where they can form a conspicuous part of the flower-visiting insect fauna [118].…”