A temperature‐dependent phenology model for Apanteles subandinus Blanchard, parasitoid of Phthorimaea operculella Zeller and Symmetrischema tangolias (Gyen)

Abstract

The potato tuber moth (Phthorimaea operculella Zeller) is a major invasive pest of potato (Solanum tuberosum L.) worldwide. Classical biological control using parasitoids had been of primary interest during the last decades to control this pest. More than twenty parasitoid species have been reported parasitizing P. operculella. Apanteles subandinus Blanchard had been successfully used in different countries. Determination of the parasitoid's temperature-dependent development is crucial for better predicting the potential of the parasitoid to establish in a new region and to control the target pest. Therefore, the effect of temperature on the development and reproduction of A. subandinus was studied at five constant temperatures ranging from 11-30°C in its main host P. operculella. The Insect Life Cycle Modeling (ILCYM) software was used to fit nonlinear equations to collected life table data and to establish an overall phenology model to simulate life table parameters based on temperature. The parasitoid completed its life cycle at constant temperatures from 15 to 30°C. Temperature of 11°C was lethal to pupae, and at 35°C no larvae development was possible. The theoretical lower threshold temperatures for the development of egg-larvae and pupae were 10.3°C and 11.8°C respectively. The model predicted limits for survival at around 12°C and 33°C. The lowest senescence rate was observed within the temperature range of 15-25°C. Oviposition time decreased significantly with increasing temperature from 12.2 days (15°C) to 1.8 days (30°C). The highest fertility was predicted at 27°C. Maximum population growth is expected around 26.78°C with a finite rate of increase, λ of 1.0445, which corresponds to a population doubling time of 15.9 days. The highest values for gross reproduction rate (GRR) and net reproduction rate (R0) were found between 24 and 25°C, and the shortest mean generation time (T) was observed at 30°C (23.48 d). The use of the phenology model in the context of classical biological control of P. operculella is discussed.

Host–Parasitoid Phenology, Distribution, and Biological Control under Climate Change

“…Nevertheless, in the case of parasitoids, if the ambient temperature is below the optimal temperature, increasing the temperature to close to the optimal temperature will accelerate their development [64][65][66]; however, for some species living in the tropics, the ambient temperature is near their optimal temperature (they are already living close to their thermal limits), and extreme heat waves will cause high preadult stage mortality and decrease parasitoids' demography [44]. Furthermore, slightly warmer conditions may result in earlier adult emergence [67], benefiting some arthropod populations by increasing the number of generations per season [66], thus disrupting the relative timing of interacting species: e.g., a change in phenological synchrony between host-parasitoid interactions [5,38,[68][69][70][71], affecting mismatched species' fitness and abundance [6], disturbing ecosystem functioning [37,69,72], and ultimately leading to pest outbreaks [15,73].…”

“…The adult female parasitoid deposits one egg (or more than one) inside (endoparasitoid) or attached to the host surface (ectoparasitoid); the eggs hatch into larvae, which develop by feeding on their hosts' bodies and eventually die (Figure 1a) [42]. The atmospheric temperature is intimately linked to the development and survival of parasitoid preadult/immature stages because their phenology, morphology, physiology, demography, and behavior have evolved and adapted in accordance with a specific range of thermal limits, enabling them to adapt to their surrounding environments [44]. However, it is likely that the newly predicted extreme climatic conditions will vary over time and space, thus challenging terrestrial arthropods' life-history parameters/traits, due to the temperature-dependent nature of ectotherm activity and metabolism [45].…”