Impacts of Climate Change on the Number of Days per Generation of the Egg-Parasitoid Telenomus Remus Nixon, 1937 (Hymenoptera: Scelionidae) in Egypt

Abstract

In this research, we forecasted both the degree-day units and annual generations of the egg parasitoid Telenomus remus Nixon, which parasitizes fall armyworm (Spodoptera frugiperda). The aim was to comprehend its potential spread across diverse agro-climatic zones, considering both current conditions and potential future climates. This was achieved by examining the correlation between degree-day units and population fluctuations. Climate change data from the HadCM3 model was utilized, focusing on A1 scenarios recommended by the Intergovernmental Panel on Climate Change (IPCC). We aimed to evaluate how temperature projections are anticipated to impact the annual generations in three Egyptian governorates. The investigation revealed that T. remus populations in Aswan, an Upper Egyptian governorate, exhibited a higher number of generations compared to other regions, namely El Sharkia and Beni Suef governorates, in the current climate. The completion of generations by T. remus in El Sharkia, Beni Suef, and Aswan took 13.42, 12.6, and 10.08 days, respectively. The results highlighted that the average generation period in 2021 was the longest, reaching 13.42 ± 6.17 days in El Sharkia governorate. Predictions suggest that T. remus is anticipated to undergo 23 generations between 2040 and 2060, indicating a two-generation increase from 2021. Conversely, in the Beni Suef governorate, where T. remus completed generations in 10.86 ± 5.72 days, the generation period was the longest in 2021. Projections indicate that T. remus is expected to have 24 generations in 2040 and 28 generations in 2060, compared to 22 generations in 2021. Additionally, Aswan’s T. remus is forecasted to experience 32 generations in 2040 and 35 generations in 2060, up from 29 generations in the 2021 climate. The duration of the first generation took 13, 11, and 12 days in the years 2021, 2040, and 2060, respectively. A comprehensive understanding of thermal requirements and biological factors is crucial for accurately predicting generation duration, serving as a valuable reference for the mass production and preservation of parasitoids.