| Abstract: |
Simple Summary: Bathycoelia distincta poses a significant threat to the South African macadamia industry. Despite the acknowledged influence of temperature on insects, a comprehensive developmental biology investigation for B. distincta has not been undertaken to date. This study systematically presents empirical data on the effects of temperature on the developmental duration, survival, and developmental thresholds of B. distincta's life stages under constant temperatures. The findings of this study reveal that the thermal developmental range of this pest ranges from 13.5 to 38.0 °C, with an optimum temperature of 29.5 °C. Moreover, B. distincta requires 783 degree days to develop from an egg to the adult stage. Considering the prevailing global warming trends, the South African Macadamia industry may experience more damage due to a faster development at warmer temperatures. Temperature is the most influential condition affecting insect development and population dynamics. Understanding its impact and other important factors, such as diet, could provide fine-scale predictions of species abundance and distribution in space and time. The two-spotted stink bug, Bathycoelia distincta Distant (Hemiptera: Pentatomidae), is a significant pest of macadamia in South Africa for which limited information on developmental biology exists. Here, for the first time, variations in key developmental parameters of the B. distincta biology were studied systematically. The developmental duration, survival rate, development rate, lower developmental threshold (Tmin), optimum developmental threshold (Topt), upper developmental threshold (Tmax), and thermal constant were quantified for each developmental stage of B. distincta. In addition, the effect of diet (macadamia nut and sweetcorn) on the developmental duration and survival rate were quantified. This study was conducted at five constant temperatures (18, 21, 22, 25, and 29 °C) with relative humidity (RH) variations. The developmental duration from egg to adult decreased significantly with increased temperature: 21 °C (±60 days) to 29 °C (±32 days). The survival rate was significantly different for instar 2 between temperatures. Nymphs (instars 2 and 4) developed faster on the sweetcorn diet than on a macadamia diet, but the total developmental time did not differ significantly between the diets. Development from egg to adult required 783 degree days (DD), with a Tmin of 13.5 °C, Topt of 29.5 °C, and Tmax of 38 °C. Ongoing global warming will increase the population growth of B. distincta through increased development rate, resulting in more damage to macadamia nuts. Understanding the developmental biology and thresholds for the DD model of B. distincta is fundamental for predicting its phenology and outbreaks in macadamia orchards. [ABSTRACT FROM AUTHOR] |
