Dr Syed Zulfiqar Mehdi Rizvi1, Dr Bishwo Mainali1

1Macquarie University, Macquarie Park, Australia

Biography:

Dr Syed Rizvi is an applied entomologist and has a keen interest in the behavioural ecology of herbivorous insects and its utilisation in developing sustainable IPM techniques. Syed’s past projects focused on understanding the influence of landscape structure and complexity on different trophic levels in agricultural landscapes, containing both natural and managed ecosystems.

Abstract:

Leptocoris tagalicus, a hemipteran pest that feeds on several Australian native plants in the family Sapindaceae is increasingly impacting macadamia crops in Australia. Limited knowledge about their biology, ecology, and natural enemies calls for a comprehensive study to explore potential management strategies against the pest. This study was conducted to assess life-history traits from hatching of the eggs to developmental time and survival rates of all the life stages of L. tagalicus, to longevity of adults and their fecundity across six different temperatures ranging from 10°C to 35°C. L. tagalicus eggs did not hatch at 10°C and 15°C. The neonate mortality was significantly higher at 35°C, where the rate exceeded 80%. The lowest mortality rate occurred at 20°C, 25°C and 30°C. The study finds significant temperature-induced variations in critical developmental stages such as egg hatching and molting duration. These stages were significantly delayed at 20°C, but the duration decreased as the temperature increased. This trend was also consistent in the overall developmental duration, indicating the possibility of multiple generations at higher temperature regions. In terms of reproductive potential, both the daily and total number of eggs laid showed temperature-dependent changes, decreasing with an increase in temperature. The viability of laid eggs was significantly higher at 25°C compared to that at 20°C and 30°C, whereas the complete absence of emergence from eggs laid at 35°C indicates an upper thermal limit for the species' developmental viability. These findings offer a comprehensive view of the ecological adaptability and resilience of L. tagalicus, particularly in the context of its evolving role as a pest in macadamia cultivation. Understanding these dynamics is pivotal for developing effective integrated pest management strategies, especially in the face of limited insecticide options and the species' resistance to conventional treatments.