National University of Singapore
At the end of 2019, I sampled in Sandakan in Sabah (Borneo). Together with previous sound data collected from Brunei and Singapore, I could use the call structures, stridulum morphology along with traditional morphology to investigate cryptic species in the big-eyed katydids Lipotactes. The use of ultrasonic call structures and stridulum morphology was done for the first time, and using integrative taxonomy, I could resolve the taxonomy of Bornean species, and described a new species, Lipotactes kabili from Sandakan (Fig. 1). This was eventually published in Systematics and Biodiversity.
During the COVID-19 pandemic, a lockdown was imposed in Singapore. I used the opportunity to record the calls of crickets in urban areas where I was restricted to. In total, calling songs of 10 species with distinct call signatures in both the time and frequency domains were recorded and was dominated by Polionemobius taprobanensis and Gryllodes sigillatus (Fig. 2). These data allowed me to understand the acoustic community of urban orthopterans for the first time. This study has been published in Bioacoustics.
Prior to and after the lockdown, I also recorded the calls of different populations of Lebinthus luae in Singapore to examine microevolution and phenotypic plasticity in their call properties. After the lockdown, I also continued sampling for calls of ultrasonic-singing katydids in Singapore. With the manuscript under review and preparation, respectively, I will provide more details once they are published. Looking forward, I hope to survey around Southeast Asia once the travel restrictions are lifted.
The COVID-19 pandemic has disrupted the lives of everyone all around the world. Many countries went into national lockdowns when the number of cases and deaths soared during the spring of 2020. “When life throws you lemon, you made lemonade”, I decided to make the best out of the unprecedented global crisis, by studying how the lockdowns for human can in turn influence the acoustic behaviours of crickets.
Specifically, I collected the male adult of the Lebinthus luae crickets from three isolated populations around Singapore: Hindhede Nature Park, Labrador Nature Reserve and Pulau Ubin (Fig. 1). I used the EchoMeter Touch Pro 2 to record the calls of these crickets to compare the call parameters between the three populations. The experiment was halted when Singapore when into a 7.5-weeks national lockdown (i.e., Circuit Breaker). The experiment was repeated once the lockdown was lifted and field work can resume.
It was observed that L. luae exhibit significant population differences in the call and trill durations (Fig. 2). More interestingly, it was found that different population also exhibit different response in the trill duration before and after the Circuit Breaker period. Specifically, the crickets from Hindhede produce significantly shorter trills after the Circuit Breaker, not observed in other populations (Fig. 2). Being surrounded by dense housing estates in the heart of Singapore and traditionally a popular nature park for hikers, crickets found in Hindhede produce shorter trills than other populations as a response to these elevated human pressures. During the Circuit Breaker, residents nearby can still visit parks and in fact more frequently due to teleworking and school closures. The further elevation in human pressures may have led to the crickets producing even shorter trills after the Circuit Breaker.
This study is published in the Ecology journal (https://doi.org/10.1002/ecy.33...) and represents the first published report on the effect of the COVID-19 pandemic on natural populations of invertebrates. It demonstrates that even a short Circuit Breaker has had an impact on the behaviours of the small and overlooked crickets, which in turns can drive the microevolution of different populations.
I spent the last five months in the Paris Museum as part of my postdoctoral research, and did not have the chance to do fieldwork in Southeast Asia to collect new sound data of katydids. Nonetheless, I am currently collaborating with Prof. Fernando Montealegre-Z of the University of Lincoln on the bioacoustics and the wing morphology responsible for ultrasonic sound production. This is based on the 24 species of katydids from Southeast Asia that I recorded in 2020 and early 2021 (Table 1). We made three-dimensional images of the stridulatory files and mirror area using the Infinite Focus camera (Fig. 1). The sound files recorded using the Wildlife Acoustics EchoMeter Touch Pro were also analysed (Fig. 1). We are moving into the stage of writing up the manuscript to describe the calls and the wing morphology and aim to submit the manuscript before the end of 2021. I will return to Southeast Asia by August 2021, during which I would aim to collect sound data for more species of katydids from this region.