InfoSAWIT, JAKARTA – Efforts to find an effective solution for controlling the rhinoceros beetle (Oryctes rhinoceros) are once again a key focus. Following an international publication last year reporting the potential of the plant Senna multijuga, or the "Golden Shower Tree," as both an attractant and bio-insecticide for the rhinoceros beetle, great hope has emerged among researchers and plantation owners.
The publication titled "First Report: Senna multijuga Subsp. multijuga (Fabales: Fabaceae) as an Attractant and Bioinsecticide for Oryctes rhinoceros," written by Ruli Wandri and his team, indeed caused a stir. The report claimed that the plant was not only capable of attracting rhinoceros beetles but could also kill them after the insects fed on parts of it.
However, a year later, further news about the plant's effectiveness seems to have stalled at the laboratory level. "Initially, that publication was like a downpour in a long drought for rhinoceros beetle control techniques. Moreover, if it really could be both an attractant and a poison, that would be a 'windfall' for palm oil planters," said Heri Sunarko, an Integrated Pest Management (IPM) expert, quoted by InfoSAWIT from his LinkedIn page on Wednesday (9/17/2025).
Between Hope and Doubt
According to Heri, in the theory of Host Plant-Insect Preference, insects do respond to volatile compounds released by plants. An insect can be attracted by a unique aroma and then be exposed to toxic compounds that are lethal. "That would be a complete and perfect combination," Heri said.
If this were true, subsequent research should only focus on two things: exploring specific attractant compounds and identifying potential toxic compounds to be developed into a bio-insecticide. "Imagine, there would be no more need to bother with burying trunks, chipping stems, or worrying about applying empty fruit bunches. Just plant Senna multijuga, and the Oryctes problem is solved," he added.
However, Heri emphasized an important point that should not be ignored. In the publication by Wandri et al., there was no detailed explanation or representative image showing that the trapped beetles were actually O. rhinoceros. "It is highly likely that the attracted beetles were not the Oryctes species, but rather Xylotrupes sp.," he stated.
Senna vs. Eucalyptus: Two Plants, Two Stories
In addition to Senna multijuga, Heri also mentioned the potential of another plant that attracts rhinoceros beetles: Eucalyptus. This plant, which is commonly found in industrial forest areas, can also lure certain types of beetles, according to his observations. The difference is that Eucalyptus is not poisonous. "Although they bore into the stem until the bark peels off, the beetles remain alive," Heri explained, showing personal documentation from his field observations.
The beetles that bore into eucalyptus are known to be Xylotrupes sp., not Oryctes. Heri said this further strengthens the suspicion that the beetles attracted to S. multijuga in the previous study were also not the main pest of palm oil plantations.
Misidentifying the insect can have serious implications. O. rhinoceros has a distinctive single horn on its head, for both males and females, though the female's is shorter. In contrast, the male Xylotrupes has two pincer-like horns, and the female has none.
"The Xylotrupes population in palm oil plantations is also not as dominant as Oryctes. So, if it turns out that only Xylotrupes are attracted to S. multijuga, then that great hope could collapse," Heri explained.
Awaiting Further Research
Nevertheless, the initial publication on Senna multijuga still creates room for optimism. The fact that the plant can attract beetles, regardless of the species, remains an important finding that can be developed. What is needed now is more rigorous follow-up research with visual and genetic verification to confirm the beetle species involved.
"If it's truly confirmed that Senna multijuga can be both a natural attractant and an insecticide for Oryctes, it will be a major breakthrough. But if not, at least we will learn that this research path needs to be more accurately targeted," Heri concluded. (T2)
