Planthopper: A Hidden Threat to Rice Plants

Rice is a staple food for a significant portion of the world’s population. However, there is an often overlooked threat to rice production: planthoppers. These small insects can cause significant damage to rice crops, leading to crop loss and reduced yields.

The Culprits: Brown Planthopper and Whitebacked Planthopper

Two species of planthopper are particularly problematic for rice farmers. The brown planthopper (BPH), scientifically known as Nilaparvata lugens (Stal), and the whitebacked planthopper (WBPH), known as Sogatella furcifera (Horvath), are the primary culprits behind the devastation of rice crops.

Planthopper

Unveiling the Damage

A high population of planthoppers can wreak havoc on rice plants. The leaves start by turning orange-yellow before eventually becoming brown and dry. This condition is known as hopperburn, and it can quickly kill the plant. In addition to causing hopperburn, BPH can also transmit Rice Ragged Stunt and Rice Grassy Stunt diseases, both incurable conditions.

The Perfect Habitat

Planthoppers thrive in both rainfed and irrigated wetland environments. They also tend to occur in areas with continuous submerged conditions, high shade, and humidity. Factors such as a closed canopy of rice plants, densely seeded crops, excessive use of nitrogen, and early-season insecticide spraying further favor their development.

Brown Planthopper

Identifying the Invaders

To combat planthoppers effectively, it’s crucial to identify their presence accurately. Look for the following signs:

  • Crescent-shaped white eggs inserted into the midrib or leaf sheath.
  • White to brown nymphs.
  • Brown or white adults feeding near the base of tillers.
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Additionally, check your field for signs such as hopperburn or yellowing, browning, and drying of plants. Ovipositional marks exposing the plant to fungal and bacterial infections, the presence of honeydew and sooty molds in the bases of infected areas, and plants with ragged stunt or grassy stunt virus diseases can also indicate planthopper infestation. It’s worth noting that hopperburn can be mistaken for feeding damage caused by the rice black bug. To confirm hopperburn due to planthoppers, check for the presence of sooty molds at the base of the plant.

The Impact of Planthopper Infestation

Hopperburn caused by planthoppers

The feeding damage inflicted by planthoppers leads to the yellowing of rice plants. When their population density is high, complete drying of the plants can occur—a stage known as hopperburn. At this level, crop loss can be as high as 100%. In the past, BPH was considered a significant threat to rice production in Asia. Both BPH and WBPH can also transmit Rice Ragged Stunt and Rice Grassy Stunt viruses.

At a population density of 400−500 BPH nymphs or 200 adults per plant, WBPH can cause the complete loss of rice plants. Past outbreaks of WBPH have been reported in Pakistan, Malaysia, and India. The impact of planthopper infestation cannot be underestimated, making it crucial to manage this threat effectively.

Managing Planthoppers: Strategies for Success

To prevent planthopper outbreaks, it’s important to tackle the underlying causes. Here are some strategies to consider:

  • Weed Control: Remove weeds not just from the field but also from the surrounding areas.
  • Minimize Insecticide Use: Avoid indiscriminate use of insecticides, as this can destroy natural enemies that keep planthopper populations in check.
  • Resistant Varieties: Utilize rice varieties that are resistant to planthopper infestation. Consult your local agriculture office for an up-to-date list of recommended options.
  • Monitoring: Regularly check for planthoppers in the seedbed or field, depending on the plant’s growth stage. Look for signs of infestation such as egg clusters, nymphs, and adults. If a light trap is used, pay close attention to any sudden increase in planthopper activity, which may indicate a need for immediate action.
  • Mechanical and Physical Measures: Flooding the seedbed for a day can help control planthoppers. Additionally, sweeping small seedbeds with a net can remove some planthoppers, although this method is less effective against high-density infestations.
  • Biological Control: Encouraging natural enemies of planthoppers, such as water striders, mirid bugs, spiders, and egg parasitoids, can help keep their populations in check.
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It’s essential to resort to chemical control methods only if all conditions are met, such as a planthopper population density exceeding that of natural enemies and flooding the seedbed not being a viable option.

By implementing these management strategies, rice farmers can protect their crops and ensure a more secure and bountiful harvest.

Remember, awareness is the first step in combating the hidden threat posed by planthoppers. Stay vigilant, monitor your fields, and take proactive measures to protect your rice plants from these destructive insects.


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