Forecasting Insect Behaviors
Managing farms is no longer just about waiting for things to happen. There needs to be more initiative to actively collate data to predict future trends about the behavior of insects. At the very least, we can reduce the brunt of getting hit with sudden unpredictable trends.
Using the RYNAN InSENTINEL Insect Monitoring System, our team at RYNAN Agriculture monitored the changes in insect behavior in the Mekong Delta region during the month of June 2025. The insect situation on rice crops in the region showed complex developments, with different areas showing variations in the insect populations for both preys and predators.
Pests
Can Tho City was shown to have an increase in several pest species, which were mainly:
Nilaparvata lugens (Brown planthopper): An average of 1,633 individuals per day.
Sogatella furcifera (White - Backed planthopper): More than 3,500 individuals per day.
Recilia dorsalis (Zigzag leafhopper): Reached a peak of more than 15,000 individuals per day.
Nephotettix sp. (Green leafhopper): An average of 190 individuals per day.
Scirpophaga incertulas (Yellow stem borer): More than 800 individuals per day.
In June, more than 40% of the rice plantation regions in Can Tho city were undergoing the tillering and panicle initiation stages. The tillering and panicle stages occur when the rice is around 16 to 65 days old on average, and are critical growth periods for rice cultivation. However, these growth stages also provide ideal conditions for pests to thrive and spread rapidly, leading to significant crop damages. As a result, out of the total rice plantation areas of 2,237 hectares (excluding embankments), 1,079 were at risk of pest attacks. This is close to 50% of all the rice plantation areas.
On the other hand, other regions saw relatively lower pest densities compared to Can Tho city.
Vinh Long Province:
Brown planthoppers and zigzag leafhoppers: Primarily had densities below 700 individuals per day.
White - Backed planthopper: An average of around 400 individuals per day.
Small leafroller moths: An average of 79 individuals per day.
An Giang Province:
Green leafhopper: An average of around 70 individuals per day.
Rice weevils: An average of 4 individuals per day.
Tay Ninh Province:
Yellow stem borer: An average of around 130 individuals per day.
Predators
The presence of beneficial natural enemies
The InSENTINEL system also recorded the presence of important natural predators of these pests, which are responsible for controlling the latter’s population.
Cyrtorhinus lividipennis (Green mirid bug): Tay Ninh province recorded an average of 2,590 individuals per day. The ratio of the Brown planthopper (pest) and the Green mirid bug (predator) was 0.44, which is considered a safe pest-predator balance for controlling brown planthopper outbreaks.
Temelucha basiornata (Parasitic wasp): Can Tho City recorded around 55 individuals per day, while Tay Ninh province recorded about10 individuals per day.
Micraspis sp. (Ladybug beetle): Can Tho City saw around 139 individuals per day, while Dong Thap province had around 22 individuals per day.
Despite the relatively high numbers of pests in Can Tho City, the presence of these natural enemies in the area shows that predation through biological control is still available, which is a good sign for crop development.
Understanding the characteristics of insects
To make accurate predictions about the insects’ behavior, it is important to have a deep understanding of the nature of the targeted insect species. A thorough understanding of the insects allows for more accurate and reliable modelling of future expected outcomes. As such, extensive research on the features, behaviors, feeding habits and more on the insects should be conducted.
Pests
The brown planthopper.
The life cycle of brown planthoppers is approximately 25–30 days, consisting of: eggs (4–5 days), nymphs (6–8 days) and adults (12–20 days). These insects feed on the sap of the rice stalks and leaves, reducing the plant's ability to photosynthesize and accumulate nutrients. As a result, the rice plants turn yellow, leading to a symptom known as Hopperburn. Additionally, brown planthoppers are vectors for viruses that cause yellow dwarf and leaf rolling diseases.
The white-backed, green and zigzag planthoppers
Both the white-backed and green leafhoppers suck sap from the plant, causing the rice to weaken, yellow, stunt in growth and even dry up. The white-backed planthopper is responsible for transmitting the black streaked dwarf disease, while the green leafhopper transmits viruses such as Tungro and yellow decline. Similarly, the zigzag leafhopper also feeds on the plant’s sap, causing the leaf tips to dry out, turning them yellow-orange, with the leaf margins curling. Excess plant damages from the zigzag leafhopper results in the transmitting of diseases such as bushy stunt and Tungro to rice.
Predators
The white-backed, green and zigzag planthoppers
An important natural enemy in rice farming is the green mirid bug. They play a crucial role in naturally controlling harmful planthopper species, especially the brown planthopper, white - backed planthopper, zigzag leafhopper and green leafhopper. These predators are effective hunters, with each adult capable of eliminating 1 to 5 nymphs or adults per day, significantly reducing pest pressure in the field.
Forecasting the insect behaviors
Using the InSENTINEL system and pre-exisiting information about the insects’ characteristics and population trends in June 2025, information about the insect developments in the Mekong Delta region were forecasted for the week of July 16 to 22.
Possible Increase in Pests population
An Giang and Can Tho City were expected to see a significant increase in pest density. Specifically, in localities such as Long Phu commune, Long My ward, Chau Thanh commune and Tri Ton commune, the brown planthopper density was likely to range from 1,200 to 1,700 individuals daily. Other types of planthoppers will also see a possible increase, such as the zigzag leafhoppers ranging from 500 to 1,000 individuals per day and green leafhopper ranging from 20 to 90 individuals per day.
Possible Decrease in Pests population
On the other hand, Dong Thap, Vinh Long, Ca Mau and Tay Ninh were expected to experience moderate to low pest densities. Dong Thap province was likely to have a low brown planthopper density, under 450 individuals per day, while Vinh Long province was expected to have the lowest densities of white-backed planthoppers, zigzag leafhoppers and green leafhopper.
Overall, the pest situations in An Giang province and Can Tho City were forecasted to be more severe than the provinces. Knowing this information enables farmers to have an idea of the estimated trends in the insects’ behavioral patterns ahead of time. They would be able to make predictions about the estimated trends in the insects’ behavioral patterns, detect potential risks early and implement timely, effective and cost-efficient control measures. The RYNAN Agriculture team subsequently monitored the actual insects’ populations for the period of July 16 to 22, and the predicted insects’ populations was shown to be highly accurate.
Forecasting is now necessary for quality crop management
An InSENTINEL system in a fruit orchard in Tay Ninh province
The InSENTINEL system not only effectively works for rice plantations, but as well as fruit orchards. Currently, RYNAN’s InSENTINEL system has successfully been used for mango, grapefruit, orange, durian and seedless lime orchards.
In the mango orchard in Cu Lao Gieng commune, An Giang province, the system was able to record a density of Bactrocera dorsalis (Oriental fruit fly) of up to 1,011 individuals per day. In the durian orchard in Binh Thanh commune, Tay Ninh province, the density of Amrasca biguttula (Cotton leafhoppers) reached 72 individuals per day. Meanwhile, several natural enemies such as parasitic wasps, green mirid bugs and ladybug beetle appeared in the fruit orchards with relatively low densities, ranging from 1 to 10 individuals per day.
With the rapidly changing environmental landscape, insects’ populations and behaviors are very prone to variations, which makes crops susceptible to unpredictable damages by insects. This makes knowing and planning a crucial skill that modern farmers need to invest in and possess. RYNAN Smart Agriculture recognizes this importance, which is why the InSENTINEL system was innovated to support both old and new farmers in better managing their agricultural farms.