Effect of Pyripridone Suspension in Controlling Whitebacked Planthopper in Field
Cheng Jinsheng, Jiangxi Province Xinjian County Plant Protection & Phytosanitary Inspection Station, Wu Wei, Jiangsu Kesheng Group Co., Ltd.
Abstract: A field trial was conducted using 25% pyripridone suspension to control the whitebacked planthopper (Sogatella furcifera) in paddy fields. The treatment was applied during the peak period of young nymphs. The results showed that after 2 days, the control efficacy reached 78.29%, and by day 5, it increased to 92.55%. After 10 days, the control effect remained at 97.96%. The product was found to be safe for natural enemies, making it a suitable choice for integrated pest management.
Key words: pyripridone, suspension, whitebacked planthopper, control efficacy
Pyripridone suspension is a new insecticide developed by Jiangsu Kesheng Group Co., Ltd. to manage rice planthoppers. To evaluate its effectiveness against the whitebacked planthopper, a field experiment was conducted in June 2008. Below are the findings from this study.
First, Materials and Methods
1. Test Subject: Sogatella furcifera.
2. Test Agent: 25% pyripridone suspension provided by Jiangsu Kesheng Group Co., Ltd.
3. Dose of Agent: Three treatments were tested: 16g/acre, 20g/acre, and 24g/acre.
4. Experimental Design: There were 12 plots, each measuring 16.6m², with three replications. The plots were randomly arranged and separated by small ditches.
5. Test Site Overview: The test was conducted in Yujia Village, Shijie Town, Xinjian County. The area is a double-season paddy field with good fertility and adequate irrigation. At the time of application, the rice was in the booting stage, with a water layer of 3–4 cm. Some alfalfa grass was present, and the soil was muddy with a pH of 6.5. The whitebacked planthopper population was moderate, mainly consisting of young nymphs.
Meteorological Data: The pesticide was applied on June 19. The weather was cloudy, with wind speed of level 2. The following day was sunny and cloudy.
6. Application Method: The treatment was applied once on June 19, using a "Farm/Farmers 16" manual sprayer. Each treatment used 1.25 kg of water per plot (equivalent to 50 kg per acre), and the spray was fine.
7. Previous Pest Control: Before the experiment, 75% mancozeb (40g/30kg water) and 20% triazophos (100g/30kg water) were used as preventive treatments. These were applied on May 2 to control the rice stem borer and blast. On May 20, 5% Ruijin Special (50g/30kg water) was sprayed to manage the first generation of rice leaf folders.
Survey Records and Methods
1. Investigation Time: Insect populations were recorded before treatment (June 18), 2 days post-treatment (June 21), 5 days (June 24), 7 days (June 26), and 10 days (June 29). The number of live insects in each plot was recorded.
2. Survey Method: A parallel jump method was used, with 10 sampling points and 2 clusters per point. A white porcelain plate was placed at the base of the rice plant, and the base of the rice bundle was manually crushed three times from the other side. The number of planthoppers in the dish was counted.
3. Efficacy Calculation:
Insect Reduction Rate (%) = (Pre-treatment Insects - Post-treatment Insects) / Pre-treatment Insects × 100
Corrected Control Effect (%) = (Pre-treatment Insect Population - Post-treatment Insect Population) / Pre-treatment Insect Population × 100
4. Visual Inspection of Crops and Non-target Organisms
Second, Results and Analysis
1. According to Table 1, the control effect of 25% pyripridone suspension at 24g/acre was 78.29% after 2 days, 92.55% after 5 days, and 97.96% after 10 days. As the dosage increased from 16g/acre to 24g/acre, the control effect improved significantly.
Table 1 Field Efficacy Test Results of 25% Pyripridone Suspension Against Whitebacked Planthopper
Treatment
Before Treatment
Number (head/20 bundles)
2 Days After
5 Days After
7 Days After
10 Days After
Live Insects
Decrease Rate (%)
Correction Control Effect (%)
Live Insects
Decrease Rate (%)
Correction Control Effect (%)
Live Insects
Decrease Rate (%)
Correction Control Effect (%)
Live Insects
Decrease Rate (%)
Correction Control Effect (%)
25% Pyripridone 16g/Mu
57.67
37
35.84
57.72
24.33
57.81
85.30
15
73.99
93.64
12
79.16
93.97
25% Pyripridone 20g/Mu
43
23.67
44.95
63.73
13
69.77
89.47
8.67
79.84
95.07
6.33
85.28
95.74
25% Pyripridone 24g/Mu
56.67
18.67
67.05
78.29
12.33
78.62
92.55
6.67
88.23
97.12
4
92.94
97.96
CK
41
62.33
51.76
--
117.67
187
--
167.6
308.95
--
141.67
245.5
--
2. Impact on Crops and Non-target Organisms
No adverse effects were observed on early rice at the recommended dose, and no impact was noted on field spiders.
Third, Conclusion and Discussion
1. The 25% pyripridone suspension developed by Jiangsu Kesheng Group Co., Ltd. showed excellent efficacy in controlling the whitebacked planthopper. Within 5 days, the control rate reached 92.55%, close to the peak of efficacy. After 10 days, the control rate remained high at 97.96%. It was also safe for natural enemies, making it a promising option for large-scale use. For medium-to-heavy infestations, it is recommended to apply 18–20g/acre, while for reinfestation years, 20–24g/acre is advised.
2. The best time to apply the suspension is during the peak of the 1st to 2nd instar stages of Sogatella furcifera, ensuring maximum efficacy.
3. A water layer of 3–5 cm in the field is essential for optimal absorption and distribution of the suspension within the rice plants.
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