Natural Enemy Associated with Brown Planthopper Outbreaks at Red River

Transcription

1 The species diversity of an Herbivore- Natural Enemy Associated with Brown Planthopper Outbreaks at Red River Delta, Viet Nam Pham Van Lam 1 Ho Thi Thu Giang 2 1 National Institutes for Plant Protection, Dong Ngac, Tu Liem 2 Ha Noi University of Agriculture, Gia Lam, Ha Noi, Viet Nam

2 Introduction Viet Nam is known as an agricultural country, approximately % of population live in and depend on agriculture with rice as the main food crop The rice cultivated in two delta regions: Red River Delta (RRD): 1.66 million ha Mekong River Delta (MRD): 3.96 million ha The amount of rice produce >70% of ftotal t rice production in Viet Nam 2

3 VIETNAM Total: 329,560 sq km Land: 325,360 sq km Red River Delta (RRD) Mekong River Delta (MRD)

4 Introduction There were many reasons that contributed in the change in structure of arthropod community in rice fields. The farmer used the highest amount of insecticides and sprayed most frequently Pest resistance and outbreak of most importance insect pests (such as the brown planthopper ) Hybrid rice introduced into Viet Nam in the 1990s from China also changes technical 4 system as fertilizers, pesticides and irrigation

5 2. Material and methods Data collection: from Statistical Year books of MARD. Sampling sites Ha Nam, Ha Noi, Ha Tay, Vinh Phuc, and secondary data stems from review of literature cited. Rice cultivars including Hybrid rice (Nhi Uu 838, Nhi Uu 63, D. Uu 527, VN 20, TH3-3, HC1 ), Inbred rice (Khang Dan, C70, C71, Q5), Local sticky rice.

6 Fig. 1. Map of the Red River Delta.

7 To determine species composition: surveys and collections were carried out at weekly interval Population Dynamics: every seven days at five sampling points in two diagonal of each the field To calculate the species diversity of an herbivore- natural enemy community in rice fields according to the equation given by Colwell ll (2000), Hill (1973) The Shanon diversity index (H ) Simpson s index: D

8 The field surveys were carried out in sites with brown planthopper outbreaks. In each site, 3-5 homogenous fields were selected for taking samples. Samples were taken freely in rice field with or without brown planthopper outbreaks. All collected samples based on brown planthopper density and status of hopper burn, were categorized into 4 groups

9 Sample I: From fields with hopper burn Sample II: from fields in which hopper burn happened after the survey for 1-2 days Sample III: from fields with high density of brown plant hopper but no hopper burn Sample IV: from fields with low density of BPH and no hopper burn

10 3R 3. Results and ddiscussioni The species diversity of arthropod community in the rice fields Indices of biological diversity of arthropods in the rice fields with brown planthopper outbreaks

11 Species composition of pests and natural enemies collected in rice fields in Criteria Co Duc Nhat Tan - Tien Total Nhue Tu Van Xa Phong (Ha (Ha (Ha Nam) (Vinh Noi) Noi) Phuc) Number of species Rice pests Natural enemies Different species

12 Species composition of pests collected in rice fields in compared with another documents Criteria Ha Noi Ha Nam Vinh Phuc Refer Refere Refere ences 2005 nces 2005 nces 2005 Order Family Species

13 Recent investigation i i in in rice fields did not find the species - For pest: Aiolopus tamulus, Stenocatantops spendes, leptocorisa costalis, L. varicornis, Plautia crossota, Tetroda histeroides, Chilo auricilius, ili Phloeothrips oryzae, Mythimna loreyi. - For natural enemies as Coccygomimus aethiops, C. nipponisus, Enicospillus sp., Eriborus ryukuensis, E. vulgaris, Stenobracon nicevillei. ill i

14 Affect of the rice based ecosystems on the structure t of an herbivore-natural enemy community in summer season 2005 Sampling sites Type of rice fields for sampling N 0 N 1 N 2 E 5 Co Nhue: Rice Tien Phong Rice - Flower and vegetable Duc Tu Van Xa Sticky rice with intensive cultivation Sticky rice with extensive cultivation Rice Sticky rice with intensive cultivation Sticky rice with extensive cultivation N0: Total number of species N1: Number of abundant species N 2 : Number of very abundant E 5 : Species evenness or equitability

15 Decrease of bio- diversification caused by: - Over use of chemicals - Extending of production area due to higher land use index; - Change of cropping system; - Less organic matters and alternative pest control measures - Shortage of knowledge on proper use of chemicals

16 s) Quan ntify (ton Insecticides Fungicides Herbicides Year Fig. 1 Dynamic of pesticides id use in Viet Nam during

17 Current trend of cropping pattern and varieties using in spring winter crops in northern Vietnam Variety using Cropping pattern Year IRRIs Varieties and others Chinese varieties Early spring Mid. spring Late spring ,

18 The species composition of pest- natural enemy communities residing in the base of rice stems is very poor in the case of brown plant hopper outbreaks The number of discovered species of natural enemies in collected samples is different. This number depends upon location and status of BPH population density in surveyed rice fields. Spider constitutes a large group of predators in rice fields

19 Species composition of pests and natural enemies collected in the rice fields with brown plant hopper outbreaks in some sites at RRD Scientific name of insect pests/natural enemies Frequency of occurrence (%) Dong Anh Phuc tho Binh luc Vu Ban Sample Sample Sample Sample Sample Sample Sample Sample Sample Sample I II I II III IV I II I II Nilaparvata lugens (Stal) 1 Sogatella furcifera (Horv.) 1 Nephotettix virescens (Dist.) 1 Lycosa sp Pardosa pseudoannulata B.&Str. 2 Tetragnatha maxilosa Thorell Tetragnatha javana Thorell 2

20 Scientific name of insect pests/natural t enemies Frequency of occurrence (%) Dong Anh Phuc tho Binh luc Vu Ban Sample I Sample II Sample I Sample II Sample III Sample IV Sample I Sample II Sample I Sample II Oxyopes javanus Thorell 2 Dyschiriognatha tenera Kars. 2 Araneus inustus (Koch.) 2 Clubiona japonicolla B.&Str. 2 Micraspis discolor (Farb.) 2 Cyrtorhinus lividipennis Reut Paederus fuscipes Curtis 2 Paederus tamulus Erich Ophionea indica (Thunb.) 2 Anagrus optabilis (Perk.) 2 Total species

21 Brown Planthopper Nilaparvata lugen Stal.

22 White Backed Planthopper Sogatella furcifera Horvath

23 Tetragnatha maxilosa Bianor hottingchiehi S.

24 Pardosa pseudoannulata Oxyopes javanus

25 Araneus inustus Koch Lycosa sp.

26 Ophionea indica Thunbr. Paederus fuscipes Curt.

27 Micraspis discolor (Fabr.) Cyrtorhinus lividipennis Reuter

28 Main reasons of BPH outbreaks in 2005 Cultivation of good quality for eating varieties and susceptible to BPH. In the rice field there are many crop stages. Farmers are still growing rice with old methods : using own seeds, high rate seeds and nitrogenous fertilizer applications. Pesticide application with wrong method Pesticide application with wrong method (apply on the upper leaves only).

29 Pesticide application on leaves: wrong method

30 Pesticide application on leaves: right method

31 Hopper burn whole field after insecticide application 4 times

32 Hopper burn whole field

33 No The species diversity of an herbivore- natural enemy community associated with brown planthopper outbreak Types of rice fields for Total abudance Shannon s sampling index (H ) Simpson s index (D) 1. Sample I in Phuc Tho Sample IIi in Phuc Tho Sample III in Phuc Tho Sample IV in Phuc Tho Sample II in Dong Anh Sample III in Dong Anh Sample I in Vu Ban Sample II in Vu Ban Sample I in Binh hluc Sample II in Binh Luc Note: I - Hopper burn is happening II - Hopper burn happened after surveys III - High density of BPH, but no hopper burn IV No Hopper burn

34 The species diversity of an herbivore- natural enemy community in the rice fields without brown planthopper pp outbreaks Sampling sites Tu Liem district Me Linh district Dong Anh district Total Shannon s Simpson s abundance index (H ) index (D)

35 Some main indices describing the species diversity of an herbivore- natural enemy community associated with brown planthopper outbreak No Types of rice fields for sampling N 0 N 1 N 2 E 5 1. Sample I in Phuc Tho Sample II in Phuc Tho Sample III in Phuc Tho Sample IVi in Phuc Tho Sample II in Dong Anh Sample III in Dong Anh Sample I in Vu Ban Sample II in Vu Ban Sample I in Binh Luc Sample II in Binh Luc N N T l b fdi d i N N b f b d Note: N 0: Total number of discovered species N 2 : Number of very abundant N 1: Number of abundant species in the sample E 5 : Species evenness or equitability

36 Numbe er of spe ecies Phu Tho I Phu Tho III Number of species collection Phu Tho II Phu Tho IV Fig. 2 Correlate bettwen number of species in the sample associated with brown planthopper outbreak

37 Numbe er of spe ecies Sè loµi Vu Ban I Sè lo oµi Binh Luc I Sè loµi Sè loµ µi Vu Ban II Binh Luc II Number of species collection Fig. 3 Correlate bettwen number of species in the sample associated with brown planthopper pp outbreak

38 Some main indices describing the species diversity of an herbivore- natural enemy community in the rice fields without brown planthopper outbreaks Sampling sites Values of some indices Tu Liem district Me Linh district N 0 N 1 N 2 E Dong Anh district Kim bang district Note: N 0: Total number of species N 1: Number of abundant species in the sample N 2 : Number of very abundant E 5 : Species evenness or equitability

39 Conclusion 1. All discovered d species from different rice ecosystems in Ha Noi, Ha Nam, Vinh Phuc were 242 species. 2. Number of discovered species in rice field interplant with Flowers was the fewest (106 species). 3. Number of recorded species in local sticky rice was higher than hybrid rice. 4. Pesticides influenced the population abudance and composition of herbivore- natural enemy communities.

40 5. All samples collected ed from rice fields associated with BPH outbreaks have very high total abundance and varies from to The Shannon s index H in rice fields associated with BPH outbreaks was very low, only in comparison with 0.82 in rice fields without BPH outbreaks.

41 7. In the years without BPH outbreaks, the Shannon index H in rice fields can reach The Simpson s s index D in rice fields associated with BPH outbreaks was very high, and reached an approximation of 1. The index D in the rice fields without t BPH outbreaks was lower, only Species richness in the rice fields associated with BPH outbreaks was not high

42 Thank you for your attention