Parasitoid Biodiversity Increases in Ecological Engineering Fields of Chainat, Thailand

In Chainat Rice Research Center, we used part of the farm to evaluate the impact of ecological engineering on the biodiversity of arthropods. The areas surrounding the rice fields were replaced with several species of flowering plants and vegetables to provide habitats and nectar resources to natural enemies.

Another area of the farm was left as the control with no modifications to the surrounding bunds. Several ecological sampling techniques applied to record arthropod species (ecological sampling protocols).

We have sorted out the samples of arthropods collected using the yellow pan traps set up for 24 hours each during the tillering, maximum tillering and maturing stages of the rice crop.  The pooled data of all samples in the control and ecological engineering fields were compared.

CRR-site-map

Map of ecological engineering and control fields in Chainat Rice research Center

The arthropods were grouped into guilds or functions and the functional biodiversity analyzed using indices computed by ECOSIM (Gotelli and Entsminger 2005) and EstimateS (Colwell 2006).

To avoid sample size sensitivity, rarefaction techniques were used to compute species richness. The indices that have less sample size sensitivity and with more discriminating abilities were used for comparison (Magurran 1988).

Table 1 shows the biodiversity indices of the arthropod guilds of the control and ecological engineering fields and the rarefaction curves are also presented.

YPT

Yellow pan traps set up in the rice fields to record arthropods

Table 1: Comparison of arthropod biodiversity from yellow pan traps in ecological engineering and control fields in Chainat Rice Research Center. 2009.

Guilds

Biodiversity parameters

Control

Eco Eng

Herbivores

% abundance

10.4%

13.2%

Cell

Species richness, S or Esn (rarefaction)

13

13.8

Cell

Log series index alpha

4.60

5.06

Cell

Reciprocal Simpson’s (1/D)

0.16

0.16

Cell

Exp Shannon or Hill N1

7.86

8.04

Guilds

Biodiversity parameters

Control

Eco Eng

Predators

% abundance

32.9%

20.9%

Cell

Species richness, S or Esn (rarefaction)

26

27.3

Cell

Log series index alpha

8.37

9.38

Cell

Reciprocal Simpson’s (1/D)

0.14

0.13

Cell

Exp Shannon or Hill N1

11.82

12.50

Guilds

Biodiversity parameters

Control

Eco Eng

Predators

% abundance

45.9%

13.2%

Cell

Species richness, S or Esn (rarefaction)

15.99

30

Cell

Log series index alpha

8.84

17.56

Cell

Reciprocal Simpson’s (1/D)

0.36

0.05

Cell

Exp Shannon or Hill N1

6.15

21.2

Guilds

Biodiversity parameters

Control

Eco Eng

Others

% abundance

22.7%

40.7%

Cell

Species richness, S or Esn (rarefaction)

6

5.67

Cell

Log series index alpha

1.12

1.23

Cell

Reciprocal Simpson’s (1/D)

0.42

0.57

Cell

Exp Shannon or Hill N1

2.89

2.38

Biodiversity of herbivores, predators and others in the control and ecological engineering plots were rather similar.  For the parasitoids, species richness S (after rarefaction) increased significantly from 16 to 30. There were more hymenopteran species in the ecological engineering plot than in the control.

pic-4-rarefaction2

Rarefaction curves of parasitoids of samples collected in ecological engineering and control fields in Chainat Rice Research Center.

Changes in parasitoid biodiversity is further evident from the diversity index, alpha, of the log series which has good discriminant ability of richness (Taylor 1998). Biodiversity doubled in the ecological engineering fields (17.6 and 8.8). There are similar increases in the diversity index, exponential Shannon or Hill’s N1 which also reflects richness, from 6.2 to 21.2.

References

Colwell, R.K. 2009. EstimateS: Statistical estimation of species richness and shared species from samples. Version 8. http://viceroy.eeb.uconn.edu/estimates

Gotelli, N.J. and Entsminger, G.L. 2005. Ecosim: Null Models Software for Ecology. Version 7.72. Acquired Intelligence Inc, & Kesey-Bear. Magurran, A.E. 1988. Ecological Diversity and Its Measurement. Croom Helm Ltd, London. http://www.garyentsminger.com/ecosim/index.htm

Taylor, L.R. 1978. Bates, Williams, Hutchinson – a variety of diversities. Pp 1 – 18. In L.A. Mould and N. Warloff (eds) Diversity of Insect faunas: 9th Symposium of the Royal Entomological Society. Blackwell, Oxford.

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