1. A COMPARATIVE STUDY OF COLOR SENSITIVITY COMBINED WITH OPENED AND PROTECTED TRAPS FOR INSECT PEST MANAGEMENT IN CHINESE KALE (Brassica oleraceae L.) By V.N. Wickramaarachchi (106296) Agricultural Systems & Engineering School of Environment, Resources and Development Asian Institute of Technology, Thailand Thesis Advisor : Dr. S.L. Ranamukhaarachchi

2.  Motivation... Demands excessive use of pesticides (Indiscriminate use) Consumers consume Pesticide contaminated vegetables Consumers consume Pesticide contaminated vegetables Disrupt delicate balance Between insect pest and natural enemies Disrupt delicate balance Between insect pest and natural enemies Integrated Pest Management (IPM) Uses combination of complementary methods Year round cultivation Increases pest insidence, continuation severity of damage

3.  Use of color traps in various ways  Colored objects  Colored mulches  Color lights

4. Most Commonly Used Color Traps

5. General objective To determine the performance of different color based modified traps and their efficacy for enhancing insect pest attraction and conservation of natural enemies Problem statement Lure insect pests along with the beneficial insects (natural enemies)

6.  Experimental design  Treatments (10)  Complete Randomized Design (CRD)  Yellow, white, red color cards combined with glue alone glue + protective mesh without glue nor protective mesh control (no color card)  Four replicates  Treatment coding system X X X Colour of the trap Y – Yellow W – White R – Red Glue coating 0 – without glue G – with glue Protective cover 0 – No cover P – with cover

7. Opened sticky color trap model Protected sticky color trap model

8.  Reflectance pattern from mature and immature leaves  Reflectance pattern from color cards (a) Without glue (b) With glue(c) With protective net structure  Similar reflectance pattern  Higher reflection in Immature leaves (yellow)  Lower reflection in Mature leaves (dark green) (b) With glue

9.  Cabbage aphid  Stripped flea beetle  Attraction for yellow colour is significant  Significant effect through out the observation period and yellow shows highest mean

10.  Cluster caterpillar  Diamondback moth  Both yellow and white attracted, but ot red  No specific color response

11.  Thrips  Fungus gnats  Found in large numbers each color card  Red attracted most

12.  Lady bird beetle  Yellow colour shows dominent effect  Color card traps with protective mesh trapped only few LB’s  They could be protected

13.  Lacewing  Parasitic wasp  Green lacewings are common  Yellow and white attracted most  Highest attraction on 3-4 weeks  Not sensitive to red colour

14.  Population dynamics of insect pests pest count increases  Fungus gant - Significant rate of development  Reduction of green lacewing  Flea beetle - population increased  All natural enemies remains constant from the 5th week onwards (except lady beetle)  Lady beetles found in large numbers

15.  Cabbage aphids & Lady beetles  Lady beetles (main predators for aphids) are voracious feeders (adult lady beetle consumes around 50 aphids per day)  Cabbage aphid density is relatively higher than lady beetle, to facilitate lady beetles to be performed effectively (Ferguson, 2005 online).  Apart from that modified sticky trap also contribute (80 % of natural enemies are protected with the protected net structure) Good example on natural biological control in the crop field.

16. Other examples………. Spider with its prey inside the web Ant feeding on aphids

17.  Is it effective?  57% reduction in captured insects to the YGP traps, but same time 85 % of reduction in natural enemies  WGP shows 44% and 87% reduction in insect pests and natural enemies respectively.  RGP does not show similar trends as yellow and white traps  Great improvement in the natural enemy conservation point of view  But the capturing of insect pests by the modified sticky trap is reduced around 50% than that of traditional sticky colour trap. Why………. Net size and net structure may disturb the pest movement towards the sticky trap thereby they move away from the trap.

18.  Chinese kale leaf infestation level

19.  Total harvested and damage yields  Control plot – Avg. damaged yield is higher, leaf infestation lower values  Control plots are surrounded by plots having color cards  Damage done by pests who are survive  Latter stage – damage in control plot high because of high pest population and limited food  At harvest –quantity of damage high  Early harvesting  Uncontrolled sampling errors  YG0 – highest yield, YGP –lowest pest damage  Due to planting density difference  Total yld (stem, good leaf,damage leaf wt)  Weight distribution different  Total yield is not significantly different 1/ Average total yield (t/ha) 2/ Average damage yield (t/ha) 3/ Average within the column followed by the same letter are not significantly different

20. Non- sticky trap performance vs. control  Cabbage aphid wingless forms colonize mostly in the lower part of the leaf.  Highest aphid & Flea beetle population in yellow cards, lowest in red cards  Squash bug – high in red cards  Control plot had the highest pest population.  Plots with yellow cards had the maximum of Lady beetles. Highest crop damage in control site Natural biological control process in plots with colour cards is functioning effectively (Y00,W00,R00 lower damage yield compare to control)

21.  Conclusions  Use of the yellow, white and red cards was found effective in reducing pest populations and increasing natural enemy population in Chinese kale  The protected mesh showed slight reduction in the insect pests trapped, and a greater reduction in the number of natural enemies on glued color cards  The number of insects and damaged yield were lower in plots provided with red color indicating that it has a repellence effect  Yellow performed well in all color cards in terms of attracting the highest number of insect pests and natural enemies, but final marketable yield remained unchanged, yet the control had the lowest. This indicates the efficacy of using color sensitivity for managing insect pests in Chinese kale

22.  Recommendations  Conducting further studies with different protective mesh sizes that could facilitate the movement across the net for insect pests and discourage the passage of natural enemies  Considering the extent of cultivation, the optimum size and the number of traps could be determined with further studies  Use of modified sticky trap integrated with pest repellent plants  It would be useful to develop a method that could not only capture those insects, but also to capture live, because sweep net method was not applicable for these low moving insects and also for caterpillars and finally they could be used for further studies