THE POPULATION SUCCESSION PATTERNS OF CABBAGE MAIN PEST Plutella xylostella L. AND Crocidolomia pavonana Fab AT CABBAGE PLANTATION

Ketut Ayu Yuliadhi1, I Wayan Supartha1, I Nyoman Wijaya1, and Pudjianto2 1Program Study of Agroecotechnology, Faculty of Agriculture, Udayana University 2Department of Plant 2Protection, Faculty of Agriculture, Bogor Agricultural University, Indonesia *

*Corresponding author: [email protected]

ABSTRACT

This study was aimed to investigate the population dynamics of the cabbage insect pests, Plutella xylostella and Crocidolomia pavonana under natural conditions. The population succession patterns of both pests were determined by observing the abundance of their population on a regular basis from the beginning to the end of the planting season. Understanding the population succession patterns of P. xylostella and C. pavonana will give an idea the shifting time by both pests on attacking the crops, therefore on deciding the time of controlling. The population succession patterns occur in 8 weeks of planting season. P. xylostella dominated the cabbage plants when they were 1-5 weeks after planting (WAP), but when the cabbage plants were more than 5 weeks old they were dominated by C pavonana.

Keywords : Crocidolomia pavonana, cabbage, Plutella xylostella, succession

INTRODUCTION

Among the types of insects that have been reported to be pests on cabbage, there are two types that are the most important pests of cabbage in Indonesia namely the Plutella xylostella Linn. (Lepidoptera: Plutellidae) that attatcks leaves and Crocidolomia pavonana Fab. (Lepidoptera: Pyralidae) that attack the crops. P. xylostell is the main cabbage (key pest) on cabbage plantation at high altitude. They commonly attack cabbage before the development of crops, by attacking underpart of leaf tissues and leaving the upper epidermal tissues as white nets. Meanwhile, C pavonana attacks cabbage plants when the crops are formed, damaging leaves in the form of holes, and if they attack on primordial tissues, result in plant to stop growing. If there is no control to the plantation for both pests, particularly in the dry season, can result in crop failure .

Sembel et al. , (1994) states that the level of damage caused by P. xylostella can

reach 34.8 % , and when the larvae of P. xylostella attack cabbage at the same time as the Crocidolomia pavonana larvae, result in reduction of crop products by 79.81 % . Therefore, pest control has to be based on ecological and economic approaches, do not pollute the environment and safe for the consumers. One concept of pest control which is based on ecological and economic approach is integrated pest management (IPM).

Management of plant pests control should be based on observations of the pest density, stadia of pests and pest species, rather than using pesticides directly. Kumarawati (2013) states that the cabbage moth Plutella xylostella already started to live in cabbage at 4 weeks after planting (WAP), and the population reached a peak at the age of 8 weeks. While, the cabbage crop caterpillars Crocidolomia pavonana has begun attacking cabbage plants when the plants aged 6 WAP, and the highest population density found when the cabbage

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were 10 (WAP) at the age of 10 MST cabbage. However, there is no information relating to the attacks succession pattern between the two types of these pests, so studies related to this matter would be very useful. If there is succession it would be interesting to know whether it was caused by the plant content or due to the nature of the pests. This is very importance in order to find the best way to control them, both in terms of time and model that will be implemented. Understanding the succession pattern between Plutella xylostella and Crocidolomia pavonana on cabbage will provide appropriate time and techniques of controling them. This is a problem that needs to be explored in terms of its understanding of pest target. The information of population succession patterns of Plutella xylostella and Crocidolomia pavonana on cabbage is important in terms of their interactions. Plant phenology has shown that plants provide different habitat and niche for cabbage leaf-eating pests. Although both pests, P. xylostella and C. pavonana exist on the same plant , but they occupied different resources.

MATERIALS AND METHODS

This study was conducted to determine the pest population succession patterns of of P. xylostella and C. pavonana under field conditions. The Experiment was conducted in August 2013, in the area of vegetable production centers in Pancasari Village , District of Sukasada , Buleleng , which are endemic areas of P. xylostella and C. pavonana. Cabbage plants were prepared on an area of 100 m2. Cabbages were planted with a distance of 50 cm x 50 cm, so there are 400 cabbage plants in the area.

Cabbage cultivation was done in accordance with local practice, but without the use of pesticides, so naturally enable a wide range of organisms (including insect pests and their natural enemies) associated with cabbage plants.In order to determine the succession pattern of C. pavonana P. xylostella in cabbage, the plant was determined in such that the plants evenly in field with an adequate amount. In this experiment, 100 plants were employed which has been selected using a U-shaped random sampling.

Observation of the plant age and the pest population density (egg, larva, pupa, and imago) of P. xylostella and C. pavonana were caried out weekly from the first cabbage were planted until harvesting. Observations were made on a fixed sample of plants (plant sample has been determined before the observations and the observations made on the same sample plants until the experiment was completed). The density of egg, nymph, pupa, and imago of both insect pests were tabulated according to the observation time (to show the plant age / plants phenology) to determine the pattern of succession occurring of both pests.

RESULTS AND DISCUSSION

The populations succession pattern of P. xylostella and C. pavonana on Cabbage

The results of the two main pest species compositions that attack cabbage plants showed that P. xylostella dominated plant aged 1-5 weeks after planting (WAP), but when cabbage plant were more than 5 weeks old, they were dominated by C. pavonana (Figure 1).

These results demonstrated that P. xylostella are pests that attack plants in the vegetative phase which damage the leaves,

THE POPULATION SUCCESSION PATTERNS OF CABBAGE MAIN PEST Plutella xylostella L. AND Crocidolomia pavonana Fab AT CABBAGE PLANTATION | Ketut Ayu Yuliadhi, I Wayan Supartha, I Nyoman Wijaya, and Pudjianto

so it is known as the leaf cabbage moth. The results also proved that C. pavonana are pests that attack cabbage crop after crop formation, that is known as cabbage crop pests.

The present of pest populations of P. xylostella on plants over 12 time observations consisted of egg, larva, pupa, and imago stages. The results of the field observations of P. xylostella found that the eggs began to occupy the cabbage plants after one week old, while the larvae P. xylostella was found on cabbage plants in two weeks after plantation, with 11 individuals/100 plants. Plutella xylostella pupae began to be observed in two week old cabbage plants, with 7 indivuduals/100 plants, and imago were established on cabbage plants in three weeks after planting with the number of 2 individuals/100 plants. The population of P. xylostella larvae reached a peak when plants were 7 WAP, with 41 individuals over 100 plants (0.41 birds per plant). In the 8th weeks of observation, the population of P. xylostella

larvae began to decline, and there was P. xylostella was observed when the plants were 12 weeks old (Figure 1).

As on P. xylostella, the present of C. pavonana in cabbage plants also found as eggs, larvae, pupae and imago stages. The population of C. pavonana larvae was first observed when the cabbages were four weeks old (33 individual / 100 plants). The number of larvae reached a peak when the plants were 10 WAP, which were 260 individuals in 100 plants (2.6 larvae/plant ). The pupae was observed when the plants were 6 WAP (3pupae / 100plants), and imago when the plants were 8 WAP (1 imago/100 plants).

The presence of both pests on cabbage plants was dominated by larval stage. The larvae increased significantly in cabbage plants 5 weeks after of planting, which were 35 larvae of P. xylostella and 56 larvae of C. pavonana. At this plant development time, the C. pavonana was started to dominate the plants. The number of P. xylostella started to decrease when

Fig. 1 Population succession pattern of P. xylostella and C. pavonana on cabbage plants


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plants were 8 weeks old, but the number of larvae of C. pavonana was increased.

Based on this field study, it can be stated that before the cabbage plants forming crops, the plants were dominated by P. xylostella, but when the crops have been formed the plants were dominated by C. pavonana, and its domination has begun to decline when plants were 5 weeks old. The substitution of P. xylostella by C. pavonana occurred when plants were 8 weeks old.

CONCLUSION

The succession population patterns of P. xylostella to C. pavonana on cabbage plants occur in 8 weeks after planting. P. xylostella dominated the plants cabbage in 1-5 weeks after planting (WAP), then shifted by C. pavonana after the plants were older than 5 weeks.

Suggestion

Based on the result of this study, it can be suggested that further research can be conducted to examine the usage of succession patterns of P. xylostella dan C. pavonana in controlling pests on cabbage plantations.

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