Spatial dynamics of teak defoliator (Hyblaea puera Cramer) - Cochin ...

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light-trap. A total of 596 moths were collected on days preceding the start of this outbreak. Locally emerged moths were present during this period. No moths were collected prior to the last outbreak which was 0.05 km away from the trap and which extended to 435.3 ha. There were no locally emerged moths during the period. It can be seen that out of seven outbreaks which occurred during the study period, occurrence of two outbreaks (s1.nos. 2 and 7) could not be detected by light-trap catch eventhough the sites infested were very close (0.5 and 0.05 km respectively) to the trap. Very few moths were collected during the 4 th and 5 th outbreaks (l and 9 respectively) which also occurred near to the light-trap (0.5 and 0.05 km respectively). Only the occurrence of three outbreaks (s1.nos. 1,3 and 6) among the total seven was well indicated by trap catch. Majority of moths were collected during the l" and 6 th outbreaks (145 and 596 respectively) during which moths were emerging locally from earlier outbreaks. Only the occurrence of the third outbreak was well indicated (74 moths were collected) by trap-catch when no locally emerged moths were present. Thus when no locally emerged moths were present, only one of the five impending outbreaks was predictable by a high trap catch. 7.4. DISCUSSION This study indicates that eventhough the moths were collected in the light-trap during the period of the year when teak defoliator outbreaks are prevalent, it does not always collect moths, which arrive in the plantation for egg laying. Large number of moths was collected while they were emerging from the plantations nearby. But the trap was unable to attract and collect moths every time they arrived at the plantation for egg laying. The reason is not well understood but it appears that the moth aggregation that arrives for egg laying respond primarily to the chemical signals from the host plant. This study has shown that the light-trap cannot be relied upon as an outbreak detection device. Detection of an outbreak needs ground observations. These observations can be limited to areas, which have tender 84
foliage. If folds are detected, observations have to be made' in transects radiating in four directions from the site where folds are detected. At these transects, tender leaves have to be closely observed for the presence of defoliator eggs or first instar larvae. Eggs are oval and white. The first instar larvae will be feeding by scraping the leaves near the veins. This observation is needed because egg laying can occur for more than one day and sites with eggs and first instar larvae can go unnoticed in an observation from ground. 85
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SPATIAL DYNAMICS OF TEAK DEFOLIATOR
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CERTIFICATE This is to certify that
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Mr. Rajan James, Mr. A. Moosa, Mr.
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4.3.5. Correlation between outbreak
Page 9 and 10:
CHAPTER I INTRODUCTION Insects are
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covering the entire plantations of
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Burma and recommended that providin
Page 16 and 17:
In a two-year light trap study at J
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during 1983-94 and 1987-89 recorded
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area of 50 ha. A group of ten grids
Page 23 and 24:
CHAPTER IV STUDIES ON THE SPATIAL D
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within these various spatially refe
Page 27 and 28:
4.2.3. Correlation between outbreak
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4.3. 2. Outbreak pattern, 1993 The
Page 33 and 34:
4.3.3. Outbreak pattern, 1994 Table
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_ 0 _ 1 0 2 _ 3 _ 4 _ 5
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_ 0 _ 1 0 1 _ 3
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Table 4.7. The relationship between
Page 41 and 42: Fig. 8. Location of first outbreak
Page 43 and 44: Table 4.9. Elevation and aspect oft
Page 45 and 46: aspect and outbreak frequency. The
Page 47 and 48: map. The methodology adopted for da
Page 49 and 50: The sixth outbreak occurred on 26 M
Page 51 and 52: explained as caused by progenies of
Page 55 and 56: Fig.5.3. Map ofNilambur teak planta
Page 61: Fig.5.9. Map ofNilambur teak planta
Page 67 and 68: Fig.5 .15. Map ofNilambur teak plan
Page 71 and 72: Fig.5.l9. Map ofNilambur teak plant
Page 73 and 74: Fig.5 .21. Map ofNilambur teak plan
Page 75: '------------------ ------- --- ---
Page 78 and 79: 6.2. METHODS In this study, post em
Page 80 and 81: was observed at around 06.15 h on t
Page 82 and 83: Two moths (one male and one female)
Page 84 and 85: Aggregations of the moths were pred
Page 86 and 87: CHAPTER VII DEVELOPMENT OF OUTBREAK
Page 88 and 89: -.-.-._ --- _--. Black light tube -
Page 91: Table 7.1. Correspondence between l
Page 95 and 96: study has considerable bearing on t
Page 97 and 98: maximum of 13 ha (see Section 5.2,
Page 99 and 100: c) Variation in plant quality I ava
Page 102 and 103: away places. These populations seld
Page 104 and 105: Berryman, A. A. (1987) The theory a
Page 106: Nair, K. S. S., Mohanadas, K and Su
Page 109: APPENDIX A ALGORITHM: FOR COMPUTATI
Page 112 and 113: Date *No. of Incidence Local Date *
Page 115: Date "No. of Incidence local Date "
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