«A THESIS SUBMITTED TO THE BHARATHIAR UNIVERSITY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN ENTOMOLOGY BY SACHIN. P. JAMES UNDER THE GUIDANCE OF Dr. R. ...»
STUDIES ON CERTAIN PLANT VOLATILES ATTRACTING
THE SHOT HOLE BORER, Euwallacea fornicatus (EICHHOFF)
(SCOLYTIDAE: COLEOPTERA) INFESTING TEA
A THESIS SUBMITTED TO THE BHARATHIAR UNIVERSITY
FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY IN ENTOMOLOGY
SACHIN. P. JAMES
UNDER THE GUIDANCE OFDr. R. SELVASUNDARAM
DIVISION OF ENTOMOLOGY
UPASI TEA RESEARCH INSTITUTEVALPARAI- 642 127, COIMBATORE DIST.
TAMIL NADU, INDIADECEMBER 2007
I further certify that this research work has not previously formed the basis for the award of any other Degree or Diploma or Associateship or Fellowship or other similar title to any candidate of this or any other University.
Countersigned Signature of the Guide Head of the Institution Dr. N. MURALEEDHARAN Dr. R. SELVASUNDARAM Director Sr. Entomologist & HOD UPASI Tea Research Foundation UPASI Tea Research Foundation Tea Research Institute Tea Research Institute Nirar Dam BPO, Valparai - 642 127 Nirar Dam BPO, Valparai - 642 127 Coimbatore District Coimbatore District Place : Valparai Date : 24.12.07
DECLARATIONI do hereby declare that the thesis entitled "Studies on certain plant volatiles attracting the shot hole borer, Euwallacea fornicatus (Eichhoff) (Scolytidae:Coleoptera), infesting tea" submitted to the Bharathiar University, Coimbatore - 641 046, for the award of the Degree of Doctor of Philosophy in Entomology, is a record of original and independent research work done by me during 2004 to 2007 under the supervision and guidance of Dr. R. Selvasundaram, Sr. Entomologist, Division of Entomology, United Planters' Association of Southern India Tea Research Foundation (UPASI TRF), Tea Research Institute, Valparai - 642 127, Coimbatore Dist., India and it has not previously formed the basis for the award of any other De- gree, Diploma, Associateship, Fellowship or other similar title to any candidate in any University.
1. Volatile compounds and their relative quantity in the partially dried stems of Montanoa bipinnatifida
2. Method of identification and purity of authentic standards of volatile compounds emitted from partially dried stems of M. bipinnatifida
3. Response of SHB beetles to different blends in the wind tunnel
4. Rate of release of individual compounds and most effective blends from different dispensers
5. Effect of temperature on the rate of release of multiple blend from polyethylene tube dispenser
6. Response of SHB beetles to blends in electro antennogram
7. Effect of different dispensers on trap catch
8. Number of beetles trapped by individual volatile compounds of M.bipinnatifida
9. Mean number of beetles attracted to different blends in the field traps
10. Effect of different ratio of the blended compounds in multiple blend on shot hole borer attraction in the field
LIST OF FIGURES
1. Tea growing areas in southern India
2. GC-MS chromatogram of partially dried stems of Montanoa bipinnatifida
3. Attraction of SHB to volatile compounds of M. bipinnatifda in the wind tunnel
4. Dose response of SHB to individual volatile compounds in wind tunnel
5. Attraction of SHB in wind tunnel to different ratios of blended compounds in the multiple blend
6. Retention of attractant in PET after exposure
7. Retention of attractant in ring septa after exposure
8. Retention of attractant in rubber septa after exposure
9. Effect of temperature on the retention of multiple blend in PET
10. SHB attraction to different types of dispensers and duration of its attractiveness in wind tunnel
11. Wind tunnel studies on the influence of quantity of attractant on SHB attraction
12. EAG response of SHB to individual volatile compounds of M. bipinnatifida
13. Dose response of SHB to individual volatile compounds in EAG
14. EAG response of SHB to different ratios of blended compounds in the multiple blend
15. EAG response of SHB to different quantities of blend per dispenser
16. Number of SHB captured in different types of traps in the field
17. Effect of number of funnels in the MFT on the SHB catch
18. Effect of trap height on shot hole borer catch
19. Effect of position of trap on SHB catch
20. Influence of quantity of attractant on SHB trapping
21. Duration of attractiveness of PET dispenser to SHB in the field
22. Influence of the number of traps/ha on SHB catch
23. Pilot scale SHB trapping in the field
24. SHB trapping and weather conditions in the Valparai
25. SHB trapping and weather conditions in Vandiperiyar
LIST OF PLATES
1. Different types of SHB galleries
2. Life history of shot hole borer
3. Montanoa bipinnatifida plant 4a.Dynamic head space (DHS) volatile extraction unit.
4b.Gas chromatograph with mass spectroscopy
5. Instruments used for laboratory bioassay
6. Different types of dispensers
7. Different types of traps tested in the field
8. Traps at different heights in the field
9. Position of trap in tea field
10.SEM of shot hole borer beetle antennae I ntroduction
INTRODUCTIONTea is one of the popular beverages all over the world due to its special aroma, flavor and health benefits. The crop plant belongs to Camelliaceae and is perennial in nature. All the cultivated tea plants belong to two distinct taxa, viz., Camellia sinensis (L.) O. Kuntze the short leaved “China” plants and Camellia assamica (Masters) Wight, the broad leaved “Assam” cultivar. The “Cambod” variety, a subspecies of the latter, is classified as C. assamica spp. lasiocalyx (Planchon ex watt) Wight (Wight, 1959).
“China”, “Assam”, “Cambod” ‘jats’ and a large number of their hybrids are exploited commercially in majority of the tea plantations. It is believed that many wild species of Camellia have also contributed to the present day hybrid population of cultivated tea plants. This crop is predominantly grown in Asia followed by Africa and to a very small extend in Europe, South America and Australia. India is the largest producer and consumer of black tea in the world. More than 520,000 ha is under tea cultivation in India. Majority of the tea plantations are situated in the north eastern and southern region of the country. Tea plantations in south India are spread over the slopes of Western Ghats of Wynaad, Central Travancore, High Ranges, Nilgiris, Anamallais and Chikmagalur of Karnataka (Fig.1) Like any other plantation crop, tea is also affected by an array of pests mainly arthropods. More than one thousand species of pests have been reported to affect different parts of tea plants. Insects and mites are the major group of pests attacking the tea plants. Being a perennial crop and grown as monoculture, the tea ecosystem provides a stable favorable environment and undisturbed food supply to the pests.
Insect pests which are predominant in the southern tea growing areas of the country include shot hole borer, thrips and tea mosquito. Apart from these some leaf eating caterpillars are also reported as minor pests which account for a very low economic damage and often controlled by the cultural operations carried out in tea plantations.
1 Fig.1. Tea growing areas of southern India Among the pests, the shot hole borer (SHB), Euwallacea fornicatus (Eichhoff) (Scolytidae: Coleoptera) (= Xyleborous fornicatus) is a serious pest of tea in south India. Even though the occurrence of SHB of tea is reported in Indonesia, Malaysia, Taiwan, Philippines, New Guinea, Hawai, Fiji and New Hebrides, it gained major pest status only in Sri Lanka and south India. The life history and control measures of this beetle had been described by several authors (Gadd, 1941a&b; Muraleedharan, 1986a ; 1997; Muraleedharan and Radhakrishnan, 1989; 1994).
Female beetles are black, 2.0 to 2.5 mm long with strongly sclerotised body, well developed wings and mouthparts. In males, eyes, wings and mouthparts are atrophied and therefore they are unable to fly or bore into hard wood. Both these functions are carried out by the females. Newly emerged, creamy white/yellow adult beetles turned into light brown and then to characteristic black colour in six to twelve days. Scolytid beetles belonging to the tribe Xyleborini have symbiotic relationship with ambrosia fungus. In the case of E. fornicatus the symbiotic fungus is Fusarium bugnicourtii (Bray ford). The fungal spores are carried by the beetles in special organs called mycangia located in the buccal cavity of head (Parthiban and Muraleedharan, 1996). Spores of the ambrosia fungus borne by the female beetles adhere to the walls of the stem galleries. On germination of spores, the grubs and adults feed on the fungus. The female, a few days after emergence from the parental gallery, establishes its own gallery measuring 1.5 mm diameter on the branches of tea bush.
There are two types of galleries, viz., circular and longitudinal and more often both type of galleries observed in the same stem or branch which is called as mixed gallery (Plate. 1). Almost all females are fertilized by the less numerous males and mating takes place inside the parental gallery. Unmated females also lay eggs and such unfertilized eggs develop into males. Females start to lay eggs after a pre-oviposition period of six to eight days. Eggs are laid singly and are creamy white in colour, oval in shape and measures about 0.5 to 0.6 mm long. They hatch in four to six days and the newly emerged grubs (larvae) are also creamy white. They are about 3 mm long and start feeding on the fungus growing inside the stem galleries as mentioned earlier.
There are three larval instars and the larval stage is completed in 16 - 18 days.
Pupation takes place inside the same gallery. Adults emerge within seven to nine days and remain in the parental gallery for some time. They also feed on the fungus and the male: female ratio is found to 1: 8 (Muraleedharan, 1991a).
Plate.1.Different types of SHB galleries a-Infested stem; b-circular gallery; c-longitudinal gallery; d-Mixed gallery Adult beetles and their life stages are multivoltine (Plate 2) Incidence of SHB attains its peak during certain months in the Anamallais, population reached high levels during April/May, July, October and December (Muraleedharan, 1991 a & b). In Vandiperiyar region, the trend of population dynamics was similar, except a peak in December which is not very distinct. Adult beetles are active during day time, especially at noon. Calnaido (1965) reported that their speed of flight ranged between 0.3 to 0.6 cm/sec and maximum duration of flight was less than an hour.
At present, infestation by the SHB is known from most of the tea growing areas of south India, but its depredations are more pronounced in the mid elevation tea areas ( 1250 m above MSL) of Anamallais (Coimbatore District), Vandiperiyar and Peermade (Idukki District), Nelliampathy (Palakkad District) Wynaad (Wyanaad District) and Nilgiri (Gudalur Taluk of Nilgiri District). SHB infestation causes not only the loss in economic yield but also intensify the capital loss by weakening of bushes, branch breakage and debilitation of bushes. During the past one decade, management of this pest is mainly achieved by adopting certain cultural, chemical and biological control measures (Selvasundaram et al., 2001). Achievement of control is moderate due to the peculiar habitat of these beetles. Escalating concern on the adverse effect of usage of pesticides on the environment and the presence of residues in made tea have precipitated a strong decision for limited and discriminate use of pesticides. This led to the development of an integrated pest management strategy in tea. To meet the expanding demand for safer tea, search for more effective and alternative procedures to control the pest based on sound biological principles is warranted.
The use of attractant trap has long been practiced by the entomologists in general and applied entomologist in particular (Nordlund et al., 1981). Though the progress from a suction trap to more sophisticated trap was rapid and one of the greatest advantages of attractant trap is the specificity to the target insect. In course of time, many investigations had been made on different orders, genera and species that have attraction towards their own species (sex pheromones), or to other species (kairomones). The first isolation and identification of a pheromone was reported by Butenandt et al., (1959) which sparked a busting activity in chemical ecology.
Plate 2. Life history of shot hole borer The field of chemical ecology rapidly improved with the advent of recent chemical technologies particularly for the past thirty years.