Mealybugs of vegetable ecosystems and tritrophic interactions of brinjal mealybugs (Record no. 289679)
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| 000 -LEADER | |
|---|---|
| fixed length control field | 09252nam a22001937a 4500 |
| 082 ## - DEWEY DECIMAL CLASSIFICATION NUMBER | |
| Classification number | 632.6 |
| Item number | MIT/ME PhD |
| 100 ## - MAIN ENTRY--PERSONAL NAME | |
| Personal name | Mithra Mohan |
| 245 ## - TITLE STATEMENT | |
| Title | Mealybugs of vegetable ecosystems and tritrophic interactions of brinjal mealybugs |
| 260 ## - PUBLICATION, DISTRIBUTION, ETC. (IMPRINT) | |
| Place of publication, distribution, etc | Vellayani |
| Name of publisher, distributor, etc | Department of Agricultural Entomology, College of Agriculture |
| Date of publication, distribution, etc | 2022 |
| 300 ## - PHYSICAL DESCRIPTION | |
| Extent | 207p. |
| 502 ## - DISSERTATION NOTE | |
| Dissertation note | PhD |
| 520 ## - SUMMARY, ETC. | |
| Abstract | The study on “Mealybugs of vegetable ecosystems and tritrophic <br/>interactions of brinjal mealybugs” was conducted at College of Agriculture, <br/>Vellayani during 2017 to 2020 with the objectives to identify mealybugs and their <br/>natural enemy fauna in solanaceous and cucurbitaceous vegetables, to carry out <br/>the molecular characterization of mealy bugs in solanaceous and cucurbitaceous <br/>vegetables and to find out the tritrophic interactions of mealybugs infesting <br/>brinjal.<br/>An investigation on mealybug diversity in solanaceous and cucurbitaceous <br/>crops of Kerala revealed a total of six mealybug species viz., Coccidohystrix <br/>insolita, Ferrisia virgata, Paracoccus marginatus, Phenacoccus solenopsis, <br/>Planococcus citri and Pseudococcus jackbeardsleyi. Besides, four mealybugs viz.,<br/>Crisicoccus hirsutus, Maconellicoccus hirsutus, Planococcus lilacinus and <br/>Rastrococcus iceryoides infesting other vegetable crops were also recorded from <br/>Kerala. The study also revealed that the population of mealybug, C. insolita<br/>collected from different regions of Kerala exhibited significant morphological <br/>variation. The molecular characterization studies proved that the population <br/>belongs to C. insolita and the variations may be environmental induced.<br/>An exploration of the host range of mealybugs infesting solanaceous and <br/>cucurbitaceous vegetables in Kerala revealed a total of 113 plants under 73 genera <br/>belonging to 31 families, out of which 14 plants were recorded as new host <br/>reports. A rich natural enemy fauna on mealybugs belongs to five orders viz.,<br/>Coleoptera, Lepidoptera, Diptera, Neuroptera and Hymenoptera were documented <br/>from Kerala. Twenty species of mealybug predators from five different families <br/>were recorded, among which the predominant family was Coccinellidae with 16 <br/>species under six genera. Among the various predators collected, Cacoxenus sp. <br/>was recorded for the first time as a predator of P. jackbeardsleyi. <br/>Eleven hymenopteran parasitoids belonging to five families were <br/>documented from mealybugs, of which the majority belongs to the family <br/>Encyrtidae. Four new host-parasitoid associations were also recorded for the first <br/>288<br/>time. The study also identified six hyperparasitoids under the family Encyrtidae, <br/>of which two species were recorded as new report which includes Cheiloneurus<br/>sp. and Prochilonerus sp. associated with the mealybug P. solenopsis.<br/>The ants associated with mealybugs in different agroecosystems were also <br/>investigated and a total of 14 species of ants belonging to nine genera under three <br/>subfamilies were recorded, of which the most dominant subfamily was <br/>Formicinae followed by Myrmicinae and Dolichoderinae. The present study also <br/>revealed 15 new ant-mealybug associations for the first time.<br/>The molecular characterization of eight mealybug species was carried out <br/>that complemented the morphological identification of species. A total of eight <br/>nucleotide sequences were submitted to NCBI GenBank and accession numbers <br/>were generated. The sequences were also submitted to BOLD and illustrative <br/>barcodes were generated. The barcodes of C. insolita, C. hirsutus and <br/>P. jackbeardsleyi were generated for the first time. The diversity of <br/>endosymbionts of the mealybug C. insolita was carried out for the first time. The <br/>study revealed a total of 15 phyla of endosymbionts on C. insolita, of which <br/>Proteobacteria was the predominant one.<br/>An experiment was conducted at Instructional Farm, Vellayani to identify the <br/>tritrophic interaction in brinjal, C. insolita and its natural enemies. The study <br/>revealed that out of the ten brinjal cultivars evaluated, the lowest mean population <br/>of mealybugs was observed in Pusa Uttam whereas the hybrid cultivar, Udit <br/>recorded the highest number of mealybugs. The lowest mean per cent leaf <br/>infestation was recorded in Pusa Purple Long which was statistically on par with <br/>Pusa Uttam whereas the hybrid cultivar, Udit was severely damaged by the <br/>mealybugs. Among the tested cultivars, Pusa Purple Long was recorded under the <br/>group resistant whereas Udit and Haritha were included under the highly <br/>susceptible group based on the mean per cent leaf infestation caused by <br/>C. insolita. The cultivar Haritha attracted the highest number of predators whereas <br/>the maximum mean population of spiders were observed in Pusa Purple Long.<br/>289<br/>The correlation analysis on the mean population of mealy bugs with <br/>biophysical parameters revealed that trichome density, length width ratio of leaf <br/>and number of branches exhibited a significant positive correlation with mean <br/>population of mealybugs. Correlation studies on the mean population of natural <br/>enemies with biophysical parameters revealed that plant height exhibited a <br/>significant negative correlation whereas leaf thickness and number of branches <br/>revealed a non-significant negative correlation with the mean population of <br/>natural enemies. Among the biochemical parameters of brinjal cultivars, total <br/>phenol content exhibited a significant negative correlation with the mean <br/>population of mealybugs whereas total chlorophyll content showed a significant <br/>positive correlation. The correlation between biochemical parameters of brinjal <br/>cultivars with the mean population of natural enemies revealed that total phenol <br/>and carotenoid content exhibited a non-significant negative correlation whereas <br/>total protein content, reducing sugar and total chlorophyll content showed a nonsignificant positive correlation. <br/>The info-chemical mediated interactions in brinjal cultivars, mealybug and its <br/>natural enemies were studied using a multi-armed olfactometer and Y-shaped <br/>olfactometer assay. The results revealed that the cultivar Udit attracted the highest <br/>number of natural enemy Chrysoperla zastrowii sillemi while the cultivar Pusa <br/>Uttam attracted the lowest number. The variation in preference shown by the <br/>natural enemies may be related to the difference in volatile compounds emanating <br/>from the host cultivar. The GC-MS analysis of the synomonal compounds of the <br/>cultivar, Udit revealed a total of eleven compounds whereas the cultivar Pusa <br/>Uttam was recorded with a total of five compounds. The Y shaped olfactometer <br/>studies revealed that C. zastrowi sillemi adults showed more preference towards <br/>the synomonal compounds of mealybug infested plants than that of healthy plant <br/>synomonal extracts. On comparing the volatile profile of synomones of mealybug <br/>infested and healthy plants revealed that the synomonal extracts of the mealybug <br/>infested cultivar Udit comprised of 11 compounds whereas healthy plant <br/>synomonal extracts contained nine compounds. <br/>290<br/>The relative response of C. zastrowi sillemi towards the kairomonal <br/>compounds of C. insolita was evaluated in a Y tube olfactometer and the results <br/>revealed that the highest mean number of adult lacewings were attracted to the <br/>kairomonal compounds of mealybug compared to control. The kairomonal <br/>extracts of the mealybug comprised of seven compounds and the composition of <br/>these hydrocarbons may determine the selectivity of natural enemies towards the <br/>preferred host.<br/>The present study recorded a total of six mealybug species infesting <br/>solanaceous and cucurbitaceous vegetables and its host range, natural enemies and <br/>associated ants in different agro ecological regions of Kerala. The molecular <br/>characterization studies supported the morphological taxonomy and the sequences <br/>were submitted to NCBI Genbank and BOLD. The study also elucidated the <br/>interactions mediated by plant traits and info-chemicals in brinjal-mealybugnatural enemy tritrophic systems. The study recorded Pusa Purple Long as <br/>resistant cultivar and Udit and Haritha as highly susceptible cultivar to C. insolita. <br/>The plant traits viz., trichome density, length width ratio of leaf, number of <br/>branches, total phenol content and total chlorophyll content exhibited significant <br/>correlation with mean population of mealybugs whereas plant height exhibited <br/>significant correlation with mean population of natural enemies. The study on <br/>info-chemical mediated tritrophic interactions revealed that the concentration and <br/>composition of volatile compounds determine the differential selectivity of natural <br/>enemies. The volatile compounds identified in this study can also be used as a cue <br/>in moderating the behavior of natural enemies in the ecosystems. So a thorough <br/>knowledge on the tritrophic relations in the ecosystem will aid in manipulating <br/>these interactions to devise a better pest management strategy. |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM | |
| Topical term or geographic name as entry element | Agricultural Entomology |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM | |
| Topical term or geographic name as entry element | Brinjal |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM | |
| Topical term or geographic name as entry element | Mealybugs |
| 700 ## - ADDED ENTRY--PERSONAL NAME | |
| Personal name | N Anitha (Guide) |
| 856 ## - ELECTRONIC LOCATION AND ACCESS | |
| Uniform Resource Identifier | https://krishikosh.egranth.ac.in/handle/1/5810197405 |
| 942 ## - ADDED ENTRY ELEMENTS (KOHA) | |
| Source of classification or shelving scheme | Dewey Decimal Classification |
| Item type | Theses |
| Not for loan | Collection code | Home library | Current library | Shelving location | Date acquired | Full call number | Barcode | Date last seen | Koha item type |
|---|---|---|---|---|---|---|---|---|---|
| Not For Loan | Reference Book | KAU Central Library, Thrissur | KAU Central Library, Thrissur | Theses | 12/07/2022 | 632.6 MIT/ME PhD | 175347 | 12/07/2022 | Theses |