Diversity of root mealybugs of Kerala

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dc.contributor.advisorDeepthy, K B
dc.contributor.authorSachin G, Pai
dc.contributor.authorKAU
dc.date.accessioned2021-09-08T07:03:05Z
dc.date.available2021-09-08T07:03:05Z
dc.date.issued2020
dc.descriptionPGen_US
dc.description.abstractMealybugs (Homoptera: Pseudococcidae) are oval, soft bodied insects causing severe damage to plants not only by sucking the sap but also as vectors of viral diseases of crop plants. The mealybugs infesting roots of crop plants are termed as subterranean mealybugs or root mealybugs. Honeydew excreted by mealybugs attracts ants, and in turn they provide protection to mealybugs from their natural enemies and also help in transportation to other fields. Recently, root mealybug infestation was reported from different localities of Kerala. However, studies on diversity of root mealybug - ant association and seasonal incidence were scanty. Hence the present study, ‘Diversity of root mealybugs of Kerala’ had been carried out to identify the root mealybugs and associated ant species and to study the seasonal incidence, host range and geographical distribution of major root mealybugs. Purposive sampling surveys were carried out at different districts of Kerala covering 30 locations and 11 host plants. The root mealybugs and associated ants were collected separately in vials with 90 per cent ethanol. The specimens were labeled with sample codes and preserved as per standard protocols. The study revealed the presence of eight species of root mealybugs belonging to five genera viz., Formicococcus Takahashi, Planococcus Ferris , Dysmicoccus Ferris, Antonina Signoret and Xenococcus Silvestri. Maximum diversity was found in the genus Formicococcus, representing three species viz., Formicococcus polysperes Williams, Formicococcus lingnani Ferris and Formicococcus mangiferacola Williams. The genus Planococcus was represented by Planococcus lilacinus and Planococcus sp. The genus Dysmicoccus, Antonina and Xenococcus were represented viz., Dysmicoccus brevipes Cockerell, Antonina graminis Maskell and Xenococcus annandalei Silvestri, respectively. Three species viz., F. lingnani, F.mangiferacola and A. graminis were recorded for the first time from Kerala. The root mealybug, F.polysperes was recorded to be having wider host range and was found infesting black pepper, banana, avocado and goat weed. Pineapple mealybug, D. brevipes was recorded on pineapple and nut grass, while Planococcus sp. was reported on durian and black pepper. Root mealybugs, F. lingnani, F. mangiferacola, A. graminis, P. lilacinus and X. annandalei were recorded from single host plant each viz., nut grass, mango, paragrass, coffee and cardamom respectively. The morphological identification of ants associated with root mealybugs revealed seven species of ants of which maximum number of ant species were associated with root mealybug, F. polysperes. The ants associated with F. polysperes were Nylandria indica Forel, Tapionoma indicum Forel, Myrmicaria brunnea Saunders, W.W. and Crematogaster rogenhoferi Mayr . The ant associated with F. lingnani was N. indica; while Carebara affinis Emery with D. brevipes and Paratrechina longicornis Latreille with Planococcus sp. on pepper. Ant seen in association with the subterranean mealybug, X. annandalei was Acropyga acutiventris Roger. Among the ant species, N. indica was found to be the major species associated with Formicococcus from Kasaragod, Kannur, and Wayanad districts. The major root mealybug species, F. polysperes was, noted from seven locations of three districts viz., Kasaragod, Kannur and Wayanad respectively. The root mealybugs, F. lingnani, F. mangiferacola, A. graminis, P. lilacinus and Planococcus sp were reported from Wayanad whereas D. brevipes was recorded from Wayanad and Thrissur districts. Molecular characterization of root mealybugs and ants was performed by isolation of genomic DNA and amplification of mitochondrial cytochrome oxidase one (mtCO1) locus using specific primers. The sequencing of polymerase chain reaction (PCR) product and in- silico analysis of eight species of mealybugs and one species of ant was carried out. The sequence data of the following four root mealybugs viz., F. mangiferacola, F. lingnani, A. graminis and X. annandalei were absent in the NCBI data base. The sequences of these mealybugs were deposited in the NCBI database for the first time. Remaining four species of mealybugs showed 91-100 per cent similarity and were in agreement with the morphological identification. The sequences were submitted to NCBIGenbank for future access and use. The sequences were also uploaded to Barcode of Life Data systems (BOLD) and generated barcodes for eight species of mealybugs and one species of ant. The study on seasonal incidence of root mealybug F. polysperes showed that the population of mealybugs increased during rainy season from June and reached its peak in the month of September when the rains subside. The population was least during the summer months. Correlation of mealybug population with weather parameters indicated a significant negative correlation with maximum soil temperature and significant positive correlation with relative humidity and number of rainy days.en_US
dc.identifier.urihttps://krishikosh.egranth.ac.in/handle/1/5810175362
dc.keywordsAgricultural entomology, viral diseases of crop plants, root mealybugsen_US
dc.language.isoEnglishen_US
dc.pages66p.en_US
dc.publisherDepartment of Agricultural Entomology, College of Horticulture, Vellanikkaraen_US
dc.subAgricultural Entomologyen_US
dc.themeidentify the root mealybugs and associated ant speciesen_US
dc.these.typeM.Scen_US
dc.titleDiversity of root mealybugs of Keralaen_US
dc.typeThesisen_US
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