Development of molecular diagnostic tools for armored scale insects (Hemiptera: Diaspididae) and their natural enemies on coconut and associated crops

Date

2016

Abstract

In support for the efficient and accurate identification of armored scale insects and their natural enemies, a molecular-based diagnostic protocol was developed. Armored scale insects and their associated natural enemies were collected from 16 provinces in the country. A diagnostic protocol was optimized using the 28S ribosomal DNA as molecular barcode to identify the armored scale insects collection. Fourteen scale insect species belonging to the family Diaspididae, the armored scale insects, and 6 non-diaspidid scale insects species under the families Coccidae and Eriococcidae were identified. Comparison with the BLAST database revealed significant hits for armored scale insects namely, Abgrallaspis cyanophylli (99%) from coconut, Aonidiella citrina (98%) from banana, Aspidiotus cryptomeriae (100%) from ornamental anahaw, As. Destructor (99 to 100%) from cconut and banana, As. Excises (99%) from squash and coconut, As. Rigidus (99 to 100%) from coconut, mangosteen, palmera, Manila palm, red palm squash, and nipa, Chrysomphalus aonidium (99%) from coconut, Hemiberlesia palmae (99%) from coconut, Pinnapis aspidistrae from gabi San Fernando (99%), and Pseudaulacaspis pentagona (98%) from coconut. On the other hand, armored scale insect with no significant BLAST hit since they shared less than 98% nucleotide identity were found to be closely related to Chinonaspis wisteriae (94 to 95%) and Ps. cockerelli (93%), both collected from coconut. Those diaspidids collected from lanzones were closely related to Unaspis environmental (95%) and U. euonymi (95%). On the other hand, non-diaspidid species collected from cocon ut under the family Coccidae were positively identified as Coccus formicarii (10 0%), C. hesperidum (99%), Paralecanium expansum (98%). Other coccids positively identified as Parasaissetia nigra (99%), Pulvinaria psidii (99%) were collected from coffee and banana, respectively. In addition, the only eriococcid from coco nut only had 87% nucleotide identity with Eriococcus spurious. Three marker gene s, namely 28S, ITS2 and COI genes were used to optimize a molecular-based diagno stic protocol for the accurate identification of the natural enemies of the armored scale insects in the study. Among the marker genes tested, the 28S gave the best results, however due to the absence of significant nucleotide sequence hits in the GenBank database, the natural enemies were only identified up to the gen us level. A Comperiella sp., with only 83% to 87% nucleotide identity with Compe riella bifasciata, was found to be associated with As. rigidus infesting coconut and banana in Laguna, coconut and nipa in Basilan suggested that the Comperiella sp. from these sites might be distinct from each other. Marietta sp. was also detected in As. rigidus from Basilan. A Coccophaginae species was found to be as sociated with As. destructor infesting coconut from Zamboanga (89 to 91%) and Ca marines Norte, while those from Quezon was associated with Encarsia sp. (92%). Another parasitoid identified closely related to Pteropterix sp. (89%) was found to be associated with Ps. Cockerel infesting coconut in Zamboanga. As. excisus r eared on squash fruit in Basilan was found to be parasitized with Encarsia sp. that is closely related to E. heratyi (91%). Meanwhile the predators identified closely related to Telsimia sp. (89 to 90%) was identified feeding on As. destructor from Albay, Agusan del Sur, Camarines Norte and Camarines Sur. Chilocorus sp. closely related to C. cacti (92%) was also preying on As. destructor from Agus an del Sur. Pseudoscymnus sp. (91%) and Nothocolus sp. (84%) was also associated with As. destructor from Camarines del Norte. With the absence of significance hit in the Genbank database for species identification of some scale insects and natural enemies collected in this study, careful examination of these samples b y the alpha taxonomists should be done for accurate identification up to species level. Only then that the barcodes for these insects will be assigned for the specific species.

Language

English

Document Type

Article

Pages /Collation

167 leaves

En – AGROVOC descriptors

COCONUTS; DNA; DIAGNOSIS; GENE BANKS; COCCOIDEA; NATURAL ENEMIES; PREDATORS

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