Project's information

Project's title Predatory Mites (Acari: Phytoseiidae): Enhancing and Biocontrol Agents Against Mites on Citrus Trees
Project’s code KHCBSS.01/20-22
Research hosting institution Institute of Tropical Biology
Project leader’s name Assoc.Prof. Dr. Nguyen Thi Phuong Thao
Project duration 01/01/2020 - 31/12/2023
Project’s budget 1,500 million VND
Classify Excellent
Goal and objectives of the project

Evaluate the composition of mites and predatory mites on citrus trees.
Propose biocontrol solutions to manage mites on citrus trees, catering to organic agriculture aimed at exportation.

Main results
- Theoretical results:
* Evaluated the cultivation status of citrus trees in the provinces of the Mekong Delta, encompassing production methods and farming experiences, information on varieties and cultivation techniques, fertilizer usage, growth-stimulating agents, as well as the prevalent pests and diseases, including the primary agents used on Green-skinned pomelo in surveyed households. Identified 14 species of mites and harmful insects on citrus trees. Four mites found to be detrimental are the citrus red mite (Panonychus citri McGregor), two-spotted spider mite (Tetranychus urticae), citrus rust mite (Phyllocoptruta oleivora), and broad mite (Polyphagotarsonemus latus Bank). Among them, P. citri appeared more frequently compared to the other recorded species.
* Five species of predatory mites have been identified on citrus trees in the provinces of the Mekong Delta: Amblyseius eharai, Amblyseius lenis, Amblyseius obtuserellus, Typhlodromus ndibu, and Amblyseius polisensis. Among these, three species—A. eharai, A. lenis, and T. ndibu—are newly recorded for the first time in Vietnam. All five species are present in VietGap and organic farming models, while in traditional farming models, only A. eharai and A. lenis are detected. The population density of these species in the VietGap and organic models is higher compared to traditional farming methods. The diversity of Phytoseiidae family predatory mite species has been determined using diversity indices across provinces and different seasons within a year. A. eharai exhibits the highest richness, with its presence being more frequent in both sunny and rainy seasons, consistently higher than other species across surveyed areas.
* The predatory feeding capacity during the immature and adult stages of Amblyseius eharai on citrus trees has been evaluated. Among these, the species P. citri is preferred as prey for the A. eharai. Additionally, a procedure for mass rearing of the potential predatory mite, A. eharai, has been established using Artemia franciscana cysts as alternative food sources, with the possibility of supplementing their diet with natural prey (such as citrus red mite) during the rearing process. Female predatory mites that have undergone mating are best preserved under conditions of 5°C temperature, 95% humidity, and complete darkness for a period of 30 days. Under these conditions, the reproductive capacity and the feeding ability of subsequent generations of females after storage remain unaffected by the duration of preservation.
* The tolerance of two predatory mites, T. ndibu and A. eharai, to commonly used pesticides on citrus trees was assessed under laboratory conditions. Four pesticides—Ortus 5EC, Fastac 5EC, Chess 50WG, and Applaud 10WP—were found to be toxic to both immature and adult stages of T. ndibu and A. eharai. They inhibited the establishment of populations for both species. The bio-origin pesticide Kobisuper 1SL (Matrine) showed non-toxic effects on the adult stages of T. ndibu and A. eharai, while exerting minimal toxicity on the immature stages. Conversely, the NeemNim pesticide derived from Neem trees exhibited no toxicity towards both adult and immature stages of A. eharai, while also not affecting the reproductive capability of subsequent generations of A. eharai. 
* Releasing predatory mites to control mites on citrus trees in cultivation areas: Identified suitable release ratios between A. eharai predatory mites and their prey: 1:4 between A. eharai and T. urticae, and 1:3 between A. eharai and P. citri. Utilizing chemical pesticides or releasing A. eharai alone, or in combination with biopesticides, effectively suppressed P. citri infestations. A. eharai predatory mites were able to establish robust populations after release under natural conditions. Evaluated the economic efficiency of control methods: Releasing predatory mites singly or in conjunction with biopesticides proved effective in managing harmful insects and mites on pomelo trees, leading to profits despite the pomelos being sold at prices similar to conventionally produced ones rather than organic products.
- Applied results:
* A straightforward, easily applicable mass rearing process for A. eharai predatory mites, suitable for implementation in scientific and technological application centers at institutes, universities, and agricultural companies.;
* The procedure for releasing A. eharai predatory mites to control pests and mites on citrus trees can be employed in organic farming or VietGap-compliant orchards to produce high-quality, clean fruit with minimal chemical residue.
Products of the project

- Scientific papers in referred journals (list):
1. Nguyen T. P. Thao*, Nguyen T. Thuy and Ho L. Quyen (2023) Effects of different diets on biological characteristics of predatory mite Amblyseius eharai (Acari: Phytoseiidae). Insects 14, 519.
2. Nguyen T. P. Thao*, Nguyen T. Thuy (2023) Effects of certain pesticides on the predatory mite Typhlodromus ndibu Pritchard and Baker (Acari: Phytoseiidae). Agriculture 13, 1776.
3. Nguyen T. P. Thao*, Nguyen T. Thuy (2022) Effects of some pesticides on the predatory mite, Amblyseius eharai (Acari: Phytoseiidae). Plant protection journal, (5): 33-38.
4. Nguyen T. P. Thao*, Nguyen T. Thuy, Ho Le Quyen (2023) Biology and life-table of predatory mite Typhlodromus sp. (Acari: Phytoseiidae) fed on Panonychus citri Mcgregor (Acari: Tetranychidae) and Tetranychus urticae Koch (Acari: Tetranychidae). The 11th Vietnam National Conference on Entomology.
- Patents (list):
- Technological products (describe in details: technical characteristics, place):
* A minimum collection of 5 predatory mite species gathered from citrus trees and maintained in laboratory conditions.
* Mass rearing procedure for A. eharai predatory mites;
* Procedure for releasing A. eharai predatory mites to control pests, mites on citrus trees;
* Handbook/reference book detailing various predatory mite species present on citrus trees in selected provinces of the Southern region of Vietnam (draft version).

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