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ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Crop and Commodity Protection Research » Research » Research Project #434941

Research Project: Phytosanitary Irradiation Effects on the Semi-slug Parmarion Martensi

Location: Tropical Crop and Commodity Protection Research

Project Number: 2040-43000-017-15-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Jun 15, 2018
End Date: Jun 14, 2019

Objective:
The overall goal of this project is to determine the effects of phytosanitary irradiation treatments on the semi-slug Parmarion martensi. Sweet potatoes are irradiated in Hawaii before export to control several quarantine insect pests, and P. martensi has been detected on sweet potatoes during inspection in Hawaii and on the U.S. mainland and may cause rejection of shipments. P. martensi also may be infected with the nematode Angiostrongylus cantonensis (rat lungworm), a human pathogen and leading cause of eosinophiliic meningitis worldwide. There is evidence that phytosanitary irradiation at the dose used to control quarantine insects can also control this pathogenic nematode. Specific objectives are to: 1) evaluate rearing systems for P. martensi, 2) conduct irradiation dose response tests with P. martensi adults to identify a sterilizing dose, and 3) examine the effects of phytosanitary irradiation doses on A. cantonensis, particularly at 400 Gy which is a generic dose for control of insects.

Approach:
Several different rearing substrates for Parmarion martensi will be tested including lettuce, cabbage, and dog food. Large slugs will be collected from the wild and held for egg laying. Newly hatched eggs will be used to start a slug colony without the nematode on various diets. For irradiation dose response tests, adult slugs will be transferred to ventilated containers containing coir, food and moss and irradiated at 0, 150, 400 Gy. Additional non-irradiated adult slugs will be similarly maintained and serve as controls. After irradiation, containers with slugs will be checked 1-2 times per week for egg clutches. Eggs will be transferred to Petri dishes with moist filter paper for hatch. Several reports suggest the nematode A. cantonensis may be devitalized at the phytosanitary irradiation doses used to control insects. Large slugs will be dropped in a vial of water for 48 hrs to extract A. cantonensis larvae. Third larval stage A. cantonensis will be transferred to another vial for irradiation treatment at 0, 150, and 400 Gy. Non-irradiated larvae will serve as a control. At 48 h after treatment, half the A. cantonensis larvae will be treated with propidium iodide which stains dead cells to test for mortality, and the other half will be inspected by microscopy for any signs of movement or behavioral changes.