Use of Gamma Radiation as an Alternative Method for Mite Control in Postharvest Storage of Garlic Bulbs (Allium sativum) Cv. Perla

Rhizoglyphus echinopus is the most important mite species in garlic crop in Mexico and its effect during the postharvest storage of bulbs can generate total product loss. The procedures for control of this pest include applying acaricides compounds in planting and crop development, which can generate resistance and difficulties in the controlling of this pest. The application of low-dose gamma rays can be a clean alternative that could control the mite population in bulbs stored by sterilizing individuals, thus preventing its reproduction.  The aim of this work was to study the effect of two doses of irradiation (150 and 300 Gy) in the mite population and in the overall quality of the bulbs. Two sets of 12 boxes of ‘Perla’ garlic bulbs produced and harvested at Aguascalientes, Mexico, were irradiated at 150 and 300 Gy in a commercial irradiator of Co₆₀ gamma rays (Benebion Co.) and a third group was the control group (0 Gy). The bulbs were stored at room temperature (RT) and 0 °C for 83 and 200 days. Every 15 days, different samples of bulbs were taken to analyze the bulb firmness, weight loss, sprouting index or IB (100* length sprout / clove length), and the count of adult mite population per bulb. After 83 days of storage at RT, the application of 300 Gy controlled the mite population (2–150 adult individuals per bulb) compared to non-irradiated bulbs that reached counts of 150–1300 adult individuals per bulb. The bulbs irradiated at 300 Gy maintained a better firmness both RT and at 0 °C. This treatment did not affect the internal quality of the cloves or its weight loss (4% to 6.5 %) and decreased the IB (33% at RT and 0 Gy and 27 % at 300 Gy). Storage at 0 °C for 200 days was a synergistic factor that helped control the incidence of this pest during postharvest storage (6 adult individual per bulb) in comparison with the control group (198 adult individual per bulb). The application of 300 Gy in ‘Perla’ garlic bulbs  can be recommended for the control of this pest in stored bulbs. It is possible that other varieties of white garlic, such as as 'California Early' or 'California Late', could also usethis treatment for pest control.