Rhizoglyphus robini, a pest mite of saffron, is unable to resist extracellular ice formation.

The saffron mite, Rhizoglyphus robini Claparède (Acari, Astigmata: Acaridae), is one of the most important pests of saffron-producing regions in Iran. It causes yellowing and decreases saffron growth, and finally it destroys the bulbs. In this research, the cold tolerance and supercooling point (SCP) of the saffron mite were measured in three populations and two temperature regimes. Our results showed that the mean SCP of the saffron mite was approximately -14.6 °C without significant difference among the populations. On the contrary, acclimation of the mites significantly decreased their SCP to a mean of approximately -16.5 °C. Exposure of the mites for 24 h to 0 and -2.5 °C had no significant effect on the survival of the mites but when the mites were exposed to -5.0 °C for 24 h, survival of the three populations reached the lowest level of roughly 60%. By 24-h exposure to -7.5 °C, survival of the mites was almost negligible. As a large proportion of mortality was observed above the SCP, and LT50 > SCP, it can be inferred that the saffron mite is likely a chill-susceptible species. This suggests that the saffron mite lacks the ability to withstand extracellular ice formation. Overall, the results of the current study suggest no significant physiological differences between populations of the saffron mite.

Encapsulation of Plant Biocontrol Bacteria with Alginate as a Main Polymer Material.

One of the most favored trends in modern agriculture is biological control. However, many reports show that survival of biocontrol bacteria is poor in host plants. Providing biocontrol agents with protection by encapsulation within external coatings has therefore become a popular idea. Various techniques, including extrusion, spray drying, and emulsion, have been introduced for encapsulation of biocontrol bacteria. One commonly used biopolymer for this type of microencapsulation is alginate, a biopolymer extracted from seaweed. Recent progress has resulted in the production of alginate-based microcapsules that meet key bacterial encapsulation requirements, including biocompatibility, biodegradability, and support of long-term survival and function. However, more studies are needed regarding the effect of encapsulation on protective bacteria and their targeted release in organic crop production systems. Most importantly, the efficacy of alginate use for the encapsulation of biocontrol bacteria in pest and disease management requires further verification. Achieving a new formulation based on biodegradable polymers can have significant effects on increasing the quantity and quality of agricultural products.