Bionomics of wheat seed gall nematode Anguina tritici

The wheat seed gall nematode Anguina tritici is a scientifically interesting nematode due to its aerial parasitic behaviour and ability to survive for years under desiccated conditions in seed galls. However, Anguina's life cycle and its correlation with host-plant growth and environment are poorly understood. Here, we conducted a microplot study at IARI, New Delhi, India, to examine the effects of early and late sowing dates on the life cycle of the wheat seed gall nematode using growing degree days (GDD). The study confirmed the presence of juvenile stages in the soft, undifferentiated floral mass and the upper one-third part of the stem. During the early stage of floral differentiation, the plant ovary develops into milky grains, while the galls (false ovules) become fully green. An increase in size and gonad cell development was observed when nematode J2S entered the floral tissue. The count of adult females in galls marginally surpasses that of adult males, and the female: male ratio ranged from 1.46 : 1.00 to 1.48 : 1.00. After GDD and cGDD (cumulative growing degree days) calculation, we found that the nematode completed its life cycle in 90 to 140 days, depending on the wheat sowing dates and change in temperature. The study also showed that nematode development was in sync with wheat plant growth and development. The information developed from the study such as the cumulative GDD and it's correlation with Anguina's life cycle, presence of nematode in stem, flower and gall, it's migration from collar to flower, presence of various stages of nematode in different plant tissues, and it's undergoing the anhydrobiotic process in seed galls may be used to determine the best time to intervene and manage nematode infestations.