Embryogenesis, penetration and post penetration development of Meloidogyne enterolobii in Guava (Psidium guajava L.)

Abstract

Guava (Psidium guajava L.) is one of the important commercial fruit crops grown in India. A new species of rootknot nematode Meloidogyne enterolobii reported first from India by Poornima et al., 2016, has become a fast spreading problem in guava cultivation causing severe reduction in yield and decline of guava orchards across the country and world. The present study was taken up to observe the activity of developmental stages such as embryonic, penetration and post penetration stages of M. enterolobii in order to get a clear picture of the vulnerable stage for managing the nematode. It was observed that the average size of a viable egg was 42.48 μm (±4.20 μm) in length and 20.21 μm (±1.70 μm) in width (n = 10). The average number of eggs/egg masses was 179 (±16) (n = 10). These dimensions are comparable to the dimensions described for eggs of many other plant parasitic nematode species. The 3rd stage juveniles were observed in 2–3 days after Jstage and Jstages were observed in 4–5 days after J3 stage. The swollen female or immature stage of females were seen at 2–3 days after J4 stage, fully developed female was observed in guava roots at 24–28 days starting with single cell stage, the female starts laying eggs at 28–30 days from single cell stage. The optimal temperature for development of M. enterolobii is 28°C, and corresponds to the geographical distribution of this nematode in subtropical regions. At this temperature it takes approximately 3 weeks to complete one life cycle.