Nemato-toxic potential of Betel (Piper betle L.) (Piperaceae) leaf

Abstract

In vitro and in-planta trials were conducted to determine the nemato-toxic potential of aqueous leaf extracts of Betel (Piper betle L.) against the root-knot nematode species, Meloidogyne incognita, at five concentrations, standard extract (S) [1:2 (w/v] and its four dilutions, 20%, 40%, 60%. 80% of S. In the in vitro trials, second-stage juveniles (J2s) and eggs of M. incognita were directly exposed to the extract while in the in-planta trials, the effect of the extract was evaluated as a root dip treatment using tomato plants. The findings indicated that the extract was lethal to J2s but also inhibited egg hatch. The seedling dip treatments reduced root infestations in terms of gall formation, egg production and J2 population densities in soil while simultaneously enhancing the growth of tomato plants. All these effects varied in a dose-dependent manner. Based on the LC50 value, the eggs were found to be less sensitive to the extract than J2s. One hundred percent of mortality of J2s was recorded at four concentration levels, 40%, 60% and 80% of S and S, while 100% egg inhibition was only recorded at S. The highest reductions in gall formation (i.e., number of galls/root system), egg production and J2 population were all recorded at S as 83%, 87% and 84% compared to the untreated water control. The maximum growth enhancement, which was 235% of the control, was detected in the root length of treated tomato plants. It appears the aqueous leaf extract of P. betle shows promise as a sustainable eco-friendly nematicide for the management of M. incognita.