Distribution of Parthenium hysterophorus and one of its biological control agents (Coleoptera: Zygogramma bicolorata) in Nepal

Abstract

Summary Parthenium hysterophorus is a noxious invasive weed of both agricultural and natural ecosystems, spreading aggressively in Nepal. Management of this weed in Nepal has been limited, mainly because of the lack of geo‐referenced data concerning the weed's distribution. We conducted a nationwide survey of P. hysterophorus and its coleopteran biological control agent Zygogramma bicolorata from 2013 to 2016 to determine their spatial distribution. Both were widespread, with the distribution of Z. bicolorata lagging behind the invasion front of P. hysterophorus. The weed was present in 21.2% of the 4838 locations examined, including several isolated satellite populations. The weed was found in the Tarai, Siwalik, Middle Mountains and High Mountains regions, reaching up to 2000 m asl. It has invaded natural and modified ecosystems including all six protected areas in the Tarai and Siwalik regions. Road access appears to be the major pathway for its long‐distance dispersal. Zygogramma bicolorata had spread from the east to the west and was present in 15.4% of the weed occurrence locations, inflicting a low amount of damage. A CLIMEX modelling projection revealed the presence of additional geographic areas in Nepal which are climatically suitable for both P. hysterophorus and Z. bicolorata. Eradication of satellite populations of the weed by physical and chemical measures, and the release of Z. bicolorata into new, but climatically suitable, locations should be prioritised for P. hysterophorus management in Nepal. In conclusion, P. hysterophorus has rapidly become widespread in Nepal and the currently available biological control agent has not been able to prevent further spread of the weed.

Abundance and impact of Parthenium hysterophorus L., an alien invasive herb on plant species diversity in invaded areas of Queen Elizabeth National Park, Uganda

“…The study findings are in line with CLIMEX simulation results that recorded P. hysterophorus in drainage trenches, dumpsites, abandoned buildings, construction sites, residential areas, rangelands and crop fields (Wabuyele et al, 2014 ;Horo et al, 2020). The results also agree with a report from the distribution survey made in Nepal, where P. hysterophorus dispersal was directly associated with vehicle movements (Shrestha et al, 2019). Water channels were highly infested with Parthenium weed in Awash National Park in Ethiopia; thus, water was one of the dispersing egents of this weed (Etana et al, 2015).…”

“…Direct contact with the dry parts of P. hysterophorus, causes asthma and skin irritations (Kumar et al, 2012). Body dehydration, inflammation of soft body membranes, miscarriage and headache have also been reported (Shrestha et al, 2019). An amount of 10-50% of P. hysterophorus in the animals' fodder kills livestock and buffaloes (Sahrawat et al, 2018).…”

Distribution and impact of invasive alien plant species in Bardia National Park, western Nepal

“…Some of the species that are currently frequent (e.g., A. houstonianum, P. hysterophorus) were not reported in the previous studies. In recent decades, these species have been spreading rapidly, invading new areas in Nepal with multiple socio-ecological impacts (Shrestha et al 2019a(Shrestha et al , 2019b. Although PAs are expected to have fewer IAPS than their surroundings (Foxcroft et al 2013), the buffering effect of the PAs could have become weak due to continuous pressure from local communities for resource utilization from inside the parks (Brown 1997, Thapa & Chapman 2010 and the occurrence of human-constructed (e.g., road) and natural dispersal corridors (e.g., rivers).…”

“…However, a biological control programme has not been initiated in Nepal, although a few biological control agents of P. hysterophorus and A. adenophora from neighbouring countries, where they were released, have spread naturally into Nepal and been established with some impacts . Among these established biological control agents, Zygogramma bicolorata Pallister is particularly effective in controlling P. hysterophorus in Nepal (Shrestha et al 2019a). Release of laboratory-reared Z. bicolorata could be a sustainable way of controlling P. hysterophorus in BNP and other PAs of Nepal.…”

Evaluation of host-specificity of Zygogramma bicolorata Pallister (Coleoptra: Chrysomelidae) for the biological control of Parthenium hysterophorus L. (Asteraceae: Heliantheae) in Nepal

“…Evaluation of host-specificity of Zygogramma bicolorata Pallister (Coleoptra: Chrysomelidae) for the biological control of Parthenium hysterophorus L. (Asteraceae: Heliantheae) in Nepal range of edaphic conditions and also exhibits C3/C4 phtosynthetic mechanism (Shrestha et al, 2019). Parthenium is native to region surrounding the Gulf of Mexico including southern United States, northern Argentina, southern Bolivia and south-west Brazil (Navie et al, 1996).…”