First report of entomopathogenic nematodes from Tanzania and their virulence against larvae and adults of the banana weevil Cosmopolites sordidus (Coleoptera: Curculionidae)

Abstract

A survey on the occurrence of entomopathogenic nematodes (EPNs) was conducted in selected banana fields from three regions in Tanzania, namely Mbeya (Southern Highlands), Morogoro (Lowland) and Pwani (Coast). The main objective of this study was to isolate EPNs naturally occurring in banana fields in Tanzania and to test their effect on banana weevil (Cosmopolites sordidus Germar 1824). We report for the first time the presence of EPNs in Tanzania where four (4.4%) out of 90 samples contained nematodes in the genera Steinernema and Heterorhabditis. EPNs were only isolated in the coastal region in soils with a high sand content. The virulence of nine EPN isolates was tested against larvae and adults of C. sordidus. All isolates caused mortality of the larval stages, whereas the adults appeared resistant to nematode infection. Larval mortality was found to increase significantly with increasing nematode dose. It was also shown that nematodes were able to penetrate and establish in the banana weevil larvae in increasing numbers with increasing nematode dose. The study indicates the potential for including EPNs in management strategies of banana weevil.

New entomopathogenic nematodes from semi-natural and small-holder farming habitats of Rwanda

“…Although African EPN surveys have included Egypt (Glazer, Galper, & Sharon, 1991;Shamseldean, Abou El-Sooud, Abd-Elgawad, & Saleh, 1996), Kenya (Burnell & Stock, 2000), Ethiopia (Mekete, Gaugler, Nguyen, Mandefro, & Tessera, 2005), Tanzania (Mwaitulo, Haukeland, Saethre, Laudisoit, & Maerere, 2011), South Africa (Malan, Knoetze, & Moore, 2011), Cameroon (Kanga, Waeyenberge, Hauser, & Moens, 2012) and Nigeria (Akyazi, Ansari, Ahmed, Crow, & Mekete, 2012), the number of African surveys has been small when compared with the other continents (with the exception of Antarctica). As far as the authors are aware, there is no information on the occurrence and diversity of EPNs in Rwanda.…”

Entomopathogenic Nematodes Combined with Adjuvants Presents a New Potential Biological Control Method for Managing the Wheat Stem Sawfly, Cephus cinctus (Hymenoptera: Cephidae)

“…Steinernema and Heterorhabditis spp. are reported to infect banana weevil larvae ( Cosmopolites sordidus Germar) inside the plant stems [25]. Field applications of S .…”

“…EPNs have been used successfully to manage a large number of insect pests, including some insects that live above-ground and stem borers [23, 24, 25, 26, 27, 28]. EPNs are generally applied to above ground vegetation using conventional spray equipment, but EPNs will only survive for a few hours on exposed foliage because they desiccate quickly and they are sensitive to UV rays [29, 22].…”

A farmer participatory research approach to assess the effectiveness of field sanitation and regular trapping on banana weevil populations

“…The average number of weevils captured in a trap per month was assumed to have a normal distribution. The model is expressed as follows: y ijt = µ + α i + β·t + (αβ) i ·t + S j + (αS) ij + (βS) j ·t + ε ijt (where y ijt is the average number of weevils captured in a trap of type i [i = 1 (CD), i = 2 (DOS), i = 3 (PS)], at site j [j = 1 (SUA), j = 2 (Kyimo), j = 3 (Bujela)], and in month t (t = 5,6,7,8,9,10,11,12,13,14)). Observations (= average number of weevils per trap per month) was weighted according to the number of traps the average capture was based on.…”

“…Several methods to control weevil damage have been developed or explored, including pesticides [9], botanicals [10], biological control [11], endophytes [12], entomopathogenic fungi [13] and entomopathogenic nematodes [14]. Only a few methods are at the applied stage, and most methods are impractical for small-scale farmers in countries such as Tanzania due to the lack of distribution systems and high costs.…”