Potential of entomopathogenic nematodes for the control of the banded fruit weevil,Phlyctinus callosus(Schönherr) (Coleoptera: Curculionidae)

Abstract

Entomopathogenic nematodes (EPN) were evaluated for their potential use as biological control agents against Phlyctinus callosus, the banded fruit weevil (BFW). The susceptibility of larvae and adults to EPN was evaluated using 400 infective juveniles (IJ) per insect after 4 days in 24-well bioassay trays. The nematode isolates used were all able to infect BFW, although the larvae were found to be more susceptible than were the adults. The percentage mortality for BFW larvae ranged from 41 to 73% and for BFW adults from 13 to 45%. The most effective isolate, SF41 of Heterorhabditis zealandica, was used to investigate the effect of vertical movement of nematodes in sand and sandy loam soil, at specified concentration and temperature. A higher (82.2 ± 0.084%) percentage mortality rate was obtained with the sandy loam soil, than with the use of sand (67.5 ± 0.12%). The LD50 and LD90 values after 4 days of incubation were 96 and 278 IJ/50 μl, respectively. Nematodes were inactive below 15 °C, with the highest mortality of 74 ± 0.081% for BFW larvae recorded at 25 °C. Heterorhabditis zealandica was able to complete its life cycle successfully in sixth-instar BFW larvae after a period of 22 days. The study showed BFW larvae not to be as susceptible to nematode infection as they need a high concentration (400 IJ/larva) and 4 days to give effective control.

The Potential Use of Entomopathogenic Nematodes to Control Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae)

“…1, 2013 complement earlier work conducted on different mealybug species, specifically on P. viburni by Stokwe (2009) and on P. citri by Van Niekerk and Malan (2012). Heterorhabditis zealandica and S. yirgalemense were among the four most pathogenic species in the study conducted by Stokwe (2009), while they were the best two species, producing very high percentages of mortality, of 91% and 97% respectively, in Van Niekerk and Malan's (2012) Malan et al (2011) showed S. yirgalemense to be highly virulent against false codling moth, Thaumatotibia leucotreta (Meyrick), while the work conducted by Ferreira and Malan (2013) held Mixture of recovered pre-adults and adults (females containing eggs) 4…”

“…Despite this outcome, both candidates performed well, and H. zealandica should not be disregarded completely, especially when considering previous work that has been performed and the successful results that have already been achieved. Ferreira and Malan (2013) conducted soil column tests by inoculating P. callosus larvae placed at different depths, with the deepest at 15 cm, with H. zealandica, which were then left for seven days. No significant differences in mortality were found between the burial depths.…”

Biological Control ofPhyllophaga vetula(Horn)1, and Lethal Concentrations and Times of Entomopathogenic Nematodes

“…(2001) found 44% of larvae of pecan weevil, Curculio caryae (Horn) (Coleoptera: Curculionidae), were killed when H. megidis was applied at a concentration of 1,500 per larva, a lower percentage than for P. vetula in this study; however, the nematode and the pest in the two experiments were different. Ferreira and Malan (2014) found that H. zealandica (SF41) and H. bacteriophora (SF134 and SF351) killed 73.3 ± 0.066, 66.6 ± 0.098, and 41.6 ± 0.127%, respectively, of larvae of banded fruit weevil, Phlyctinus callosus (Schönherr) (Coleoptera: Curculionidae). With all three species, 400 infective juvenile nematodes were applied per larva and the number killed was counted 4 days later.…”

“…S. glaseri, with LC 95 of 1,035, was nearest this recommendation. Ferreira and Malan (2014) reported LC 50 and LC 90 of 96 and 278 for H. zealandica (SF41) after 4 days to control P. callosus. De Waal (2008) reported LC 50 and LC 90 of 72 and 275, respectively, to control codling moth larvae.…”

The Potential Use of Entomopathogenic Nematodes to Control Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae)

“…2, 2013 complement earlier work conducted on different mealybug species, specifically on P. viburni by Stokwe (2009) and on P. citri by Van Niekerk and Malan (2012). Heterorhabditis zealandica and S. yirgalemense were among the four most pathogenic species in the study conducted by Stokwe (2009), while they were the best two species, producing very high percentages of mortality, of 91% and 97% respectively, in Van Niekerk and Malan's (2012) Malan et al (2011) showed S. yirgalemense to be highly virulent against false codling moth, Thaumatotibia leucotreta (Meyrick), while the work conducted by Ferreira and Malan (2013) held Mixture of recovered pre-adults and adults (females containing eggs) 4…”