Submitted to: Florida Entomologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/20/2007
Publication Date: 3/1/2008
Citation: Jenkins, D.A., Shapiro Ilan, D.I., Goenaga, R.J. 2008. Efficacy of entomopathogenic nematodes versus Diaprepes abbreviatus (Coleoptera:Curculionidae) larvae in a high clay-content Oxisol soil: Greenhouse trials with potted Litchi chinensis. Florida Entomologist. 91:75-78. Interpretive Summary: Soil-borne pests, such as the larvae of the citrus root weevil, cause extensive damage to the roots of fruit trees, often killing young seedlings. Current treatments are limited to soil applications of highly toxic pesticides that are detrimental to the environment, hazardous to applicators, and have limited effect on the larvae. Although nematodes have been used to control larvae of citrus root weevil in Florida, most people thought that the heavy clay soils of Puerto Rico would prohibit their use there. These trials show that a number of species and strains of nematodes are capable of significantly increasing the mortality of citrus root weevils in high clay-content soils, several even providing complete control at relative low rates. This suggests that nematodes provide a viable biological control method for soil-borne pests of fruit trees in Puerto Rico.
Technical Abstract: In a prior study, laboratory trials indicated that nine strains and species of entomopathogenic nematodes (EPN) were pathogenic against larvae of Diaprepes abbreviatus in an Oxisol from Puerto Rico. In this study we tested the efficacy of five species/strains of EPN in an Oxisol under greenhouse conditions. The nematodes were applied at 100 infective juveniles per cm2 to 19 liter pots containing a high clay-content Oxisol (69% clay) and three seedlings of Litchi chinensis. All treatments significantly reduced the mean proportion of D. abbreviatus larvae surviving compared to untreated controls (percent surviving for all treatments ranged from 0 to 36 + 6 SEM). This suggests that EPN’s may play a role in integrated pest management strategies against soil-borne arthropods in tropical soils with high clay content.