Biological control of black weevil larvae (cosmopolites sordidus) with the application of heterorhabditis bacteriophora entomopathogenic nematodes on banana crop

Abstract

The need to reduce the excessive number of insecticide applications for its adverse effects on the environment and human health has led us to seek other alternatives in combating insect pests. One option for the biological control of them is entomopathogenic nematodes of H. bacteriophora gender, offering high potential for use. The objective of this research was to biologically control the black weevil larvae (C. sordidus) using the H. bacteriophora nematode on banana crop to reduce insecticide applications. We conducted a field bioassay to choose a crescent surface at 1,5 m2 around each plant that was covered with a solution of 5 liters by spraying it with a high volume hand pump without nozzle. As an indicator to realize the action of nematodes semicircular type traps were made that were placed inside the crescent surface, the weevils that were in them were collected and taken to the laboratory and kept there eight days to see if they died within this period of time. The doses used were 66 667, 83 333 and100 000 nematodes/plant in a randomized complete block design. The dose of H. bacteriophora that caused the great dead adult weevils was 100 000 nematodes/plant, with an average of 6,69 per plant 15 days after the application of nematodes in field. The corms of banana plants where nematode doses were applied were not pierced by black weevil larvae. The symptoms caused by the nematodes on the dead bodies of black weevil adults was at eight days, presenting a brown coloration. The higher cost ofimplementation was obtained with the dose of 150 million ofnematodes per hectare, with a value of $ 238.