Mortality Rates of the Coffee Leaf Miner

The coffee leaf miner is a pest of coffee plants in neotropical countries, it can have a devastating impact and in areas of great infestication in Brazil can lower the yield of the coffee plant by up to 80%. The pest is mainly controlled by insecticides, but this action is not likely to be effected indefinitely due to a build up of resistance by the coffee leaf miners to insecticides. Pereira and colleagues have taken a look into the seasonable mortality of the pest to better understand it and lay the groundwork for better biological control of the species.

Findings of Research into the Coffee Leaf Miner Pest

It was found that there was a great variation in the mortality rates of the coffee leaf miner in the rainy and dry seasons, with deaths being much higher in the former. This was mainly due to there being a higher mortality in the eggs and larvae. For the pupae this was the opposite, with mortality being lower in the rainy season. The location of the leaf miner on the coffee plant did not seem to matter with regards of the mortality rate. It was found that overall in the rainy season mortality was 94.3% compared with 89% in the dry season.

Mortality in Coffee Leaf Miner Eggs

In the rainy season it was found that the major cause of mortality in the eggs was egg inviability and rainfall. This contrasts to the dry season where the major cause of coffee leaf miner egg mortality is predication and egg inviability.

For larvae the main causes of death in the rainy season were rainfall, incomplete moulting and parasitism. In the dry season incomplete moulting, rainfall and predation were the major factors that contributed to the mortality rates of the coffee leaf miner.

It is suggested by Pereira that as parasitic wasps and hymenopteran parasitoids prey on the coffee leaf miner, that they may be useful as biological controls of the pest, and they should be taken into account by farmers when they are trying to control infestications of the pest.

References
Pereira et al. (2007) Seasonal mortality factors of the coffee leaf miner, Leucoptera coffeella. Bulletin of Entomological Research 97, 421–432