Crop loss assessment of lixus incanescens boh. (Coleoptera : Curculionidae)‎ on sugar beet, beta vulgaris L.

الملخص EN

Sugar beet weevil, Lixus incanescens Boh., is one of the most important pests of sugar beet in many parts of Iran and neighbor countries.

The leaf and petioles of sugar beet are attacked by adults and larvae.

The economic losses due to L.

incanescens damage have not been estimated in Iran.

Moreover, chemical application is currently the conventional control method.

Therefore, it was necessary to assess crop losses.

This project was done in a sugar beet field during 2006 and 2007 in Tehran (Iran) using fenvalerate EC20 % (1 L / ha).

The number of infested petioles in 50 plants was counted in treated and untreated plots once a month until the harvesting time.

Then, the weight (kg), sugar content (%), sugar extraction coefficient (%) and white sugar content (%) of roots were measured.

The results showed that in both years, there was significant difference between the mean number of infested petioles in each plant in treated (0.47 ± 0.03 and 0.047 ± 0.003 in first and second years, respectively) and untreated (6.53 ± 0.33 and 4.82 ± 0.52 in first and second years, respectively) plots.

But, there were not significant differences regarding the indices including weight, sugar content, sugar extraction coefficient and white sugar content.

The cost-benefit ratio was 2.65- 3.7, when the field had an average of 5-6 infested petioles per plant.