Keywords : Phalaenidae

Mortality factors on the hibernating larvae of the corn borer Sesamia cretica Led. (Phalaenidae: Lepidoptera)

Hameed H. Al; Karboli

ANBAR JOURNAL OF AGRICULTURAL SCIENCES, 2010, Volume 8, Issue 1, Pages 249-257

This study was conducted on the hibernating larvae of the corn borer, Sesamia cretica Led. after the harvest of sorghum crop at the experimental fields of the college of Agriculture in Abu-Ghraib, Baghdad of the fall season 2008. Laboratory results showed the isolation and identification of two entomopathogenic fungi, Metarhizium anisopliae (Metchnikoff) Sorokin, Verticillium lecanii, the bacteria Bacillus subtilis and the Ichneumonid wasp Coelichneumon sp. (Ichneumonidae: Hymenoptera) from the hibernating larvae of the corn borer S. cretica which considered to be as a new records on the corn borer in Iraq. Symptoms of the infection on hibernating larvae begans on January and continued till the emergence of the first generation of the borer. Laboratory inspection of 706 hibernating larvae showed mortalities of 7.22%, 0.70%, 0.99% and 0.42% for entomopathogenic fungi, bacteria, Ichneumon wasp Coelichneumon sp and for unknown reasons respectively, However fungal parasitism was considered to be the most important and could have a role as a mortality factor for the hibernating larvae that decrease adult emergence from the hibernation. Results of the pathogencity test of M. anisopliae on different stages of the borer revealed that fungus suspension caused significant and high mortality rates on eggs, reaches more than 98% after 3 days of treatment. Mortality of the fifth instars' larvae after 6 days was 23.3%. Percentage of treated larvae reached pupal stage was 63.3% compared with 90% for the control treatment. However pupal stage found to be less sensitive to pathogen infection, mortality rates found to be decreased to only about 6.6%. The possible use of the entomopathogenic fungi M. anisopliae after its formulation as a biocontrol agent for the corn stem borer and other insect pest was also discussed.

The influence of the biological insecticide Agreen and two growth regulators, Cascade and Insegar, on corn stalk borer Sesamia cretica Led. (Phalaenidae: Lepidoptera).

A. A. Ali

ANBAR JOURNAL OF AGRICULTURAL SCIENCES, 2007, Volume 5, Issue 1, Pages 267-278

Several studies were conducted to investigate the influence of Agreen (Bacillus thuringicasis agypti ) and the growth regulators, Cascade (Flufenoxuron) and Insegar (Fenoxycarb) on some biological aspects of corn stalk borer, Sesamia cretica Led. Results indicated no significant effect of Agreen on egg hatch. However an obvious reduction in hatching percentage was recorded for one day and four days old eggs treated with Cascade and Insegar.Hatching percentages were 64 and 69 % for one day and four days old eggs treated respectively with Cascade .The growth regulator Insegar resulted in 75 and 85 % of egg hatch for the two stages respectively .Results also showed that the susceptibility of first instar larvae was higher than that of the fourth instar larvae. The growth regulator Cascade showed highly influences on treated stages with percent of killing reached 81.5 and 82.1 % for 1st and 4th instar larvae respectively. A continous effects were also recorded on subsequent stages originated from individuals treated with Agreen and growth regulators.These include; delayed larval and pupal development, increased pupae and adults deformations.and reduced adults longevity and females fecundity. However, females originated from larvae treated with the growth regulators failed to lay any egg and died shortly after emergence. Results of this study will hopfully improve the management system for the control of corn stalk borer.