| Abstrakt: |
The pest status of Lygus bugs as a Texas High Plain cotton pest has increased in recent years. Insecticides are commonly used for Lygus population management in this region. Six commonly used insecticides, Vydate, Brigade, Orthene, Endosulfan, Carbine and Ammo, at high and low concentrations (H and L), were tested for their field weathered activity on adults of Lygus hesperus. In the laboratory, L. hesperus adults caged in petri dishes containing excised cotton leaves. The cotton field was sprayed and leaves collected at 0, 3, 7, and 14 days after treatment (DAT), and were tested for any residual insecticide activity on adult Lygus. Check plots were untreated. Observations on the mortality of the insects were taken until the fifth day of exposure in petri dishes. However, for comparison purposes, mortality data at 48 hours after exposure (HAE) were utilized for all insecticides except Carbine for which 96 HAE readings were utilized. Results indicated that the insecticide residues remained on the plant for 7 days. Ammo (H and L), Vydate (H) and Orthene (H) recorded significantly higher mortality than all other treatments. Carbine was the least toxic compound tested at the 48 HAE observations, but at 96 HAE, its higher rate provided 88.4 and 73.4% mortality at 3 DAT and 7 DAT, respectively. The effectiveness of Endosulfan, Orthene and Brigade lasted less than a week after which these compounds, even at their higher dose, failed to provide >50% mortality. Rainfall (1.07 inches) recorded between 7 DAT and 14 DAT may have contributed to the drop in the mortality for the 14 DAT samples. [ABSTRACT FROM AUTHOR] |
