58 



vlrescens (F.)» and to larvae of S strain (LD^^ 0.24) of the bollwonn, H. zea 

 (Boddie) . The chemical was highly toxic (LD-^, 0.13) to adult lady beetles, 

 Hlppodamla convergens Guerin-Meneville, but relatively inactive (LD^q 2.4) 

 against the boll weevil, Anthonomus grandis grandls Boheman. Studies with 

 topically applied •'■^C-labeled sulprofos suggested that these differences in 

 toxicity were related to the rates at which the chemical was absorbed by the 

 insects. In the greenhouse, foliar applications of sulprofos on potted cotton 

 plants were generally more effective against 3rd-stage (S) tobacco budworm 

 larvae than against adult boll weevils. Field tests of sulprofos (0.56, 1.12 

 kg/ha) against natural populations of Heliothis spp. in cotton demonstrated 

 that control was ca. equivalent to that obtained with the synthetic pyrethroids 

 permethrin (0.11, 0.22 kg/ha) and fenvalerate (0.11 kg/ha) or a standard in- 

 secticide mixture of toxaphene, methyl parathion, and chlordimeform (0.86 + 

 1.68 + O.IA kg/ha). 



101. . 1980. Fate of diflubenzuron after application to cotton and the 



boll weevil. Southwest. Entomol. Suppl. 1: 2-7. 

 Very little diflubenzuron is absorbed by the leaves of cotton plants treated 

 by foliar application. This compound adheres well to foliage and is highly 

 resistant to photodegradation on foli'.^ surfaces and to metabolism within 

 "leaves. Hov;ever> this unusual persistance of dif lubenzuron».on cotton does 

 not result in the accumulation of significant residues in seeds. The chemical 

 is somewhat stable in the soil as long as it is associated with plant litter 

 and it does not leach appreciably. Diflubenzuron is active against female 

 boll weevils exposed by either ingestion or co- tact. It inhibits the hatch 

 of eggs of exposed females if sufficient concentrations are secreted into the 

 eggs. As time after exposure is extended, treated females recover fertility, 

 and retreatment is required to maintain a significant suppression of egg hatch. 



