J. R. Young

Labeling of Trichogramma pretiosum by Rearing on Eggs from 32P-fed Adults of Heliothis zea,,

Heliothis zea (Boddie) female moths were labeled with /sup 32/P as orthophosphate using a feeding process and their eggs used as hosts in the rearing of Trichogramma pretiosum Riley. The percentage radioactive eggs oviposited by H. zea moths corresponded almost identically with the percentage radioactive parasites emerging from the eggs. The average counts per minute for the eggs and parasites were closely related with the high 1st day counts, declining progressively on following days of the study. Thus, Trichogramma can be reared on /sup 32/P-labeled H. zea eggs without affecting the parasites ability to further parasitize H. zea eggs under laboratory conditions. There is no difference in the number of parasites emerging from control eggs and /sup 32/P-labeled eggs when used in the rearing of Trichogramma pretiosum. Greenhouse data suggest that this process might be used to monitor parasite activities in the field.

Field experiments on the insecticidal control of insects attacking peas, snap and lima beans.

Methyl Trithion® ( O,O -dimethyl S -( p -chlorophenylthio) methyl phosphorodithioate), dimethoate, phosphamidon, and Thiodan® (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin-3-oxide), gave high reductions of pea aphid ( Macrosiphum pisi (Harris)) on peas. Dibrom® (1,2,-dibromo-2,2-dichloroethyl dimethyl phosphate), phosphamidon, Dilan® (1 part of 1,1-bis( p -chlorophenyl)-2-nitropropane plus 2 parts of 1,1-bis(p-chlorophenyl)-2-nitrobutane) and ethion showed considerable effectiveness against the potato leafhopper ( Empoasca fabae (Harr.)) on snap beans; dimethoate gave best control. Sevin® (1-napthyl methylcarbamate) and DDT gave 95% to 100% reduction of corn earworm ( Heliothis zea (Boddie)) injury to green beans. Lesser reductions were obtained with Methyl Trithion, ethion, dimethoate, Dylox® (dimethyl 2,2,2-trichloro-1-hydroxyethylphosphonate), Thiodan, and phosphamidon. On lima beans 98.9% to 99.4% clean pods were obtained by sprays of DDT and Sevin repeated at 10-day intervals. There was no significant difference between 1- and 2-pound per acre rates of application of Sevin and DDT against the corn earworm on lima beans.