An Ecological Study of Cabbage Looper and Imported Cabbageworm Populations on Cruciferous Crops in Southern California1

Publisher Website
Google Scholar
Abstract
Ecological studies of the cabbage looper, Trichoplusia ni (Hubner), and imported cabbageworm, Pieris rapae (L.), on cruciferous crops were conducted in southern California during 1963-64. Eggs, larvae, and pupae were collected at random from consecutive plantings for 1 hr. at weekly intervals for 1 yr, and held for completion of development and/or parasite emergence. Totals of 566 cabbage looper eggs and 2439 imported cabbageworm eggs were collected, of which 93.5% and 92.0% hatched, 5.6% and 7.5% failed to hatch, and 0.9% and 0.4% were parasitized for total egg mortalities of 6.5% and 7.9% respectively. The imported cabbageworm egg population reached a peak of 179 eggs/1 hr search on July 30 and 72 eggs for the cabbage looper on August 6. Trichogramma pretiosum Riley was the only parasite reared from the egg stage. Totals of 1737 larvae and 68 pupae of the cabbage looper, and 960 larvae and 181 pupae of the imported cabbageworm were collected. Six generations of each species occurred during the year, the imported cabbageworm reaching a peak of 78 larvae/1 hr search on July 24, and 130 for the cabbage looper on Sept. 26. Twenty-six percent of the cabbage looper larvae were parasitized, of which 90% were by tachinids and 10% by hymenopterous parasites. Pupae were not parasitized. Twenty-three percent of the imported cabbageworm larvae and 51% of the pupae were parasitized for a total of 74% parasitization. Tachinids accounted for 57% of the total larval and 5% of the pupal parasitization, and hymenopterous parasites 43% and 46%, respectively. Voria ruralis (Fallen) and Copidosoma truncatellum (Dalman) were the principal tachinid and hymenopterous parasites, respectively, on cabbage looper larvae, and Madremyia saundersii (Williston) and Apanteles glomeratus (L.) on imported cabbageworm larvae. Pteromalus puparum (L.)was the main pupal parasite of the latter. Altogether, 10 parasites were reared from the cabbage looper and 10 from the imported cabbageworm.

This publication has 0 references indexed in Scilit: