Studies on the population dynamics of the potato tuber moth (Phthorimaea operculella Zell. (Lep., Gelechiidae)) in the Republic of Yemen.
The development of Phthorimaea operculella in Yemen was strongly determined by climatic factors. Reproduction took place in the summer between June and August, and there were 8 generations within 1 year. The period of development from egg to adult took less than 30 days in the summer and at least 70 days in the winter. Non-harvested potato tubers served as places for hibernation. Secondary host plants, such as Datura stramonium, were destroyed by frost and did not contribute to hibernation. The build-up of the pest population resulted predominantly from the farmers' practice of using infested seed potatoes. The parasitization rate by Diadegma molliplum [?D. mollipla] and Chelonus phthorimaeae reached 30-40% at the beginning of the vegetative period from March to April, and 60-80% in the 2nd cultivation period from August to September. Other natural enemies included Carabidae, Coccinellidae, Staphylinidae, Syrphidae and Chrysopidae, and a specific granulosis virus belonging to the Baculoviridae occurred endemically. These factors are discussed as part of an integrated pest management programme for P. operculella.