Studies on the population dynamics of the potato tuber moth (Phthorimaea operculella Zell. (Lep., Gelechiidae) in the Republic of Yemen

Abstract The development of the potato tuber moth is strongly determined by climatic factors. In Yemen, mass propagation takes place in summer between June and August. Within 1 year, the potato tuber moth develops eight generations. The period of development from the egg to the adult stage takes less than 30 days in summer and at least 70 days in winter. After the crop‐free winter season (November‐February), the population has to build up again in the field. To some extent, non‐harvested tubers serve as places for hibernation. Secondary host plants as Datura stramonium L. are destroyed by frost and do not contribute to hibernation, The build‐up of the potato tuber moth population results predominantly from the farmers' practice of using infestea seed potatoes. The parasitoids Diadegma molliplum Holm. (Hym., Ichneumonidae) and Chelonus phthorimaeae Gah. (Hym., Braconidae) reach parasitization rates of 30–40% at the beginning of the vegetation period, from March to April, and 60–80% in the second potato‐cultivation period from August to September. Along with numerous entomophages of Carabidae, Coccinellidae, Staphylinidae, Syrphidae and Chrysopidae, a specific granulosis virus occurs endemically in the production system. These factors are discussed as part of an integrated pest‐management programme for the potato tuber moth.