Batrachedra amydraula Meyrick
Common name: Lesser date moth.
Taxonomic position: Insecta, Holometabola, Lepidoptera, Batrachedridae.
Geographical distribution: From North Africa through the Middle East to Iran, Iraq and to Saudi Arabia, India and Pakistan.
Host plants: Date and Derris trifoliata Lour.
Morphology: This pest has a wingspread of 11-14 mm and is grey-brown, marked by a gray longitudinal central stripe on both and long fringes. The fully-grown larvae are 8-12 mm long, white-grey. Each segment bears several tubercles that bear setae. Prolegs occur on abdominal segments III-VI and on the last segment.
Life history: Eggs (25-45/ female) are laid on immature date fruits and strands, individually or in batches of 2-5. They feed on the developing fruit, and spin a silky cocoon at the base of the fronds or in the soil in order to pupate. The pest raises 3 annual generations. Development from egg to adult takes about 6 weeks at 25°C. Third generation mature larvae (occurring during late July to early August) do not pupate, but enter diapause. As diapause terminates in the spring of the following season, the larvae pupate and the emerging adults infest the newly set date fruits. The shortening of daylight during late summer is the main factor inducing larval diapause, whereas the increase in day length in early spring induces diapause termination.
Economic importance: This moth is a major pest of dates and may cause 50-75% losses due to fruit drop. Injury is inflicted by the larvae that spin a web around the fruits and attaches them to the strands or to other fruits. They then enter the fruit near its sepals, or less frequently at other sites, and feed on the pulp and immature seeds. When small fruits are infested they usually remain attached to the strand by silken threads. In their first generation the larvae infest several fruits before completing development, thus increasing the damage. Large fruits usually drop after being attacked. Heavily infested fruit bunches cease to grow and dry. Dates in stores may also be affected.
Management
Monitoring: With sex pheromone traps.
Horticultural methods: Bunch remnant pruning and bunch covering, when applied along with chemicals, greatly decreased pest infestation in Iran. Other methods include destroying the larvae by removing them from the fibrous strands around the bases of the terminal fronds, wherein they diapause.
Plant resistance: Date palm varieties (like “Sammany”) with a relatively higher wax content, were more tolerant to the pest than those with less wax (like “Hayany”). Furthermore, the tolerant variety had a better structure of the outer and inner layers of fruits tissues.
Chemical control: This moth has developed much resistance to pesticides. Plastic strips impregnated with the organochloride dichlorvos (20%), suspended within the bunch, also provide satisfactory control, as do insect growth regulators. Spinosad controlled the pest In Egypt.
Biological control: Two larval ectoparasitoids attack B. amydraula in Israel: Bracon sp. (Braconidae) and Goniozus legneri (formerly listed as Parasierola swirskiana Argaman). The former attacks larvae of various lepidopteran species; its effect on pest numbers is not known. Inundative releases of the egg parasitoid Trichogramma cacoeciae Marchal (Trichogrammatidae](entry/Trichgrammatidae) are continuing. Anthocoridae, mostly Orius spp., as well as spiders, contribute to the natural control of B. amydraula in immature dates. Various products of Bacillus thuringiensis were effective in controlling the pest, especially those infesting small fruits of which the pests consumes several. An Israeli-developed Bt blend, “Bitayon”, based on 20% concentrated liquid mixed with wheat flour and yeast extract (as a phagostimulant), added to date pollen, provided date fertilization as well as protection for small fruits. The blend is harmless to parasitoids and predators.
References
Blumberg, D. 2008. Review: Date palm arthropod pests and their management in Israel. Phytoparasitica 36: 411-448.
Eitam, A. 2001. Oviposition behavior and development of immature stages of Parasierola swirskiana, a parasitoid of the lesser date moth Batrachedra amydraula. Phytoparasitica 29: 405-412.
Harhash, M., Mourad, A.K. and Hammad, S.M. 2003. Integrated crop management of the lesser date moth Batrachedra amydraula Meyr. (Lepidoptera: Cosmopteridae) infesting some date-palm varieties in Egypt. Communications in Agricultural and Applied Biological Sciences 68: 209-21.
Latifian, M. 2012. The effects of cultural management on the lesser date moth (Batrachedra amydraula Myer) infestation. Emirates Journal of Food & Agriculture 24: 224.
Shayesteh, N., Marouf, A. and Amir-Maafi, M. 2010. Some biological characteristics of the Batrachedra amydraula Meyrick (Lepidoptera: Batrachedridae) on main varieties of dry and semi-dry date palm of Iran. Proceedings of the 10th International Working Conference on Stored Product Protection, pp. 151-155.