Two new Lasioptera species infesting tomato: Lasioptera tomaticola and L. yoichiensis
Two new species of gall midges (Diptera: Cecidomyiidae) infesting tomato (Solanum lycopersicum) crops have been described from two different regions of the world: Lasioptera tomaticola infesting tomato and cucumber (Cucumis sativus) in the Mediterranean region (Greece, Romania and Türkiye) and Lasioptera yoichiensis infesting tomato in Japan (Hokkaido).
- Lasioptera tomaticola
In 2001, unusual damage caused by insect larvae was first observed in cucumber (Cucumis sativus) crops in Trifylia (Western Peloponnesus), Greece, and was attributed to an unidentified species of Lasioptera. In the following years, this insect was observed in glasshouse cucumber and tomato crops in Trifylia, as well as in glasshouses close to Athens. Damage is caused by larvae living gregariously inside plant stems. Their feeding activity induces necrosis of plant tissues, wilting, stem breakage and reduction of fruit production. Damaged plant tissues are also invaded by fungi. Similar damage and the presence of a Lasioptera species were then also recorded in Türkiye and Romania. In 2020, this insect was described as new species and called Lasioptera tomaticola.
In Türkiye, L. tomaticola was first found in 2012 in tomato-producing areas in Mersin and then in Antalya and Çanakkale, as well as in cucumber in Izmir. In Romania, the first signs of infestation were observed in 2011 in Dâmbovița county. In 2020, L. tomaticola was also found in tomato and cucumber samples collected from Dolj county. Surveys carried out from 2020 to 2022 detected the pest in greenhouse tomato and cucumber crops in Timiş county.
Genetic studies identified at least 6 different haplotypes within L. tomaticola, indicating that it has been present in the Mediterranean region for a long time before its infestations were noticed. Although these studies could not conclude as to whether L. tomaticola originates from the Palaearctic region or not, the appearance of new damage in crops that have been widely grown in the Mediterranean Basin for many years might suggest an accidental introduction or a change in host range.
- Lasioptera yoichiensis
In 2010, necrosis on tomato stems was observed in a farmer’s glasshouses in Yoichi, Hokkaido, Japan. In 2012, damage on tomato stems and fruit was observed in other glasshouses in Yoichi and Niki, a neighbouring town. Damaged stems and fruit contained larvae and pupae of a Cecidomyiidae which was identified as a new species and called Lasioptera yoichiensis. For the moment, the fungal pathogens that are observed in association with L. yoichiensis damage have not been identified. L. yoichiensis has only been found on tomato and in Hokkaido (Yoichi and adjacent areas). Genetic studies have identified only one haplotype. Considering its limited distribution in Hokkaido and its low genetic diversity, it is suggested that L. yoichiensis has recently been introduced into Japan, but its possible origin and pathways of introduction remain unknown.
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