Warsito Tantowijoyo PhD Candidate,
Funded by the Australian Centre for International Agricultural Research.

Among genus Liriomyza, there are more than 300 species, but only 5 species are considered truly polyphagous.  Two polypaghous that commonly found in Indonesia are Liriomyza huidobrensis Blanchard and L. sativae Blanchard and both species economically become a serious pest, attacking many important crops. Therefore the study aimed to examine the importance of altitudinal ecological factors influencing the distribution and interactions of agromyzid leaf miners and their parasitoids.

The study was conducted in the Dieng mountainous area located in Central Java, Indonesia which the altitude ranges from 0 to 3,200 m ASL.  Two main trials were carried out, monthly surveys of population of leaf miner larva and imagoes and natural enemies at 100 meter altitude distance by collecting damaged foliages and direct trapping and field and laboratory competition trials by releasing L. huidobrensis and L. sativae in particular proportions. Environmental variables, such as temperature and habitat composition were intensively recorded to support the study.

In progress, with bigger variations on thorax length and wing centroid, L. huidobrensis tended to colonize in wider altitudes (200-2200 m ASL) compared to L. sativae which was only found in low altitudes (200-1000 m ASL). Along altitude, the temperature lapse rate (TLR) was counted around 5.4^oC with a clear gap at the lowest altitude (119 m ASL) and the highest altitude (2166 m ASL) at around 15^oC-20^oC.  Different crop compositions were also recorded in this study, which in high altitude were mostly dominated by monoculture of potato and cabbage, while in low altitude, host crops were patchy scattered on staple crops, such as corn, rice and cassava. Leaf miner was found attacking cucumbers (Cucumis sativus), petsai (Brassica chinensis), long beans (Vigna sinensis), snap bean (Phaseolus vulgaris), red beans (V. sinensis), potatos (S. tuberosum), and broad beans (V. faba L). 

Fifteen species of parasitoids was found associated with leaf miner.  The parasitoids fell into three families: Hemiptarsenus varicornis, Cirrospilus ambiguus, Neochrysocharis formosa, Asecodes delucchii, N. beasley, , Chrysocharis sp., A. erxias, N. okazakii, Quadrastichus liriomyzae and Closterocerus sp. are from the Eulophidae family, Gronotoma micromorpha is from the Eucolidae family, and Opius sp. x. is from the Braconidae family. owever, among those, there are only four dominant species which distributed in different altitude and in a particular altitude, it was shared more 20% in the composition.  The dominant parasitoids are N. beasley, A. delucchii, N. Formosa, G. micromorpha, H. varicornis and Opius sp. x.  The diversity index of parasitoid negatively associated with altitude and in high altitudes only Opius sp was abundantly found. However, the percentage of parasitism increased along altitudes reaching more 30% in above 1800 m ASL.

Even though the comprehensive analysis is still needed, L. huidobrensis likely had a bigger competition capacity showed by increases of their proportion both in laboratory and field experiment.