Cecidochares connexa (Macquart) (=Procecidochares connexa (Macquart))

Chromolaena stem gall fly

Diptera: Brachycera: Tephritidae

Adult female with orange-yellow head, eyes bright reddish. Thorax black with conspicuous white setae. Abdomen black, posterior margins of first four tergites with white areas, ovipositor subconical and prominent. Wings with black fasciae. Male similar, except abdomen dark brown and apically broadly rounded.

   
Adult female        Adult male          Mating pair
   Puparia of the fly inside the gall
 Pupal case inside the gall
   Galls with window

Introduced in Indonesia, Thailand, Papua New Guinea, East Timor, and India. It was introduced in India in 2002 (Bhumannavar et al., 2004).

The stem gall fly is specific to Siam weed, Chromolaena odorata, which is a major invasive weed. The weed is a native of tropical America and is a serious invasive weed in India, particularly in the northeastern and southern states. In India, host-specificity tests carried out on 75 host plants belonging to 29 families indicated that the gall fly could feed and reproduce only on C. odorata. Its biology under quarantine has been studied in India (Bhumannavar et al., 2004).

Limited field releases have been carried out in some states such as Assam, Kerala and Karnataka and recoveries made in some places in Karnataka and Kerala, in which the fly has been found promising. Several plant growth parameters were found to be severely affected in gall fly-infested plants. Ormyrus orientalis Walker (Hymenoptera: Ormyridae) has been found to parasitise this species with moderate to high levels of parasitism.