Biology and rearing of the cogongrass gall midge, Orseolia javanica Kieffer & Docters van Leeuwen-Reijnvaan (Diptera: Cecidomyiidae)

ABSTRACTImperata cylindrica (L.) Beauv. (Poaceae) is one of the most harmful weeds in the world because of its ability to spread and form high density, monospecific stands that exclude other vegetation. The cogongrass gall midge, Orseolia javanica Kieffer & Docters van Leeuwen-Reijnvaan (Diptera: Cecidomyiidae), is a stem galling insect that is only known to develop in cogongrass and has only been found on the island of Java in Indonesia. The midge attacks very young shoots, which stimulates abnormal growth, resulting in the formation of a purplish, elongate stem gall tappered to a point at the apical end. The aim of the current research was to describe the biology of the midge and develop a rearing method. Orseolia javanica completed its life cycle in 12-38 days with average egg, larval, and pupal periodes of 4.0 ± 0.0, 13.5 ± 3.8, and 8.6 ± 6.6 days (mean ± SD), respectively. Mated female, unmated female, and male longevities were 1.7 ± 0.47, 1.2 ± 0.41, and 1.0 ± 0.00 days (mean ± SD). Galls began to appear 29 days after larval infestation, and stem death coincided with emergence of the adult midge. The midge may have potential for biological control of cogongrass if future studies confirm a restricted host range.

Nomenclature and redescription of the Jaumave Valley (Mexico) populations of Astrophytum myriostigma (Cactaceae)

Astrophytum myriostigma Lem. subsp. quadricostatum (H. Moller) K. Kayser and Astrophytum myriostigma Lem. subsp. tamaulipense K. Kayser are both validly published names, but the subspecific epithet quadricostatum has priority (published in 1927) over tamaulipense (published in 1932) and is, therefore, the correct name for the Jaumave Valley Bishop’s Cap. The Jaumave Valley populations have differentiated from subsp. myriostigma in several morphological characters. Both taxa have distinctly different stem morphology as seedlings but become similar in early maturity, although older Jaumave plants are usually slightly taller and more slender than subsp. myriostigma. As seedlings several years of age, the Jaumave plants have a slender, elongate stem resembling that of subsp. tulense K. Kayser, but they differ from both subsp. myriostigma and subsp. tulense in having black spines up to 4 mm long. The flowers of subsp. quadricostatum are slightly smaller and have fewer tepal rows than those of subsp. myriostigma. The smallest flowers, with one or two tepal rows, are typically found in subsp. tulense. Further comparisons among the three taxa must await the completion of studies now in progress.