Heterostemma trilobatum sp. nov. (Apocynaceae: Asclepiadoideae) from Thailand

A new species, Heterostemma trilobatum A. Kidyoo & Thaithong has been discovered in northern, northeastern and southeastern Thailand. It is here described, illustrated and meticulously compared with a morphologically similar species, H. xuansonense T. B. Tran & J. Hw. Kim. Both species resemble each other, having sessile to subsessile cymes, five glands on the inside of the calyx and dark red to purplish red ovate corona lobes. However, H.trilobatum is markedly differentiated by much smaller size of flowers and the presence of peculiar trilobed corona appendages.     

Preparation of spray-dried wettable powder formulations of Bacillus thuringiensis-based biopesticides

Bacillus thuringiensis is the most widely used biopesticide among many methods available to control insects. To make a saleable product, B. thuringiensis must be substantially concentrated by removal of water and formulated to improve longevity, efficacy, and ease of transport of the product. B. thuringiensis subsp. aizawai culture broth as an active ingredient was mixed with various adjuvants and then spray dried. The optimum conditions for spray drying were found to be an outlet temperature of 60-85 degrees C and an inlet temperature of 120-180 degrees C. Various adjuvants had different effects on physical and biological properties of the dried product. Gelatinized tapioca starch and milk powder improved suspensibility but adversely affected wettability of the dried formulated product. Vegetable oil and Tween 20 enhanced wettability but resulted in poor suspensibility. Silica fume was used to enhance flowability because it reduced clumping and caking of the powder resulting from the addition of vegetable oil. Formulation containing 10% wt:wt B. thuringiensis, 10% wt:wt gelatinized tapioca starch, 10% wt:wt sucrose, 38% wt:wt tapioca starch, 20% wt:wt milk powder, 10% wt:wt silica fume, 2% wt:wt polyvinyl alcohol, 5% vol:vol Tween 20, 1% vol:vol refined rice bran oil, and 1% vol:vol antifoam solution was found to be optimum in terms of the physical and biological properties of the dried product. This formulation had 55% suspensibility, 24 s for wetting time, and 5.69 x 10(4) CFU/ml of LC50 value against Spodoptera exigua larvae.     

Dischidia kerrii sp. nov. (Apocynaceae: Asclepiadoideae) from northeastern Thailand

Dischidia kerrii is presented as a new species from northeastern Thailand. This newly discovered species is thoroughly described, discussed and illustrated. A comparison is made with the putative closely related species D. acuminata. They can be distinguished by differences in corolla lobes and staminal corona lobes.     

Localization of production and emission of pollinator attractant on whole leaves of Chamaerops humilis (Arecaceae)

Volatile compounds, which frequently play important roles in plant-insect interaction, can be produced either by flowers to attract pollinators or by leaves to deter herbivores. The specialized structures associated with odor production differ in these two organs. The European dwarf palm Chamaerops humilis represents a unique intermediate between these two. In previous work, its leaves were shown to produce volatile organic compounds (VOCs) that attract pollinators only during flowering. Because the leaf sinuses look like a gland, the sinus was examined histologically and with environmental scanning electron microscopy (ESEM) for evidence that the sinus emits VOCs. Volatile compounds emitted by the different parts of the leaf were extracted by washes and headspace then analyzed by gas chromatograph-mass spectrometer (GC-MS). The sinus does not have the expected gland-like structure; the VOCs are actually produced by the whole leaf, even if the composition of the VOCs emitted by the sinus slightly differs. Thus, attraction of pollinators does not result from specialized secreting cells in leaves of flowering European dwarf palms. The results are discussed in the context of a convergent evolution of leaves toward petals.     

Ceropegia thaithongiae sp. nov. (Apocynaceae,Asclepiadoideae) from northern Thailand and preliminary observations on impacts of climate change on its only known population

A new pendulous herb, Ceropegia thaithongiae Kidyoo (Apocynaceae, Asclepiadoideae), is described from northern Thailand. This plant is strictly endemic to Chiang Dao Wildlife Sanctuary and critically endangered owing to it living in an ecosystem affected by frequent natural disturbances. It is here described, illustrated and compared to the similar species, C. mairei. Both species have fusiform rootstocks, 1–2‐flowered cymes, deeply bifid outer corona lobes and linear, hairy inner corona lobes. However, the new species can be distinguished by its glabrous stem, leaf covered with hairs on both surfaces and glabrous corolla tube and lobes.     

Gymnemopsis phuwuaensis (Apocynaceae,Asclepiadoideae), a new species from northeastern Thailand

A new species, Gymnemopsis phuwuaensis A. Kidyoo, has been discovered in northeastern Thailand and is here described and illustrated. An identification key to all species of the genus is provided. Photographs and a diagnostic comparison with the morphologically similar species G. calcicola Kerr, are also provided. Gymnemopsis phuwuaensis displays clear differences in form and color of the corolla as well as in size of bract and flower. A lectotype for Gymnemopsis pierrei is also designated.