Some ultrastructural superficial changes in house fly (Diptera: Muscidae) and blow fly (Diptera: Calliphoridae) larvae induced by eucalyptol oil

Alterações ultraestruturais superficiais no terceiro estágio da mosca doméstica (Musca domestica) e da mosca varejeira (Chrysomya megacephala) induzidas pelo óleo de eucalipto foram observadas usando-se microscopia eletrônica de varredura. Imersos em 0,902 g/ml de óleo de eucalipto durante 30 segundos os tegumentos das larvas de ambas espécies mostraram aparência aberrante significativa da superfície corporal, particularmente edema do tegumento, formação de bolhas, fenda parcial e deformação das espículas.

Effects of eucalyptol on house fly (Diptera: Muscidae) and blow fly (Diptera: Calliphoridae)

Foram avaliados os efeitos do eucaliptol contra a mosca doméstica, Musca domestica L. e a mosca varejeira, Chrysomya megacephala (F.). O bioensaio de adultos, usando-se aplicação tópica, indicaram que os machos da M. domestica eram mais susceptíveis que fêmeas, com LD50 sendo 118 e 177 µg/mosca, respectivamente. Foi obtido mais alto LD50 da C. megacephala; 197 µg/mosca para machos e 221 µg/mosca para fêmeas. Moscas vivas de ambas espécies tiveram vida menor após tratamento com eucaliptol. O bioensaio de larvas, usando o "dipping method" no terceiro estágio, mostrou que M. domestica foi mais susceptível que C. megacephala com seu LD50 sendo 101 e 642 µg/µl, respectivamente. A emergência de adultos, que tinham sido tratados com eucaliptol na larva diminuiu somente na M. domestica. Tendo propriedade volátil, fumigação ou teste do papel impregnado por eucaliptol ou a eficácia de repelência ou de atração merecem investigações posteriores para aumentar a eficácia do bio-inseticida.

Fine structure of the eggs of blowflies Aldrichina grahami and Chrysomya pacifica (Diptera: Calliphoridae)

We report here the fine structure of the eggs of blowflies Aldrichina grahami (Aldrich) and Chrysomya pacifica Kurahashi. For A. grahami, the plastron is wide and extends to almost the entire length of the eggs. The plastron near the micropyle is truncated. The polygonal patterns of chorionic sculpture bear a distinct swollen boundary. Regarding C. pacifica, the plastron is narrow and extends to almost the entire length of the eggs. The plastron near the micropyle bifurcates to a Y-shape, but the arms of the 'Y' are short. Information presented herein allows some distinctive features to differentiate among eggs of blowfly species.

Comparison of the effectiveness of baits used in traps for adult fly collection.

The effectiveness of 6 different baits used in fly traps for adult fly collection was compared in October-November, 2000, near the cafeteria of Maharaj Nakhon Chiang Mai Hospital, Chiang Mai Province, northern Thailand. The baits used were fresh viscera (pork, beef and fish) and fresh meat (pork, beef and fish), with 500 g of each kind being used in each fly trap for each experiment. All were replicated four times. Pork viscera yielded the highest effectiveness (35.2%), followed by fish meat (30%). Four other kinds of bait showed relatively low efficiency, ie fish viscera (12.0%), beef viscera (9.0%), pork meat (8.4%) and beef meat (5.4%). The calliphorid Chrysomya megacephala was the most abundant fly species collected, while sarcophagids and muscid flies were found in much smaller numbers. The number of females was higher than males in all collections. Although all baits used were parts of animal carcasses that were very attractive for adult flies to feed upon and oviposit, the result of this study showed the differences in their effectiveness for fly collection, particularly during the late rainy season to early winter in Chiang Mai. Pork viscera showed the highest efficacy for metallic fly collection, but not for all species. Further study of suitable baits for the medically important fly species that exist in urban areas should, therefore, be performed.

Surface ultrastructure of third-instar Megaselia scalaris (Diptera: Phoridae)

We describe some ultrastructure of the third-instar Megaselia scalaris (Diptera: Phoridae) using scanning electron microscopy, with the cephalic segment, anterior spiracle and posterior spiracle being emphasized. This study provides the taxonomic information of this larval species, which may be useful to differentiate from other closely-related species