Tilting chains of negative curves on rational surfaces

We introduce the notion of exact tilting objects, which are partial tilting objects $T$ inducing an equivalence between the abelian category generated by $T$ and the category of modules over the endomorphism algebra of $T$. Given a chain of sufficiently negative rational curves on a rational surface, we construct an exceptional sequence whose universal extension is an exact tilting object. For a chain of (-2)-curves, we obtain an equivalence with modules over a well known algebra.Comment: 13 page

Ecology of the African maize stalk borer, Bussolea fusca (Lepidoptera: Noctuidae) with special reference to insect-plant interactions

Busseola fusca (Lepidoptera: Noctuidae) is an important pest of maize and sorghum in sub-Saharan Africa. One century after its first description by Fuller in 1901, inaccurate information based on earlier reports are still propagated on its distribution (e.g., absent from the lower altitudes in East Africa) and host plant range (e.g., feeding on a large range of wild grass species). This review provides updated information on the biology, distribution and genetics of B. fusca with emphasis on insect-plant interactions. Related to this, new avenues of stem borer management are proposed

Аналіз сучасних підходів до визначення поняття “регіон”

Мета статті. Дослідити основні підходи до трактування поняття “регіон”

Temporal patterns of emergence, calling behaviour and oviposition period of the maize stem borer, Busseola fusca (Fuller) (Lepidoptera : Noctuidae)

Sexual behaviour in most of the noctuid Lepidoptera follows a diel periodicity and is limited to a precise period of either the day or the night. The periodicity and the maturation periods are specific as well as the onset of oviposition behaviour. The knowledge of these traits of biology is an essential prerequisite for all the studies in chemical ecology. The periodicity of adult emergence, calling behaviour and oviposition of Busseola fusca (Fuller) was studied under laboratory conditions. Most males emerged before onset of the scotophase whereas most females did so one hour later. The virgin females started to exhibit calling behaviour few hours after emergence and there is no sexual maturation time. The calling behaviour starts the fourth hour after the onset of the scotophase but is lightly delayed for females having emerged the same night as compared to older females. Sexual and oviposition behaviours occur during the dark period. Oviposition started the first night after the mating night, peaked during the second night and then gradually decreased until the fifth night. The first night of oviposition, females laid eggs during the first three hours and after the 5(th) hour of the scotophase with a maximum during the 8(th) and 9(th) hour. During the second night, oviposition peaked during the second hour and tended to decrease thereafter

Importation and Preliminary Evaluation of the Stem Boring Moth Buakea kaeuae as a Potential Biological Control Agent of Invasive Guineagrass, Megathyrsus maximus

Abstract. Guineagrass, Megathyrsus maximus (Jacq.) B.K.Simon & S.W.L.Jacobs, is an African grass that is invasive in Florida, Hawaii, southern Texas, and northeastern Mexico. Buakea kaeuae Moyal et al., a stem-boring African moth found only on M. maximus, was imported from Kenya and evaluated for its ability to feed and develop on Guineagrass naturalized in southern Texas. Neither larvae nor adults developed or reproduced on Texas Guineagrass. Resumen. El zacate Guinea (Megathyrsus maximus (Jacq.) B.K.Simon & S.W.L.Jacobs), originario de África, es considerado invasivo en Florida, Hawaii, sur de Texas, y noreste de México. Buakea kaeuae Moyal et al. es una palomilla especifica de M. maximus que ataca a los tallos de esta maleza. Esta palomilla fue importada de Kenia y ha sido evaluada por su habilidad para alimentarse y desarrollar su ciclo biológico solo en plantas de zacate guinea, naturalizadas en el sur de Texas. Ni las larvas ni los adultos de B. kaeuae, se desarrollan y reproducen en especies de zacate Guinea de Texas

Гендерний аспект вивчення жаргонної лексики

В статье определяется понятие "общий жаргон", обосновывается актуальность гендерного подхода к изучению жаргонизмов. На материале выборок из словарей, художественной литературы, по результатам проведенного автором психолингвистического эксперимента осуществляется семантический анализ, определяются способы образования жаргонизмов на обозначение женщин в украинском языке.У статті визначається поняття "загальний жаргон", обґрунтовується актуальность ґендерного підходу до вивчення жаргонізмів. На матеріалі вибірок зі словників, художньої літератури, за результатами проведеного автором психолінгвістичного експерименту здійснюється семантичний аналіз, визначаються способи утворення жаргонізмів на позначення жінок в українській мові.The author of the article defines the concept "general jargon", bases actuality of gender aspect of jargon words investigation. Using dictionaries, literature and the results of psycho-linguistic experiment, the author analyses semantic and formation ways of jargon words for designation of women in Ukrainian

Опыт лечения врожденных кист яичников у девочек на первом году жизни

В статті представлено три випадки оперативного лікування методом лапароскопії вроджених кист яєчника. Найчастіше перекрут вродженої кисти яєчника відбувається внутрішньоутробно, що може привести до самоампутації додатків матки з боку ураження. Показанням до оперативного лікування можуть слугувати відсутність регресу утворення, характерні ехоскопічні та доплерометричні ознаки.Three cases of laparoscopic treatment of congenital ovarian cysts are presented in the article. More often twisting of congenital ovarian cyst could happen intrauterously, what could cause autoamputation of adnexa. Indications to surgery could be an absence of regression of cyst and/or certain ultrasound and Doppler signs

Salivary α-Amylase of Stem Borer Hosts Determines Host Recognition and Acceptance for Oviposition by Cotesia spp. (Hymenoptera, Braconidae)

Foraging insect parasitoids use specific chemical cues to discriminate between host and non-host species. Several compounds have been identified in “host location and acceptance.” However, nothing is known about the molecular variations in these compounds that could account for host-range differences between parasitoid species. In a previous study, it was shown that during the host-finding process, contact between the braconid Cotesia flavipes and its host is crucial, and that α-amylase of oral secretions from the host plays a key role for host acceptance and oviposition by the parasitoid. The present study sought to establish whether the variations in this enzyme could explain specific host recognition in different host-parasitoid associations. Different species and populations of the C. flavipes complex specialized on graminaceous lepidopteran stemborers were used. Electrophoresis of α-amylase revealed different isoforms that mediate the parasitoid's oviposition acceptance and preference for a specific host. This discovery opens up new avenues for investigating the evolutionary processes at play in chemically-mediated host specialization in the species-rich Cotesia genus

Parasitism of Lepidopterous Stem Borers in Cultivated and Natural Habitats

Plant infestation, stem borer density, parasitism, and parasitoid abundance were assessed during two years in two host plants, Zea mays (L.) (Cyperales: Poaceae) and Sorghum bicolor (L.) (Cyperales: Poaceae), in cultivated habitats. The four major host plants (Cyperus spp., Panicum spp., Pennisetum spp., and Sorghum spp.) found in natural habitats were also assessed, and both the cultivated and natural habitat species occurred in four agroecological zones in Kenya. Across habitats, plant infestation (23.2%), stem borer density (2.2 per plant), and larval parasitism (15.0%) were highest in maize in cultivated habitats. Pupal parasitism was not higher than 4.7% in both habitats, and did not vary with locality during each season or with host plant between each season. Cotesia sesamiae (Cameron) and C. flavipes Cameron (Hymenoptera: Braconidae) were the key parasitoids in cultivated habitats (both species accounted for 76.4% of parasitized stem borers in cereal crops), but not in natural habitats (the two Cotesia species accounted for 14.5% of parasitized stem borers in wild host plants). No single parasitoid species exerted high parasitism rates on stem borer populations in wild host plants. Low stem borer densities across seasons in natural habitats indicate that cereal stem borer pests do not necessarily survive the non-cropping season feeding actively in wild host plants. Although natural habitats provided refuges for some parasitoid species, stem borer parasitism was generally low in wild host plants. Overall, because parasitoids contribute little in reducing cereal stem borer pest populations in cultivated habitats, there is need to further enhance their effectiveness in the field to regulate these pests