title: Active aggregation among sexes in bean flower thrips (Megalurothrips sjostedti) on cowpea (Vigna unguiculata).
abstract: Male sexual aggregations are a common territorial, mating-related or resource-based, behaviour observed in diverse organisms, including insects such as thrips. The influence of factors such as plant substrate, time of day, and geographic location on aggregation of thrips is uncertain, therefore we monitored the dispersion of male and female bean flower thrips (BFT),Megalurothrips sjostedti(Trybom) (Thysanoptera: Thripidae), on cowpea,Vigna unguiculata(L.) Walp. (Fabaceae), over three cowpea growth stages and across three cowpea-growing areas of Kenya. Our results indicated that for all the crop growth stages, the density of BFTs varied over the time of day, with higher densities at 10:00, 13:00, and 16:00 hours than at 07:00 hours. Thrips densities did not differ among blocks at the budding stage, but they did at peak flowering and podding stages. Dispersion indices suggested that both male and female BFTs were aggregated. Active male aggregation occurred only on green plant parts and it varied across blocks, crop stages, and locations. Similarly, active female aggregation was observed in peak flowering and podding stages. Such active aggregation indicates a semiochemical or behaviour-mediated aggregation. Identification of such a semiochemical may offer new opportunities for refining monitoring and management strategies for BFT on cowpea, the most important grain legume in sub-Saharan Africa.
authors.affiliation: International Centre of Insect Physiology and Ecology PO Box 30772-00100, Nairobi, Kenya.
authors.forename: Saliou
authors.initials: S
authors.lastname: Niassy
authors.affiliation: International Centre of Insect Physiology and Ecology PO Box 30772-00100, Nairobi, Kenya.
authors.forename: Sunday
authors.initials: S
authors.lastname: Ekesi
authors.affiliation: International Centre of Insect Physiology and Ecology PO Box 30772-00100, Nairobi, Kenya.
authors.forename: Nguya K
authors.initials: NK
authors.lastname: Maniania
authors.affiliation: International Centre of Insect Physiology and Ecology PO Box 30772-00100, Nairobi, Kenya.
authors.forename: Benedict
authors.initials: B
authors.lastname: Orindi
authors.affiliation: Faculty of Natural Sciences I, Institute of Biology, Martin Luther University Halle-Wittenberg, Domplatz 4, 06108, Halle (Saale), Germany.
authors.forename: Gerald B
authors.initials: GB
authors.lastname: Moritz
authors.affiliation: Plant Research International Wageningen UR, PO Box 16, 6700AA, Wageningen, The Netherlands.
authors.forename: Willem J
authors.initials: WJ
authors.lastname: de Kogel
authors.affiliation: International Centre of Insect Physiology and Ecology PO Box 30772-00100, Nairobi, Kenya.
authors.forename: Sevgan
authors.initials: S
authors.lastname: Subramanian
keywords: Fabaceae; Thripidae; Thysanoptera; aggregation behaviour; dispersion index; grain legumes; semiochemical