Nocturnal Pollination by the Carpenter Bee Xylocopa tenuiscapa (Apidae) and the Effect of Floral Display on Fruit Set of Heterophragma quadriloculare (Bignoniaceae) in India¹

Abstract

We provide the first data on nocturnal pollination by bees. Heterophragma quadriloculare is a self–incompatible hermaphroditic tree solely pollinated at night by the carpenter bee Xylocopa (Mesotrichia) tenuiscapa Westwood, whose pollinating flights were lunar insensitive and unaffected by low nighttime temperatures (2–l4°C). The number of carpenter bees visiting a tree per minute and the number of flowers visited per foraging bout were positively related to the size of the floral display. We found that floral display size was negatively related to fruit set but positively related to absolute fruit numbers. In pollen carryover experiments, cross–pollen did not travel far in sequences of non–emasculated flowers (up to the 4th flower), but traveled farther in emasculated flower sequences (up to the 15th flower) as evidenced by fruit set in these sequences. The relatively poor fruit set on trees with many open flowers may have resulted from deposition of self–pollen on touch–sensitive stigmas, which close on first contact. Because large–girth trees tend to have large floral displays, trees may increasingly realize a higher percentage of fitness through male rather than female function as they age. The steady–state flowering phenology of H. quadriloculare may limit reduction in the female function compared to the cornucopia strategy of many other members of the Bignoniaceae and may also provide a reliable resource for X. tenuiscapa. RESUMES Investigou‐se a relação entre salinidade intersticial, esclerofilia da folha, vigor da planta e densidade de galhas provocadas pelo inseto galhador foliar, Cecidomyia avicenniae (Diptera: Cecidomyiidae), em sua planta hospedeira Avicennia germinans (Avicenniaceae). As coletas foram realizadas em seis mangues e em uma mata de várzea, no Maranhão, nordeste do Brasil. Em cada local, dez ramos foram coletados aleatoriamente em cinco árvores de A. germinans. De cada ramo foram obtidos o número total de galhas e o comprimento (cm). Médias do comprimento, largura, biomassa e área das folhas por ramo foram também registradas. A esclerofilia foliar foi quantificada atraves da biomassa por unidade de área foliar (g/cm2). Amostras da água intersticial foram obtidas através de um tubo de PVC de 1,3 cm de diàmetro á uma profundidade de 80 cm, e a salinidade (ppm) medida com um refratômetro. A esclerofilia das folhas apresentou uma forte corrclação positiva com a salinidade intersticial (R2=0,77; P < 0,05). Observou‐se também correlações entre a densidade de galhas por unidade de área foliar (cm2) e a salinidade intersticial (r=0,36; P < 0,05), e entre densidade de galhas e a esclerofilia das folhas (r=0,40; P < 0,05). Salinidade e esclerofilia juntas explicaram 22 por cento da variação na densidade de galhas de C. avicenniae. Observou‐se, ainda, uma relação negativa entre a densidade de galhas por centímetre e o comprimento do ramo (R2=0,50; P < 0,05). Portanto, ramos mais longos de A. germinans apresentaram menor densidade de galhas. Nossos resultados sugerem que a densidade de galha...

The life-history traits influencing reproduction success and the recruitment of seedlings of Dianthus superbus L. in different stages of meadow overgrowing

“…A positive correlation between flower display and activity of crepuscular pollinators, ensuring pollen receipt and donation, was observed by S o m a n a t h a m and B o r g e s [25]. The increase in capsule and seed production in the populations of Dianthus superbus L. along the successional gradient is in accordance with the observations carried out in the populations of other species inhabiting abandoned Molinietum caeruleae.…”

Rush hours in flower visitors over a day–night cycle

“…A recent review on nocturnal pollination, reports that nocturnal pollinators are often adapted to fly at low temperatures and in dark conditions (Borges et al, 2016). On the other hand, one of the few studies that related flower visitation of a nocturnal bee species to moon light intensity and temperature, found no relationship (Somanathan & Borges, 2001). Thus, we currently lack a general understanding of which abiotic factors drive the abundance and diversity of nocturnal flower visitors.…”

Comparisons in nesting biology of two sympatric carpenter bee species (Apidae: Xylocopini)

“…On the other hand, they can present specialized behaviours such as buzz pollination on flowers with poricidal anthers (Buchmann 1983;Oliveira-Rebouças and Gimenes 2004) and nectar collection on flowers that present flag morphology or a long tubular corolla (Gottsberger et al 1988;Somanathan and Borges 2001). On these flowers, Xylocopa species may also act as nectar thieves, retrieving the nectar by perforating the flower (Barrows 1980;Maloof and Inouye 2000;Richardson 2004).…”