DOI: 10.5061/dryad.dr7sqv9v2
title: Pollination by bats enhances both quality and yield of a major cash crop in Mexico

description: We used exclusion experiments to determine the effect of different
 pollinator taxa on the yield and quality of pitayas (fruit of Stenocereus
 queretaroensis (F.A.C. Weber) Buxbaum), a major crop in central Mexico. We
 studied the three most economically important cultivars and wild
 individuals in the principal region for pitaya production. For each
 pollinator taxa we recorded fruit set and measured three key parameters of
 fruit quality: weight, sucrose concentration and seed set. When bats were
 excluded from flowers and flowers were pollinated by other taxa (i.e.
 diurnal birds and insects), pitaya yield decreased by 35%, though
 pollination dependence varied between cultivars. Fruit quality decreased
 significantly in the absence of bat pollination across all cultivars, with
 fruits 46% lighter and 13% less sweet when pollinated by other taxa, thus
 reducing economic value as size determines market price. Additionally,
 seed set (an indicator of effective pollination) was significantly lower
 in the absence of bat pollinators.
description: We conducted
 this research in the municipality of Techaluta de Montenegro, Jalisco,
 Mexico (20.074°, -103.550°), one of the most important areas for pitaya
 production (Pimienta-Barrios and Nobel 1994), during 2016 and
 2017. We studied wild individuals of <i>S.
 queretaroensis</i> (cacti of 50+ years grown naturally) as well as
 three cultivars (Blanco, Mamey and Tenamaxtle) chosen for their economic
 importance, accounting for the majority of fruit production in the area.
 The study was carried out in six plantations, each containing all three
 cultivars; and six ranches with wild cacti. We carried out exclusion experiments to
 determine the efficiency of different pollinators, using six pollination
 treatments to differentiate between both nocturnal and diurnal
 pollinators, as well as invertebrate and vertebrate pollinators.
 To exclude certain pollinators, bags of different mesh sizes
 were placed on flowers either during the day or at night. Bags made from a
 very fine mesh prevented all pollinators from visiting the flower, and
 bags made from 2 cm<sup>2</sup> mesh allowed only insects to
 pollinate flowers (i.e. vertebrate pollinators excluded). We randomly
 selected five cacti of each cultivar in each plantation, and five wild
 cacti at each ranch. Six different treatments were carried out on each
 cactus, with each treatment on a separate flower: nocturnal pollinators
 only (NP: fine mesh bag during the day and unbagged at night), nocturnal
 insects only (NI: fine mesh bag during the day and large mesh bag at
 night), diurnal pollinators only (DP: unbagged during the day and fine
 mesh bag at night), diurnal insects only (DI: large mesh bag during the
 day and fine mesh bag at night), open pollinated control (OC: unbagged
 during the day and at night), and closed control (CC: fine mesh bag during
 the day and at night). Bags were changed at 06:00 and 18:00, with
 experiments lasting 24 hours. We placed all treatments on flowers opening
 on the same night where possible and on consecutive nights if not. We used
 randomised stratification to ensure a range of flower heights for each
 pollination treatment and recorded flower height. To assess the impact of treatment
 on pitaya yield and quality we monitored experimental flowers to record
 mature fruit set (success or failure). We collected successful fruits to
 measure six different variables of interest: fruit length, fruit width,
 pulp weight, fruit weight, sucrose content and seed set. We used the
 ripening times of the first fruits to mature to establish standardised
 collection times of 52, 57, 54 and 52 days for Blanco, Mamey, Tenamaxtle
 and wild fruits respectively. We excluded fruits that were damaged by
 insects or by local people. We weighed each fruit
 without spines, and measured the length and width. We peeled the fruits
 and weighed the fruit pulp. We chose fruit weight as the final indicator
 of fruit size, as it showed the strongest correlation with the other size
 parameters (Table S2). Sucrose content in one quarter of the fruit pulp
 (by wet weight) was measured using a handheld refractometer. We calculated
 seed set for each fruit by dividing the total seed number (estimated from
 counting the seeds in one quarter of the fruit by wet weight, and
 multiplying by four) by the average number of ovules counted in fifteen
 extra flowers from each cultivar type and wild individuals (collected from
 cacti not used in exclusion experiments, but from the same
 sites).
description: Treatment key for pollinator exclusion: CC =
 closed control. NP = nocturnal pollinators only. NI = nocturnal insects
 only. DP = diurnal pollinators only. DI = diurnal insects only. OC = open
 control, pollination under natural conditions. Cactus
 type = individual is a cultivar (we studied three cultivars - Blanco,
 Mamey and Tenamaxtle) or a wild plant.