Yield and its components
Lack of pollination (P-) decreased total bean weight per plant, mean
number of beans per pod and total number of beans per plant,
independently of the herbivory treatment (Table 1, Fig. 1b,c, Fig. S4).
In the absence of insect pollination, bean weight and number of beans
per plant decreased by 15% and 17%, respectively. There was a marginal
(p= 0.06) interactive effect of pollination and herbivory on individual
bean weight, with pollination increasing individual bean weight but only
in the absence of herbivory (Table 1, Fig. 1a, Fig. S4). Herbivory
increased percent damaged beans, with on average 39% damaged beans in
the H+ treatment (Table 1, Fig. S3), which is over tenfold the economic
injury threshold set for beans targeting human consumption and could
lead to up to 78% economical losses (Bachmann et al., 2020; Roubinet,
2016). There was no effect of pollination nor herbivory treatments on
yield (kg.ha-1), or mature or total number of pods per
plant, however, proportion of mature pods was lower with lack of
pollination, due to higher numbers of unfertilized and immature pods
(Table 1, Fig. 1d, Fig. S4).
When herbivory damage on each plant was used as an explanatory variable
(% Damage), there were interactive effects of pollination and herbivory
damage on individual bean weight, total bean weight per plant, and
number of beans per pod (Table 1, Fig. 2, Fig. S5). In the absence of
pollination, there were positive relationships between yield and
herbivory damage for several yield components (individual bean weight:
est=0.001, se=0.0004, p<0.01; total bean weight: est=0.06,
se=0.02, p<0.01; and number of beans per pod: est=0.007,
se=0.002, p<0.01) (Fig. 2, Fig. S5). In the presence of insect
pollination, there were no relationships with herbivory damage. In
addition, number of beans per plant increased with increasing herbivory
damage independent of pollination treatment (Table 1). Number of pods
per plant was not affected, but proportion of mature pods increased with
herbivory damage due to a decrease in the number of unfertilized and
immature pods (Table 1).