Economic value of bat predation services – A review and new estimates from macadamia orchards

Abstract

The economic value of natural regulation of agricultural pests by bats has been estimated both by avoided cost models and by experimental predator-exclusion approaches. We review published studies globally from both complementary approaches. We further present an economic model for the avoided cost of bat predation on stinkbugs, the major economic pest of macadamias in South Africa, currently the world's largest macadamia producer. We calculated both the direct (reduced stinkbug damage due to bat predation) and indirect (reduced pesticide use) avoided costs. We estimated the density of bats in a macadamia-growing region of South Africa to be 7.5-22.5 bats/ha, based on opportunistic data from the Merlin DeTEct (Inc.) avian-avoidance radar system. Current economic parameters for macadamia production, stinkbug injury coefficients and life history were obtained from the literature and from the Southern African Macadamia Association (SAMAC).We estimated the level of bat predation on pest stinkbugs in macadamia orchards from published dietary studies combined with both high and low published values for insect consumption rates relative to bat body mass. We found that the protected yield due to bat predation of stink bugs amounted to 0.53% (low consumption rates) to 1.29% (high consumption rates) of annual macadamia production in South Africa for 2015. Based on current macadamia prices, the approximate avoided cost values of these combined direct and indirect bat predation services varied between 9% and 23% of the current annual estimated cost of damage caused by stinkbugs to South African macadamia orchards (US$613/ha). Losing bats to disease epidemics, wind farms, human persecution or excessive or highly toxic pesticide applications could therefore significantly increase annual losses to the macadamia industry in South Africa caused by stinkbugs.

Reproduction of East-African bats may guide risk mitigation for coronavirus spillover

“…The members of this order, bats, provide important ecosystem services (reviewed in [2,3]). For example, insectivorous bats can reduce arthropod herbivory [4][5][6], increase agricultural yields [7], reduce the need for insecticides [8], and prevent large financial losses in agriculture [9][10][11].…”

An appetite for pests: Synanthropic insectivorous bats exploit cotton pest irruptions and consume various deleterious arthropods

“…Several studies have shown an increase in arthropod pest infestation or yield loss when preventing insectivorous bats from foraging in plots within crop fields or agroforests (Maas et al, 2016; Maine & Boyles, 2015; Taylor, Grass, Alberts, Joubert, & Tscharntke, 2018). Accordingly, the ecosystem services provided by bats, particularly pest suppression, are now considered economically important (Boyles, Cryan, McCracken, & Kunz, 2011; Kunz, Braun de Torrez, Bauer, Lobova, & Fleming, 2011; Taylor et al, 2018). For example, the suppression of cotton pests by Brazilian free‐tailed bats ( Tadarida brasiliensis) in the United States has been estimated to be worth billions of dollars annually (Boyles et al, 2011).…”

Research trends on bats in China: A twenty-first century review

“…The ecological services provided by bats should be better quantified and monetized in future projects (e.g. Boyles et al, 2011;Taylor et al, 2018) to highlight their economic value for the Chinese private sector and governments.…”

“…For example, bats positively affect the economy by acting as insect pest suppressors saving billions of dollars annually on pesticides in agroecosystems (Boyles et al, 2011;Russo et al, 2018), pollinators of commercial plants (e.g. fruit bats are the major pollinators of durian, Durio zibethinus, a highly economic fruit crop in southeast Asia (Bumrungsri et al, 2008), and seed dispersers (maintaining and regenerating forests) (Kasso and Balakrishnan, 2013;Saldaña-Vázquez et al, 2019;Taylor et al, 2018). Bats can also be used as bioindicators of environmental pollutants (Heiker et al, 2018;Zukal et al, 2015), a well-known problem of the Chinese large cities.…”