Conserving carnivorous arthropods: an example from early-season cranberry (Ericaceae) flooding

Abstract

Biological control plays an important role in many integrated pest management programmes, but can be disrupted by other control strategies, including chemical and cultural controls. In commercial cranberry (Vaccinium macrocarpon Aiton; Ericaceae) production, a spring flood can replace an insecticide application, providing an opportunity to study the compatibility of the flood (a cultural control) with biological control. We suspect that chemical controls will tend to reduce the number of natural enemies, while the flood, through removal of detritus and detritivores, may cause generalist predators to prey-switch to consume proportionally more pest individuals. We measured the abundance of herbivores (Lepidoptera), detritivores, Arachnida, and parasitoids (Hymenoptera) every week for six weeks in Wisconsin (United States of America) cranberry beds following either an insecticide spray or a cultural control flood. We found that detritivore populations rapidly declined in both flood and spray treatments; conversely, carnivore populations (spiders and parasitoids) were more abundant in the flooded beds than in sprayed beds. Populations of key cranberry pests were similar between flooded and sprayed beds. Our results showed that early-season flooding preserved more natural enemies than an insecticide application. This increase in natural enemy abundance after the flood may allow for greater continuity in herbivore suppression, potentially providing a basis for long-term cranberry pest management.

Advances in cranberry insect pest management: A literature synthesis

“…The recently discovered nematode Oscheius onirici Torrini et al (Rhabditida: Rhabditidae) can kill S. sulfureana (Ye et al, 2018;Foye and Steffan, 2019) and A. vaccinii (Ye et al, 2018), as well as suppress S. frontalis (Foye and Steffan, 2019). Other predators that are commonly present in cranberry ecosystems include spiders (Bardwell and Averill, 1996;van Zoeren et al, 2018;de Lange et al, 2019b), staphylinid beetles (Haase-Statz, 1997, coccinellid beetles (Rodriguez-Saona et al, 2011a;Salamanca et al, 2017;de Lange et al, 2019b;Salamanca et al, 2019), chrysopid lacewings (Rodriguez-Saona et al, 2011a;de Lange et al, 2019b;Salamanca et al, 2019), and syrphid flies (Rodriguez-Saona et al, 2011a;Salamanca et al, 2017;de Lange et al, 2019b;Rodriguez-Saona et al, 2020c).…”

“…Flooding also has been prescribed throughout the year to control E. apiata, L. dispar, X. nupera, the white grub, Phyllophaga anxia LeConte (Coleoptera: Scarabaeidae), and the southern red mite, Oligonychus ilicis McGregor (Trombidiformes: Tetranychidae) (Averill et al, 1997). Additionally, early season flooding has been shown to increase natural enemy abundance, such as spiders and parasitoids (van Zoeren et al, 2018). Flooding is also used in IPM against certain weeds (Demoranville et al, 2005) and fungi (Averill et al, 1997).…”

Pollination practices and grower perceptions of managed bumble bees (Bombus spp.) as pollinators of cranberry in Quebec and Wisconsin

“…This high reliance on rented honey bees in both regions for cranberry pollination mirrors the broader reliance of many agricultural crops on managed bees for pollination (Klein et al, 2007), though growers in some systems, including apples and pumpkins (Park et al, 2020;McGrady, Troyer and Fleischer, 2020), have found that honey bees can be superfluous in terms of their effects on crop yield. Managed bees are brought to farms between 10-15% cranberry bloom in either region, which is calculated by growers dividing the number of open flowers on ten cranberry uprights by the number of flowers and buds on those uprights (van Zoeren and Guédot, 2018). In both regions, the majority of respondents report determining when to bring in managed pollinators by calculating the percent bloom themselves (57.14% WI, 81.82% QC).…”

Conserving carnivorous arthropods: an example from early-season cranberry (Ericaceae) flooding—ADDENDUM

“…The copyright statement for the article by van Zoeren et al . (2018) in the April 2018 issue of The Canadian Entomologist was incorrectly listed. The correct copyright should have appeared as follows, and has been changed in the original:…”