Bumble bee colony health is diminished in a mesotunnel enclosure planted with a cucurbit monoculture crop

A bumble bee visiting a muskmelon flower.

By Gauger et al.

Vegetable growers commonly use forms of protective covers to help shield crops from insect pests, plant pathogens, and unfavorable climatic conditions. In particular, producers in the eastern and midwestern United States have adopted “mesotunnel” systems (a fine plastic mesh row-cover suspended over crop plants) for pest exclusion from cucurbits (melons, squashes, and pumpkins) and other crops. Cucurbit crops under the mesotunnel system require special management in order to achieve pollination, such as placing a commercial bumble bee colony into the mesotunnels, but little is known about how this environment affects bumble bee colonies’ health and reproduction.

Our primary goal for this study was to document initial evidence about commercial bumble bee colonies’ health outcomes in a cucurbit monoculture mesotunnel system. In the summers of 2022 and 2023, we planted large mesotunnels with cucurbit crops (muskmelon or acorn squash) and allowed Koppert Bombus impatiens colonies to forage within them for ~4 weeks. We dissected these colonies and compared them to colonies that did not forage at all, and colonies that foraged freely on the 100-acre organic research farm. We found that in 2023, colonies from the cucurbit mesotunnel had worse reproductive and overall health than free-foraging colonies, and in some measurements, performed no better than colonies that did not forage at all. This indicates that something about the cucurbit mesotunnel system is constraining bumble bee colonies’ growth and health.

Read the scientific publication in JPE 

 

A field note on Monarch butterflies

Monarch butterfly on Baccharis solicifolia

By Carlos Alvarez-Pereyra, biologist. 

Last August, me and a colleague were sampling plants in one of Saltillo’s arroyo named “El Cuatro” back in northern Mexico..

Among several flowering plants in and out the bed of this arroyo we noticed that flowering Baccharis was visited by harvesting honey bees (Apis mellifera) and feeding Monarch butterflies (Danaus plexippus) at midday.

The presence of at least one migrating Monarch in this time of the year is quite rare because migration normally starts late October – early November in this latitude. Residents honey bees harvest all year long on all kind of flowers.

Honeybees on Baccharis

Baccharis salicifolia is a blooming shrub native to the desert southwest of the United States and northern Mexico, as well as parts of South America. This is a large bush with sticky foliage which bears plentiful small, fuzzy, pink or red-tinged white flowers which are highly attractive to butterflies.

I thought it could be helpful to some colleague working with these species somewhere in the world.