Title

Factors Influencing Honeybee (Apis Mellifera L.) Visits to Crepe Myrtles (Lagerstroemia Sp.)

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ag Science and Natural Resources

Date of Award

Fall 2020

Abstract

Honeybees (Apis mellifera L.) are important pollinators and will selectively forage on crepe myrtles (CM) during the summer months. Unfortunately, pests of crepe myrtle, such as crepe myrtle bark scale (CMBS) (Acanthococcus lagerstroemiae), are commonly treated with systemic pesticides, causing pollen contamination at levels sufficient to cause harm to both individual bees and bee hives. An experiment was conducted on the campus of Texas A&M University-Commerce in July and August 2019 and 2020 to better understand honeybee visits to CM. Comparisons were made among four cultivars (Natchez, Tuscarora, Ebony Fire, and Pocomoke) and between two different environments. One location was isolated [Crepe Myrtle Research Gardens (CMRG)] while the second location [Plant Science Center (PSC)] included pollinator-friendly plants, including a perennial bed with pollinator-friendly plants planted immediately adjacent to the PSC CM beds in 2020. Honeybee visits were counted using visual observations during 7-minute weekly transects, initiated when trees averaged at least two large flower clusters per tree. Data included bees per tree, other pollinator species, and, in 2020, bloom number per tree. ‘Natchez’ had the most honeybee visits per tree, averaging 1.4 in 2019 and 1.2 in 2020, followed by ‘Tuscarora’ with 0.8 and 0.4 honeybee visits per tree, in 2019 and 2020, respectively. In 2020, there was a significant, moderate correlation (P ≤ 0.001, R = 0.51) between bloom number and honeybee visits, with ‘Natchez’ (158.9) and ‘Tuscarora’ (148.2) having more average blooms per tree than ‘Ebony Fire’ (35.6) and ‘Pocomoke’ (35.7). Landscape environment and proximity to pollinator-friendly plants did not affect honeybee visits to crepe myrtles as honeybee visits per tree averaged 0.16 at the isolated location and 0.25 at the PSC, and honeybee foraging in the perennial bed was virtually nonexistent. CM remain an important foraging resource for honeybees in the summer, and honeybees have a strong preference for cultivars with large, productive bloom clusters. Also, honeybees appear to forage CM even when other sources are readily available. Therefore, CM pests and pesticide applications must be managed in such a way that honeybee injury is minimized.

Advisor

Derald Harp

Subject Categories

Agriculture | Animal Sciences | Life Sciences

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