A survey of bee species found pollinating watermelons in the Lower Rio Grande Valley of Texas

Authors: Henne, Chanda; Rodriguez, Eloy; Adamczyk, John

Submitted to: Psyche
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2012
Publication Date: 4/18/2012
Citation: Henne, C.S., Rodriguez, E., Adamczyk Jr, J.J. 2012. A survey of bee species found pollinating watermelons in the Lower Rio Grande Valley of Texas. Psyche. doi:10.1155/2012/357250.

Interpretive Summary: Watermelons are pollinated by insects, with bees being the primary pollinator. Farmers often rely on managed honey bee hives from beekeepers to ensure good pollination in order to set as much fruit as possible. In the Lower Rio Grande Valley (LRGV) of Texas watermelons are grown in the spring as well as in the fall months. Because of the subtropical climate, the LRGV spring crop is planted much earlier in the spring than other parts of the United States. Consequently, many times managed honey bee hives are in much demand and the beekeepers are not able to meet the farmer’s needs. Recently, a few farmers in the LRGV are using managed bumble bees as pollinators. However, we do not know if this bee species, commonly called the Eastern bumble bee, is suitable for the harsh, subtropical climate. In addition, because of the vast abundance of feral Africanized honey bees in the LRGV, it is very possible that these bees make up a large percentage of all bee species pollinating watermelons and perhaps in many situations, managed honey bee hives may not be needed. Until now, there has never been a documented survey to determine the abundance and species composition of bees pollinating watermelons in the LRGV. In the spring of 2011, we conducted a survey of bee species pollinating three watermelon fields in the LRGV of Texas. A total of 15 species were collected or observed from all three fields combined. Of these species, only four were found to be very abundant: Agapostemon angelicus Cockerell/texanus Cresson, A. mellifera (Africanized-honey bees), Lasioglossum coactum (Cresson) and Melissodes thelypodii Cockerell. Africanized-honey bees comprised 46% of all bee species collected from all three fields combined and was highly abundant in two of the three fields. In the third field, however, Africanized-honey bees and Agapostemon angelicus/texanus were equally abundant. Surprisingly, Eastern bumble bees comprised only 1% of the total bees surveyed in all three fields combined, despite two of the fields having several managed hives each.

Technical Abstract: Using a combination of flower traps and visual observations, we surveyed three watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] fields in the Lower Rio Grande Valley to determine what bees inhabit this crop in this region. No managed honey bee (Apis mellifera L.) hives were in any of the fields; however, two contained managed hives of the common eastern bumble bee, Bombus impatiens (Cresson). A total of 15 species were collected or observed from all three fields combined. Of these species, only four were found to be very abundant: Agapostemon angelicus Cockerell/texanus Cresson, A. mellifera, Lasioglossum coactum (Cresson) and Melissodes thelypodii Cockerell. Apis mellifera comprised 46% of all bees collected from all three fields combined, and was highly abundant in two of the three fields. In the third field, however, A. mellifera and Agapostemon angelicus/texanus were equally abundant. Surprisingly, B. impatiens comprised only 1% of the total bees surveyed in all three fields combined, despite two of the fields having several managed hives each. As B. impatiens is not native to this region, it was not surprising that none were collected or observed in the field with no managed hives.