Frequent Insect Visitors Are Not Always Pollen Carriers in Hybrid Carrot Pollination.

Philip H Brown,Ann Gaffney,Stephen R Quarrell,Geoff R Allen,Björn Bohman

doi:10.3390/insects9020061

Philip H Brown, Ann Gaffney + Show 3 more

Open Access

https://doi.org/10.3390/insects9020061

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Abstract

Insect crop visitations do not necessarily translate to carriage or transfer of pollen. To evaluate the potential of the various insects visiting hybrid carrot flowers to facilitate pollen transfer, this study examines insect visitation rates to hybrid carrot seed crops in relation to weather, time of day and season, pollen carrying capacity, inter-row movement, and visitation frequency to male-fertile and male-sterile umbels. The highest pollen loads were carried by nectar scarabs, honey bees, and the hover fly Eristalis tenax (Linnaeus). Honey bees and muscoid flies were observed to forage mostly within the male fertile carrot row while nectar scarabs and E. tenax foraged across rows, carrying equal pollen loads regardless of their distance from the pollen source. All observed insect taxa were more frequently seen visiting male-fertile than male-sterile umbels. In contrast to other visiting insects, honey bees were abundant and frequent visitors and were observed carrying high pollen loads. Consequently, we suggest both optimizing honey bee management and improving the attraction of carrot lines to honey bees to improve pollination rates for hybrid carrot seed crops.

Highlights

Effective pollination of carrot seed crops through insect vectors is critical to commercial success. surveys of carrot seed crops have revealed that many potential pollinator species visit carrot seed crops at flowering [1,2], poor pollination is a known problem for the growers [3].For carrot flowers, the duration of flowering in a single crop is approximately six weeks [4], over which time the crop may experience fluctuations in pollinator visitation
Surveys of carrot seed crops have revealed that many potential pollinator species visit carrot seed crops at flowering [1,2], poor pollination is a known problem for the growers [3]
Both beetle groups were significantly aggregated, with variance to mean ratios (VMRs) much greater than 1: Phyllotocus spp. (1.42) and soldier beetles (1.49), no more than three beetles were present on any one umbel

Summary

Introduction

Effective pollination of carrot seed crops through insect vectors is critical to commercial success. surveys of carrot seed crops have revealed that many potential pollinator species visit carrot seed crops at flowering [1,2], poor pollination is a known problem for the growers [3].For carrot flowers, the duration of flowering in a single crop is approximately six weeks [4], over which time the crop may experience fluctuations in pollinator visitation. Effective pollination of carrot seed crops through insect vectors is critical to commercial success. Surveys of carrot seed crops have revealed that many potential pollinator species visit carrot seed crops at flowering [1,2], poor pollination is a known problem for the growers [3]. The duration of flowering in a single crop is approximately six weeks [4], over which time the crop may experience fluctuations in pollinator visitation. Each umbel is receptive to pollen for a period of two to four days [5]. This means that a single plant within a crop is potentially attractive to insect pollinators for two to three weeks

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