Correct insect pest identification is a crucial first step for the implementation of effective Integrated Pest Management (IPM) programs in the fruit and wine industries. IPM is based on the concept that targeted controls of specific pests will have less harmful side effects and will be more cost effective in the long run than application of general wide-ranging insecticides. Therefore, effective IPM requires sound knowledge of a pest’s biology and correct identification of the pest species. Since 2014, the IPM research group at Stellenbosch University’s Department of Conservation Ecology and Entomology has provided a user-pay insect ID service for the fruit and wine industry, and the general public.

Since 2008 when the service first started as a four year, industry funded project, the Insect ID service has processed over 500 samples submitted by a variety of users and industries. On average, 1.5 samples have been processed per week throughout the year, with peaks in the summertime when insects are more active and destructive to crops. Approximately half of all samples (47%) were submitted by non-wine fruit industries, particularly pome fruits and berries, while one-tenth were samples from the wine industry (Fig. 1). Samples which were submitted ranged from photographs of leaf or fruit damage to whole insects, larvae, pupae or adults, found in orchards or vineyards. Moths (Lepidoptera) were the most frequently identified pest insects, on various crops and weeds in vineyards/orchards (Fig. 2).

Of the specimens submitted to the Insect ID service, the four most common insect orders were the moths and butterflies (order Lepidoptera, 26% of specimens), weevils and beetles (Coleoptera, 19%), true bugs, stinkbugs and mealybugs (Hemiptera, 17%), and flies (Diptera, 9%). The remaining specimens belonged to a variety of arthropod orders including mites, ants, cockroaches, silverfish and thrips (16% of specimens). A significant proportion of submitted samples consisted of damaged plant material which could not be attributed to mites, insects, or any other arthropods (13% of specimens).

Newinsect_figure1
FIGURE 1. Percentage of samples submitted to Stellenbosch University’s Insect ID service by commodity.
FIGURE 2. Distribution of samples submitted for insect ID over a four year period from 2008, by insect order. Lepidoptera (= moths and butterflies), Coleoptera (= beetles), Hemiptera (= sucking bugs, e.g. mealybugs and aphids), and Diptera (= flies).
FIGURE 3. Various species of insects causing damage on vines: a) Trimen’s False Tiger, Agoma trimenii (Lepidoptera: Agaristidae) (Photo: Henk Geerstema); b) Tomato Moth larvae, Spodoptera littoralis (Lepidotera: Noctuidae); c) Adult Tomato Moth.

 

Thirty-five pests are known to occur in South African grapevines (Allsopp et al., 2015). Of the wine industry samples submitted to the Insect ID service, 39% belonged to one of those 35 species, and one submitted sample of Spotted Amber Ladybird is a known predator of mealybug and is, therefore, a beneficial insect. The remaining samples were most likely incidental collections of insects that make up the natural biodiversity within a wine production area.

The submission of these insects to the Insect ID service attests to the important role that the service plays for the fruit and wine industry. For example, moths and caterpillars can be notoriously hard to identify, even by seasoned entomologists. Ten moth species were submitted to the Insect ID service, six of which are listed as pests of grapevines:

  • False Codling Moth (FCM),
  • Trimen’s False Tiger,
  • Apple Trunk Borer,
  • Large Striped Hawk Moth,
  • Grapevine Hawk Moth, and
  • Tomato Moth (see Fig. 3 for some examples).

These six species require monitoring, in certain cases, more intense management, while the four other incidental species do not. In this case, submission of samples to the Insect ID service was able to provide an early identification of species and to distinguish between those species which are pests versus those which are not. This hopefully contributed to saving the grower time and money by allowing for the prediction of potential pest outbreaks early and to manage accordingly. The service therefore aims to help save costs associated with incorrect management for species which are not economic pests and would not cause significant damage, while also minimising the effects of such treatments on the environment.

To date, the Insect ID service has focused its efforts on developing a database of fruit pests of the Western Cape. Future efforts will focus on expanding the Insect ID service to provide a greater volume of targeted identification of pests and damage, and ultimately to promote IPM strategies as a viable alternative to traditional pest management techniques.

References

Allsopp, E., Barnes, B.N., Blomefield, T.L. & Pringle, K.L., 2015. Grapevine. Insects of cultivated plants and natural pastures in Southern Africa (edited by G.L. Prinsloo & V.M. Uys), pp. 420 – 437. Entomological Society of Southern Africa, Hatfield.

This article originates from research funded by Winetech and the final report of project US E PA 01, “Generating a taxonomic database of fruit pests in the Western Cape”, can be downloaded from http://www.sawislibrary.co.za/dbtextimages/AddisonP8.pdf.

– For more information, contact Pia Addison at pia@sun.ac.za.

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