common name: common blossom thrips
scientific name: Frankliniella schultzei Trybom (Insecta: Thysanoptera: Thripidae)

Introduction - Synonymy - Distribution - Description - Life Cycle - Hosts - Economic Importance - Management - Selected References

Introduction

Florida is home to a large number of invasive as well as native species of thrips. Hot temperatures and high humidity are important factors supporting huge populations of thrips in Florida. In the genus Frankliniella, the common blossom thrips, F. schultzei Trybom, is a relatively new vegetable pest in South Florida. It is a key pest in tomato and cucumber fields in South America.

adult

Synonymy

In Australia, F. schultzei was earlier known as F. lycopersici Steele, while in South America it was described as F. paucispinosa Moulton (Sakimura 1969).

Other synonymies of F. schultzei include:

Distribution

The common blossom thrips has a very wide distribution and is mainly found in tropical and subtropical areas throughout the world (Vierbergen and Mantel 1991).

Reported worldwide distribution is as follows:

Description

Frankliniella schultzei manifest two different color morphs, a dark and a pale form (Sakimura 1969). The two forms are anatomically similar to each other (Mound 1968). Sakimura (1969) reported the varied distribution of the two color morphs across the globe: Mixed colonies of both color forms are reported by Mound (1968) in Egypt, India, Kenya, Puerto Rico, Sudan, Uganda, and New Guinea.

Thrips are a very small insects. Adult females are 1.1-1.5 mm long, whereas adult males are 1.0-1.6 mm in length. Thrips species usually are identified by body color, body setae and a comb on the 8th abdominal segment. The following text and images describe identifying characteristics of F. schultzei.

adult with dimensions

The interocellar setae arise along an imaginary line across the front edges of the two hind ocelli.

head with interocellar setae

The postocular setae are slightly shorter than interocellar setae on the head of adult female F. schultzei.

head with postocellar and interocellar setae

The anteromarginal setae are slightly shorter than anteroangular setae on the anterior of the prothorax.

prothorax with anteromarginal and anteroangular setae

The abdominal comb is weakly developed on the 8th abdominal segment.

abdomen with comb

THRIPS: A Knowledgebase of Vegetable Thrips, developed by Glades Crop Care and the University of Florida, includes a graphical identification key for a number of thrips species, including F. schultzei, and is available online at http://www.gladescropcare.com/GCC_software.html (Frantz and Fasulo 1997).

Life Cycle

There are two larval instars and two inactive and non-feeding stages in the life cycle. The latter two stages are known as prepupa and pupa. Females of F. schultzei insert their eggs in flower tissue. Silvia et al. (1998) in Brazil studied this thrips life cycle at 24.5°C and reported that a complete generation takes around 12.6 days. The embryonic stage lasts for four days and the 1st and 2nd larval instars, prepupa and pupa take an average of 2.5, 2.5, 1.2, and 2.1 days respectively. The adult female and male longevity is approximately 13 days.

Hosts

Frankliniella schultzei is a polyphagous pest feeding on various ornamental and vegetable hosts in different parts of the world (Milne et al. 1996). It has been recorded from 83 species of plants among 35 families (Palmer 1990). The major hosts of F. schultzei are cotton, groundnut, beans and pigeon pea.

However, due to its polyphagous feeding behavior, F. schultzei also attacks tomato, sweet potato, coffee, sorghum, chillies, onion and sunflower (Hill 1975).

Economic Importance

Crops suffering economic damage due to F. schultzei in different part of the world include tomato, tobacco, cotton, grain legumes, groundnut and lettuce in India; ladys fingers, thistle, Japanese daisies, irises, spinach, tomato, carnation, pumpkin, carola (Tagates erecta), aubergine and kidney beans in Cuba; Allium sp. (cepa) flowers in Netherland; and cotton, tomato, lettuce, pepper, cucumber and tobacco in Brazil.

Frankliniella schultzei can cause both direct and indirect damages to crop. Both adults and nymphs feed on pollen and floral tissue, leading to flower abortion. Severe infestations can cause discoloration and stunted growth of the plant (Amin & Palmer 1985). However, indirect damage by F. schultzei is due to the virus transmission.

feeding damage on flower

distorted fruits

Tomato spotted wilt virus (Tospovirus), is a serious virus causing damage to a wide range of plant species (Prins and Goldbach 1998). The tospoviruses can only be transmitted by thrips and the first record of thrips as vector of plant viruses was by Best (1968).

In Florida, four species in the genus Frankliniella are responsible for the transmission of tomato spotted wilt virus (TSWV). These are F. bispinosa, F. fusca (Hinds), F. occidentalis and F. schultzei (Mound 2004).

The dark form of F. schultzei is known to vector at least four tospoviruses: TSWV (Sakimura 1969, Wijkamp et al. 1995) causing damage to tomato cropc in Brazil (Monteiro et al. 2001) and in Paraguay (Ishijima 2002); tomato chlorotic spot virus (TCSV); groundnut ringspot virus (GRSV) (Wijkamp et al. 1995) affecting several crops in Africa (Nakahara 1997); and chrysanthemum stem necrosis virus (Nagata and de Avila 2000). However, the pale form of F. schultzei is reported to be a weak vector of TSWV and TCSV and a non-vector of GRSV (Sakimura 1969, Cho et al. 1988).

Management

Sampling. Frankliniella schultzei is an anthophilous thrips species and is frequently found feeding on the flowers of its host plant. Like other thrips, F. schultzei can also be sampled using colored sticky traps. A study done in Australia reported sexual discrepancies among F. schultzei in color preference. In that study, male thrips were most attracted to yellow sticky traps while female thrips were more attracted to pink sticky traps (Yaku et al. 2007).

Biological control. The efficiency of two predatory mites, Amblyseius cucumeris Oudemans and A. swirskii Athias-Henriot, as potential biocontrol agents controlling F. schultzei populations is under investigation. Recently, the two predatory mites were found to be effective in suppressing the chilli thrips, Scirtothrips dorsalis Hood, populations on pepper plants (Arthurs et al. 2009).

Selected References


Authors: Garima Kakkar, Dakshina R. Seal, and Vivek Kumar, University of Florida
Photographs: Garima Kakkar and Vivek Kumar, University of Florida
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-477
Publication Date: July 2010
Copyright 2010 University of Florida

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