‘Phytophagous’ thrips are facultative predators of twospotted spider mites (Acari: Tetranychidae) on cotton in Australia

1996 ◽  
Vol 86 (3) ◽  
pp. 297-305 ◽  
Author(s):  
L. J. Wilson ◽  
L. R. Bauer ◽  
G.H. Walter

AbstractPredatory feeding on Tetranychus urticae Koch (Acari: Tetranychidae) populations on cotton by phytophagous thrips, Thrips imaginis Bagnall, T. tabaci Lindeman and Frankliniella schultzei Trybom (Thysanoptera: Thripidae), was investigated in the field and laboratory. Phytophagous thrips are a common early season pest of cotton in Australia, though their true pest status is undefined. In California, the phytophagous thrips (Frankliniella occidentalis (Pergande)) is regarded as an opportunistic predator of mite eggs, their consumption of which increases fitness over a diet of leaf tissue alone. Thrips are among the most abundant of insects on young cotton. If they consume mite eggs, even at relatively low rates, they could have a significant influence on the probability of survival of early season spider mites. Consumption of eggs of T. urticae by thrips was investigated in the laboratory. Second instar F. schultzei consumed more eggs per day (ca. 4 eggs per day) than did second instar T. tabaci or T. imaginis (ca. l egg per day). Consumption by first instar F. schultzei was much lower than for second instars. Adult T. tabaci consumed ca. l egg per day whilst adults of F. schultzei consumed only ca. 0.5 eggs per day, although some individuals of this species did consume substantial numbers of eggs. Larvae of all thrips species showed a type II functional response to prey density. In the field, adults and larvae of T. tabaci and F. schultzei showed a preference for cotton seedlings that were also infested by spider mites. In a glasshouse, larvae of T. tabaci showed a highly significant preference for feeding within mite colonies. In the field, suppression of predators, predominantly T. tabaci and F. schultzei, with a broad spectrum insecticide (dimethoate) contributed to outbreaks of mites occurring earlier than they would have otherwise. The results show that phytophagous thrips eat mite eggs and that they are potentially important predators of spider mites in the field, especially given their abundance on young cotton and preference for inhabiting situations in which mite colonies are found.

2020 ◽  
Vol 49 (2) ◽  
pp. 461-472
Author(s):  
Robert Brenner ◽  
Deirdre A Prischmann-Voldseth

Abstract Insecticidal neonicotinoid seed treatments are a common agricultural insect pest management strategy; however, effects on nontarget pests and omnivorous arthropods are understudied. We used a series of experiments to evaluate impacts of the neonicotinoid seed treatment thiamethoxam on densities of herbivorous twospotted spider mites (Tetranychus urticae Koch [Acari: Tetranychidae]) and feeding behavior of western flower thrips (Frankliniella occidentalis Pergande [Thysanoptera: Thripidae]), an omnivore that feeds on spider mite eggs but is also a significant plant pest. Spider mite densities were higher on neonicotinoid-treated soybeans, but only when mites were not spatially confined. We then examined how availability of thiamethoxam-treated food items (i.e., eggs from spider mites reared on treated soybeans, soybean leaf discs, or a combination of the two), and previous exposure to thiamethoxam-treated soybean impacted thrips feeding. Regardless of the presence of leaf tissue, thrips consumed fewer spider mite eggs laid by females reared on treated soybeans, suggesting spider mite eggs can serve as poisoned prey. Overall, thrips consumed less treated soybean leaf tissue, and thrips on treated leaf discs had a lower percentage of herbivorous feeding events and consumed more nontreated spider mite eggs, indicating a dietary shift from herbivory to predation. The neonicotinoid status of spider mite eggs and prior exposure of thrips also caused shifts in the number and size of leaf scars, likely as a result of altered foraging behavior and/or movement. Shifts between herbivory and predation have implications for thrips damage, virus transmission, and pest management, especially in systems with mixtures of nontreated and neonicotinoid-treated plants.


Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 392
Author(s):  
Amalendu Ghosh ◽  
Priti ◽  
Bikash Mandal ◽  
Ralf G. Dietzgen

Thrips are important pests of agricultural, horticultural, and forest crops worldwide. In addition to direct damages caused by feeding, several thrips species can transmit diverse tospoviruses. The present understanding of thrips–tospovirus relationships is largely based on studies of tomato spotted wilt virus (TSWV) and Western flower thrips (Frankliniella occidentalis). Little is known about other predominant tospoviruses and their thrips vectors. In this study, we report the progression of watermelon bud necrosis virus (WBNV) infection in its vector, melon thrips (Thrips palmi). Virus infection was visualized in different life stages of thrips using WBNV-nucleocapsid protein antibodies detected with FITC-conjugated secondary antibodies. The anterior midgut was the first to be infected with WBNV in the first instar larvae. The midgut of T. palmi was connected to the principal salivary glands (PSG) via ligaments and the tubular salivary glands (TSG). The infection progressed to the PSG primarily through the connecting ligaments during early larval instars. The TSG may also have an ancillary role in disseminating WBNV from the midgut to PSG in older instars of T. palmi. Infection of WBNV was also spread to the Malpighian tubules, hindgut, and posterior portion of the foregut during the adult stage. Maximum virus-specific fluorescence in the anterior midgut and PSG indicated the primary sites for WBNV replication. These findings will help to better understand the thrips–tospovirus molecular relationships and identify novel potential targets for their management. To our knowledge, this is the first report of the WBNV dissemination path in its vector, T. palmi.


PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254963
Author(s):  
Youhei Suzuki ◽  
Takahiro Shiotsuki ◽  
Akiya Jouraku ◽  
Ken Miura ◽  
Chieka Minakuchi

Insect metamorphosis into an adult occurs after the juvenile hormone (JH) titer decreases at the end of the juvenile stage. This generally coincides with decreased transcript levels of JH-response transcription factors Krüppel homolog 1 (Kr-h1) and broad (br), and increased transcript levels of the adult specifier E93. Thrips (Thysanoptera) develop through inactive and non-feeding stages referred to as “propupa” and “pupa”, and this type of distinctive metamorphosis is called neometaboly. To understand the mechanisms of hormonal regulation in thrips metamorphosis, we previously analyzed the transcript levels of Kr-h1 and br in two thrips species, Frankliniella occidentalis (Thripidae) and Haplothrips brevitubus (Phlaeothripidae). In both species, the transcript levels of Kr-h1 and br decreased in the “propupal” and “pupal” stages, and their transcription was upregulated by exogenous JH mimic treatment. Here we analyzed the developmental profiles of E93 in these two thrips species. Quantitative RT-PCR revealed that E93 expression started to increase at the end of the larval stage in F. occidentalis and in the “propupal” stage of H. brevitubus, as Kr-h1 and br mRNA levels decreased. Treatment with an exogenous JH mimic at the onset of metamorphosis prevented pupal-adult transition and caused repression of E93. These results indicated that E93 is involved in adult differentiation after JH titer decreases at the end of the larval stage of thrips. By comparing the expression profiles of Kr-h1, br, and E93 among insect species, we propose that the “propupal” and “pupal” stages of thrips have some similarities with the holometabolous prepupal and pupal stages, respectively.


2017 ◽  
Vol 8 ◽  
Author(s):  
Guangdi Yuan ◽  
Yanran Wan ◽  
Xiaoyu Li ◽  
Bingqing He ◽  
Youjun Zhang ◽  
...  

2020 ◽  
Vol 49 (1) ◽  
pp. 73-87 ◽  
Author(s):  
Rafia A Khan ◽  
Dakshina R Seal ◽  
Shouan Zhang ◽  
Oscar E Liburd ◽  
Rajagopalbabu Srinivasan ◽  
...  

Abstract Tomato chlorotic spot virus (TCSV) is an orthotospovirus that causes a devastating disease in tomato (Lycopersicon esculentum Miller). TCSV emerged recently in South Florida. Studies were conducted in three commercial tomato fields in Miami-Dade County, Florida during the vegetable-growing seasons from October to April in 2015 through 2017. Each year, data were collected at 3, 6, and 9 wk after transplanting at various distances from the edges of each fields. Based on 3 yr total samples, three species of thrips were commonly observed melon thrips, Thrips palmi Karny (62.16 ± 0.79%), being the most abundant species followed by common blossom thrips, Frankliniella schultzei Trybom (21.55 ± 0.66%), and western flower thrips, Frankliniella occidentalis (Pergande) (16.26 ± 0.61%). Abundance of all thrips and TCSV infected plants was high at the edge of a tomato field 3 wk after transplanting with significantly fewer infected plants toward the center of the field. The distribution patterns of thrips and TCSV in various fields were mostly regular and aggregated across the sampling dates during the study period. Abundance of TCSV symptomatic plants and thrips species was high at the edge of the field and increased over time. The number of samples required to accurately determine population density of thrips was calculated by using three precision levels (0.10, 0.20, 0.30) at three predetermined densities of thrips (0.10, 0.20, and 0.40 per sample). This information will provide guidelines to growers, crop protection personnel, agricultural scouts, and researchers to develop a sustainable thrips and tospovirus management program.


1999 ◽  
Vol 28 (3) ◽  
pp. 535-539 ◽  
Author(s):  
Tatsuya Nagata ◽  
Laurence A. Mound ◽  
Felix H. França ◽  
Antonio C. de Ávila

The disease caused by the viruses belonging to the genus Tospovirus is a serious problem in horticultural and ornamental crops in Brazil. In the field, this virus group is transmitted by the insect vector, thrips. Little is known about the thrips species occurring in Brazil, and which species are important for the dissemination of these diseases. For the study of epidemiology of this virus group, different thrips populations, which may have the capacity to be vectors of tospoviruses, were collected in the Federal District. Four species were identified: Frankliniella occidentalis Pergande, F. schultzei Trybom, Thrips palmi Karny and T. tabaci Lindeman. This is the first report of the occurrence of F. occidentalis and T. palmi in the Federal District. A methodology for the rearing of these four thrips is described in this report.


1990 ◽  
Vol 25 (3) ◽  
pp. 427-438 ◽  
Author(s):  
C. E. Yonce ◽  
R. J. Beshear ◽  
J. A. Payne ◽  
D. L. Horton

Thrips populations and injury attributed to thrips feeding on fruit surfaces was monitored in unsprayed middle Georgia nectarines during 1986 – 1988. The flower thrips, Frankliniella tritici (Fitch), the western flower thrips, Frankliniella occidentalis (Pergande), and the soybean thrips, Neohydatothrips variabilis (Beach), were the most abundant thrips species recovered from the orchard. Their relative abundance changed each year. The western flower thrips particularly appears to be most damaging in causing russeting on fruit surfaces. Silvering injury was caused by either or both of the flower thrips and coincided with peak populations of adults at or near final fruit swell. Soybean thrips caused little or no injury to fruit. None of the above mentioned flower thrips species were recovered from various weed and grass species in and near the nectarine orchard during two years of overwintering studies.


2017 ◽  
Vol 108 (3) ◽  
pp. 413-420 ◽  
Author(s):  
Arnika Przybylska ◽  
Żaneta Fiedler ◽  
Patryk Frąckowiak ◽  
Aleksandra Obrępalska-Stęplowska

AbstractThrips palmi and Frankliniella occidentalis (order Thysanoptera) are thrips species that represent major plant pests. They are polyphagous insects capable of adversely affecting crop production. As such, in the European Union, these thrips species should be regulated as quarantine organisms. T. palmi and F. occidentalis can cause considerable damage to susceptible plants by feeding on them and transmitting several viruses responsible for serious plant diseases. Successful pest control strategies are based on an early, fast, and reliable diagnosis, which precedes the selection of appropriate steps to limit the effects of harmful organisms. We herein describe a novel diagnostic approach that enables the sensitive and species-specific detection (and differentiation) of these pests in a duplex polymerase chain reaction assay, which was adapted for both standard and real-time quantitative assays. Our method is based on the amplification of a 5.8S-internal transcribed spacer 2 ribosomal DNA fragment that is conserved between T. palmi and F. occidentalis.


Plant Disease ◽  
2001 ◽  
Vol 85 (8) ◽  
pp. 838-842 ◽  
Author(s):  
A. Kritzman ◽  
M. Lampel ◽  
B. Raccah ◽  
A. Gera

Iris yellow spot virus (IYSV), a new tospovirus associated with a disease in onion (Allium cepa) that is known to growers in Israel as “straw bleaching,” was identified and further characterized by host range, serology, electron microscopy, and molecular analysis of the nucleocapsid gene. The transmissibility of IYSV by Thrips tabaci and Frankliniella occidentalis was studied. IYSV was efficiently transmitted by T. tabaci from infected to healthy onion seedlings and leaf pieces. Two biotypes of F. occidentalis, collected from two different locations in Israel, failed to transmit the virus. Surveys to relate the incidence of thrips populations to that of IYSV were conducted in onion fields. They revealed that the onion thrips T. tabaci was the predominant thrips species, and that its incidence was strongly related to that of IYSV. Forty-five percent of the thrips population collected from IYSV-infected onion and garlic fields in Israel transmitted the virus. IYSV was not transmitted to onion seedlings from infected mother plants through the seed, and was not located in bulbs of infected plants.


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