scholarly journals Inter-species horizontal toxicity: Experimental control of Argentine ants and their citrophilus mealybug mutualists in a viticultural system

2021 ◽  
Author(s):  
◽  
Catherine Hardiman

<p>The invasive Argentine ant, Linepithema humile, is known to form a trophobiotic association with honeydew excreting homopterans Pseudococcus sp. providing protection from natural enemies in exchange for the honeydew they excrete. The vine mealybug Pseudococcus calceolariae, can transmit Grapevine leafroll- associated virus 3 (GLRaV-3) between vines as it travels and feeds with the ensuing leafroll disease negatively impacting on vine health and wine quality. Therefore, if an effective chemical control method targeting incursions of Argentine ants in vineyards contributes to the dissociation of this invasive ant species with its citrophilus mealybug mutualist, then in theory the spread of GLRaV-3 in vineyards by its mealybug vector can be stemmed. Three insecticidal treatments targeting Argentine ants in the canopy of potted Pinot Noir grapevines inoculated with citrophilus mealybugs were trialled at a field site established in Nelson during the summer of 2016/2017. Bifenthrin (1200ppm) was sprayed on vine trunks and the low- toxicity baits, thiamethoxam (0.0006%) or boric acid (0.5%) carried in polyacrylamide gel with 25% sucrose and 0.15% citric acid solution, were placed at the base of vines. A significant decline in ant activity (p < 0.001) and citrophilus mealybugs was observed for the bifenthrin treatment. A follow-on bioassay was conducted at Mt. Albert Plant and Food Research, in the absence of P. calceolariae’s natural enemies to test the hypothesis that the decline in citrophilus mealybugs in response to vines treated with bifenthrin, could in fact be due to inter-species horizontal toxicity because of Argentine ants transferring the toxicant bifenthrin to citrophilus mealybugs while tending them or contaminating the substrate that they fed on. The significant decrease in average citrophilus mealybug activity rate (p < 0.001) for bifenthrin treatments compared with the controls provides evidence for inter-species horizontal toxicity. Bifenthrin sprayed on grapevine trunks may be suitable to control Argentine ants in the vine canopy and indirectly control P. calceolariae, a known vector of GLRaV-3 between grapevine hosts. The concept of inter-species horizontal toxicity could become a model for targeted pest management by exploiting different insect mutualisms in various horticultural cropping systems.</p>

2021 ◽  
Author(s):  
◽  
Catherine Hardiman

<p>The invasive Argentine ant, Linepithema humile, is known to form a trophobiotic association with honeydew excreting homopterans Pseudococcus sp. providing protection from natural enemies in exchange for the honeydew they excrete. The vine mealybug Pseudococcus calceolariae, can transmit Grapevine leafroll- associated virus 3 (GLRaV-3) between vines as it travels and feeds with the ensuing leafroll disease negatively impacting on vine health and wine quality. Therefore, if an effective chemical control method targeting incursions of Argentine ants in vineyards contributes to the dissociation of this invasive ant species with its citrophilus mealybug mutualist, then in theory the spread of GLRaV-3 in vineyards by its mealybug vector can be stemmed. Three insecticidal treatments targeting Argentine ants in the canopy of potted Pinot Noir grapevines inoculated with citrophilus mealybugs were trialled at a field site established in Nelson during the summer of 2016/2017. Bifenthrin (1200ppm) was sprayed on vine trunks and the low- toxicity baits, thiamethoxam (0.0006%) or boric acid (0.5%) carried in polyacrylamide gel with 25% sucrose and 0.15% citric acid solution, were placed at the base of vines. A significant decline in ant activity (p < 0.001) and citrophilus mealybugs was observed for the bifenthrin treatment. A follow-on bioassay was conducted at Mt. Albert Plant and Food Research, in the absence of P. calceolariae’s natural enemies to test the hypothesis that the decline in citrophilus mealybugs in response to vines treated with bifenthrin, could in fact be due to inter-species horizontal toxicity because of Argentine ants transferring the toxicant bifenthrin to citrophilus mealybugs while tending them or contaminating the substrate that they fed on. The significant decrease in average citrophilus mealybug activity rate (p < 0.001) for bifenthrin treatments compared with the controls provides evidence for inter-species horizontal toxicity. Bifenthrin sprayed on grapevine trunks may be suitable to control Argentine ants in the vine canopy and indirectly control P. calceolariae, a known vector of GLRaV-3 between grapevine hosts. The concept of inter-species horizontal toxicity could become a model for targeted pest management by exploiting different insect mutualisms in various horticultural cropping systems.</p>


Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 591
Author(s):  
Irene Castañeda ◽  
Elsa Bonnaud ◽  
Franck Courchamp ◽  
Gloria Luque

As a critical stage in the life cycle of ant colonies, nest establishment depends on external and internal factors. This study investigates the effect of the number of queens on queen and worker behavior during nest establishment in invasive Argentine ants (Linepitema humile) and native Mediterranean Tapinoma nigerrimum. We set up experimental colonies with the same number of workers but with one or six queens. At different time points, we recorded the positions of queens and workers inside and outside the nest. Our results highlight the influence of the number of queens on the position of queens and workers with between-species differences. Queens of both species entered the nests more quickly when there were six queens. During nest establishment, more workers were inside nests with six queens for both species, with this effect being greater for T. nigerrimum. Once nests were established, fewer workers of both species were engaged in nest maintenance and feeding in nests with six queens; T. nigerrimum had fewer workers engaged in patrolling. These results suggest that the number of queens is a key factor driving queen and worker behavior during and after nest establishment with different species responses.


2021 ◽  
Vol 18 (1) ◽  
pp. 27-32
Author(s):  
A.M. Zongoma ◽  
D.B. Dangora ◽  
M. Sétamou ◽  
M.D. Alegbejo ◽  
O.J. Alabi

Insect-vectored viruses are a major threat to grapevine production but there is a dearth of information on the occurrence and distribution of key grapevine pests in Nigeria. The recent detection of grapevine leafroll associated virus-1 (GLRaV-1), a known insect-vectored ampelovirus, in Nigeria elevates the importance of the identification of its potential vectors as a precursor to assessing the risk of grapevine leafroll disease spread. This study was conducted to determine the occurrence and diversity of potential vectors of grapevine viruses and their natural enemies in vineyards across the savannah agro-ecological region of Nigeria. Forty vineyard and nursery locations were surveyed during 2016 and 45 arthropod samples were collected. The samples were first morphologically identified, and DNA barcoding was conducted on a subset of 16 representative samples using universal primers specific to the Mitochondrial Cytochrome Oxidase subunit I (mtCOI) gene of most insects. The results indicated the presence of two species of scale insects (Parasaissetia nigra and Saissetia coffeae) and two mealybug species (Maconellicoccus hirsutus and Ferrisia virgata), some ofwhich are potential grapevine virus vectors, in Nigerian vineyards. In addition, the natural enemies of these insect species were detected which includes three species of parasitoids (Anagyrus kamali, Anagyrus pseudococci and Encarsia inaron) and one predator (Hyperaspidius mimus). While the detection of mealybugs and scale insects underscore the risk of vector-mediated virus spread in Nigerian vineyards, the identification of their natural enemies indicates presence of natural biological control agents to facilitate an integrated management of economically important grapevine virus diseases in the country. Keywords: Mealybugs; scale insects; parasitoids and predators; insect vectors; grapevine viruses.


Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 128 ◽  
Author(s):  
Shovon Chandra Sarkar ◽  
Endong Wang ◽  
Shengyong Wu ◽  
Zhongren Lei

Companion planting is a well-known strategy to manage insect pests and support a natural enemy population through vegetative diversification. Trap cropping is one such type of special companion planting strategy that is traditionally used for insect pest management through vegetative diversification used to attract insect pests away from the main crops during a critical time period by providing them an alternative preferred choice. Trap crops not only attract the insects for feeding and oviposition, but also act as a sink for any pathogen that may be a vector. Considerable research has been conducted on different trap crops as companion plant species to develop improved pest management strategies. Despite this, little consensus exists regarding optimal trap cropping systems for diverse pest management situations. An advantage of trap cropping over an artificially released natural enemy-based biological control could be an attractive remedy for natural enemies in cropping systems. Besides, many trap crop species can conserve natural enemies. This secondary effect of attracting natural enemies may be an advantage compared to the conventional means of pest control. However, this additional consideration requires a more knowledge-intensive background to designing an effective trap cropping system. We have provided information based on different trap crops as companion plant, their functions and an updated list of trap cropping applications to attract insect pests and natural enemies that should be proven as helpful in future trap cropping endeavors.


1989 ◽  
Vol 79 (1) ◽  
pp. 115-121 ◽  
Author(s):  
Clifford S. Gold ◽  
Miguel A. Altieri ◽  
Anthony C. Bellotti

AbstractCassava intercropped with cowpea in Colombia had lower numbers of Aleurotrachelus socialis Bondar and Trialeurodes variabilis (Quaintance) per leaf and per plant than did monoculture cassava. These differences persisted for up to six months after harvest of the cowpea. These results are examined in light of the natural enemies hypothesis, which suggests that natural enemies may be favoured in diversified systems, thereby reducting herbivore load. In this regard, the effects of different cropping systems on the whitefly predator Delphastus pusillus (Le Conte) and on the combined action of the parasitoids Amitus aleurodinus Haldeman and Eretmocerus aleyrodiphaga (Risbec) are discussed. D. pusillus displayed a functional responce and was more abundant in monocultures than in intercrops. Predator:prey ratios were similar between treatments and so low that predation appeared to have little impact on whitefly numbers. Parasitism levels of Aleurotrachelus socialis were not affected by crop combinations. The data suggest that the activity of the natural enemies does not explain cropping system effects on cassava whitefly populations.


Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 823
Author(s):  
Arash Kheirodin ◽  
Alvin M. Simmons ◽  
Jesusa C. Legaspi ◽  
Erin E. Grabarczyk ◽  
Michael D. Toews ◽  
...  

The whitefly, Bemisia tabaci, has developed resistance to many insecticides, renewing interest in the biological control of this global pest. Generalist predators might contribute to whitefly suppression if they commonly occur in infested fields and generally complement rather than interfere with specialized natural enemies. Here, we review literature from the last 20 years, across US cropping systems, which considers the impacts of generalist predators on B. tabaci. Laboratory feeding trials and molecular gut content analysis suggest that at least 30 different generalist predator species willingly and/or regularly feed on these whiteflies. Nine of these predators appear to be particularly impactful, and a higher abundance of a few of these predator species has been shown to correlate with greater B. tabaci predation in the field. Predator species often occupy complementary feeding niches, which would be expected to strengthen biocontrol, although intraguild predation is also common and might be disruptive. Overall, our review suggests that a bio-diverse community of generalist predators commonly attacks B. tabaci, with the potential to exert substantial control in the field. The key challenge will be to develop reduced-spray plans so that generalist predators, and other more specialized natural enemies, are abundant enough that their biocontrol potential is realized.


Viruses ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1142
Author(s):  
Mamadou L. Fall ◽  
Dong Xu ◽  
Pierre Lemoyne ◽  
Issam E. Ben Moussa ◽  
Carole Beaulieu ◽  
...  

Quebec is the third-largest wine grape producing province in Canada, and the industry is constantly expanding. Traditionally, 90% of the grapevine cultivars grown in Quebec were winter hardy and largely dominated by interspecific hybrid Vitis sp. cultivars. Over the years, the winter protection techniques adopted by growers and climate changes have offered an opportunity to establish V. vinifera L. cultivars (e.g., Pinot noir). We characterized the virome of leafroll-infected interspecific hybrid cultivar and compared it to the virome of V. vinifera cultivar to support and facilitate the transition of the industry. A dsRNA sequencing method was used to sequence symptomatic and asymptomatic grapevine leaves of different cultivars. The results suggested a complex virome in terms of composition, abundance, richness, and phylogenetic diversity. Three viruses, grapevine Rupestris stem pitting-associated virus, grapevine leafroll-associated virus (GLRaV) 3 and 2 and hop stunt viroid (HSVd) largely dominated the virome. However, their presence and abundance varied among grapevine cultivars. The symptomless grapevine cultivar Vidal was frequently infected by multiple virus and viroid species and different strains of the same virus, including GLRaV-3 and 2. Our data show that viruses and viroids associated with the highest number of grapevines expressing symptoms included HSVd, GLRaV-3 and GLRaV-2, in gradient order. However, co-occurrence analysis revealed that the presence of GLRaV species was randomly associated with the development of virus-like symptoms. These findings and their implications for grapevine leafroll disease management are discussed.


2020 ◽  
Vol 10 (2) ◽  
pp. 709-716
Author(s):  
M. Mala ◽  
M. M. I. Mollah ◽  
M. Baishnab

Traditional there are two strategies to handle pest problems in crop production, either dependence on non-chemical agricultural practices (such as cultural, mechanical, biological practices etc.) or reliance on existing natural pest control mechanisms. Intercropping is a cultural non-chemical agricultural practice where two or more crops are grown on the same field in a year with different cropping patterns. In this multiple cropping system, biodiversity and pest suppression are increased. Biodiversity can restore the natural elements of agro ecosystem because almost all favorable elements of natural enemies are available in diversified agro ecosystem. Energy intensive modern technology in agriculture is one of the vital causes for loss of biodiversity. In intercropping system biological pest control method can be ensured with higher level of crop diversity instead of energy intensive agriculture. Intercropping provides different benefits on pest management with two available hypotheses or mechanism. One of the hypotheses is the ‘resource concentration hypothesis’ and another is the ‘natural enemies hypothesis’. Intercropping, directly and indirectly, influences to increase biodiversity which results in reduction of pest densities in crop fields. As a result, less expense for use of pesticide is required and finally higher yield also add some financial benefits. Intercropping system utilizes inherent ability of plant to protect pests. Therefore further knowledge about genotypic crop diversity, diversity of natural enemies, chemically-mediated mechanisms of Volatile Organic Compounds (VOCs) will be effective for further improvement of intercropping system for greater benefits.


Plant Disease ◽  
2015 ◽  
Vol 99 (2) ◽  
pp. 293-293 ◽  
Author(s):  
M. Beuve ◽  
T. Candresse ◽  
M. Tannières ◽  
O. Lemaire

Grapevine Pinot gris virus (GPGV), belonging to the genus Trichovirus of the family Betaflexiviridae, was first identified by siRNA sequencing in northern Italy in 2012, in the grapevine varieties Pinot gris, Traminer, and Pinot Noir, which exhibited mottling and leaf deformation (1), and in asymptomatic vines, with a lower frequency. Since 2012, this virus has also been reported in South Korea, Slovenia, Greece (3), Czech Republic (2), Slovakia (2), and southern Italy (4). In 2014, GPGV was identified by Illumina sequencing of total RNAs extracted from leaves of the Merlot variety (Vitis vinifera) grafted onto Gravesac rootstock originated from a vineyard in the Bordeaux region of France. This Merlot plant exhibited fanleaf-like degeneration symptoms associated with Tomato black ring virus (TBRV) infection. Cuttings were collected in 2010 and maintained thereafter in a greenhouse. The full-length genome was assembled either de novo or by mapping of the Illumina reads on a reference GPGV genome (GenBank FR877530) using the CLC Genomics workbench software (CLC Bio, Qiagen, USA). The French GPGV isolate “Mer” (7,223 nucleotides, GenBank KM491305) is closely related to other European GPGV sequences; it exhibits 95.4% nucleotide identity with the reference Italian isolate (NC_015782) and 98 to 98.3% identity with Slovak isolates (KF134123 to KF134125). The higher divergence between French and Italian GPGV isolates was mainly due to differences in the 5′ extremity of the genome, as already shown with the Slovak GPGV isolates. RNA extracted from phloem scrapings of 19 cv. Merlot vines from the same plot collected in 2014 were analyzed by RT-PCR using the specific primer pair Pg-Mer-F1 (5′-GGAGTTGCCTTCGTTTACGA-3′) and Pg-Mer-R1 (5′-GTACTTGATTCGCCTC GCTCA-3′), designed on the basis of alignments of all available GPGV sequences from GenBank. The resulting amplicon of 770 bp corresponded to a fragment of the putative movement protein (MP) gene. Seven (35%) of the tested plants gave a strong positive amplification. Three RT-PCR products were directly sequenced and showed 99.3 to 99.5% identity within the MP gene of the GPGV-Mer isolate. Given the mixed viral infection status of the vines found infected by GPGV, it was not possible to associate a specific symptomatology with the presence of GPGV. Furthermore, similar RT-PCR tests were also performed on RNA extracts prepared from two plants of cv. Carignan that originated from a French grapevine collection, exhibiting fanleaf-like symptoms without any nepovirus detection. These samples similarly gave a strong positive amplification. The sequences obtained from the two Carignan vines showed 98.4 and 97.8% identity with the GPGV-Mer isolate. To our knowledge, this is the first report of GPGV in France. GPGV has been discovered in white and red berry cultivars, suggesting that its prevalence could be important in European vineyards (2). Further large-scale studies will be essential to determine the world prevalence of GPGV and to evaluate its potential effects on yield and on wine quality, as well as to shed light on GPGV epidemiology. Of particular concern is whether, like the other grapevine-infecting Trichovirus, Grapevine berry inner necrosis virus (GPGV) can be transmitted by the eryophid mite Colomerus vitis. References: (1) A. Giampetruzzi et al. Virus Res. 163: 262, 2012. (2) M. Glasa et al. Arch. Virol. 159: 2103, 2014. (3) G. P. Martelli, J. Plant Pathol. 96: S105, 2014. (4) M. Morelli et al. J. Plant Pathol. 96:431, 2014.


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