Citrus Insect Interactions: Implications for Pest Management (original) (raw)
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Journal of Agricultural Science and Technology
Fruit flies are causing extensive socio-economic losses in citrus orchards in Ghana. The flies as quarantine pests have detrimental effects on the export market due to international trade regulations. Oecophylla species have been tested as biological control agents on other crops, and have shown great potential in reducing the effects of pests. The effectiveness of Oecophylla as a biocontrol agent of fruit flies was compared with insecticide, Cypermethrin + Dimethoate (Cydim super®) at Forest and Horticultural Crops Research Centre, Kade, in the Eastern Region of Ghana. The results have shown that trees colonized by Oecophylla had between 6%-10% fly infestation and Cypermethrin + Dimethoate (1614 mg a.i. mL -1 tree -1 ) recorded 3.0% infestation. Cypermethrin + Dimethoate treatment recorded 3.50 ± 0.87 dropped fruits, and Oecophylla colonized-trees recorded 15 to 19.20 ± 3.61. Oecophylla colonized-trees recorded yield values from 12.90 to 15.20 tons ha -1 whilst Cypermethrin + Dimethoate treatment recorded 27.90 tons ha -1 fruit yield. Total number of fly landings in the presence of Oecophylla (72.00) was significantly lower than the absence of Oecophylla (114.20). Set-up with no Oecophylla recorded the highest infestation index (71.17) while the presence recorded 45.83. These results suggest that Oecophylla longinoda can be used as a biocontrol agent for IPM programs in citrus orchards.
Impact of three ant species on pest populations in Mediterranean citrus orchards
We conducted an ant-exclusion experiment to study the influence of three ant species, the native to the Mediterranean Pheidole pallidula (Nylander) and Lasius grandis (Forel) and the invasive Linepithema humile (Mayr), on the population densities and parasitism rates of three citrus pests: the honeydew producer woolly whitefly Aleurothrixus floccosus (Maskell) and the non-honeydew producers, California red scale Aonidiella aurantii (Maskell) and citrus leafminer Phyllocnistis citrella Stainton). The ant-exclusion was carried out in three citrus orchards, each one dominated by one ant species, from April 2011 to November 2012. We measured ant activity, California red scale densities on fruits and twigs, whitefly and citrus leafminer population densities as well as the parasitism of these pests in ant-allowed and ant-excluded trees. The most active ant species was L. humile, while P. pallidula and L. grandis showed considerably lower activity levels. On fruits, A. aurantii densities in the ant-excluded trees were on average 27% lower for the three ant species studied than in the antallowed trees. On twigs, differences in A. aurantii densities were detected between treatments only for L. grandis. In the case of A. floccosus, differences between ant-excluded and ant-allowed treatments were found for P. pallidula and L. humile. For P. citrella, we found no significant differences in the percent of leaf surface loss. Regarding the parasitism, we only found higher percent parasitism in the case of P. citrella in L. humile dominated orchard. These results show that ant activity may have an effect on the abundance of honeydew and non-honeydew producing pests, yet this effect depends on the ant species involved. This effect is possibly not produced through parasitism since our results show no differences in percent parasitism for the three ant species studied between ant-allowed and antexcluded treatments.
Bulletin of Entomological Research, 2014
Mutualistic relationships between honeydew-producing insects and ants have been widely recognized for several decades. Iridomyrmex rufoniger (Lowne) is the commonest ant species associated with black scale, Saissetia oleae (Olivier), in the citrus orchards of the mid latitudes of coastal New South Wales. Citrus trees with high densities of both red and black scale and high ant activity were identified and the results of excluding ants from half of those trees (using a polybutene band on each trunk) were compared with the results of not excluding ants from the other half. Trees with a low incidence of black scale and ants were also studied. Exclusion of ants from trees was soon followed by collapse of black scale populations because most individuals were asphyxiated by their own honeydew. Also, parasitism of the red scale by Encarsia perniciosi (Tower) and Encarsia citrina Craw was significantly higher than in the control trees over the following year, as was the predation rate on red scale due to three coccinellid predators, Halmus chalybeus (Boisduval), Rhyzobius hirtellus Crotch and Rhyzobius lophanthae (Blaisdell). In contrast, another coccinellid, Orcus australasiae (Boisduval), and a noctuid moth larva, Mataeomera dubia Butler, were seen in low numbers on banded (ant exclusion) trees, probably because of the low availability of their black scale prey, but were significantly higher on control trees apparently because of their invulnerability to ants.
Annals of Applied Biology, 2018
The parasitoid wasp Spalangia cameroni and the predatory beetle Pseudoophonus rufipes have long been studied for use as biological control agents against the Mediterranean fruit fly Ceratitis capitata, particularly in citrus fruit orchards. Nevertheless, these two species of natural enemies, when competing for a common resource, may experience intraguild predation (IGP) interactions. These possible interactions, affecting parasitism and predation, have been evaluated in the present work, under laboratory conditions, through potential changes in functional response. Regarding host/prey density, both natural enemies, when acting alone, showed a type II functional response. Nevertheless, due to IGP, S. cameroni, in the presence of P. rufipes, showed a higher fertility rate and a type III functional response. The parasitism behaviour of S. cameroni was affected by the presence of the predator, reducing the host handling time. Conversely, the parasitism rate of S. cameroni did not vary i...
Journal of Animal Ecology, 2019
1. Biological control has traditionally simplified the view of trophic relationships between herbivorous pests and their natural enemies in agriculture. The success or failure of this pest management strategy is still mainly attributed to the ability of a few key natural enemies to suppress the pest density. For example, successful regulation of the California red scale (Aonidiella aurantii) a key citrus pest, is generally credited to specific parasitoids of the Aphytis genus. Currently, research is revealing how herbivore regulation in agroecosystems can be alternatively achieved with a greater number of trophic associations within the system. 2. The goals of the present study were: i) to unravel species-specific trophic links between A. aurantii, and its natural enemies in citrus agroecosystems, and ii) to assess their contribution to control of A. aurantii. 3. Predation and parasitism of this herbivorous pest were assessed through exclusion experiments. Species-specific trophic links between this herbivorous pest and its natural enemies were studied using gut-content analysis of field collected predators employing prey specific DNA molecular markers. Relative predation rates of the species involved in A. aurantii regulation were estimated. 4. Predation was found to be the main biotic component of A. aurantii mortality, causing reductions of more than 75% in recently settled cohorts. Aonidiella aurantii DNA was detected in the digestive system of 11 species of predators. Generalist and stenophagous predators, mainly associated with other citrus pests such as aphids, proved to be the most important biological control agents of this pest. Complex trophic relationships, such as apparent competition between two key citrus pests, were revealed. 5. The present study highlights the role of predation as biotic mortality factor of key pests in perennial agroecosystems; wherein, it is a rich complex of indigenous or naturalized generalist predators that are primarily responsible for this mortality. The results herein presented may therefore offer another perspective on the biological control of one of the key worldwide citrus Accepted Article This article is protected by copyright. All rights reserved. pests; at least in those regions where specific parasitoids are not able to successfully regulate the scale populations.
International Journal of Scientific Research in Science and Technology, 2019
Prays endocarpa Meyrick is a kind of pest that attacks pummelo (Citrus maxima Merr.) lowering the quality and the selling price of the fruits. Information about the use of ants as a pest predator has been widely found. This research aims to test the use of Oecophylla smaragdina ant to control attack from P. endocarpa on pummelo. Two treatments were carried out, namely treatment with exposure of O. smaragdina ants on fruiting stalks and without exposure of O. smaragdina ants. Exposure of O. smaragdina was carried out for three weeks since the fruits were still young, sized 10-15 millimeters. The level of attack and the number of fallen pummelo fruits were observed during six weeks of treatment. The observations showed that the average rate of damage of P. endocarpa was lower in treatment with exposure of O. smaragdina (17.24%) compared to treatment without (81.25%). Likewise, the results found on average of the number of fallen fruits were lower in treatment with exposure of O. smara...