Contribution of predation to the biological control of a key herbivorous pest in citrus agroecosystems (original) (raw)
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Aphid predators in citrus crops: the least voracious predators are the most effective
Journal of Pest Science, 2020
Rich and abundant predator complexes are frequently associated with aphids in perennial agroecosystems. The ability of these predators to successfully suppress aphid populations is nevertheless highly variable. The development of operative conservation biological control strategies is mostly hindered by the lack of knowledge of the specific roles of the aphidophagous assemblage components, their intraguild relationships and the predatory attributes that chiefly determine their effectiveness. The role of predation in the biological control of aphids in perennial agroecosystems was assessed through exclusion experiments in aphid infested citrus crops. Important predator attributes such as recruitment, aphid consumption rates, and foraging strategies were related to their efficacy. Predation greatly affected aphid colony phenology as well as size. Predators with lower aphid consumption rates (Micro-coccinellid species and Cecidomyiidae) were revealed to be the most efficient aphidophaga. These predators encountered aphid colonies at earlier colony stages and significantly reduced their population growth rates. Later more voracious aphidophaga groups (Chrysopidae and Macrococcinellids) did not present effective biological control of the colonies. Contrarily to what was widely believed, the less voracious aphidophaga groups such as the Micrococcinellids and Cecidomyiids are probably the groups who are mostly responsible for aphid suppression. Future conservation biological control studies in this crop should therefore chiefly focus on these groups.
Revalorización del complejo de depredadores polífagos asociado al cultivo de los cítricos, como agentes de control biológico de xv abstract Predators have been considered as one of the most important groups of pest natural enemies in agroecosystems. However, their complex biology and behaviour have hindered in many cases evaluating its true role as biological control agents. Studies on predators have mostly focused on the simple relationships between specialist predators and their prey since these systems are easier to parameterize. Though, there is a growing interest in the control exerted by generalist predators owing to their ability to keep prey densities in stable equilibrium in ways not dependent on their density. The importance of predation as a biotic mortality factor of key citrus pests in systems under conservation biological control management strategies was assessed. The California red scale, Aonidiella aurantii, was used as a model pest in clementine citrus groves. Through the use of field exclusion techniques and PCR detection of prey DNA in the gut content of predators, it was found that a rich complex of indigenous and naturalized generalist and stenophagous predators are the main mortality factor of this pest.
Citrus Insect Interactions: Implications for Pest Management
We observed that insect interactions lead to damaged fruits, leaves, stems, and exposed fruits and tree trunks to pathogenic infection, however, some citrus trees were protected by these interactions. Our study shows that Oecophylla longinoda and Crematogaster spp. protect citrus aphids and citrus scale insects from their natural enemies leading to their outbreak and further damage to the citrus plant. Citrus trees with more Oecophylla and Crematogaster had fewer pests such as fruit flies, termites and the variegated grasshopper, Zonocerus variegatus. Our study shows that “chain” formation by weaver ants, Oecophylla enables them to reach the same colony in different citrus trees. We identified wild passion plant, Passiflora sp. as an alternate host for Leptoglossus spp. We recommend Oecophylla and Crematogaster as biological control agents against fruit flies, termites and the variegated grasshopper; however, they could lead to an outbreak of citrus aphids and citrus scale insects. Phasmomyrmex aberrans is antagonistic to Oecophylla and so in an attempt to utilize Oecophylla as a biological control agent, we recommed that care must be taken to ensure that they do not come together. As biological control agents in orchards that do not have closed canopies, we recommend that sticks or ropes be connected to adjacent trees to facilitate movement of the ants to enhance their dispersal in orchards. Care must be taken to clear all Passiflora sp. from citrus orchards.
Experimental and Applied Acarology
The generalist predator Euseius stipulatus (Athias-Henriot) and the Tetranychidae-specialist predators Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias-Henriot play a key role in the regulation of Tetranychus urticae Koch in Spanish citrus orchards. Previous studies have shown that sour orange (Citrus aurantium L.) and Cleopatra mandarin (Citrus reshni hort. ex Tan.) display extreme resistance and susceptibility to T. urticae, respectively. When offered a choice between these two genotypes infested by T. urticae, E. stipulatus preferred Cleopatra mandarin, whereas the specialists did not show any preference. The present study was undertaken to check whether these preferences could be related to the feeding of E. stipulatus on the host plant and/or to differences in prey feeding on the two plants. Our results demonstrate that E. stipulatus is a zoophytophagous mite, which can engage in direct plant feeding in sour orange and Cleopatra mandarin, whereas neither N....
Biological Control, 2010
The California red scale (CRS), Aonidiella aurantii, a worldwide citrus pest, has the ectoparasitoid Aphytis melinus as its main natural control agent. Other natural enemies can complement A. melinus in the pest control. For 3 years we studied the incidence of the parasitoids and predators on CRS populations of 19 citrus groves divided in four groups according to its parasitoid composition to determine which combination of natural enemies reaches higher effectiveness in the biological control of CRS in field conditions. The parasitoids species preferred different scale instars and different periods of the year for parasitism. In the groves where A. melinus was present in high numbers, either alone or coexisting with Aphytis chrysomphali, parasitism rates reached 22.4% on average, whereas parasitism rates were much lower (11.5%) when A. chrysomphali was the dominant parasitoid. The best parasitism level was achieved when these ectoparasitoids occurred together with the endoparasitoid Encarsia perniciosi. The average annual mortality rate of A. aurantii was 73.6%. The analysis of dead scales killed by Aphytis confirms the results obtained in parasitism of live scales. The more abundant predators were Lestodiplosis aonidiellae and Rhyzobius lophantae. The incidence of predators on the CRS populations was comparatively much lower.
Trophic ecology of citrus pests based on stable isotope analysis
Scientia Agricola
Macrodactylus pumilio Burm. (Coleoptera: Scarabeidae) and Naupactus cervinus (Boh.) (Coleoptera: Curculionidae) are considered primary pests in citrus crops in Brazil, causing damage to plants and decreasing productivity. However, few studies investigate the ecology of these insects. In this context, the use of stable isotopes analysis (SIA) emerges as an alternative technique to conventional studies of behavioral ecology because it is faster and may explain feeding behavior based on the food source for each species. Field sampling and laboratory experiments were carried out to examine the changes of carbon and nitrogen stable isotope ratios (δ 13 C and δ 15 N) among pests and host plants (C 3 citrus and C 4 grasses), providing means to examine trophic interactions. Beetles were collected at the municipality of Gavião Peixoto, São Paulo State, identified and kept at 5 °C in saturated saline solution until the SIA. Two patterns for both species were found: δ 13 C value for N. cervinus was-23.6 ‰ and-13 ‰ for M. pumilio, indicating similarity between the results of δ 13 C of N. cervinus and citrus plants (-26 ‰) and dependence on grasses (-12 ‰) for M. pumilio individuals. The mean δ 15 N value was 4.3 and 5.8 ‰ for citrus plants and grass leaves, respectively, and the mean δ 15 N value was 4.4 ‰ for N. cervinus and 4.9 ‰ for M. pumilio. The results showed a higher affinity of N. cervinus for citrus roots since the larval stage compared with the alternative diet on M. pumilio.
Journal of Pest Science, 2019
Sour orange, Citrus aurantium, displays higher constitutive and earlier inducible direct defenses against the two-spotted spider mite, Tetranychus urticae, than Cleopatra mandarin, Citrus reshni. Moreover, herbivore induced plant volatiles (HIPVs) produced by sour orange upon infestation can induce resistance in Cleopatra mandarin but not viceversa. Because the role of these HIPVs in indirect resistance remains ignored, we have carried out a series of behavioral assays with three predatory mites with different levels of specialization on this herbivore, from strict entomophagy to omnivory. We have further characterized the volatile blend associated with T. urticae, which interestingly includes the HIPV methyl salycilate, as well as that produced by induced Cleopatra mandarin plants. Although a preference for less defended plants with presumably higher prey densities (i.e., C. reshni) was expected, this was not always the case. Because predators' responses changed with diet width, with omnivore predators responding to both HIPVs and prey-related odors and specialized ones mostly to prey, our results reveal that these responses depend on plant genotype, prey presence, and predator diet specialization. As the different volatile blends produced by infested sour orange, induced Cleopatra mandarin and T. urticae itself are attractive to T. urticae natural enemies but not to the herbivore, they may provide clues to develop new more sustainable tools to manipulate these agriculturally relevant species.
Kinnow (Citrus nobilis) and orange (Citrus reticulata) are fruits having significant economic, cultural and social impact throughout the world. Orchards of these fruits serve as a host of many insects but interaction of citrus host with insect fauna varies from pest to predator that show symbiotic relationship and ultimately lowers fruit production. The present study was conducted from July to December, 2015 to record occurrence and interaction of pest vs. predator communities along the temperature gradient on citrus orchards under the ecological conditions of district Toba Tek Singh (Punjab), Pakistan. The abundance of pest was found to increase rapidly in late July, and reached its first peak in late-August, then followed by the second peak in mid-October among orange orchards. Few numbers of natural enemy species were discovered and recorded highest in September in association with pest species. Among kinnow orchards, pest abundance was found to increase in late-August, than followed by the second peak in early October: Dalbulus maidis (Cicadellidae) was recorded as an extraordinary contributing pest species. However population densities of natural enemies were highest from September to October and lowest densities were recorded in early July and in late-December. In case of natural enemies, Raphidopalapa foveicollis (Chrysomelidae) was recorded abundantly. Findings from this study suggested that under field conditions, various indigenous natural enemies (predators of different sizes) may act for suppression of pest species to great extent but they were quite low in number. However, results of analysis of variance regarding pest and predator densities among both orchards were not significant (F = 2.20; P = 0.1601 " orange " and F = 1.33; P = 0.2686 " Kinnow ").
EFFICACY OF CERTAIN PREDATORS IN CONTROLLING APHIDS ON NAVEL ORANGE TREES
EFFICACY OF CERTAIN PREDATORS IN CONTROLLING APHIDS ON NAVEL ORANGE TREES, 2023
The aim of this research was to assess the efficacy of some predators worked as a biocontrol tool against the navel orange aphid species (Aphis gossypii (Glover), Aphis citricola (van der Goot), Myzus persicae (Sulzer), and Aphis craccivora Koch.) during a period of two seasons in 2021 and 2022. Aphis gossypii and Aphis citricola are the two main species of aphid discovered on navel orange plants. In the two seasons of the study, there were three abundance peaks of Aphis gossypii. In 2021, the numbers recorded in the third week in April and May, as well as the second week in June were 370, 450 and 454 individuals/40 leaves and recorded 281, 386, and 500 individuals during the first and fourth weeks of April and the fourth week of May in 2022, respectively. Meanwhile, A. citricola had two abundance peaks in both seasons: in 2021 (181 and 98 individuals/40 leaves) and in 2022 (245 and 295 individuals/40 leaves). Coccinella undecimpunctata L., Chrysoperla carnea Steph, C. septempunctata, Metasyrphus corollae Fand Cydonia vicina isis were the most common predators discovered on navel orange trees.. A few number of Paederus alfierii (Koch) and true spiders were the most common predators caught in navel orange trees. On navel orange trees, these predators recorded two peaks in two seasons (73 and 77 predators/40 leaves) during the first season, and (83 and 88 predators/40 leaves) during the second season, respectively. Two predators, C. undecimpunctata and C. carnea, that prey on A. gossypii were researched from a biological perspective at 21±1°C and 65± 5% R.H. C. undecimpunctata and C. carnea took 23.49 ± 1.40 and 25.01 ± 2.63 days, respectively, to develop from egg hatching to adult exclusion. The total consumption rate per C. undecimpunctata and C. carnea larva fed on A. gossypii were 567.50 ± 6.90 and 587.63 ± 9.27 when fed on A. gossypii. During their larval stages, C. undecimpunctata and C. carnea females generally lay around 315.85±5.17 and 321.52±6.19 eggs.