Factors influencing citrus fruit scarring caused by Pezothrips kellyanus

[EN] Kelly s citrus thrips (KCT) Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) is a recently recorded cosmopolitan citrus pest, causing fruit scarring that results in downgrading of fruit. Due to the detrimental effects caused on fruits by KCT, we wanted to study some of the factors influencing fruit scarring. Specifically, the objectives were: (1) to determine the fruit development stage when citrus fruits are damaged by KCT and the population structure of KCT during this period, (2) to study the influence of temperature on intensity of damage, and finally, (3) to identify alternative host plants. KCT populations on flowers and fruitlets and alternate plant hosts were sampled in four citrus orchards from 2008 to 2010. The percentage of damaged fruits was also recorded. The exotic vine Araujia sericifera (Apocynaceae) was recorded as a new host for KCT. Thrips scarring started to increase at 350 650 degree-days (DD) above 10.2 C, coinciding with a peak abundance of the second instar larval stages over all 3 years of the study. The maximum percentage of larval stages of KCT was observed in the 3 years at about 500 DD, a period which corresponds to the end of May or early June. Variation in the severity of fruit scarring appeared to be related to air temperature. Temperature likely affects the synchronisation between the peak in abundance of KCT larvae, and the period when fruitlets are susceptible to thrips damage. Temperature can also influence the survival and development of KCT populations in citrus and other host plants in the citrus agro-ecosystem.The authors thank Alejandro Tena for his valuable suggestions and two anonymous referees for their careful review and helpful comments. We also extend our thanks to the owners of the commercial orchards for giving us permission to use their citrus orchards. 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Study of trapping systems for control of bactrocera oleae (gmelin)(diptera:tephritidae) in crete olive groves

Studies have been carried out the last four years to search for improved mass trapping systems for the control of olive fruit fly in olive groves in Chania, Crete (Greece). Trapping materials, which include various food and sex attractants and different types of traps (liquid and paper traps), were tested for their attractiveness and effectiveness in field trials. Among the tested attractants (Entomella 50 (E50), Entomella 75 (E75), Dacus bait 100 (Db100), Ammonium sulphate (As) and Sex pheromone (Sp)), the hydrolyzed protein ‘Db100’ showed the highest attractiveness regardless of the ‘Sp’. Among the tested traps (Daidalos, Elcofon, Zervas, Agrisense & Ecotrap), Daidalos captured significantly more flies than the other traps. When the traps were tested in mass trapping conditions, no statistical differences were observed among the tested traps (chemical control was applied when was necessary) , but all were different from the reference product (classical chemical control). In addition, when Spinosad, a novel natural compound derived from fermentation of the bacterium Saccharopolyspora spinosa, was applied as complementary sprays in the Mass trapping field, it also provided comparable and significant control for B. oleae (Gmel.) in comparison to the classical control

Effect of Temperature on the Development and Longevity of Pezothrips kellyanus (Thysanoptera: Thripidae)

The developmental biology and adult longevity of Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) on lemon (Citrus limon L.) leaves was studied at five constant temperatures (15, 20, 25, 30, 32.5, and 35 degrees C) under laboratory conditions. Developmental time and adult longevity were inversely related to temperature. The developmental time from egg to adult ranged from 10.1 d at 32.5 degrees C to 40.3 d at 15 degrees C. Adult thrips lived from 5.3 d at 35 degrees C to 45.9 d at 15 degrees C and females tended to live significantly longer than males at these two extreme temperatures. No significant differences were found in developmental times between male and female immature stages of P. kellyanus within each tested temperature regime. The highest larval to adult survival (80.6%) was found at 25 degrees C and the lowest (50%) at 32.5 degrees C. No larvae hatched from eggs incubated at 35 degrees C. Both linear and nonlinear models adequately described the relationship between temperature and developmental rates for immature stages of P. kellyanus. Thus, thrips required 204.5 degree-days to complete development from egg to adult stage, above a minimum threshold of 10.2 degrees C as estimated by linear regression. The temperature thresholds for all immature stages except for pupae of P. kellyanus, estimated by the linear model were similar to values that were estimated by the nonlinear model. The predicted upper lethal temperature was 33.12 degrees C, with a minimum threshold for total development occurring at 10 degrees C, as estimated by nonlinear model. The importance of the results in the management of this species through the prediction of its seasonal appearance and population levels are discussed

Effect of temperature on the fecundity of Pezothrips kellyanus (Thysanoptera: Thripidae)

The reproductive biology of a citrus pest Pezothrips kellyanus (Bagnall) was studied at four constant temperatures (15, 20, 25, and 30°C) on lemon leaf discs, under laboratory conditions. Lifetime fecundity of mated P. kellyanus was twofold higher at 20 and 25°C than at 15°C. Temperature had no significant effect on fecundity but daily oviposition rate increased as temperature increased. At 15°C, a female of P. kellyanus oviposited 1.13 offspring and at 30°C 5.35 offspring in average per day. Adult longevity was inversely related to temperature. Specifically, female longevity was longest at 15°C (53.90 d) and shortest at 30°C (13.64 d). Preoviposition, oviposition, and postoviposition periods decreased inversely to temperature. Sex ratio was strongly female biased (>60%) at 15 and 25°C. The net reproductive rate (Ro was highest at 15°C and lowest at 30°C. The intrinsic rate of natural increase (rm) as well as the finite rate of increase (λ) were related to temperature and were highest at 30°C. The mean generation time (T) and population doubling time (DT) were inversely related to temperature and were longest at the lowest studied temperature, 15°C. Almost all biological parameters (except preoviposition period) differed significantly between mated and unmated females when were tested at 25°C. The offspring sex ratio was significantly higher at mated than unmated females. Unmated females produced only a few female offspring confirming arrhenotoky in P. kellyanus. © 2012 Entomological Society of America

Tomato inoculation with the endophytic strain Fusarium solani K results in reduced feeding damage by the zoophytophagous predator nesidiocoris tenuis

Belowground symbiosis of plants with beneficial microbes is known to confer resistance to aboveground pests such as herbivorous arthropods and pathogens. Similarly, microbe-induced plant responses may also impact natural enemies of pests via the elicitation of plant defense responses and/or alteration of plant quality and growth. Nesidiocoris tenuis is a zoophytophagous predator and an efficient biological control agent of greenhouse pests. Its usefulness in plant protection is often hindered by its ability to damage plants at high predator population densities or when prey is scarce. In this study, we investigated the effect of Fusarium solani strain K (FsK), an endophytic fungal isolate that colonizes tomato root tissues, on the capability of N. tenuis to cause necrotic rings, an easily discernible symptom, on tomato stems and leaves. We found significantly less necrotic rings formed on FsK-inoculated plants for all tomato cultivars tested. FsK has been previously shown to confer ethylene-mediated tomato resistance to both foliar and root fungal pathogens; thus, the ethylene-insensitive Never ripe (Nr) and epinastic (epi) tomato plant mutant lines were included in our study to assess the role of ethylene in the recorded FsK-mediated plant damage reduction. The jasmonic acid (JA)-biosynthesis tomato mutant def-1 was also used since JA is known to mediate major anti-herbivore plant responses. We show that ethylene and JA are required for FsK to efficiently protect tomato plants from N. tenuis feeding. No necrotic rings were recorded on FsK-inoculated epi plants suggesting that ethylene overproduction may be key to tomato resistance to N. tenuis feeding. © 2018 Garantonakis, Pappas, Varikou, Skiada, Broufas, Kavroulakis and Papadopoulou

Tomato Inoculation With the Endophytic Strain Fusarium solani K Results in Reduced Feeding Damage by the Zoophytophagous Predator Nesidiocoris tenuis

Belowground symbiosis of plants with beneficial microbes is known to confer resistance to aboveground pests such as herbivorous arthropods and pathogens. Similarly, microbe-induced plant responses may also impact natural enemies of pests via the elicitation of plant defense responses and/or alteration of plant quality and growth. Nesidiocoris tenuis is a zoophytophagous predator and an efficient biological control agent of greenhouse pests. Its usefulness in plant protection is often hindered by its ability to damage plants at high predator population densities or when prey is scarce. In this study, we investigated the effect of Fusarium solani strain K (FsK), an endophytic fungal isolate that colonizes tomato root tissues, on the capability of N. tenuis to cause necrotic rings, an easily discernible symptom, on tomato stems and leaves. We found significantly less necrotic rings formed on FsK-inoculated plants for all tomato cultivars tested. FsK has been previously shown to confer ethylene-mediated tomato resistance to both foliar and root fungal pathogens; thus, the ethylene-insensitive Never ripe (Nr) and epinastic (epi) tomato plant mutant lines were included in our study to assess the role of ethylene in the recorded FsK-mediated plant damage reduction. The jasmonic acid (JA)-biosynthesis tomato mutant def-1 was also used since JA is known to mediate major anti-herbivore plant responses. We show that ethylene and JA are required for FsK to efficiently protect tomato plants from N. tenuis feeding. No necrotic rings were recorded on FsK-inoculated epi plants suggesting that ethylene overproduction may be key to tomato resistance to N. tenuis feeding

Effect of Diet on Development and Reproduction of Pezothrips kellyanus (Thysanoptera: Thripidae)

The developmental time, fecundity, and longevity of Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) encaged on lemon, Citrus limon (L.) Burm.f., leaves supplied with different food sources (pollen, sucrose, and honey) were compared at 25 degrees C. Only the addition of pollen offered a nutritional benefit for this thrips species. Pollen to the lemon leaf reduced total developmental time from egg to adult from 12.42 to 9.68 d, increased survival from 22.6 to 80.6%, and increased fecundity. When sugar was offered, only 10% of larvae survived. P. kellyanus larvae were unable to grow on lemon leaves as well as when honey was supplied to the leaves (recorded survival was 22.6 and 42.86%, respectively), and adult females were slightly able to reproduce (1.4 and 4.2 larvae per female, respectively). Pollen and honey supplements fed to adults double and triple adult longevity, respectively