Assessing the impact of areawide pheromone trapping,pesticide applications,and eradication of infested date palms for Rhynchophorus ferrugineus (Coleoptera: Curculionidae) management in Al Ghowaybah,Saudi Arabia

The red palm weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) is a highly destructive pest of date palms, Phoenix dactylifera L. (Arecales: Arecaceae), in Saudi Arabia. Data spanning a six year period (2007–2012) from Al Ghowaybah, a 1104 ha date producing region in the Al Ahsaa Directorate in Saudi Arabia, were analyzed to assess the impact enhanced management efforts that commenced in Oct. 2009 had against this pest. Within six months of initiating the areawide management program significant reductions in the mean monthly number of weevils trapped and percentage traps with R. ferrugineus were detected. Mean monthly trap captures of R. ferrugineus and the percentage of traps capturing weevils declined significantly from 2009 to 2012 by an average of 65% and 90%, respectively, indicating that trapping and dispersal pressure was significantly reduced. By 2011, average monthly trap captures and percentage of traps with R. ferrugineus were significantly lower than all pre-management capture data and this was maintained through 2012 when data collection ceased. Additionally, over the period 2010–2012, insecticide application and palm eradication rates dropped by 91% and 89%, respectively. The total number of R. ferrugineus captured in 2012 declined by 86% when compared to total captures for 2010. At the end of 2012, the estimated infestation rate of date palms in Al Ghowaybah was 0.36%, which was below the economic threshold of a 1% infestation rate set by the Directorate of Agriculture supervising the program. It is concluded that the mandatory areawide management program that commenced in Oct. 2009 against R. ferrugineus in Al Ghowaybah had a significant and rapid impact against this pest.     

Resistance monitoring for eight insecticides in Plutella xylostella in central China

The diamondback moth, Plutella xylostella L., is one of the most important pests of cruciferous vegetables in the world. Assessment of changing insecticide resistance is essential for maintaining control efficiency and resistance management. In this study, four field populations of P. xylostella were collected from cabbage (Brassica oleracea, var. capitata L.) fields in central China from 2010 to 2012 to monitor their resistance to abamectin, Bacillus thuringiensis (BT) subsp. kurstaki (WG-001), spinosad, chlorfluazuron, chlorfenapyr, diafenthiuron, indoxacarb and beta-cypermethrin by using a leaf-dipping bioassay method. The results indicated that chlorfenapyr and diafenthiuron showed high toxicity to P. xylostella in central China, with no obvious toxicity change during the three years. The resistance of P. xylostella to spinosad was at low to moderate levels of resistance in all three years. Resistance of P. xylostella to abamectin, chlorfluazuron and indoxacarb varied greatly among the four regions. P. xylostella exhibited moderate and high levels of resistance to abamectin, chlorfluazuron and indoxacarb. The resistance of this pest to BT (WG-001) and beta-cypermethrin was severe in the four regions. Our study was conducive for developing a more effective resistance management program for P. xylostella.     

Sublethal and transgenerational effects of chlorantraniliprole on biological traits of the diamondback moth,Plutella xylostella L.

The diamondback moth, Plutella xylostella (L.), is an important international pest of cruciferous vegetables. The effects of the new diamide insecticide chlorantraniliprole, at a lethal concentration inducing only 25% mortality (LC₂₅), were assessed on the development and reproductive parameters of P. xylostella under laboratory conditions. In addition, effects on development time, pupation rate, larval and pupae weight, fertility, and survival in the parent and F1 generations were assessed. When 4th instar P. xylostella larvae were exposed to LC₂₅ of chlorantraniliprole on a cabbage (Brassica oleracea var. capitata L.) leaf for 96 h, we observed increased developmental time for 4th instar larval to pupa period (4.27 days vs. 3.34 days in the control), lower pupal weight (3.58 mg vs. 4.17 mg in the control) and decreased adult fecundity (by 42%). F1 generation underwent transgenerational effects, i.e. higher developmental time from egg to pre-pupae and lower egg hatching rate occurred. Demographic growth parameters, such as the net reproductive rate (R₀), the intrinsic rate of increase (r_m), and finite rate of increase (λ) were significantly lower for the LC₂₅ chlorantraniliprole treated group than for the untreated control. Our results suggest that exposure to LC₂₅ of chlorantraniliprole may have negative effects both on exposed individuals and on subsequent generations in P. xylostella.     

Effect of different host plants on the fitness of diamond-back moth, Plutella xylostella (Lepidoptera: Plutellidae)

The diamond-back moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) is a destructive cosmopolitan pest of cruciferous crops. The pest is present wherever its host plants exist and is considered to be one of the most widely distributed of all the Lepidoptera. We investigated the effect of various host plants on the fitness of P. xylostella and tested the hypothesis by studying development time, growth, fecundity and survival on cabbage (Brassica oleracea capitata), cauliflower (Brassica oleracea botrytis), radish (Raphanus sativus), turnip (Brassica rapa), mustard (Brassica compestris) and canola (Brassica napus var. canola). The developmental time from eggs to adult eclosion was the shortest (10 days) on canola and the longest (13 days) on turnip. Fecundity was greatest on canola (350) followed by cauliflower (268 eggs) by females eclosed from the pupae reared on canola and cauliflower, respectively, while the minimum numbers of eggs (184) were observed on cabbage. The number of eggs hatched was the highest (80%) when larvae fed on cauliflower. Survival to the adult stage was the highest (94%) on mustard followed by cauliflower and lowest (64%) on turnip. The net replacement rate was lowest for populations reared on cabbage (32.3), which was also reflected by the lowest intrinsic rate of population increase (0.20). The correlation between the intrinsic rate of population increase (r_m) and the mean relative growth rate was significant (t = 20.02 d.f. = 4, P < 0.05). Canola and mustard proved to be the most suitable hosts for P. xylostella because of shorter developmental period, higher percentage of survival and higher number of eggs. The data point to the role of host plants in increasing local P. xylostella populations.     

Relative toxicity of insecticides to the crucifer pests Plutella xylostella and Myzus persicae and their natural enemies

The widespread and intensive use of conventional pesticides, particularly insecticides, presents a major risk to natural enemies of target pests, as well as to the environment in general. The aim of this study was to investigate the differential intrinsic toxicity of insecticides to two key pests of crucifers, Plutella xylostella and Myzus persicae and their respective hymenopteran parasitoids, Cotesia vestalis and Aphidius colemani. Such knowledge can help inform effective integration of insecticides and biological control in IPM systems. Three insecticides generally regarded as being compatible with natural enemies (abamectin, spinosad and indoxacarb) and one compound regarded as harmful to natural enemies (lambda-cyhalothrin) were examined. A comparative measure of the intrinsic toxicity of fresh deposits of insecticides on Chinese cabbage leaf discs was determined for both pest and parasitoids species after exposure to insecticide for 24 h and 120 h, and after 24 h exposure to insecticide plus 96 h on untreated leaf discs. Differences in the susceptibility of pests and parasitoids to different insecticides were marked for P. xylostella and C. vestalis, LC₅₀ values being significantly lower for the pest species. Such differences were not observed for M. persicae and A. colemani. There was a direct relationship between dose, exposure time and toxicity for all insecticides tested. All insecticides tested showed lower toxicity to both parasitoids compared with P. xylostella, which suggests that for this pest species side-effects on parasitoids can be minimised through IPM practices that reduce exposure time to such non-target organisms.     

Effect of climate change on Spodoptera litura Fab. on peanut: A life table approach

Investigations were conducted to understand the direct effects of rising temperature and the host-mediated effects of elevated CO₂ (eCO₂) on Spodoptera litura (Fabricius) (Noctuidae: Lepidoptera). This study involved i. the construction of life tables of S. litura at six constant temperatures viz., 20, 25, 27, 30, 33 and 35°C ± 0.5 °C reared on peanut (Arachis hypogaea L.) grown under eCO₂ (550 ppm) concentration in open top chambers ii. Estimation of threshold temperatures and thermal constants and iii. Prediction of the pest scenarios during near and distant future climate change periods. Significantly lower leaf nitrogen, higher carbon and a higher relative proportion of carbon to nitrogen (C:N) were observed in peanut foliage grown under eCO₂ over ambient CO₂ (aCO₂). The mean development time (days) of each stage, egg, larva, pupa, pre-oviposition and total life span decreased from 20 to 35 °C temperature on eCO₂ foliage. The thermal requirement of S. litura from egg to egg (within the range of 20 °C–35 °C) was 538.5 DD on eCO₂ as against 494.5 DD on aCO₂ foliage. Finite (λ) and intrinsic rates of increase (r_m), net reproductive rate (R_o), mean generation time (T) and doubling time (DT) of S. litura varied significantly with temperature and CO₂ and were found to have quadratic relationships with temperature. The present results on life table parameters estimated by the bootstrap technique showed that the ‘r_m’ values of S. litura on eCO₂ foliage were higher than those in the literature indicating a significant influence of eCO₂. The reduction of ‘T’ was noticed from a maximum of 50 days at 20 °C to minimum of 22 days at 35 °C and ‘λ’ which is the indicator of reproductive value of new eggs was highest at 35 °C and showed a negative relationship with temperature. The data on these life table parameters were plotted against temperature and two non-linear models developed for both CO₂ conditions and used for predicting the pest scenarios. Prediction of pest scenarios based on PRECIS A1B emission scenario data at eleven peanut growing locations of the country during near future (NF) and distant future (DF) climate change periods showed an increase of ‘r_m’ and ‘λ’ with varied ‘R_o’ and reduced ‘T’. The present results indicate that temperature and CO₂ are vital in influencing the growth and life table parameters of S. litura and that pest incidence is likely to be higher in the future.     

Efficacy of endophytic and applied Metarhizium anisopliae (Metch.) Sorokin (Ascomycota: Hypocreales) against larvae of Plutella xylostella L. (Yponomeutidae: Lepidoptera) infesting Brassica napus plants

The internal colonization of Brassica napus plants by Metarhizium anisopliae was demonstrated and the endophytic and direct effects of the fungus against Plutella xylostella larvae were assessed. Internal colonization of the plant by the fungus was shown by re-isolating the fungus from leaves, petioles and stems of the plant that were not the initial site of inoculation. Results indicated that significant differences (at P = 0.05) were obtained in mean % successful re-isolation of the fungus from leaves, petioles and stems at 2, 3 and 4 weeks after inoculation. To assess the endophytic effect of the fungus, larvae of P. xylostella were introduced onto plant leaves distant from the initial site of inoculation with the fungus (one leaf per plant). Results indicated that significant differences (at P = 0.05) were obtained in mean % mortality of larvae that were introduced at 2, 3 and 4 weeks after inoculation compared to the non-inoculated control. Similar significant results were obtained when the direct effect of the fungus against the larvae was assessed. In conclusion, this research provides evidence for the first time of the endophytic action of M. anisopliae against P. xylostella larvae and the ability of the fungus to colonize the internal tissues of B. napus plants.     

Spatial and temporal abundance of the solanum fruit fly, Bactrocera latifrons (Hendel), in Morogoro,Tanzania

Bactrocera latifrons is a newly invasive pest species in eastern Africa. Surveys to determine the spatial and temporal abundance of this fruit fly in the Morogoro Region, Eastern Central Tanzania, were conducted from April 2007 to March 2008. The surveys involved trapping of adult flies and collection of host fruits to determine the emergence of adults. The results indicated that the population of B. latifrons was generally low but that adult flies were present throughout the survey period. The population of B. latifrons based on infestation rates and incidence in host fruits, seems to be relatively high during the wet seasons, probably because of availability of many hosts. However, the population of the pest as determined by trapping, indicated a low population but without a specific pattern. The pest shows minimal response to the used attractants. The surveys further indicate that B. latifrons is more abundant in low to medium altitude areas compared to high altitude areas. The results indicate that, because of its low population, B. latifrons might be a minor pest. Results further suggest the possibility of establishing B. latifrons free areas where export valued solanaceous crops can be grown, but further research over longer periods would be needed to establish this.     

Control of citrus postharvest penicillium molds with sodium ethylparaben

The curative antifungal activity of postharvest sodium ethylparaben (SEP) treatments against citrus green mold (GM) and blue mold (BM) was determined on different citrus species and cultivars artificially inoculated with Penicillium digitatum or Penicillium italicum and incubated at 20 °C and 90% RH for 7 d or stored at 5 °C and 90% RH for 8 weeks plus 7 d of shelf-life at 20 °C. The best concentration was selected in in vivo primary screenings with ‘Valencia’ oranges. SEP at 80 mM was tested at 20, 50 or 62 °C for 30, 60 or 150 s in small-scale trials to determine the best dip treatment conditions. Dips of 80 mM SEP at 20 °C for 60 s were selected and applied alone or in combination with 25 μL L⁻¹ of the conventional fungicide imazalil (SEP + IMZ 25). Imazalil at the very low concentrations of 25 (IMZ 25) or 50 μL L⁻¹ (IMZ 50) was also tested. Effectiveness of SEP alone at 20 °C for 60 s was significantly higher on oranges (cvs. ‘Valencia’ and ‘Lanelate’) than on mandarins (cvs. ‘Clemenules’, ‘Nadorcott’ and ‘Ortanique’), with GM and BM incidence reductions of up to 57–73% after 7 d at 20 °C. SEP was compatible with IMZ 25 and consistently improved its performance, irrespective of citrus cultivars and storage conditions. All treatments were less effective on ‘Clemenules’ mandarins. On ‘Valencia’ oranges stored for 8 weeks at 5 °C and 7 d at 20 °C, the combined treatment was significantly more effective than the single treatments (reductions of GM and BM incidence of about 96–93% and 55–39%, respectively). In additional tests, SEP, IMZ 25 and the combination applied at 20 °C for 60 s prevented GM on ‘Valencia’ oranges treated, inoculated with P. digitatum 24 h later and incubated at 20 °C for 7 d. It can be concluded from these results that SEP might be an integrating nonpollutant control alternative to be included in citrus postharvest disease control programs in the future.     

Evaluation of five essential oils as bio-fungicides on the control of Pilidiella granati rot in pomegranate

With recent public attention focused on chemical residues in food, the managing of plant disease organisms without the use of conventional chemical fungicides or bactericides can sometimes be a challenge. The main aim of this study was the evaluation of the antifungal activity of the essential oils of Ocimum basilicum, Origanum vulgare, Rosmarinus officinalis, Rosmarinus officinalis ‘Prostrates’, Salvia officinalis and their major constituents (carvacrol, thymol, linalool, eucalyptol) against the fungus Pilidiella granati. The results showed that the essential oil vapour of O. basilicum, S. officinalis, R. officinalis, Rosmarinus officinalis ‘Prostrates’, O. vulgare had fungicidal activities against the mycelial growth and conidia germination of P. granati, the pathogen causing postharvest fruit rots in pomegranate. However, in vivo experiments, only the essential oils of O. vulgare and O. basilicum controlled this fungus effectively with the essential oil of O. vulgare to being more effective at the same rates. Analysis showed a high number of compounds in each essential oil, with carvacrol, eucalyptol, linalool and thymol predominating. Thymol and carvacrol primarily and linalool secondary showed antifungicidal activity against P. granati. These results represent an important step towards the goal using essential oils from O. basilicum, S. officinalis, R. officinalis, R. officinalis ‘Prostrates”, O. vulgare and their constituents carvacrol and thymol to control of the pathogen P. granati of pomegranate.     

Host suitability of three avocado cultivars (Persea americana Miller: Lauraceae) to oriental fruit fly (Bactrocera (invadens) dorsalis (Hendel) (Diptera: Tephritidae))

The oriental (invasive) fruit fly Bactrocera (invadens) dorsalis (Hendel) (Diptera: Tephritidae) has invaded Africa and is currently established in over 30 countries and has caused in massive fruit losses. Avocado (Persea americana Miller) is among the fruit with which the pest is associated. The aim of the study was to determine the host status of a ‘black-skinned’ cultivar “Hass” and two ‘green-skinned’ cultivars “Pinkerton” and “Fuerte” to B. (invadens) dorsalis. In the laboratory study conducted in Kenya in 2012 and 2013, punctured and unpunctured recently-harvested fruit were exposed to sexually-mature fruit fly in ‘no-choice’ experiments. B. (invadens) dorsalis readily developed in the punctured fruit but not in the uncompromised fruit (fruit not damaged by insects or handling). This result was confirmed in Tanzania in 2013 where flies were introduced to unpunctured fruit. In the field studies the fruit of each cultivar were caged in situ with flies for 72 h. On dissection only fruit damaged by false codling moth (Thaumatotibia leucotreta (Meyrick)) were found to harbor B. (invadens) dorsalis. In the light of these results the risk imposed for “Hass”, “Pinkerton” and “Fuerte” by B. (invadens) dorsalis is negligible under standard export conditions. The findings of this study and the implications to regional and international trade are discussed.     

Determinants of parasitoid assemblages of the diamondback moth,Plutella xylostella,in cabbage farmer fields in Senegal

Conservation biological control, which fosters the optimal use of indigenous natural enemies, is a promising way for reducing pesticide reliance in horticultural systems. A two-year field survey was conducted in the main cabbage-producing area in Senegal (Niayes) to assess the potential of indigenous parasitoids to control populations of Plutella xylostella (Lepidoptera, Plutellidae). Results showed an overall low level of parasitism (11.7%) which was independent of host abundance, but was highly variable among fields (0–50%). Parasitism was predominant in the late part of dry season. Insecticide use, mostly relying on broad-spectrum insecticides, had a negative effect on the overall parasitism rate. Observations conducted throughout the cabbage crop cycle showed that parasitism unexpectedly decreased with crop aging (from 41 to 60 days post transplanting), likely due to repeated insecticide applications. Four main parasitoid species including Oomyzus sokolowskii (Kurdjumov) (Eulophidae) (48.8%), Apanteles litae Nixon (Braconidae) (32.5%), Brachymeria sp. (Chalcididae) (11.3%), and Cotesia vestalis Haliday (Braconidae) (7.3%) were identified. Parasitism due to O. sokolowskii was greater during the first part of the dry season whereas parasitism due to A. litae was greater during the second part of the dry season. Parasitism due to Brachymeria sp. was not affected by time of season but was greater in the Centre and North than in the South of Niayes. Parasitism due to C. vestalis was equal in the three zones but was higher in the late part of the dry season. The diversity of parasitoids was constant across zones but was greater during the second part of dry season. A positive relationship between diversity (Shannon diversity index H′) and parasitism rate was observed, suggesting a positive effect of parasitoid diversity on natural pest control. Parasitoids have a promising role to play as biocontrol agents of P. xylostella populations in Senegal, provided significant changes to current insecticide use are made. Better knowledge of their resource requirements including crop and non-crop habitats, and provision of these in and around crops is also needed.     

Simultaneous selection for stem borer resistance and forage related traits in maize (Zea mays ssp. mays L.) × teosinte (Zea mays ssp. mexicana L.) derived populations

Maize spotted stalk borer (Chilo partellus Swinhoe Pyralidae) (MSSB) is a serious pest of the maize (Zea mays ssp. mays L.) crop in Pakistan. This study was conducted to introgress resistance in maize against MSSB by exploring wild sources of resistance for the development of a resistant maize variety. To achieve this, teosinte (‘PI566674’) × maize (‘Sargodha-2002’) crosses were conducted and three populations (F₁, F₂ and F₃) were established. These populations were screened at various locations and in a contrasting artificial insect infestation experiment. Teosinte species ‘PI566674’, following screening, was shown to be highly resistant to MSSB and had the ability to produce a high biomass (5 times higher than susceptible genotypes) under high temperatures (36–40 °C). The biomass of the F₁ hybrid, which was highly susceptible to MSSB, was significantly reduced (P ≤ 0.05) following infestation by MSSB in all experiments. The introgression from teosinte for genes conferring resistance to MSSB was screened in segregating F₂ and F₃ generations. Despite a susceptible F₁ population, F₂ was resistant to MSSB. Twenty new recombinant plants with resistance to MSSB and a high leaf soluble solid (16 °Brix) content were identified. They were selected to grow the F₃ population. Mean values of F₃ progenies showed similar resistance to the F₂ population but a high percentage (60%) of resistant plants was recovered.     

Genetic analysis,realized heritability and synergistic suppression of indoxacarb resistance in Phenacoccus solenopsis Tinsley (Homoptera: Pseudococcidae)

Cotton mealybug Phenacoccus solenopsis Tinsley (Homoptera: Pseudococcidae) has caused huge crop and economic losses in different countries of the world including Pakistan. Considering P. solenopsis as a key cotton pest, research was conducted to understand genetics, realized heritability and preliminary mechanism of indoxacarb resistance. As a result of selection with indoxacarb, P. solenopsis developed a 2223.13-fold resistance after five generations. Indoxacarb resistance was autosomal in nature, and the degree of dominance for F₁ and F₁′ was 0.60 and 0.62, respectively, indicating the incomplete dominance of indoxacarb resistance. A monogenic model of inheritance also showed the involvement of multiple loci in indoxacarb resistance in P. solenopsis. Realized heritability for indoxacarb resistance was markedly high (h² = 1.13) in P. solenopsis suggesting how quickly resistance can develop as a result of selection. Synergism tests with piperonylbutoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF) also suggested that indoxacarb resistance in P. solenopsis was metabolism-based due to possible involvement of both mono-oxygenases and esterases. Hence, it was concluded that indoxacarb resistance in P. solenopsis was autosomal, incompletely dominant, polygenic and metabolism-based. These findings will be helpful in the management of P. solenopsis.     

Can spinosad-resistant Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) be managed with spinosad and predatory mites (Acari)?

Frankliniella occidentalis (Pergande) is a serious pest of a wide range of horticultural and ornamental crops. Populations resistant to most conventional insecticides, including–spinosad, have been detected. To control spinosad-resistant thrips, growers could use a ‘high-rate’/biological control strategy. The proposed strategy is based on a single application of spinosad at double the recommended application rate followed by releasing predatory mites (Acari), which are used as biological control agents of F. occidentalis. This study compared two resistance management strategies on a spinosad-resistant F. occidentalis strain: applying spinosad at twice the recommended rate, and spraying at twice the rate then releasing predatory mites, Typhlodromips montdorensis (Schicha), Neoseiulus cucumeris (Oudemans) and Hypoaspis miles (Berlese). Direct exposure to twice the recommended rate of spinosad killed 100% of all adults of all species of predatory mites. Spinosad residues aged 2–48 h were also highly toxic to adults of all three mite species, causing 96–100% mortality. Spinosad residues aged 48–168 h were less toxic to N. cucumeris than to T. montdorensis and H. miles. LT₂₅ of double the recommended rate of spinosad for T. montdorensis, N. cucumeris and H. miles were calculated as 6.02, 5.3, and 7.08 days, respectively. When released after applying spinosad, T. montdorensis was the most successful species in reducing thrips numbers, followed by N. cucumeris and H. miles. By releasing mites 6–7 days after a spinosad application, our results suggest that F. occidentalis can be effectively controlled. The practical implications of implementing a ’high-dose/biological control’ strategy are discussed.     

A temperature-based phenology model for predicting development,survival and population growth potential of the mealybug,Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae)

The temperature-dependent population growth potential of Phenacoccus solenopsis Tinsley, a highly polyphagous and invasive mealybug species, was studied on sprouted potatoes under laboratory conditions at six constant temperatures (15–40 °C). Several non-linear equations were fitted to the obtained data to model temperature-dependent population growth and species life history. The established equations for each life age/stage of the species were compiled to obtain an overall temperature-dependent phenology model. The life table parameters of P. solenopsis were estimated using stochastic simulation centred on a rate summation and cohort up-dating approach. The theoretical lower development threshold temperatures estimated using linear regressions applied to mean development rates were 11.2, 8.9, 9.8 and 12.7 °C, and the thermal constants for development were 93.7, 129.8, 97.1 and 100.0 degree days (DD) for nymph 1, nymph 2, nymph 3 and male pupa stages, respectively. The developed phenology model predicted temperatures between 25 and 35 °C as the favourable range for P. solenopsis development, survival and reproduction. P. solenopsis population attained a maximum net reproductive rate (107–108 females/female/generation) and total fecundity (216.6–226.5 individuals/female/generation) at temperatures between 25 and 30 °C. Mean length of generations decreased from 75.6 days at 15 °C to 21 days at 40 °C. The maximum finite rate of increase (1.12–1.16 females/female/day) and shortest doubling time (4.3–6.1 days) were also observed at temperatures between 25 and 35 °C. The simulation of phenology model at fluctuating temperatures indicated that P. solenopsis populations might potentially increase with a finite rate of 1.06 females/female/day with an average generation time of 58.7 days and a doubling time of 12.1 days. The obtained life table parameters were reasonably similar when compared with literature data. The present model can be simulated spatially for estimating the pest risk and undertaking agro-ecoregion specific pest management strategies.     

The first report on the winter breeding life history of Epuraea domina (Coleoptera: Nitidulidae) in a citrus grove in Jeju,Korea

Epuraea domina Reitter (Coleoptera: Nitidulidae) is a flower-visiting insect and a pest that causes corky scar on citrus fruit. This study was conducted to investigate the life cycle of E. domina in a citrus grove. E. domina showed the characteristics of cold breeders as they complete key life history events of oviposition and immature development during the winter. E. domina adults spent the summer in uncultivated habits started to lay eggs in soil near fallen citrus fruit in orchards during late autumn. Oviposition activity continued throughout the winter with a large decrease in activity when the minimum air temperature was <0 °C. Hatched larvae fed on decaying citrus and pupated in soil in the spring. The pupae emerged as new adults in mid-May to feed on the pollen and nectar of citrus flowers, probably followed by their migration to uncultivated habitats in the summer.     

New host resistances to Pseudocercosporella capsellae and implications for white leaf spot management in Brassicaceae crops

Effective host resistance is the most cost-effective long term prospect for successful management of white leaf spot disease (Pseudocercosporella capsellae) in Brassicaceae. In two separate field trials, 168 genotypes were screened. In the first trial, lines of Brassica oleracea var. capitata (59), Brassica napus (34), Brassica juncea (6) and B. juncea containing wild weedy Brassicaceae introgression(s) (14) were arranged; and in the second, Australian historic and current B. napus (45) and B. juncea (10) varieties were screened. There was wide variation in expression of resistance, from complete resistance to highly susceptible as assessed by two disease parameters, viz. (i), Area Under Disease Progress Curve (AUDPC) for percent leaves diseased (values 0–221.2) and (ii) Percent Leaf Collapse Index (%LCI) values for leaf collapse due to disease (0–38.7). Brassica oleracea var. capitata was overall the most resistant species, while B. juncea the most susceptible with the majority having AUDPC values >75 and B. napus was intermediate. Five B. oleracea var. capitata genotypes were completely resistant, with 0 AUDPC and %LCI values. Pioneer^® 45Y22 (RR) ‘Mystic’ and ‘Wahoo’ were also highly resistant, with the least %LCI (<3.7) and AUDPC (<20) of the Australian B. napus varieties. In contrast, ‘Thunder TT’ (AUDPC -133.6; %CLI – 15.6) and ‘Carbine’ (AUDPC – 73.8; %CLI – 12.5) were the most susceptible lines in first and second trials, respectively. The particularly high susceptibility of newly released B. juncea varieties such as ‘Xceed OasisCL’ highlights the risk of significant losses in such susceptible varieties when deployed in areas with high degree of pressure for white leaf spot disease. There was no association between AUDPC or % CLI with year of Australian varietal release, indicating that Australian breeding programs not made improvement for resistance to white leaf spot over the past two or more decades. Resistant varieties identified in this experiment can now not only be utilized in breeding programs to significantly improve overall crop resistance and management of white leaf spot disease, but also directly deployed to lower the severe inoculum load challenging current varieties.     

Yield performance and pest resistance among peanut genotypes when grown without fungicides or insecticides

Yield trials without fungicides or insecticides were conducted four consecutive years (2007–10) at the University of Georgia, Coastal Plain Experiment Station, Tifton Campus to evaluate for peanut (Arachis hypogaea L.) pest resistance. The most endemic diseases in the southeast U.S. are tomato spotted wilt (TSW) caused by Tomato spotted wilt virus, white mold (WM) caused by Sclerotium rolfsii Sacc, and both early and late leaf spot caused by Cercospora arachidicola Hori and Cercosporidium personatum (Berk & Curt.) Deighton, respectively. The most endemic insects are tobacco thrips (Frankliniella fusca Hinds) and potato leafhopper (Empoasca fabae Harris). Results from these replicated field tests showed significant differences (P ≤ 0.05) among advanced Georgia breeding lines and cultivars. Three Georgia cultivars ‘Georgia-01R’, ‘Georgia-05E’, and ‘Georgia-10T’ consistently produced among the best yields with high levels of resistance to TSW, white mold, leafhoppers, and leaf spot each year. Georgia-01R is a multiple-pest-resistant, runner-type cultivar with late maturity; whereas, Georgia-05E is a multiple-pest-resistant, virginia-type cultivar with medium-late maturity. Georgia-10T is a new runner-type cultivar with high level of TSWV and white mold resistance and late-maturity, similar to Georgia-01R, one of its parents. However, Georgia-10T does not appear to have the high level of leaf spot and leafhopper resistance as Georgia-01R, but it still had high yields in the absence of fungicides or insecticides.     

Compatibility of Phytoseiulus persimilis and Neoseiulus californicus (Acari: Phytoseiidae) with imidacloprid to manage clementine nursery pests

Biological control is not common in citrus nurseries where chemical control is prevalent. The systemic neonicotinoid imidacloprid applied as a drench is effective against three out of four key pests of young clementine plants in Spain – aphids, whiteflies, and scales. However, mites, the fourth key pest, are not control by imidacloprid and could be regulated by introduction of the predatory Phytoseiid mites Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus (McGregor). The aim of this study was to evaluate the effects of imidacloprid applied as a drench on the demographic parameters of these two predatory mites and the compatibility of P. persimilis releases with imidacloprid to control key pest populations in young clementine plants under field conditions. The results showed that some demographic parameters of P. persimilis were affected by imidacloprid. However, their combined effect on its intrinsic rate of increase was neutral. In contrast, imidacloprid negatively affected the demographic parameters of N. californicus. Field results proved that young clementine plants could be satisfactorily protected against key pests with releases of P. persimilis combined with drench applications of imidacloprid. The combination of imidacloprid with P. persimilis releases was highly effective for management of the key pests of young clementine plants in the nursery.