Greedy Scale Research Articles

Severe impact of introduced scale insects on Island Trees threatens endemic finches at the Tristan da Cunha archipelago

Inaccessible and Nightingale Islands are uninhabited islands in the Tristan da Cunha archipelago, central South Atlantic Ocean. Over the past decade, the spread and impacts of two species of invasive scale insects have increased steadily, severely affecting the Island Tree Phylica arborea woodlands and the endemic large-billed finches Nesospiza spp., which feed extensively on Phylica fruit. The first species, Greedy Scale Hemiberlesia rapax, causes local canopy diebacks and slightly reduced fruit loads. On Inaccessible, it appears to be only locally distributed, but on Nightingale it has spread rapidly since 2012 and now infects 95% of the Island Trees. The second species, Brown Soft Scale Coccus hesperidum and its associated sooty mould Seiridium phylicae, has expanded its range at Inaccessible since 2011, and colonised Nightingale by 2016. At Inaccessible, repeat transects between 2011 and 2018 show that Phylica fruit loads are markedly reduced and many large trees have died. Numbers of male Dunn's Finches N. acunhae dunnei, which rely on Phylica fruits, have declined by 50% in the last decade in heavily infested woodlands at Inaccessible Island, and some males in the most badly affected woodland are paired with small-billed Finches N. a. acunhae. If the trees on Nightingale follow a similar fate, the persistence of the endemic Wilkins' Finch N. wilkinsi will be under severe threat. The potential use of a biological agent to control C. hesperidium infestations should be investigated, since without swift and effective mitigation, we predict the health of these woodlands will degrade rapidly.

Occurrence of greedy scale, Hemiberlesia rapax (Comstock) (Hemiptera: Diaspididae), on mahogany in Brazil

The Brazilian mahogany (Swietenia macrophylla King, Meliaceae) is an important forest species known worldwide for the high commercial value of its wood. Few arthropods have been observed associated with mahogany. However, this paper reports the occurrence of Hemiberlesia rapax (Comstock) (Hemiptera: Diaspididae) in S. macrophylla plants for the first time. The greedy scales did not cause apparent damage on the trunks and petioles, but the leaves turned yellowish, dried, and fall prematurely. This is the first reported occurrence of H. rapax in S. macrophylla in the world.

Mortality of kiwifruit pests (Coccoidea) exposed to ethyl formate delivered using either carbon dioxide or nitrogen carrier gases

Ethyl formate (EF) is used as a fumigant against insect pests on many commodities. Delivery of EF uses a carrier gas, usually carbon dioxide (CO2), to reduce its flammability. However, CO2 is expensive and can only be delivered relatively slowly. Nitrogen (N2) has been proposed as an alternative. The efficacy of EF delivered using CO2 or N2, was evaluated at 5 and 15˚C, against two important postharvest pests of kiwifruit (greedy scale (Hemiberlesia rapax, Hemiptera: Diaspididae) and obscure mealybug (Pseudococcus viburni, Hemiptera: Pseudococcidae). Mortalities of both insect species were higher in the presence of CO2 than N2. There was a strong interaction with treatment temperature: N2 at 5˚C resulted in low mortality across both species. Greedy scale was more susceptible to EF than obscure mealybug across all treatments. Nitrogen as a carrier gas for EF substantially lowered the efficacy of EF as an insecticidal fumigant, relative to CO2. This is hypothesised to be caused by differing respiration rates across temperatures and CO2 concentrations. Solutions for rapid CO2 delivery should be explored over further trials with N2 at low temperatures.

Scale insect fauna (Hemiptera: Sternorrhyncha: Coccoidea) of New Zealand’s pygmy mistletoes (Korthalsella: Viscaceae) with description of three new species: Leucaspis albotecta, L. trilobata (Diaspididae) and Eriococcus korthalsellae (Eriococcidae)

The scale insect fauna recorded on the pigmy mistletoe genus Korthalsella (Viscaceae) and New Zealand’s loranthaceous mistletoes is reviewed. Three new species from New Zealand discovered on Korthalsella species during this study are described: the adult female, 2nd-instar male and female nymphs of two pupillarial species Leucaspis albotecta sp. nov. and Leucaspis trilobata sp. nov. (Diaspididae); and the adult female, 2nd-instar male and female nymphs and 1st-instar nymph of Eriococcus korthalsellae sp. nov. (Eriococcidae). A distribution map is provided for the three new species. We report the first records of adventive (exotic) scale insects on Korthalsella species in New Zealand – Ceroplastes sinensis Del Guercio, Coccus hesperidum Linnaeus, soft brown scale, Saissetia coffeae (Walker), hemispherical scale, S. oleae (Olivier), black scale (Coccidae), and Aspidiotus nerii Bouché, oleander scale, Hemiberlesia lataniae (Signoret), latania scale, H. rapax (Comstock), greedy scale (Diaspididae), while three native scale insects are also first records: Kalasiris perforata (Maskell) (Coccidae), Eriococcus pallidus Maskell (Eriococcidae) and Paracoccus glaucus (Maskell) (Pseudococcidae). Ten scale insect species are listed for New Zealand’s loranthaceous mistletoes.

DNA Diagnostics of Three Armored Scale Species on Kiwifruit in New Zealand

Three species of armored scale (Hemiptera: Diaspididae) are found on kiwifruit (Actinidia spp.) in New Zealand orchards: latania scale, Hemiberlesia lataniae (Signoret); greedy scale, Hemiberlesia rapax (Comstock); and oleander scale, Aspidiotus nerii (Bouché). Each of them is a quarantine pest in some of the markets to which New Zealand kiwifruit are exported. Adult females of the three species can be distinguished morphologically; however, the task is laborious when large numbers must be identified. Furthermore, it is not possible to distinguish among the immature stages. A DNA-based diagnostic using a multiplex polymerase chain reaction (PCR) method based on differences in the cytochrome oxidase I and II genes was developed to distinguish the three species. The test relies on the rapid isolation of amplifiable DNA by using a protease (prepGEM), followed by multiplex PCR using primers that distinguish the species at three or more nucleotide positions within cytochrome oxidase I and II, resulting in PCR products of characteristic size for each species. The test was validated in a double-blind experiment and then used to determine the relative distribution and abundance of the three species on leaves and fruit of 'Hayward' and 'Hortl6A' kiwifruit across the dominant growing regions throughout New Zealand during the 2007 season. In total, 3,418 scale insects were identified to species level: 1,904 (56%) were latania scale; 1,473 (43%) were greedy scale; and 41 (1%) were oleander scale. Since the last survey in 1988, latania scale has displaced greedy scale as the dominant species of armored scale on Hayward kiwifruit in the North Island and was found for the first time in the South Island. Only a single latania scale was found on Hortl6A fruit, consistent with previous reports of reduced rates of settlement on the fruit of this cultivar by latania scale compared with greedy scale.

Predicting armoured scale insect (Homoptera: Diaspididae) phenology on kiwifruit (Actinidia sp.)

Five years of greedy scale (Hemiberlesia rapax) phenology data from a kiwifruit (Actinidia deliciosa ’Hayward') orchard in Whangarei, New Zealand have been used to develop and partially validate a predictive equation for forecasting the timing of seasonal emergence of first generation crawlers using heat unit (day‐degree) summation above a 10°C threshold from 1 August. This was further validated against five armoured scale insect phenology data sets collected from Northland, Coromandel Peninsula, and Bay of Plenty, New Zealand. The armoured scale phenology data were similar at all sites notwithstanding measurements being taken from both ‘Hayward’ and ‘Hort16A’ commercial cultivars and there being large differences in armoured scale insect species composition among sites. The model provided predictions of the 50% crawler emergence date for the first generation of armoured scale within 1 week of observed date at four of the five sites, but was less accurate in predicting the date of 10% and 90% generational emergence. The use of this method as a tool for forecasting insecticide spray applications for the kiwifruit industry is discussed.

Enumerative and Binomial Sampling Plans for Armored Scale (Homoptera: Diaspididae) on Kiwifruit Leaves

The spatial dispersion of armored scale insects; greedy scale, Hemiberlesia rapax (Comstock); and latania scale, Hemiberlesia lataniae (Signoret), was investigated on kiwifruit, Actinidia deliciosa (A. Chevalier) C. F. Liang et A. R. Ferguson, leaves in New Zealand. A universal description for dispersion was determined using Taylor's power law, which encompassed a wide range of different orchards, blocks, block sizes, sampling times, scale control practices, regions and seasons. Scale density significantly altered dispersion, especially at the high densities found on unsprayed kiwifruit. Most commercially managed kiwifruit blocks had low densities of <0.5 scale per leaf and had a slightly aggregated scale dispersion. Wilson and Room's binomial model, which incorporates a clumping pattern as a function of density, gave a significant relationship between the proportion of infested leaves and scale density. The optimal leaf sample sizes were estimated for predetermined levels of sampling reliability. Where population estimates require a high degree of precision and enumerative sampling methods are used, 2,500 leaves should be sampled when scale densities are near the current spray threshold of 4% infested leaves and 500 leaves at 20% infested leaves. For management-decision sampling, where a lower level of precision was acceptable, enumerative sampling would require that 400 leaves be sampled at 4%; or 85 leaves at 20% infested leaves. With binomial sampling to achieve an equivalent level of precision an increased sample size of 6-11% is required.

Development and Mortality of Greedy Scale (Homoptera: Diaspididae) at Constant Temperatures

Developmental times and mortality were determined for four stages of greedy scale Hemiberlesia rapax (Comstock), a key pest of kiwifruit, Actinidia deliciosa (A. Chevalier) C. F. Liang et A. R. Ferguson variety deliciosa, in New Zealand. Scale were reared on potato tubers at seven constant temperatures and developmental stage and mortality were assessed at regular intervals. This required the removal of the scale cover to enable stage and mortality to be accurately determined. High numbers of scale (.1,400) were required at each temperature to sustain a frequent destructive sampling regime. Scale survival to the reproductive stage ranged from 0% at ,12.38C to 45% at 24.68C. The time for 50% of the live scale population to reach each developmental stage was determined using a Bayesian smoothing program. A linear model of scale development was developed for each stage based on a single, temperature-independent distribution of normalized developmental time. A linear regression of development rate against temperature was used to estimate developmental thresholds that were 9.6, 9.7, 10.3, and 10.68C and it took 257, 552, 882, and 992 degree-days (DD) to reach the second, third instar, mature, and first reproductive stages, respectively.

Incidence of armoured scale insects on persimmons

The incidence of armoured scale insects infesting persimmons (Diospyros kaki) grown in five districts (Whangarei (Northland) Pukekohe (South Auckland) Morrinsville (Waikato) Maketu (Bay of Plenty) and Gisborne (Poverty Bay)) was investigated over three growing seasons (1995/96 1996/97 and 1997/98) Three species of armoured scale insects were found on persimmon fruit greedy scale (Hemiberlesia rapax) latania scale (H lataniae) and oleander scale (Aspidiotus nerii) The species composition differed between districts with latania scale the most common species recorded overall Fruit were infested by the first and second generations of all three species Latania scale infested a higher proportion of leaves than fruit

Greedy scale,Hemiberlesia rapax(Hemiptera: Diaspididae), phenology on kiwifruit leaves and wood

Abstract Greedy scale (Hemiberlesia rapax (Comstock)) populations at Whangarei, New Zealand were monitored at regular intervals on unsprayed kiwifruit (Actinidia deliciosa (A.Chev.) C.F. Liang et A.R. Ferguson var. deliciosa) wood and leaves from 1984 to 1989 to obtain detailed stage‐specific phenological information. The relationship between relative abundance of each scale stage and Julian day or degree‐day accumulation (>9.3°C) were determined using a Bayesian smoothing programme. Two scale generations, summer and winter, were readily discernible. There was close agreement between the phenology of scale on wood and leaves. However, because of senescence and abscission in autumn there was only a partial winter generation of scale on leaves. Synchrony of stage‐specific events was enhanced using degree‐day accumulations rather than Julian days, particularly for the winter generation. Estimates of stage‐specific peaks and troughs for crawlers, white caps (first instar), yellow caps (second instar), black c...

Greedy Scale (Homoptera: Diaspididae) Phenology on Taraire Based on Julian Day and Degree–Day Accumulations

In northern New Zealand, greedy scale, Hemiberlesia rapax (Comstock), infests kiwifruit, Actinidia deliciosa (Chevalier) C. F. Liang et A. R. Ferguson variety deliciosa, by aerial invasion from adjacent host plants such as taraire, Beilshmiedia tarairi Bentham & Hooker. Greedy scale was monitored over 3 seasons using leaf samples from taraire trees adjacent to a commercial kiwifruit orchard. The seasonality of stage-specific population peaks and troughs was estimated using a Bayesian smoothing technique for both degree-day (DD) accumulations and Julian days. Two generations were observed with peaks for the 1st, 2nd, 3rd instars, and mature stages occurring on 30 December, 4 February, 17 March, and 18 April, respectively, for the summer generation, and 12 March, 13 April, 3 June, and 2 July, respectively, for the winter generation. Field populations of greedy scale were well described by physiological time ; therefore, opportunities exist for predicting stage-specific events. Total developmental time using a base temperature of 9.3°C was estimated at 1,056 DD with a standard error of 34 DD.

Seasonal Abundance of Greedy Scale (Homoptera: Diaspididae) and Associated Parasitoids on Taraire (Beilschmiedia tarairi)

Greedy scale, Hemiberlesia rapax (Comstock), is an important quarantine pest of kiwifruit, Actinidia deliciosa (A. Chevalier.) C. F. Liang & A. H. Ferguson. Scale infest kiwifruit by aerial invasion of crawlers from adjacent host plants such as taraire, Beilschmiedia tarairi Bentham & Hooker. A study on the ecology of greedy scale on taraire measured scale abundance and parasitism by a complex of 3 parasitoids, Encarsia citrina (Craw), Signiphora merceti (Malenotti), and Signiphora flavella (Girault) over 3 seasons. Greedy scale was found to have 2 generations each year. Scale populations remained low (14–38 scale per 100 leaves) over 3 successive generations when parasitism rates remained steady (16–27 parasitoids per 100 scale). Scale populations increased 7-fold in the 4th winter generation when rates of parasitism dropped to low levels (4 parasitoids per 100 scale). Scale populations remained at high levels (303–356 scale per 100 leaves) over the next 2 generations causing massive invasion of scale into the adjacent kiwifruit orchard. This was despite the resurgence in the rates of parasitism (13–29 parasitoids per 100 scale).

Efficacy and persistence of insecticide residues on fruit ofkiwifruitto prevent greedy scale (Hemiptera: Diaspididae) crawler settlement

Abstract Insecticides were applied to kiwifruit (Actinidia deliciosa) in February and April 1992 and April 1993. A bioassay technique was used to measure levels of greedy scale, Hemiberlesia rapax (Comstock), crawler settlement on fruit at various times after insecticide application. Organophosphate and pyrethroid residues remaining on the fruit were measured but not the mineral oil residues. The February and April 1992 trials showed that diazinon, chlorpyrifos, and diazinon/permethrin gave shortlived protection compared to phosmet, mineral oil, and pirimiphos‐methyl/permethrin. The residual times for 50% of fruit to be settled by scale in the April 1993 trial were: pirimiphos‐methyl/ permethrin, half rate <8 days; 1% Citrole mineral oil, 8 days; pirimiphos‐methyl/permethrin, full rate 16 days; 1% Sunspray Ultra‐Fine mineral oil, 19 days; 2% Citrole, 21 days; and 2% Ultra‐Fine, 24 days. Estimates of residue levels at which 50% of fruit were settled by scale were generally below or similar to the maximum residue levels set by the Codex Alimentarius Commission. The potential for reducing residues at harvest is discussed.

Seasonal temperatures and the phenology of greedy scale populations (Homoptera: Diaspididae) on kiwifruit vines in New Zealand

Abstract The development rate response to temperature of greedy scale, Hemiberlesia rapax, instars was determined from development times over a range of constant temperatures. A diurnal temperature simulation technique employing sine and exponential functions was coupled with these relationships and used to drive a distributed development period model of greedy scale phenology. The model was assessed against field data for its ability to predict first instar presence at one site in the Waikato, New Zealand. The model was then used to examine possible seasonal variation in the timing of first instar greedy scale production over the range of kiwifruit growing climates in New Zealand. The model duplicated field data for first instar presence well. The results obtained from simulations for a range of seasons and districts are discussed.

Armoured scale,Hemiberlesia lataniaeandH. Rapax(Hemiptera: Diaspididae), infestation of kiwifruit rejected for export at two packhouses from 1987 to 1991

Abstract Kiwifruit rejected for export because of armoured scale contamination were collected from a packhouse in Kerikeri and another in Whangarei, New Zealand from 1987 to 1991. A subsample of up to 50 scale infested fruit from each orchard was examined for scale. The 5 640 fruit which were examined yielded 14 390 scale. Latania scale, Hemiberlesia lataniae (Signoret), comprised 84% of the scale from Kerikeri and greedy scale, Hemiberlesia rapax (Comstock), 96% of the scale from Whangarei. No other scale species was found. First and second instar were the most common stages, except for the last 3 years at Kerikeri, when mature third instar predominated. The mortality of all scale stages ranged from 60 to 91%, except in 1988 at Kerikeri when a high proportion of live first instar reduced mortality to 44%. Of the supposed scale infested fruit, 56% had a single scale, 15% had no scale, and the remainder had multiple infestations. Most multiple infestations (82%) had at least one mature scale associated with immature scale indicating the survival of the first generation scale through to reproduction. Over the 5-year study period 34% of Kerikeri and 15% of Whangarei orchards submitted crop with >20 scale/ 1000 trays. Mature scale were responsible for the greatest proportion of reject fruit and are therefore the most important stage to try and control. These findings highlight the need to prevent the establishment of the first generation scale after fruit set and the second generation scale before harvest.

Armoured scale insects (Hemiptera: Diaspididae) on unsprayed kiwifruit vines in the Waikato

Two generations of greedy scale (Hemiberlesia rapax) and oleander scale (Aspidiotus nerii) were found between December and May on unsprayed kiwifruit vines in the Waikato. Few first generation scale insects of either species infested fruit with second. generation scale infesting fruit from late January onwards. The relative abundance of the 2 species on leaves and fruit differed with oleander scale infesting leaves to a lesser degree. A greater proportion of oleander scale settled on the ventral surface of leaves and they were found in more protected sites on wood than greedy scale.

Abamectin to control armoured scales (Hemiptera: Diaspididae) on kiwifruit

Abstract Abamectin (avermectin B1a) was applied during the 1989/90 season to previously unsprayed kiwifruit (Actinidia deliciosa) vines in the Waikato, New Zealand as seven regularly scheduled applications at 0.76 g a.i./100 litres, following two dormant applications of chlorpyrifos at 24 g a.i/100 litres. Microscopic assessment of harvested fruit recorded 4 scale/100 fruit for the treated vines, in comparison with 54 scale/100 fruit for untreated vines. In the subsequent season four sprays of abamectin were applied at 0.76 g a.i./100 litres combined with mineral oil (Shell Sunspray) at 0.25%. These applications were timed to coincide with the release of second generation greedy scale crawlers. Assessment of harvested fruit showed 16 scale/100 fruit for treated vines, 102 scale/100 fruit for untreated vines.

Armoured scale (Hemiptera: Diaspididae) aerial invasion into kiwifruit orchards from adjacent host plants

Abstract The aerial dispersal and settlement of armoured scale into kiwifruit Actinidia deliciosa (A. Chev.) orchards was assessed using scale-free kiwifruit trap plants. Greedy scale Hemiberlesia rapax (Comstock) invasion was monitored over five seasons from 1985 to 1990 in an orchard adjacent to taraire trees Beilschmiedia taraire Benth. and Hook. f. Two major periods of invasion occurred in summer and autumn corresponding to the two scale generations on taraire. The intensity of invasion varied between generations and seasons with a peak rate of 8.7 scale/ 100 leaves per day in January 1987. Scale invasion was highest in kiwifruit blocks immediately adjacent to the taraire trees and declined in blocks further away. A survey of 25 kiwifruit orchards identified clear gradients in both greedy scale and latania scale H. lataniae (Signoret) settlement, with higher levels closest to host plants. Scale invasion was reduced where host plants were removed or when host plants were regularly sprayed with insectic...

Influence of temperature on toxicity of diazinon to greedy scale

Influence of temperature on toxicity of diazinon to greedy scale

A survey of armoured scale species (Hemiptera: Diaspididae) in kiwifruit orchards

Many armoured scale (Hemiptera: Diaspididae) are polyphagous and the various plants growing near orchards are potential hosts for scale which can invade adjacent kiwifruit, Actinidia deliciosa, vines. Scale insects were collected from sprayed and unsprayed vines, scale-free potted kiwifruit plants which were placed in orchards, infested kiwifruit from 3 packhouses and from alternative host plants adjacent to kiwifruit vines. A total of 2661 specimens from 7 districts were identified. Greedy scale, Hemiberlesia rapax (Comstock), was the most widespread species on kiwifruit, followed by oleander scale, Aspidiotus nerii Bouché and latania scale, Hemiberlesia lataniae (Signoret). The same species was usually dominant on both kiwifruit vines and adjacent alternative host plants.