Apple Leafcurling Midge Research Articles

Temperature but Not Photoperiod Can Predict Development and Survival of an Invasive Apple Pest.

The apple leaf-curling midge, Dasineura mali Kieffer (Diptera: Cecidomyiidae), is an invasive pest of apple, and can contaminate fresh fruit for export, causing biosecurity problems. To provide crucial information for its pest risk analysis, forecast, and management, we investigated the effects of temperatures (5, 10, 15, 20 and 25 °C) and daylengths (10, 11, 12, 13, 14 and 15 h) on its development and survival. The midge eggs failed to hatch at 5 °C and larvae could not complete development at 10 °C. Pupation and emergence rates were significantly higher at 20 °C than at 15 °C and 25 °C. Daylength had no effect on these parameters. The low temperature threshold and thermal requirement to complete development from eggs to adults were 3.7 °C and 627 degree-days, respectively. The midge had a significantly lower thermal requirement for the completion of its lifecycle at 20 °C (614.5 degree-days) than at 15 °C (650.1 degree-days) and 25 °C (634.8 degree-days). The thermal model developed in this study provided accurate predictions of the number of D. mali generations and adult emergence time in each generation in different regions of New Zealand. We suggest that the model could be used to predict population dynamics of this pest in other parts of the world.

Dasineura mali (apple leaf-curling midge)

Dasineura mali (apple leaf-curling midge)

Developing apple leafcurling midge rearing techniques

Apple leafcurling midge (Dasineura mali; ALCM) is considered a quarantine pest in some of New Zealand’s valuable export markets. Research into alternatives to methyl bromide as a fumigant requires a mass rearing programme to provide large numbers of all life stages. Our aim was to focus on developing an understanding of the environmental conditions that break ALCM diapause and facilitate ALCM oviposition. A trial was conducted comparing ALCM oviposition rates on apple seedlings in a controlled temperature room versus a shade house in ambient conditions over the summer months. Additionally, long day length and high humidity conditions were tested to break the diapause of ALCM cocooning larvae. Oviposition rates on young apple seedlings were similar in the controlled environment room and the shade house; however, apple seedlings grew better in the shade house due to lower incidence of powdery mildew. Adults emerged from ALCM cocoons that had been in diapause for five months and then held at 20.9°C for seven days. Conditions to break ALCM diapause have been determined. Seedlings at the six- to eight-leaf stage have the potential to provide an oviposition substrate. Further investigations are required into artificial oviposition substrates and the development of a larval diet to mass rear ALCM larvae.

Effect of various heat treatments to target apple leafcurling midge (Dasineura mali) cocoons on apples

New Zealand apples infested with apple leafcurling midge (ALCM) cocoons are a quarantine issue for growers exporting to many markets. The presence of ALCM on apples in these markets requires fumigation with methyl bromide, which decreases fruit quality. The effectiveness of various forms of heat treatments on ALCM were evaluated as alternatives. Apples infested with ALCM cocoons were subjected to one of the following heat treatments: Controlled Atmosphere Temperature Treatment System (CATTS; 1% O2, 15% CO2, 46˚C, 3 h), hot air (46˚C, 3 h), hot water high pressure washing (hot-HPW; 55˚C, 100 psi, 15—20 s), or hot water drench (HWD; 55˚C, 40 psi, 15—20 s). ALCM removal and mortality were assessed 7-days post-treatment. The hot-air and CATTS treatments provided the greatest control, with 82.2 and 92.2% mortality respectively. More cocoons were removed with hot-HPW (46.6%) compared with ambient-HPW (27.1%). Neither HWD nor hot-HPW increased mortality of cocooned ALCM over that in untreated controls. ALCM cocoons are particularly difficult pests to remove/kill; further research should focus on incorporating multiple control measures into the current systems approach.

Annual and regional variability in adult <i>Dasineura mali</i> (apple leafcurling midge) emergence in New Zealand

Apple leafcurling midge is an important quarantine pest for New Zealand apple exports. Season-long pheromone trapping was conducted in Hawke’s Bay and Nelson from 2004—2017, and from 2012—2017 in Central Otago. Four generations occurred annually in Hawke’s Bay and Nelson and 3—4 in Central Otago. In Hawke’s Bay and Nelson, the timing of each peak varied by about 3—4 weeks between years, while the difference was ~2—3 weeks in Central Otago during fewer years of monitoring. Hawke’s Bay was up to a month earlier than Central Otago for the same peak within individual years. The major factor behind this variability was the accumulated number of growing degree-days. Insecticide sprays target midge larvae, but are timed against the second and third peaks of adult emergence. Variations in the timing of these peaks annually and across the main pipfruit growing regions, mean that specific insecticide timing recommendations are necessary each year for each region.

Development of a ‘lure and kill’ technique for apple leafcurling midge, <i>Dasineura mali</i>

Apple leafcurling midge (ALCM) is an important quarantine pest of New Zealand apples. Current methods for ALCM control have difficulty meeting the strict phytosanitary standards of some export markets. ‘Lure and kill’ is a new strategy against this pest, in which males are attracted to an insecticide-treated substrate where they collect a lethal dose. Trials were conducted using a gel matrix “Specialized Pheromone & Lure Application Technology” (SPLATâ„¢) to dispense and release the ALCM sex pheromone and the insecticide permethrin. Lures using SPLATâ„¢ were placed within plastic cylinder traps that collected the dead midges so they could be counted to determine treatment efficacy. The size, shape and age of SPLATâ„¢ spots influenced midge catches. Higher catches occurred with spots having a larger quantity of pheromone, greater surface area of SPLATâ„¢, or with fresh material. The implications for the development of a lure and kill strategy for ALCM are discussed.

Pre-treatment dips to enhance the removal of apple leafcurling midge from apples using high pressure washing


 
 
 The presence of apple leafcurling midge (ALCM) on apples is of concern for many of New Zealand’s export apple markets. High pressure washing (HPW) systems have been implemented in export packhouses to reduce the risks associated with various pests; however, higher removal rates of ALCM are required to improve access to challenging markets. A range of pre-treatment dips to improve ALCM removal efficacy when applied before HPW were tested, and the impact of these pre-treatment dips on pest viability determined. Removal of ALCM cocoons by HPW alone was 41%, compared with pre- treatments of hot water at 51˚C (66%), Saturate® (58%), Prospect oil® (57%), malic acid (53%), citric acid (48%), lactic acid (46%), acetic acid (39%), HarvestCide® (37%) or sodium bicarbonate (37%). However, only the hot-water treatment significantly enhanced removal compared with HPW alone. In a second trial, removal of ALCM cocoons with HPW was 69% and hot water + UV-C increased removal to 76%, although this difference was not statistically significant. Overall, none of the pre-treatment dips was found to reduce ALCM viability significantly compared with HPW alone.
 
 

Establishing cocooning apple leafcurling midge onto apples for disinfestation research

Apple exports intercepted with cocooning apple leafcurling midge (ALCM) are fumigated with methyl bromide (MB) which reduces apple quality ALCM is controlled in the orchard using the insecticide Movento while also being parasitised by Platygaster demades and preyed on by generalist predators such as Sejanus albisignata These ALCM control measures make it difficult to collect sufficient numbers of ALCMinfested apples for disinfestation research on alternatives to MB Therefore procedures were developed for collecting and storing cocooning ALCM on apples in the laboratory ALCMinfested leaves were collected in plastic bags saturated with water and placed at 20C The water stimulated larvae to exit the leafrolls Using a fine paint brush ten larvae were placed on the calyx of an apple and confined using a cage attached with BluTak The apples were placed in plastic bins and sprayed with water A mesh net and a brown paper bag were secured over the top of the bin to reduce condensation The bin was stored at 20C 168 lightdark for 1015 days Of 1133 apples established 988 of them (872 ) had on average 22 cocooning ACLM Large numbers of cocooning ALCM on fruit can now be provided for disinfestation research

Demographic dynamics of Platygaster demades in response to host density

Platygaster demades Walker (Hymenoptera: Platygastridae) is the only hymenopteran parasitoid of apple leaf-curling midge, Dasineura mali Kieffer (Diptera: Cecidomyiidae), in New Zealand. Prior to the present study the mechanisms behind the parasitoid–host density interactions were poorly understood. In this study we carried out both laboratory and field experiments to determine the response of P. demades to D. mali density. In the laboratory, when only a single parasitoid was allowed to forage D. mali eggs of a given density, P. demades displayed a Type II functional response leading to an inverse density-dependent parasitism. However, P. demades showed a Type III functional response in the field where females were able to freely search and disperse between apple shoots infested with D. mali eggs of different densities. As a result, the Type III response reflects a more realistic nature of P. demades in response to D. mali density. Our results also indicate that the numeric response and mutual interference in P. demades significantly contributed to the stability of the parasitoid–host system. The density-dependent parasitism in a host range of 50–300 D. mali eggs per apple shoot suggests that P. demades is highly efficient in controlling D. mali populations of the first, third and fourth generations and when necessary, argumentation measures may be taken before the onset of the second generation.

Developing ethyl formate treatment for disinfesting pipfruit

Mealybugs scale insects thrips and apple leafcurling midge (ALCM) on packed New Zealand apples are a concern for export markets and there is interest in soft technologies to remove insects in postharvest treatments Ethyl formate (EF) is a Generally Recognised As Safe (GRAS) plant volatile compound which was used in trials to reduce pest incidence on apples to acceptable rates for export markets A treatment of 03 EF (CO2) for 1 h controlled 99 of onion thrips and latania scale and 081 EF (CO2) for 1 h controlled obscure mealybug Treatment concentrations and times required to control ALCM (494 EF for 4 h) was beyond the apple quality tolerance level Further research is required to determine apple quality tolerance levels other market access pest EF concentration mortality responses sorption rates of different apple cultivars and effect of temperature on pest mortality and fruit responses

Phenology and distribution of the apple leafcurling midge (Dasineura mali (Kieffer)) (Diptera: Cecidomyiidae) and its natural enemies on apples under biological and integrated pest management in Central Otago, New Zealand

Damage by apple leafcurling midge Dasineura mali, and the numbers of its predators Orius vicinus and Sejanus albisignata, were monitored from 1994 to 1998 on terminal, lateral, spur, and fruiting shoots of a range of apple cultivars under integrated and organic pest management at Clyde, Central Otago. The predators were also monitored using beating trays. The phenology of egg laying and damage by apple leafcurling midge, and the adult numbers of its egg parasitoid Platygaster demades, were recorded on ‘Royal Gala’ apples from 1997 to 2000 at the same location. Apple leafcurling midge completed three to four generations per year depending on summer temperatures, with greatest larval damage by the second generation in December/January, particularly to terminal and lateral shoots. Although each apple cultivar was planted in a discrete block, there were large differences in damage which persisted over several seasons, suggesting significant variation in cultivar susceptibility. Colonisation of the trees by P. demades was slow but monitoring of adult numbers indicated good synchronisation with midge egg laying from the 1998–99 season. Both predatory bug species occurred at higher density on midge-damaged shoots than on undamaged shoots. Analysis of midge damage in relation to the population density of the bugs indicated that midge damage fell in response to high densities of S. albisignata and was high only when this species was at low density. On the other hand, O. vicinus appeared to be a minor predator because higher densities of O. vicinus were correlated with higher midge damage and there was no evidence that this led to a later reduction in the midge population. This research has indicated that P. demades, S. albisignata, and plant resistance can all play an important role in the biological control of apple leafcurling midge.

The use of sex pheromone lures to compare pear and apple leafcurling midge phenology

Pear leafcurling midge (Dasineura pyri PLCM) is a gall midge in the family Cecidomyiidae and is a persistent pest in New ZealandWhilst mature trees can withstand considerable damage feeding by larvae can cause severe distortion (galling) of developing leaves on younger trees Apart from obvious leaf damage PLCM activity is difficult to detect so the recent development of the synthetic sex pheromone provides a useful monitoring tool for this pest Pear leafcurling midge pheromone traps were set up in four commercial pear blocks across the Nelson district which is the main commercial peargrowing area in New Zealand to assess the ability of the pheromone lure to monitor seasonal activity of the pest Trapping results are compared and discussed in relation to apple leafcurling midge activity in five apple blocks in the same region

<i>Sejanus albisignata</i> its potential contribution towards apple leafcurling midge (<i>Dasineura mali</i>) biological control in Hawkes Bay orchards

Predation has been proposed as one of the possible reasons for the decline in apple leafcurling midge (ALCM) activity and damage observed in Hawkes Bay orchards in recent years Sejanus albisignata is a generalist predator and commonly found in apple orchards To establish if there is any relationship between ALCM and S albisignata populations of both species were monitored during 201112 on four apple orchards in Hawkes Bay Nymphs and adults of S albisignata were counted on 100 ALCM infested shoots per orchard at weekly intervals Sex pheromone traps were used to monitor numbers of male ALCM weekly throughout the season in the same orchards Sejanus albisignata and ALCM activity was well synchronized with the timing of generations one two and three of S albisignata coinciding with the second third and fourth generations of ALCM There was also a significant positive correlation between the numbers of S albisignata in each generation and the number of ALCM males trapped for each of the corresponding ALCM generations These relationships suggest that S albisignata may contribute towards ALCM control but further studies of their feeding behaviour and numerical responses are required to determine its actual contribution towards biological control of ALCM

Predation of apple leafcurling midge <i>Dasineura mali</i> by <i>Sejanus albisignata</i>

The predatory mirid bug Sejanus albisignata has been observed feeding on apple leafcurling midge (ALCM) eggs but quantitative data on its potential as a predator of ALCM are lacking Two methods were trialled to assess predation of ALCM by S albisignata In a laboratory experiment apple shoots infested with freshly laid ALCM eggs were contained with and without a S albisignata adult and in a field experiment paper bags were secured over shoots with ALCM eggs and individual S albisignata nymphs were introduced into half of these There were significant reductions of surviving midge larvae on shoots confined with adult predators and reduced numbers of midgeinfested leaves and larvae on bagged shoots with S albisignata nymphs Results from these nonchoice trials indicate that S albisignata can be an effective predator of ALCM More detailed feeding studies would determine if adult and immature S albisignata have a preference for midge eggs or larvae

A sophisticated life history strategy in a parasitoid wasp: Producing univoltine and multivoltine phenotypes in a local population

Insects may adopt a range of strategies such as diapause, migration and phenotypic plasticity to achieve maximal survival and reproduction in response to the environment. However, the phenotypic plasticity of voltinism in local populations of biological control agents is still poorly understood, making evaluation of biological control efficiency difficult. Here we report our two years’ work on a parasitic wasp, Platygaster demades Walker (Hymenoptera: Platygasteridae), a parasitoid of apple leaf-curling midge, Dasineura mali Kieffer (Diptera: Cecidomyiidae). P. demades produces aestivating and non-aestivating phenotypes at the embryonic stage over the season. It regulates the frequency and duration of aestivating phenotypes from the late spring to mid autumn and adjusts the embryonic developmental rate of non-aestivating phenotypes from the early to late autumn, producing univoltine, bivoltine, trivoltine and quadrivoltine phenotypes over the season. The regulation of aestivation frequency and duration is a temporal risk-spreading strategy for maximal survival, i.e., when the future food source is expected to be short the wasp regulates its population by entering aestivation in a frequency and duration concordant with the expected scale and duration of food shortage to avoid massive mortality. This strategy helps maintain a large overwintering population size for the next season. The adjustment of the embryonic developmental rate for the non-aestivating phenotype from the early to late autumn is an adaptive developmental strategy for maximal synchronization with the host, D. mali, i.e., the later the D. mali larvae become mature, the faster the parasitoid embryos develop. This strategy ensures that both aestivated and non-aestivated individuals reach a complete synchronization with the emergence of their hosts in the next spring.

Effect of age on the reproductive fitness of <i>Platygaster demades</i> an egg parasitoid of apple leafcurling midge

Platygaster demades is an egg parasitoid of the apple leafcurling midge (ALCM) Dasineura mali Each P demades female carries a mean preovipositional load of 1380 263 eggs Females fed with buckwheat nectar lived a maximum of 10 weeks at 15C The agedependent reproduction of female P demades was determined by a laboratory experiment at room temperature ALCM eggs on apple shoots were exposed to 1 2 4 8 and 10weekold individual P demades females and ALCM larvae that emerged from the parasitised eggs were reared on fresh apple shoots and allowed to pupate on a layer of moist soil The numbers and sex of adult P demades that emerged from the ALCM pupae were recorded Older females (8 and 10 weeks old) were able to locate and parasitise host eggs and produced as many offspring as younger females The implication of the results in terms of the reproductive fitness of P demades is discussed

European earwig as a potential biological control agent of apple leafcurling midge

The European earwig Forficula auricularia L is an important predator of aphids and scales in New Zealand apple orchards To determine whether European earwig acted as a biological control agent of apple leafcurling midge (ALCM) Dasineura mali Kieffer their prey searching and feeding activity was investigated in the field and laboratory In the field in January earwigs started to leave their shelters at about 920 pm to search for ALCM larvae and returned to the shelters before 535 am with a searching peak on apple shoots infested by ALCM larvae between 1030 pm and 130 am Significantly more ALCM infested shoots and leaves were bitten by earwigs on trees where shelters trapped earwigs than on those where shelters did not trap any earwigs In the laboratory earwigs mainly fed in the first 2 hours after lightoff and each adult consumed an average of 6770 318 mature ALCM larvae during the scotophase (8 h) Heavier earwigs consumed significantly more ALCM larvae than light ones

Effect of postharvest dips on apple surface microflora and <i>Dasineura mali</i> removal

The effectiveness of six prewashing and nine postwashing dips on loosening apple leaf curling midge (ALCM) cocoons and reducing fruit surface microflora respectively was examined In the laboratory fungal populations were significantly reduced (1217 cfu/cm2) after 10min dips in medium or high concentration Nylate (5 ppm or 10 ppm free Cl2) or SteriMaxTM (008) compared with controls (5367 cfu/cm2) An ethanol dip (1 min 50) significantly reduced fungal and yeast populations compared with all other treatments Dips in low concentration controlledrelease chlorine products (10 min) and in sodium hypochlorite (1 min 100 ppm free Cl2) did not affect fungal populations significantly The same products except ethanol which was replaced by an antifoam solution (075) were tested on ALCM cocoons but none loosened cocoons effectively compared with the control In a packhouse a 6min postwashing dip in high concentration Nylate (75 ppm free Cl2) significantly reduced fungal (25 cfu/cm2) and yeast (12 103 cfu/cm2) populations compared with washed and unwashed apples (274 fungal cfu/cm2 and 23 104 yeast cfu/cm2) Both laboratory and packhouse studies indicated that postwashing dips can lower the apple surface microflora which may reduce storage rot incidence However the prewashing dips did not appear to loosen ALCM cocoons

Aestivation in apple leafcurling midge (Diptera Cecidomyiidae) parasitoid <i>Platygaster demades</i> Walker (Hymenoptera Platygastridae)

This study reports an investigation on the aestivation and overwintering strategies of Platygaster demades an egg parasitoid of apple leafcurling midge (ALCM) Dasineura mali under natural conditions during 2005 2006 The first three generations of ALCM developed into adults during the springautumn of 2005/2006 and the fourth generation overwintered as larvae All first generation P demades emerged in the spring of 2005 About 64 of live individuals of P demades in the second generation and 38 in the third generation entered aestivation as eggs which hatched in mid March and early May 2006 respectively Parasitoid eggs of the fourth generation started to hatch four weeks after the parasitised ALCM larvae entered the soil The aestivated and fourth generation parasitoids overwintered as immature stages and started emerging in late September 2006 The emergence patterns of overwintered parasitoids and ALCM were highly synchronized in the following season

Temperature dependent emergence and survival of Platygaster demades (Hymenoptera: Platygastridae), parasitoid of apple leaf curling midge

Abstract The influence of temperature on the emergence and adult longevity of Platygaster demades Walker, an egg parasitoid of apple leaf curling midge (ALCM) was determined at five constant temperatures in the laboratory: 11, 15, 19, 23, and 27 °C. Apple leaves infested with second and fourth generation ALCM larvae were collected from three regions in New Zealand. Emergence of both ALCM and P. demades at the five temperatures were compared across two generations and three locations. Adult P. demades were fed with honey-agar diet and tested for longevity without exposure to ALCM eggs. Ten females reared at each temperature were allowed to live full life spans, and once dead were dissected to measure potential fecundity. The development period of P. demades in soil increased with increasing temperature but fewer emerged at 11 and 27 °C. The optimum temperature was 19 °C. Significant differences in development and emergence rates of P. demades between the second and fourth generations with temperature were detected ( P = 0.003), although no differences in either were found between locations ( P > 0.400). The highest longevity for females (47.9 ± 5.5 days) and males (31.3 ± 5.3 days) was recorded at 11 °C. Longevity decreased with increasing temperature. Life time fecundity did not change with age ( P = 0.888) and an average female carried a mean pre-ovipositional load of 1380 ± 263 eggs. Temperature has been considered one of the most important physical factors to influence asynchrony between second generation populations of P. demades and ALCM. Impacts of high longevity and fecundity on the ability of the parasitoid to overcome the synchrony are discussed.