Competitive displacement betweenAphytis spp. [Hym. Aphelinidae] parasites of the California red scale in cyprus

In Cyprus,Aphytis chrysomphali (Mercet) andAphytis melinus DeBach are the only significant parasites of the California red scale,Aonidiella aurantii (Maskell).A. chrysomphali, presumably native, has been virtually displaced byA. melinus from the interior dry areas of the island after the importation of the latter in 1961. Presently the former parasite dominates only in some of the coastal areas with a mild and rather humid climate.Aphytis ? coheni DeBach that initially displacedA. chrysomphali in the release areas, was replaced by the latter parasite and was occasionally found in small numbers only in one location. Traces ofAphytis ?lingnanensis Compere were also found in some locations. Two otherAphytis spp., imported from California, were released and recovered but it is too early to determine their permanent establishment and significance.     

Role of two insect growth regulators in integrated pest management of citrus scales

Portions of two commercial citrus orchards were treated for two consecutive years with buprofezin or three consecutive years with pyriproxyfen in a replicated plot design to determine the long-term impact of these insect growth regulators (IGRs) on the San Joaquin Valley California integrated pest management program. Pyriproxyfen reduced the target pest, California red scale, Aonidiella aurantii Maskell, to nondetectable levels on leaf samples approximately 4 mo after treatment. Pyriproxyfen treatments reduced the California red scale parasitoid Aphytis melinus DeBach to a greater extent than the parasitoid Comperiella bifasciata Howard collected on sticky cards. Treatments of lemons Citrus limon (L.) Burm. f. infested with scale parasitized by A. melinus showed only 33% direct mortality of the parasitoid, suggesting the population reduction observed on sticky cards was due to low host density. Three years of pyriproxyfen treatments did not maintain citricola scale, Coccus pseudomagnoliarum (Kuwana), below the treatment threshold and cottony cushion scale, Icerya purchasi Maskell, was slowly but incompletely controlled. Buprofezin reduced California red scale to very low but detectable levels approximately 5 mo after treatment. Buprofezin treatments resulted in similar levels of reduction of the two parasitoids A. melinus and C. bifasciata collected on sticky cards. Treatments of lemons infested with scale parasitized by A. melinus showed only 7% mortality of the parasitoids, suggesting the population reduction observed on sticky cards was due to low host density. Citricola scale was not present in this orchard, and cottony cushion scale was slowly and incompletely controlled by buprofezin. These field plots demonstrated that IGRs can act as organophosphate insecticide replacements for California red scale control; however, their narrower spectrum of activity and disruption of coccinellid beetles can allow other scale species to attain primary pest status.     

Role of imidacloprid in integrated pest management of California citrus

Portions of three commercial citrus orchards were treated for 1 yr with foliar imidacloprid or for 2 yr with a systemic formulation in a replicated plot design to determine the impact of this neonicotinoid on the San Joaquin Valley California citrus integrated pest management (IPM) program. Foliar-applied imidacloprid had little effect on California red scale, Aonidiella aurantii (Maskell); cottony cushion scale, Icerya purchasi Maskell; or citrus red mite, Panonychus citri (McGregor), populations. Short-term suppression of the parasitoids Aphytis melinus DeBach and Comperiella bifasciata Howard; vedalia, Rodolia cardinalis (Mulsant); and the predacious mite Euseius tularensis (Congdon) were observed. Suppression of natural enemies allowed scales and mites to maintain higher populations in the treated areas compared with the nontreated areas. Thus, foliar imidacloprid did not exhibit control of these citrus pest species, and it disrupted biological control. Systemically applied imidacloprid suppressed California red scale and citricola scale populations 2-3 mo after treatment. Suppression of parasitoids of the California red scale also was observed. Thus, treatments of systemic imidacloprid applied in areawide management programs for invasive pests would provide a benefit of California red scale and citricola scale suppression. However, this treatment provided only single-season control of citricola scale, it was somewhat disruptive of biological control, and it did not suppress densities of either scale as low as a treatment of the organophosphate chlorpyrifos for citricola scale or the insect growth regulator pyriproxyfen for California red scale. Insecticides with longer periods of efficacy and greater IPM compatibility than imidacloprid should be used for a sustainable IPM approach in California citrus.     

A history of the biological and integrated control of red scale,Aonidiella aurantii on citrus in the lower Murray valley of Australia

In the lower Murray valley of Australia, the major insect pest of citrus, California red scaleAonidiella aurantii (Maskell), is controlled by a number of introduced hymenopterous parasites. Parasite introductions began in 1943, and continued until 1979. Eight species, especially in the Encyrtid genusAphytis, were introduced and mass released. The only species to become permanently established wereAphytis chrysomphali Mercet,Comperiella bifasciata (Howard),A. melinus DeBach, andProspaltella perniciosi (Tower).A. melinus, introduced in 1961, has become widely established throughout the region, is the dominant and most important parasite, and now appears to have completely displacedA. chrysomphali (1954) in all areas.C. bifasciata (1943) is also an important parasite and is distributed throughout the area.P. perniciosi (1970) is established on a few orchards near Mildura. Most of the work on the biological and integrated control of red scale began with the establishment of laboratory and insectary facilities at Mildura in 1967 and Loxton in 1968. A commercial insectary was also established at Loxton in 1971. Biological methods of insect control were first used commercially during 1944 (war period) by a few citrus growers at Merbein in Sunraysia. However, the adoption of biological and integrated methods for the control of red scale and other citrus pests, began on a large scale in the late 1960's. The use of organophosphate insecticides on citrus has declined since that time and has been close to zero since about 1977. Parasites and petroleum oil sprays have been used together in an integrated approach to the control of California red scale on some orchards. The biological control of this key pest has led to a decline in the incidence of secondary pests to the point where all insect pests of citrus are now regarded as being under effective biological control. The incidence of red scale, and other pests, has been less under biological and integrated control than it ever was when chemical control measures were widely used in the 1960's. Factors which have contributed to the success of the programme are discussed.     

Parasitoeds (Hym.: Aphelinidae) of three scale insects (Hom.: Diaspididae) in a citrus grove in valencia,spain

The parasitoids ofAonidiella aurantii (Maskell),Lepidosaphes beckii (Newman) andParlatoria pergandii Comstock were studied in a Navel orange grove in Valencia, Spain during three years. Four species ofAphytis were identified on yellow sticky traps,Aphytis chrysomphali (Mercet),Aphytis melinus Debach,Aphytis lepidosaphes Compere andAphytis hispanicus (Mercet). No consistent annual pattern was observed in the flight of adults.A. melinus, introduced some years earlier in the grove, was found in very low numbers and showed no signs of increasing and displacingA. chrysomphali as a parasitoid ofA. aurantii. On female scales of the three species sampled at regular intervals from leaves, twigs and fruit, the mean annual rate of active parasitism was similar and ranged from 3.5% to 8%.P. pergandii males were not parasitized, inL. beckii parasitism was usually much lower in male than in female scales, and inA. aurantii it was higher in the males. Scales of the three species were less parasitized on twigs than on leaves, and so wereL. beckii on fruit. The annual trend of parasitism byAphytis on scales fluctuated without a definite pattern. Parasitism byEncarsia inquirenda (Silvestri), an endoparasitoid ofP. pergandii, was more stable throughout the year and increased steadily from year to year.     

Effect of a new insect growth regulator,RO 13-5223, on hymenopterous parasites of scale insects

The insect growth regulator, RO 13-5223, applied at concentrations up to 0.1% a.i., did not affect the normal development of immature stages of 2 hymenopterous parasites:Metaphycus bartletti Annecke & Mynhardt andAphytis holoxanthus DeBach, parasitoids ofSaissetia oleae (Olivier) andChrysomphalus aonidum (L.), respectively. Spraying citrus trees at the rate of 7.5 g. a.i./tree had no adverse effect on the activity of the following parasitoids:Aphytis chrysomphali (Mercet) andComperiella bifasciata Howard, an ecto- and endoparasite of the California red scale,Aonidiella aurantii Maskell, respectively;Aphytis hispanicus (Mercet) andProspaltella inquirenda Silvestri, an ecto- and endoparasite of the citrus chaff scale,Parlatoria pergandii Comstock, respectively.     

Observations on circular purple scaleChrysomphalus aonidum (Linn.), and two introduced parasites in western Transvaal citrus orchards

Circular purple scale,Chrysomphalus aonidum (Linn.) is localized in its appearance in South African citrus orchards. It mainly occurs along the Natal Coast, the Western Transvaal and the Transvaal Lowveld. In the Western Transvaal its importance was highlighted by the development of biological and integrated programmes chiefly directed against red scale [Aonidiella aurantii (Mask.)]. This paper reports on an attempt at the biological control of circular purple scale in the Western Transvaal by introducingComperiella bifasciata. The eggs ofC. aonidum, at 26.7°C and 50% relative humidity, hatches within two to three days. The female has two and the male four moults. The first eggs are laid approximately 43 days after settling of the crawler.C. aonidum has 4 broods a year. C. bifasciata, circular purple scale strain, is uniparental. The adults can live for only one day without food, but from 3–22 days in the laboratory when fed on honey. The photopositive adults lay the eggs internally in female scales, male scales being seldom parasitized. The eggs hatch in 3–4 days of which a female parasite lays an average of 37. The larval stages occupy 13–15 days and the pupal stage 7 days. Superparasitism does occur in which case only one larva reaches maturity. The length of the life cycle varies in various stages ofC. aonidum, the shortest was in scales 25–35 days old. ThoughC. bifasciata was established after release in citrus orchards, it maintained itself at very low levels or disappeared in competition withAphytis holoxanthus.     

Disruption of parasitism of the California red scale (Homoptera: Diaspididae) by three ant species (Hymenoptera: Formicidae)

The relative influence of the southern fire ant, Solenopsis xyloni McCook, Argentine ant, Linepithema humile (Mayr), and native gray ant, Formica aerata (Francoeur), on parasitism of California red scale, Aonidiella aurantii Maskell, was studied in the laboratory for two parasitoids, Comperiella bifasciata Howard and Aphytis melinus DeBach. All three ant species reduced percentage parasitism by C. bifasciata and both percentage parasitism and host mutilation by A. melinus. Southern fire ant was the least disruptive and native gray ant the most disruptive. Southern fire ant removed 12% of scale from the lemons, presumably to feed on them, while the other ant species did not exhibit significant removal of scale compared to the controls. Percentage parasitism of California red scale exhibited by C. bifasciata was more than 2-fold the level exhibited by A. melinus. Percentage mutilation of California red scale, including probing and host feeding, was nearly 5-fold higher for A. melinus than C. bifasciata. Because A. melinus required a longer total host examination + oviposition period in the absence of ants than C. bifasciata and because oviposition occurs as the last act in a sequence of behaviors, disruption by the ants had a more significant negative effect on oviposition by A. melinus.     

Primary parasitoids of red scale (Aonidiella aurantii) in Australia and a review of their introductions from Asia

We used morphological and molecular differences to confirm the identities of red scale (Aonidiella aurantii) and yellow scale (A. citrina), and their primary parasitoids, in Australia. An extension to the distribution of yellow scale was confirmed. Six primary parasitoids of red scale were identified: Aphytis chrysomphali, A. lingnanensis, A. melinus, Comperiella bifasciata, Encarsia citrina, and E. perniciosi. With the exception of A. lingnanensis, these parasitoids, and a species of Aphelinus, were detected in association with red scale during studies in citrus orchards in coastal New South Wales between 2009 and 2012. Two races of A. melinus were recorded: one from the Indian Subcontinent, the other previously only recorded in China. The studies, and reviews of historical records, led us to conclude that 4 parasitoids, A. lingnanensis, C. bifasciata, and both species of Encarsia, were present in Australia before successful or unsuccessful formal introductions between 1902 and 1970. The A. melinus race previously recorded in China may also have been present before the Indian Subcontinent race was formally introduced in 1961. We suggest the possibility that the natural distribution of some of the parasitoids may include East and Southeast Asia, and parts of Australasia. We found no reports of native armored scales being recorded on species and hybrids of Citrus introduced to Australia, and no reports of introduced armored scales being recorded on native Rutaceae, including 6 species of Citrus. However, we subsequently recorded yellow scale on Geijera parviflora, a native rutaceous tree.     

Pest management systems affect composition but not abundance of phytoseiid mites (Acari: Phytoseiidae) in apple orchards

We examined the faunal composition and abundance of phytoseiid mites (Acari: Phytoseiidae) in apple orchards under different pest management systems in Hungary. A total of 30 apple orchards were surveyed, including abandoned and organic orchards and orchards where integrated pest management (IPM) or broad spectrum insecticides (conventional pest management) were applied. A total of 18 phytoseiid species were found in the canopy of apple trees. Species richness was greatest in the organic orchards (mean: 3.3 species/400 leaves) and the least in the conventional orchards (1.4), with IPM (2.1) and abandoned (2.7) orchards showing intermediate values. The phytoseiid community’s Rényi diversity displayed a similar pattern. However, the total phytoseiid abundance in the orchards with different pest management systems did not differ, with abundance varying between 1.8 and 2.6 phytoseiids/10 leaves. Amblyseius andersoni, Euseius finlandicus, and Typhlodromus pyri were the three most common species. The relative abundance of A. andersoni increased with the pesticide load of the orchards whereas the relative abundance of E. finlandicus decreased. The abundance of T. pyri did not change in the apple orchards under different pest management strategies; regardless of the type of applied treatment, they only displayed greater abundance in five of the orchards. The remaining 15 phytoseiid species only occurred in small numbers, mostly from the abandoned and organic orchards. We identified a negative correlation between the abundance of T. pyri and the other phytoseiids in the abandoned and organic orchards. However, we did not find any similar link between the abundance of A. andersoni and E. finlandicus.     

Effect of the California red scale Aonidiella aurantii sex pheromone on the natural parasitism by Aphytis spp. in Mediterranean citrus

Mating disruption has proved successful against California red scale (CRS), Aonidiella aurantii Maskell (Hemiptera: Diaspididae) in Mediterranean citrus. Although mating disruption does not affect negatively the parasitism by Aphytis melinus DeBach (Hymenoptera: Aphelinidae), a CRS parasitoid introduced to the Mediterranean, there is no information regarding its potential effect on the native Aphytis species. In the present study, the effect of CRS mating disruption on the field parasitism inflicted by Aphytis spp. has been assessed and compared to a mineral oil and a control treatment. In order to confirm the effectiveness of the mating disruption we also evaluated its effect on the captures of the CRS males and on fruit infestation. Moreover, the potential role of the CRS sex pheromone as kairomone for the Aphytis species was also evaluated by comparing captures of parasitoids on sticky traps with or without pheromone. Significantly lower CRS male captures and fruit damage were registered in the mating disruption respect to the control or oil treatments indicating that mating disruption was effective. In September, when compared to the control, parasitism by Aphytis spp. was significantly lower in the mating disruption and mineral oil treatments and crucially no Aphytis chrysomphali Mercet were registered in the mating disruption treatment. Finally, while the captures of both A. melinus and Aphytis lepidosaphes (Mercet) were not significantly different between traps with or without pheromone, A. chrysomphali captures were significantly higher in traps baited with CRS pheromone. These results suggest a possible kairomonal effect of the CRS pheromone on A. chrysomphali.     

Studies onAphytis coheni,a parasite of the California red scale,Aonidiella aurantii in Israel

Studies on the development, fecundity, nutrition and the influence of temperature and humidity onAphytis coheni DeBach, an ectoparasite of the California red scale,Aonidiella aurantii (Maskell) were conducted in an effort to explain the current distribution ofA. coheni in citrus groves in Israel.     

Residual Effects of Carbaryl and Dicofol on Aphytis holoxanthus Debach (Hymenoptera: Aphelinidae)

Aphytis holoxanthus Debach is an important biological control agent of Florida red scale, Chrysomphalus aonidum (L.). Laboratory tests quantified the mortality of this hymenopteran parasite caused by field residues of carbaryl and dicofol. Behavior and mortality of adult A. holoxanthus on carbaryl-treated “Hamlin” orange leaves were related to quantities of dislodgeable pesticide residues over time as field residues weathered. After 24 h, mortality of A. holoxanthus by dicofol was not observed through day 31 when the experiment was terminated. Our data showed that field-weathered carbaryl residues killed A. holoxanthus for a period of up to 22 days posttreatment under spring conditions in Florida.     

Establishment ofEncarsia(=Prospaltella) perniciosi,a specific parasite of San Jose scale,on apple in Kashmir

Attempts were made to reduce populations of San Jose scaleQuadraspidiotus perniciosus (Comstock) by releasing populations of the parasiteEncarsia (=Prospaltella) perniciosi Tower. Several releases were made, between May and November in both 1985 and 1986. TheEncarsia were released into 2 apple orchards infested with scale. Increases in the numbers ofEncarsia caught on sticky traps in these orchards, coupled with an increase from 2.3% to 9.1% in the overall level of parasitism of the scales, suggested that the released parasites had become established. Other natural enemies found associated with San Jose scale on apple in Kashmir included 3 parasites (Marietta carnesi Howard,Azotus kashmirensis Narayanan andAphytis paramaculicornis De Bach) and 5 predators, 4 of which were coccinellids (Chilocorus bijugus Muls,Pharoscymus flexibilis, Exochomus sp. andCoccinella septempunctata) and the remaining one was a chrysopid (Chrysoperla carnea).      

Parasitic wasps attracted by the sex pheromone of their coccid host

Sticky traps baited with live virgin females of the California red scale, placed in citrus groves to capture male scales, also attracted parasitic wasps ofAphytis spp. The number of wasps captured per trap (>500) reached up to 75 % of all insects caught in some citrus groves not treated with pesticides. Laboratory experiments withAphytis melinus andA. coheni and other wasps, carried out simultaneously in two different olfactometers, showed that the two species ofAphytis were highly responsive to the sex pheromone of California female red scales.     

Farmers' Perceptions and Practices in Use of Dolichoderus thoracicus (Smith) (Hymenoptera: Formicidae) for Biological Control of Pests of Sapodilla

In 1996, a majority (61%) of 190 sapodilla farmers in the Mekong Delta, Vietnam considered the black ant, Dolichoderus thoracicus (Smith), beneficial in decreasing damage by the fruit borer Alophia sp. (51%), the mealybug Planococcus lilacinus (Cockerell) (43%), and “bad” ants, notably Cardiocondyla wroughtoni (Forel) (38%). A significantly greater proportion of orchards in Can Tho had D. thoracicus (60%) than orchards in Tra Vinh (42%) (P < 0.05). In orchards where D. thoracicus were present, 25% fewer farmers sprayed insecticides than in orchards without D. thoracicus. Promoting greater farmers' acceptance of D. thoracicus may be difficult because 30% of the farmers said that D. thoracicus increases mealybug populations. The influence of D. thoracicus on both Alophia sp. and P. lilacinus infestations was tested in both provinces in 1996 and 1997. The mealybug P. lilacinus was not affected, but Alophia sp. damage was significantly smaller in ant-abundant trees (P < 0.01). In Tra Vinh, the use of high-pressure pumps to spray tree canopies with water hampered D. thoracicus and lessened Alophia sp. control. Farmer-to-farmer training and mass media campaigns about the beneficial effect of D. thoracicus should be conducted to promote wider use of this ant species as a biological control agent and to reduce pesticide use in sapodilla orchards.     

The predator guild associated withAceria litchii (Acari: Eriophyidae) in Australia and China

Lychees were surveyed in Queensland, Australia and in Guangdong Province and Hainan Island China, for natural enemies of the lychee erinose mite,Aceria litchii (Keifer), one of the most serious pests of lychee in Australia. A guild of seventeen predators, including ten species of phytoseiid mites, was associated with lychee erinose in Queensland. Six other predaceous mite species and a cecidomyiid larva,Arthrocnodax sp. were also part of the complex. Despite the apparent predation of most of the seventeen species recorded in Queensland onA. litchii, the pest continues to cause major problems. In China, whereA. litchii is a relatively minor pest, nine phytoseiid species were collected in lychee orchards. The value of introducing additional predators to Australia, especially from China, is discussed.     

Mating disruption of the carpenter moth,Cossus insularis (Staudinger) (Lepidoptera: Cossidae) with synthetic sex pheromone in Japanese pear orchards

Mating disruption of the carpenter moth, Cossus insularis Staudinger (Lepidoptera: Cossidae), with a synthetic version of its sex pheromone, a mixture of (E)-3-tetradecenyl acetate and (Z)-3-tetradecenyl acetate, was tested for three successive years in Japanese pear (Pyrus pyrifolia var. culta) orchards. Pheromone trap catches, percentage mating of tethered females, and tree damage were measured in both the pheromone-treated and untreated control orchards. The attraction of male adults to pheromone traps was completely disrupted, and the mating of the tethered females was completely inhibited by the treatment of synthetic pheromones. The percentage of damaged trees in the pheromone-treated orchard decreased over the course of the experiment, while the damage percentage did not decrease in the untreated orchard. These results show that mating disruption with the synthetic sex pheromone is promising for the reduction of damage caused by C. insularis in apple and Japanese pear orchards.     

Priming Aphytis: behavioral modification of host selection by exposure to a synthetic contact kairomone

The introduced parasitoid, Aphytis melinus DeBach (Hymenoptera: Aphelinidae), utilizes a kairomone, O-caffeoyltyrosine, to recognize California red scale, Aonidiella aurantii (Maskell) (Homoptera: Diaspididae). Wasps used in augmentative release programs for California red scale on California citrus are reared on oleander scale, Aspidiotus nerii Bouché (Homoptera: Diaspididae), themselves reared on squash. The goals of this study were: 1) to determine if long-term rearing on oleander scale had caused A. melinus to develop a preference for oleander scale, and 2) to determine if the preference of oleander-reared A. melinus for California red scale might be enhanced by exposing them to synthetic O-caffeoyltyrosine prior to release. Wasps that were removed from their hosts as pupae and allowed to emerge as adults isolated from their hosts retained a strong preference for California red scale regardless of rearing host. This preference was reduced if wasps were allowed to emerge from oleander scale, thus acquiring early adult experience with oleander scale. The preference for California red scale was restored, however, by exposing wasps reared on oleander scale to synthetic O-caffeoyltyrosine prior to bioassay. Exposure of A. melinus reared in commercial insectaries to O-caffeoyltyrosine prior to release may be a means to improve the effectiveness of such wasps in augmentative release programs to control California red scale.     

Biological Control of Anastrepha spp. (Diptera: Tephritidae) in Mango Orchards through Augmentative Releases of Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae)

Diachasmimorpha longicaudata (Ashmead) parasitoids were released by air on a weekly basis over 1600 ha of commercial mango orchards, backyard orchards, and patches of native vegetation, at a density of ca. 940 parasitoids/ha. Releases were made during 2 consecutive years, beginning at flower onset and lasting until the end of the production cycle. Two areas, 7 km apart, were compared. In one area parasitoids were released, whereas the other area was used as a control. During the 2nd year treatments were reversed. Fruit was sampled in commercial mango orchards and in backyard orchards to assess levels of parasitism in fruit fly larvae. Highly significant differences in percentage parasitism were found in release and control zones in backyard orchards. Furthermore, trapping results indicated that D. longicaudata releases were associated with ca. 2.7-fold suppression of Anastrepha spp. populations in backyard orchards. Results suggest that suppression might be affected by environmental conditions and by the parasitoid:fly ratio achieved. Anastrepha obliqua McQuart populations were suppressed more effectively by use of parasitoids than those of Anastrepha ludens Loew, perhaps due to the type of host fruits used by each species. Augmentative parasitoid releases in marginal areas surrounding commercial orchards (backyard orchards, wild vegetation) can substantially suppress fly populations. Through this approach, the number of flies that later move into commercial orchards can be significantly reduced. Such a strategy, when combined with sound orchard management schemes, can allow growers to produce clean fruit without the need to resort to the widespread use of insecticides.