1. Population density of the eucalyptus redgum lerp psyllid,
Glycaspis brimblecombei Moore (Hemiptera: Psyllidae)
E.N. FYTROS, Κ.G. ΑRKOUMANEA and Α.Ε. TSAGKARAKIS
Laboratory of Agricultural Zoology & Entomology,
Agricultural University of Athens, 75 Iera Odos str, Athens, Greece
INTRODUCTION
Glycaspis Taylor,an Australian genus of jumping plant lice,contains 137 described species which are associated with Eucalyptus spp.. One of these, Glycaspis brimblecombei, was firstly recorded in Australia and later on, it spread in some regions of the Americas. In Europe, its first record was in 2007, in the Iberian Peninsula, while in June 2010 G. brimblecombei was found in Italy. In Greece, although G.brimblecombei was officially first observed in 2013, it is likely that existed in the country for more than a year prior to its first record, given that it was encountered at the same time in many areas of the West, Central as well as South Greece.
Psyllid adults are highly mobile, about 3mm long, alates, with white and yellow color on their thorax and head, while the abdomen is greenish. The females lay their eggs solitary, or in loose groups on both leaf sides. The eggs are of orange and yellow color, stalked and about 1mm in length. After hatching the young nymphs or "crawlers" move about the host plant searching for a place to settle; usually settling within 48 hours of hatching. Once settled they insert their stylets (mouthparts) into the leaf and begin feeding and excreting honeydew which hardens on contact with air to form a lerp. It forms 5 nymphal instars, from which the last 4 live and develop inside a crystalline, semi- transparent lerp they create. The lerp is a white conical construction that the nymph creates from honeydew and other waxy secretions, in order to be protected from enemies and uncomfortable environmental conditions.
Adult female
Fourth nymphal instar
Second nymphal instar
Eggs
Adult male
First nymphal instar
Third nymphal instar
Fifth nymphal instar
SYMPTOMS
The red gum psyllid is considered a serious pest that causes severe defoliation and some tree mortality on some Eucalyptus spp.,and has been included in the EPPO list of quarantine species since 2002.High populations of red gum lerp psyllids on infested leaves produce large amounts of waxy secretions and honeydew,and a resulting soulty mould causes premature leaf drop.In some cases,extensive defoliation and subsequent crown thinning may weaken the trees which become more vulnerable to attack by serious xylophagous pests like Phoracantha spp.
Lerp
MATERIALS AND METHODS
The first aim of this study was to observe the insect’s population density on eucalyptus. For this reason, from April to November 2014 samplings were taking place in Pefki, Maroussi and Kifissia, Attica. In each sampling , eucalyptus stems were collected, each containing 15 leaves. The collected stems were transferred to the Laboratory of Agricultural Zoology and Entomology of the Agricultural University of Athens, for stereoscope observation. Psyllid individuals of all stages and conditions (alive, dead as well as parasitized) were counted and population curves were created.
The second aim was the study of mortality percentage after treatments with synthetic and natural insecticides in Eucalyptus camaldulensis leaves. Eucalyptus leaves,representative of infestation were collected, securing almost all nymphal instars with stereoscope observation. Plant samples were placed into petris. Treatments with synthetic and natural insecticides were occured and we managed to record the dead psyllid individuals of all stages for the specification of mortality percentage.
A third nymphal instar creates a lerp (3h time lapse)
Infested Eucalyptus leaves
RESULTS AND DISCUSSION
3-4 generations were observed,during the samplings, according to population curves
Two potentially effective predators of Glycaspis brimblecombei are Anthocoris nemoralis (Heteroptera: Anthocoridae) and Zelus renardii (Hemiptera: Reduviidae).Although predators do not provide complete biological control,they can reduce psyllid abundace. Another natural enemy is Psyllaephagus bliteus (Hymenoptera: Encyrtidae),which is a parasitoid,which develops only in the red gum lerp psyllid. It can control the increasing populations of G.brimblecombei.These natural enemies have a negative impact on psyllid’s population.
The effectiveness of synthetic insecticides seemed higher in the first 24hrs observation
Plant origin interventions were more effective after 48hrs
It was a first attempt for the insect’s population density and study of mortality percentage on eucalyptus A AB B BC C
Non-ionic surfactant
Treatments
(F24=10,16 dF24= 8,83 P24<0,0001) (F48=2,62 dF48=8,80 P48<0,0133) (F72=2,89 dF72=8,87 P72<0,0066)
Anthocoris nemoralis
Zelus renardii
Mortality (mean±s.e.) of G. brimblecombei nymphs after insecticide sprayings 24, 48 and 72h after application. (Columns of the same color without common letter have significant differences)
REFERENCES
Forest Pest Species Profiles.2012.Glycaspis brimblecombei.http//
Stefania LAUDONIA,Antonio Pietro GARONNA (2010) The red gum lerp psyllid,Glycaspis brimblecombei,a new exotic pest of Eucalyptus camaldulensis in Italy. Bulletin of Insectology 63 (2)
Antonios E.Tsagkarakis,Argyro P.Kalaitzaki ,Georgios N.Balotis (2014) Note on Glycaspis brimblecombei Moore (Hemiptera Psyllidae): A new pest of Eucalyptus in Greece. Vol.2 , No.1 ,57-59http://dx.doi org/ /ae
An adult of Psyllaephagus bliteus is emerging of fifth nymphal instar of G.brimblecombei