New whitefly found!

      No Comments on New whitefly found!

Detec­tion of Q bio­type Bemisia tabaci in Aus­tralia

The pres­ence of Q bio­type Bemisia tabaci species com­plex in Aus­tralia has been con­firmed by Dr Robin Gun­ning, NSW DPI. Q bio­type was col­lect­ed from veg­eta­bles in the Bowen/Burdekin region dur­ing late 2008, as well as from cot­ton in south­ern Queens­land (Goondi­win­di) and north-west­ern NSW (Wee Waa) dur­ing 2009. It is like­ly that Q bio­type is more wide­ly dis­trib­uted than just these regions.

What are the impli­ca­tions?
Over­seas stud­ies indi­cate Q bio­type has the capac­i­ty to devel­op resis­tance to many insec­ti­cides includ­ing insect growth reg­u­la­tors (IGRs) such as Admi­ral® and neon­i­coti­noids like Con­fi­dor®. High lev­els of resis­tance to Admi­ral® have been detect­ed in hor­ti­cul­tur­al crops in a few loca­tions in north Queens­land and some field con­trol prob­lems have been observed for Admi­ral®.

Resis­tance test­ing from cot­ton pro­duc­tion areas for the 2008-09 sea­son has not shown any alarm­ing resis­tance lev­els to Admi­ral® to date.

Over­seas where pop­u­la­tions are pre­dom­i­nate­ly of Q bio­type, mod­er­ate to high resis­tance has devel­oped to Admi­ral®. Where pop­u­la­tions were most­ly B bio­type, Admi­ral® has retained high effi­ca­cy. This has been the case in Queens­land where, accord­ing to Dr Gun­ning, B bio­type pop­u­la­tions remain sus­cep­ti­ble to Admi­ral® and have a high­er sus­cep­ti­bil­i­ty to neon­i­coti­noid insec­ti­cides, com­pared to Q bio­type pop­u­la­tions. At this stage Q bio­type is show­ing marked­ly less resis­tance to pyrethroids than the B bio­type.

In Israel, Q bio­type has not devel­oped resis­tance to Pega­sus® despite sev­er­al years of reliance on this prod­uct. In hor­ti­cul­tur­al areas, sig­nif­i­cant resis­tance to Pega­sus® was not found in either bio­type.

Inte­grat­ed Pest Man­age­ment
Prac­tic­ing good IPM prin­ci­ples can dis­cour­age Q bio­type num­bers from build­ing up. Under nat­ur­al con­di­tions, B bio­type will out-com­pete Q bio­type. How­ev­er, in an envi­ron­ment of high insec­ti­cide use, the more insec­ti­cide resis­tant Q bio­type tends to dis­place B bio­type, and once this shift occurs B may not recov­er to its for­mer lev­els. Lim­it­ing the amount of chem­i­cal used against insect pests may favour the dom­i­nance of B over Q.

Q bio­type, like B, has the capac­i­ty to vec­tor the virus that caus­es cot­ton leaf curl dis­ease. This dis­ease is not present in Aus­tralia. The main risk is that any new white­fly incur­sions, whether Q or B bio­type, could car­ry virus­es that are not present in Aus­tralia.


Iden­ti­fi­ca­tion
Q bio­type and B bio­type can not be dis­tin­guished visu­al­ly. They can only be dis­tin­guished by look­ing at small dif­fer­ences in their DNA or bio­chem­i­cal make-up.

WE NEED YOUR HELP
In order to deter­mine the dis­tri­b­u­tion of Q bio­type, we are ask­ing grow­ers and con­sul­tants to send in white­fly spec­i­mens to the Queens­land Pri­ma­ry Indus­tries and Fish­eries, Toowoom­ba. Please refer to details at the bot­tom of this arti­cle.

FURTHER READING

White­flies (QDAFF)

WHITEFLY SAMPLING
Adult white­flies: In fields where white­fly are present, col­lect a min­i­mum of 30 adults from ran­dom plants through­out the crop. Place these in 65% alco­hol (watered down methy­lat­ed spir­its) in a leak proof vial or bot­tle. Note that >70% alco­hol is clas­si­fied as a dan­ger­ous liq­uid and should not be sent via post or couri­er.

Imma­tures: In fields where white­fly are present, col­lect a min­i­mum of 30 leaves from ran­dom plants through­out the crop. Aim to col­lect leaves that have large imma­ture scales (4th instar/red-eye nymphs) on their under­side. Col­lect only 1 leaf/plant. Pack the leaves into a paper bag and then inside a plas­tic bag.

For live mate­r­i­al, send by overnight couri­er to:
Richard Lloyd
DEEDI, Pri­ma­ry Indus­tries and Fish­eries
203 Tor St, Toowoom­ba Q 4350
Ph: (07) 4688 1315

Ensure sam­ples are clear­ly labeled and include the fol­low­ing infor­ma­tion:
Col­lec­tors Name, Phone No., Fax No., Email address
Farm Name, Field, Post­code, Region (e.g. Gwydir)
Date of Col­lec­tion, Host Plant (Crop)
Com­ments

Arti­cle by Zara Ludgate and David Mur­ray