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Pale cotton stainers Dysdercus sidae Cotton Stainer dd

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Pale cotton stainers Dysdercus sidae Cotton Stainer dd

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									On Farm                                                                                                                          Research & Science

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Pest Profile
On Farm Series: IPM | February 2008 | Produced by Cotton CRC



Pale cotton stainers, Dysdercus sidae
                                Lewis Wilson1, 4, Moazzem Khan2, 4, Tracey Farrell3, 4
 1
  CSIRO Plant Industry, 2Queensland Department of Primary Industries, 3NSW Department of Primary Industries, 4Cotton
                                           Catchment Communities CRC
Cotton stainers are recognised
as occassional pests of cotton




                                                                                    Photo; Lewis Wilson, CSIRO




                                                                                                                                                              Photo; Lewis Wilson, CSIRO
in Australia. Economic damage
is unusual because of their;
– incidental control when
   using broad spectrum
   insecticides for other pests;
– inability to survive;
                                         Figure 1 (above); D. sidae first instar.                                 Figure 2 (above); D. sidae third instar.
   temperatures above 40°C.              Figure 3 (below); D. sidae fourth instar                                 Figure 5 (below); D. sidae adult.
– need for free water to be
   present.
                                                                                     Photo; Lewis Wilson, CSIRO




                                                                                                                                                             Photo; Lewis Wilson, CSIRO
However in mild seasons
Bollgard II® crops maybe a
favourable environment for
cotton stainers and they may
need to be managed.


Cotton stainer bugs belong to            under debris or occasionally on                                          through five nymphal stages
the Pyrrhocorid group of bugs            the undersides of cotton leaves                                          before reaching adulthood. The
and are pests of cotton around           low in the canopy. Eggs change to                                        indicative size of a cotton stainer
the world. A range of species are        orange as they near hatching. The                                        at each stage of development is;
involved, each slightly different        time taken can vary from 5 days at                                       First Instar  2–3 mm (Figure 1)
in appearance and biology. In            30°C to 13 days at much cooler or                                        Second Instar 4–5 mm
Australia two species have been          warmer temperatures.                                                     Third Instar 6–8 mm (Figure 2)
recorded from cotton, the cotton
                                         Young cotton stainers moult                                              Note the small wing buds.
stainer (Dysdercus cingulatus) and
                                                                                                                  Fourth Instar 9–11 mm (Figure 3)
the pale cotton stainer (Dysdercus
sidae), which is generally the most                                                                               Note the larger wing buds.
common. These species look very                                                                                   Fifth Instar  12–14 mm
                                                                                     Photo; Lewis Wilson, CSIRO




similar but the pale cotton stainer                                                                               Adult         15 mm    (Figure 4)
is generally a duller brown (see
Figure 5, next page).

Lifecycle
Females lay batches of ~100
creamy white eggs in shallow             Figure 6; D. sidae eggs (1 mm diameter)
depressions in the soil (Figure 6),      laid on the soil surface.
www.cottoncrc.org.au                                                                                                                            Page 1 of 4
On Farm Series: IPM | February 2008                                                                                      Research & Science



First instars remain together and
can be observed on the ground
near to where they have hatched.
Second instars may disperse in
search of food. Their stylets are
not yet long enough to penetrate
unopen bolls and reach the seed
within. Instead they look for ripe,
exposed seed or decaying seed.
When free water is present they
are able to penetrate quite hard,
dry seeds. They may be seen
to congregate around suitable
                                                       Figure 5; The cotton stainer (Dysdercus cingulatus) (right) and the pale cotton stainer
sourses of food.
                                                       (Dysdercus sidae) (left). Insects are about 15 mm long in the body.
Once the third instar is reached,                      Images courtesy of CSIRO.
they are able to commence
feeding on developing seed within            D. sidae is one of the most frost                     strong piercing/sucking
the bolls. From this stage onward            tolerant species, being able to                       mouthparts, shown in Figure 7, to
the nymphs will disperse to feed             survive subzero conditions for up                     feed on developing and mature
and congregate to moult.                     to 7 days.                                            cotton seed. Seed weight, oil
Two days after the final moult,                                                                    content and seed viability all
                                             Arrival in Cotton
adults begin to mate. Fertility will         Usually cotton becomes infested                       decline as a result of cotton stainer
be highest when the temperature              by adults that fly into fields                        feeding. Loss of seed viability
is 30°C and low at temperature               around the time of first open                         can be substantial so should be a
extremes.                                    boll, though sometimes, perhaps                       careful consideration in pure seed
The availability of water and                due to seasonal conditions                            crops.
nectar is important for feeding and          populations can be found early,                       In bolls up to two weeks old severe
development during all growth                during boll maturation. Flights of                    attacks can kill developing seeds
stages. Adults can survive on water          up to 15 km have been recorded.                       leading to boll shedding. Where
alone for several weeks when food            Adults will mate soon after arrival.                  feeding is less severe damaged
is scarce.                                   The expanding population of
                                                                                                   bolls are retained and lint yield may
                                             developing nymphs will be the
There is no resting stage in winter.                                                               also be reduced as a secondary
                                             cause of economic damage.
Survival is dependent on them                                                                      effect of feeding. Tightlock, shown
finding food, water and shelter              Damage                                                in Figure 8, can result around
from frost. Of the cotton stainers,          Pale cotton stainers use their                        damaged seeds, preventing the lint


Other species that may be confused
                                             Photo; Jo Wessels.




                                                                                                    Photo; Jo Wessels.




with cotton stainers are Graptostethus
servus, seed eating bug (left) and
Leptocoris mitellata, the red eyes
bug (right). Note that their wings are
generally dark, rather than being orange
with a distinct dark spot. G. servus is a
pest of sorghum, soybeans, mungbeans
and cowpes. L. mitellata has a wide host
range including fruit trees and many
garden plants. They are attracted to light
and will often shelter in large numbers
around houses.
Little is known of the behaviour of these
species in cotton. If they are present,
ensure bolls are monitored for signs of
plant bug damage.




www.cottoncrc.org.au                                                                                                             Page 2 of 4
On Farm Series: IPM | February 2008                                                                                            Research & Science



from fluffing out as the boll opens.    These infections can cause                                         clusters of mating pairs. Cotton
Unlike mirids and other plant bugs,     tightlock and lint staining. The                                   stainers tend to hide during the
pale cotton stainers are able to        presence of pale cotton stainers                                   heat of the day, sometimes in
continue feeding on bolls during        when such damage occurs may                                        partially opened bolls. They are not
their later stages of development.      be coincidental.                                                   easily observed at this time.

As bolls open stainers will feed on     Monitoring for the presence                                        Once pale cotton stainers are
the mature seeds. ‘Bald patches’        of bugs                                                            observed, monitor developing and
                                        Distribution through the field                                     mature bolls for signs of damage.
where there is less lint on the
seed may become evident as the          and through the canopy can be                                      Alternate hosts
lint fluffs out. Shown in Figure 9,     quite patchy. To avoid under/over                                  Pale cotton stainers are
several seeds within each lock may      estimating abundance ensure                                        considered to be Malvaceae
be affected or only one or two          sampling occurs at multiple sites                                  feeders for development.
seeds in the boll. At present it is     spread throughout the field.                                       In Australia they have been
unclear whether this damage is a        The beat sheet is a suitable                                       observed in Malvaceae such as
result of feeding after boll opeing     sampling method to monitor
or from earlier feeding during seed     the bugs, but as some growth
development.                            stages favour the lower canopy,
Yellow staining of the lint has also    visual searching is also a good




                                                                                                                                                 Photo; Lewis Wilson, CSIRO
been observed. Shown in Figure          complementary technique.
10, it is thought to occur as a         First instar nymphs tend to be
consequence of watery faeces            found on the soil or very low in
being deposited on the lint while       the canopy. Young nymphs are
bugs are feeding in the open bolls.     gregarious and will tend to stay
Overseas, staining of cotton lint       in clusters until about the third
has occurred as a result of feeding     instar, making their distribution                                  Figure 7; Pale cotton stainers use their
in young bolls. The bugs transmit       quite patchy. At the open boll                                     strong probiscus to feed on seed in large
a fungal pathogen during feeding        stage nymphs are more visible                                      bolls and in open cotton.
causing a reddening of the lint. This   than in earlier stages of the crop.
has not been documented to occur        However they may also hide in
in Australia.                           the fluffy lint.
Staining can also occur as a result     Older nymphs tend to be found

                                                                                                                                                 Photo; Lewis Wilson, CSIRO
of bugs being squashed during           in the lower to mid canopy and as
picking.                                open bolls appear they will often
                                        been seen in the bolls feed on the
Monitoring for damage                   exposed seeds.
Bolls of varying ages should
                                        Adults can be distributed through
be cut open to confirm and
                                        the crop at low densities, often in
monitor for signs of damage.
                                        mating pairs, but sometimes they                                   Figure 9; ‘Bald patches’ on mature cotton
Study done by QDPI&F, Kingaroy
                                        can also be found in quite dense                                   seeds due to pale cotton stainer feeding.
entomologist Moazzem Khan
showed pale cotton stainer bug
caused damage to developing
bolls that was similar to that
of green vegetable bug (GVB).
This includes a black spot on the
                                                                              Photo; Lewis Wilson, CSIRO




                                                                                                                                                 Photo; Lewis Wilson, CSIRO




outside of the boll, warty growths
inside boll wall and brown
coloured lint.
The mild, wet conditions that
favour the survival of pale cotton
stainers in cotton will also favour
the occurrence of secondary             Figure 8; Tightlock associated with                                Figure 10; Lint staining caused by pale
infections by yeasts, Alternaria        pale cotton stainer feeding during boll                            cotton stainers feeding on mature seeds
and bacteria in cracked bolls.          development.                                                       after boll opening.
www.cottoncrc.org.au                                                                                                                    Page 3 of 4
On Farm Series: IPM | February 2008                                                                    Research & Science



Gossypium spp., Malvastrum spp.,       Figure 11; Comparative damage to 10 day old cotton bolls by different plant bugs.
Malva spp., Hibiscus spp. (e.g.
Norfolk Island hibiscus), Sida spp.
and Abutilon spp. Adults may
be found on a range of species,
including Brachychiton spp.
(eg Illawarra flame tree), Ceiba
pentandra (Kapok), Pennisetum
spp. (native grasses), Geijera
parviflora (Wilga) and in Sorghum
spp.

Natural Enemies
A range of natural enemies such
as Tachinids (parasitic flies) and
predatory reduvid bugs (e.g.            GVB – green vegetable bug   BSB – brown stink bug    RBSB – red banded shield bug
assassin bugs) have been recorded       GSB – green stink bug       HRLQB – harlequin bug    CSB – pale cotton stainer bug
in Africa. However, they have
                                        Source: Moazzem Khan, QDPI&F, 2004 unpublished data.
mainly exerted pressure when
cotton stainers have been feeding
                                       seed weight and seed viability.              other secondary pests should be
on native hosts rather than in
                                       Where staining is observed as in             considered.
cropping situations. The role of
natural enemies in the control of      Figure 9, a threshold of 30% of              Controlling Cotton Stainers
developing populations of pale         bolls affected should be used to             As there is no resting stage in
cotton stainers in Australia has not   prevent a colour downgrade.                  the cotton stainer’s lifecycle,
been studied.                                                                       cultural controls between cotton
                                       Reaction to Insecticides
                                       As an occasional pest, there are             seasons assist greatly in limiting
Action Threshold during Boll
Development                            few products registered for their            population development.
When adults and nymphs are             control. The synthetic pyrethroids           Fuzzy cotton seed used for
observed in the crop and damage        lambdacyhalothrin (Karate Zeon ®,            stockfeed is an important alternate
to developing bolls is detected, an    Matador ®and gamma-cyhalothrin               source of food for cotton stainers.
action threshold of 3 pale cotton      (Trojan ®) are registered; check             Avoid storing fuzzy seed in exposed
stainers/m is recommended.             the labels of these products for             places where cotton stainers can
This threshold is based on the         more information. However                    access this food source over long
relationship between cotton            their status as an occasional                periods.
stainer damage and the damage          pest is influenced by their
                                                                                    Controlling ratoon cotton and
caused by other plant bugs (see        susceptibility to insecticides used
                                                                                    cotton volunteers is important for
Figure 11). The figure shows that      for the control of Helicoverpa
                                                                                    limiting cotton stainer’s access to
pale cotton stainer bugs caused        and other pests. Cotton stainers
                                                                                    alternate food source.
only one third as much boll            will be incidentally controlled
                                       when synthetic pyrethroids,                  Further Information
damage as green vegetable bugs.
Since the action threshold for         carbamates such as carbaryl                  Lewis Wilson
green vegetable bug is 1/m, the        or organophosphates such as
                                                                                    CSIRO Plant Industry, Narrabri
action threshold for pale cotton       dimethoate are used.
                                                                                    (02) 6799 1550
stainer bug should be 3/m.             Worldwide there are few records
                                       of resistance to insecticides                Moazzem Khan
Both nymphs (usually 3rd to 5th
                                       developing in the field, however             QDPI&F, Kingaroy
stage nymphs) and adults cause
                                       cotton stainers will react to
similar amounts of damage.                                                          (07) 4160 0705
                                       selection pressure under
Action Threshold after First           laboratory conditions. Any                   Acknowledgements
Open Boll                              decision to use broad spectrum               The authors wish to thank Steve
When adults and nymphs are             insecticides such as SPs should              Maddon and Jamie Street (CCA),
observed feeding in open bolls,        take into account their impact on            Dr Stephen Allen (CSD), Mick
the threshold must consider the        beneficial insects. Particularly in          Howard and Dave Jenkins (ACS)
potential for quality downgrades       the Darling Downs and St George              and Dr Graham Matthews (Imperial
of the lint as well as the loss of     the risk of flaring whitefly and             College, London) for their assitance.
www.cottoncrc.org.au                                                                                             Page 4 of 4

								
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