INSECT PARASITES

Hokitika Guardian, 29 August 1933, Page 8

INSECT PARASITES

YVAJR ON'WHITE BUTTERFLY,

PALMERSTON NORTH, August 26; , '■ For : many - years New Zealand tomatoes have been .ravaged by a- white flyio.f unknown origin. Its depredations have been extensive in glasshouses at Auckland., - Christchurch - and’ Nelson. It thrivesT-dn leaves to an enormous extent,-• sapping the- juice "of the-plant, 1 weakening: it, besides disfiguring the fruit, which becomes ' speckled and unappetising In. appearance. Following investigations commenced two - seasons "ago, Mr J; "M; Mufggeridges 'Government Entomologist at the Plant Research Station at Palmerston North, has been successful in cstablishin g a natural enemy insect, which he has bred under laboratory 1 eonditions to such an extent that sufficient numbers will ultimately be available to fill all requiremets. It is ® s ma clear J winged insect of the same order as that which is now making wax o,n the cabbage white butterfly. Once liberated and established ■in a glasshouse, the. insect is quite sufficient to keep the white fly under control. However, it is .susceptible to outside temperatures. To hold it safely over the winter months, it is seated, heated glasshouses are necessary, thus producing the possibility of the need for annual distribution, which may present an. awkward problem. Order s to the value of £305 for. new season’s gupplies of the, prrasite to attack the -white butterfly pest this .summar. have been placed with the Imperial Institute of Entomology on behalf.. of; the Plant. IReseaxch Station. Plans -are now...being .formulated hueo-I-. laboiatiom witfi, the Fields ‘-Division : ;of the Department .of ASrihfi'Uure Tor their liberation immediately they come to h Jid. .-< ■ .K"

I'lie superintendent .of,, the division, .M r NV. J. .McCullough, ; states 'that steps: are being" taken To establish ad-, diticnal colonies of parasites ■ in the Wajrarapa and on the Poverty Bay flaks on-selected airea s in chou moellier or turnip crops infested with, the white ib utter fly. The pest hag its main breeding grounds-- inj the east- coast; districts, where conditions appear t O . be - most suitable for it. 'Expenditure on tbe war against the white butterfly •:-has been made possibly from two •bounces, 1 states (Mr. Muggeridge. ■ Recently, Hawkes Ray- f rmer's, .realising the- ■ serious .nature of the menace to crops, raised £lO5 and forwarded *it to the DirectorGeneral of Agriculture with the request that it should b e expended on : parasites for- liberation im that’ districtA uthority has just been received from i the Director-General- of ’ Agriculture to cable a further £2OO to England for the purchase of insect -enemies; Np : delay ‘has -occurred in placing The orders. "■ '' f jr

The Government Entomologist, ho>jv,: ever, has issued a note of warning against undue optimism, as the ■ problem is mot one merely to be solved in ' a season. It is intended to liberate: 'parasites as, far afield as possible, including the Manawatu district; Thc-re is, a possibility that the Plant Research Station may.be 'inundated with-, replications on the assumption that.,!The ' advent of the parasite moan's the immediate end of the white butterfly- This idea is quite erroneous.

‘•There is no knowing -how long it will take ta achieve the object,’’ said Mr Muggerioge to-day. “A great deal depends upon how the ; insects' respond to the environment. Though there is every ground for thinking that in ’the •parasite has- been found one of the nVin sources of control, I would like the people of 'New Zealand to view it as an experiment based on sound scientific practice and principles well established in -other parts of the world.” The butterfly now had a very strong hold in New Zealand, continued Mr Mug--geridge, There was every prospect thT it would' multiply and do extensive damage before it was possible to bring it under control. The parasite bred moi'e .■quickly than the butterfly, one. .;,alone being capable of ‘producing.-70Q; eggs, while for a single white butterfly The maximum number Was about 240.-While a recent survey in the field indicated a rapid percentage of .parasitism, jt wa s certain, that the full effects of their liberation would not be secured j until there had been a general distribution throughout the whole -of the affected area*.