AERIAL APPLICATIONS OF LARVEX VS. AE. TAENIORHYNCHUS IN MANGROVE SWAMPS IN THE CAYMAN ISLANDS (M E C GIGLIOLI, MRCU)

A high degree of control (95%) is possible with aerial applications of 7.4Kg a.i./ha Larvex 15 in open water or with 18.5kg a.i./ha for dense mangrove canopy......being "rained" down as a course spray from open ended pipes. Much more cost effective applications may be made using Larvex 100.

 

Larvex 15

Average no. of larvae per 10 dips

Application

Before spray

After 18 hours

% mortality

7.4kg/ha

1871.00

7.00

99.60

11.0 kg/ha

2560.00

244.00

91.30

 

 

THE CONTROL OF ANOPHELENES IN THE SUDAN BY LARVEX MONOLAYERS

(Blue Nile Health Project, Dr. C Curtis, Ross Institute, Consultant)

Larvex is highly effective in controlling the development of juvenile stages of An. Pharoensis in heavily weeded irrigation ditches in the Gezira region when applied at the rate of approx. 1.5kg/ha a.i. Curtis report states: "Checks two and four days after treatment of 300 metres of canal showed that the larval density had been suppressed to zero in most parts of the treated area and had risen somewhat in the control area."

 

 

MOSQUITO LARVAL CONTROL USING LARVEX MONOLAYER

(Blair Research Laboratory, Harare, Zimbabwe)

After one week from treatment no mosquito larvae could be collected from treated ponds whereas the control pond still had larvae present. Two weeks after treatment only 1st and 2nd instar larvae could be detected. The monolayer has excellent spreading properties which can give mosquito larval control on stable water bodies up to two weeks after a single application at 2kg/ha.

 

FIELD TRIALS OF INSOLUBLE MONOLAYERS IN MOSQUITO CONTROL AT AHERO, KENYA, 1972-75. (ANOPHELES GAMBIA)

MRC Kisumu Project

 

In most of the field experiments the LARVEX monolayer reduced the pupal and 4th stage larval counts by at least 90%, in some cases by 100%, by the day following treatment and in most cases the depletion several days after was 100%, viz.:

% depletion of:

in:

1 & 2 instars

3 & 4 instars

pupae

untreated fields

+ 103% (increase)

0.00

28%

Monolayer treated

79%

95%

92%

(Many ovipositing/emerging adult flies seen to be trapped and wetted on the surface).

 

An. Gambia in paddy-field:

   

1st and 2nd stage Larva

3rd and 4th stage Larvae

Treatment

Field No

Pre

Post

Pre

Post

Control

1.00

144.00

115.00

123.00

179.00

 

2.00

132.00

169.00

115.00

105.00

 

3.00

107.00

145.00

102.00

97.00

 

4.00

63.00

172.00

83.00

107.00

 

5.00

156.00

145.00

93.00

153.00

LARVEX 100

1a

91.00

0.00

109.00

0.00

(1kg/ha)

2a

107.00

0.00

155.00

0.00

 

3a

178.00

0.00

62.00

0.00

 

4a

128.00

0.00

118.00

0.00

 

5a

188.00

0.00

127.00

0.00

 

 

MOSQUITO CONTROL ON THE RHINE BY MONOLAYERS

Prof. W Schnetter, University of Heidelberg, & Min. of Food and Agriculture

After a single application 95% of mosquito larvae were destroyed. Estimated 50 million mosquito killed within several days. The effect on non-target organisms is very small. At dosages of 5 to 10lt/ha the mosquito population is reduced to such an extent that the normal use of insecticidal fog was discontinued. Damage to non-targets was not apparent except for Hemiptera-Corixidea. Water beetles and young fish were not harmed.

 

FIELD TRIALS IN SRI LANKA VS AN. CULICIFACIES

Wolfson Mosquito Project & Sarvodaya Movement

Larvex monolayers gave good control in pools at the rate of 3kg/ha.

Pool No

Dose (kg/ha)

3rd and 4th instars

Pupae

Days after treatment: treat

5.00

7.00

5.00

7.00

20.00

2.00

0.00

0.00

0.00

0.00

1.00

3.00

0.00

0.00

0.00

0.00

7.00

3.00

1.00

1.00

0.00

0.00

22.00

3.00

4.00

5.00

0.00

1.00

25.00

3.00

0.00

0.00

0.00

0.00

16.00

10.00

0.00

2.00

0.00

0.00

 

EFFECT OF LARVEX ON NON-TARGET ORGANISMS

Wolfson Unit of Chemical Entomology, University of Southampton

Few species of non-target organism were directly affected by Larvex, these being Gerris, Notonecta, Corixa & Dytiscus. Other organisms and several species of tropical fish gave negligible results under the monolayer. In general, fewer non-target species were affected than were those treated with Abate, a relatively non-toxic chemical larvacide. The effects of the monolayer on fish are considered negligible.

 

TRIALS OF LARVICIDAL & PUPACIDAL MONOLAYERS Vs AN. SACHAROVI IN TURKEY

Mr Espinoza, Dr. E Onori & Dr. D Muir representing W.H.O.

With all treatments the immediate effect was to reduce the numbers of pupae and fourth stage larvae, followed by a slower fall in the numbers of younger juveniles. Thus an application of 5kg/ha reduced the total juvenile count by 87% immediately (24 hours) and after respraying at 12 days the reduction was 97.4%, 16 days from commencement. At 10kg/ha the monolayer gave 100% control for at least 15 days, i.e. no larvae detected and a 5kg/ha treatment gave 100% control for more than 8 days. To these periods should be added at least a further 10 days to the reappearance of pupae, although time did not allow this to be confirmed in practice. Canal water pH was highly alkaline at pH 10.0 monolayer material was applied by throwing aliquots from a cup onto the canal surface every five paces.