A microencapsulated pesticide formulation comprises non-encapsulated pesticide as well as encapsulated pesticide. The two pesticides may be the same or different, and typically a formulation of 25% permethrin has 20% permethrin inside the capsules and 5% outside.

This invention relates to pesticidal formulations. 
It is known to encapsulate pesticidal compounds in small "microcapsules" of 
material, to provide a dry flowable formulation and/or to obtain a 
formulation having a longer effective life. The latter effect is obtained 
because the microcapsules protect the pesticide from degradation, but 
themselves slowly degrade, or are broken by applied pressure, to release 
the pesticide over a period. Alternatively, the pesticide may slowly 
diffuse through the walls of the microcapsules. 
EP 148 769 discloses microcapsule-containing formulations having 
microcapsules of varying sizes. 
It has now been found to be advantageous to include in a formulation 
comprising microcapsules containing a pesticide the same or another 
pesticide in a non-encapsulated form. 
Accordingly, one aspect of the present invention provides a pesticidal 
formulation comprising microencapsulated pesticide and 
non-microencapsulated pesticide. 
The terms "microencapsulated" or "microcapsule" are used in this 
specification to refer to capsules having a diameter of less than 4 mm, 
particularly less than 2 mm. Commonly, however, microcapsules have an 
average diameter of between 1 micron and 100 microns. 
The microencapsulated pesticide may be the same as or different from the 
non-encapsulated pesticide. More than one pesticide may be encapsulated, 
and more than one pesticide may be non-microencapsulated. The encapsulated 
pesticide(s) may be in one or more than one type of microcapsule. 
In relation to the total amount of pesticide in the formulation, the 
proportion which is non-encapsulated is preferably at least 0.5%, and, in 
order of increasing preference, at least 1%, 2%, 3%, 4%, 5% and ideally at 
least 10%. About 15-30%, particularly about 25%, is preferred. Upper 
limits of 50%, especially 40% and more especially 30%, are particularly 
preferred, in conjunction with any of the said lower limits. 
The microcapsules may be formed by any known means, for example by the 
so-called "Pennwalt" method described in UK Patent Specification No 1 091 
141, the entire contents of which are incorporated herein by reference. 
The non-encapsulated material may be a wettable powder, an emulsifiable 
concentrate, a micro-emulsion, a dust or any other suitable form. 
Any known pesticide may be used in the formulation, for example 
organochlorines such as DDT or lindane, organophosphates such as dursban 
or chlorpyrifos, formamidines such as amitraz, chitin synthesis and 
juvenile hormone inhibitors or mimics such as diflubenzuron and 
methoprene, carbamates such as carbaryl, pyrethroids such as permethrin, 
deltamethrin, cyhalothrin or cypermethrin, lipid amides ("isobutylamides") 
and bicyclooctanes. 
The total proportion of pesticide in the formulation will depend upon the 
pesticide(s) in question and the use to which the formulation is being 
put, but is generally between 0.001 and 90%, typically between 0.01 and 
90%, preferably (in the case of permethrin) 10 to 50%, conveniently 
20-40%. In the case of other pesticides, these amounts may be varied to 
suit the potency of the pesticide. For example, deltamethrin or 
cypermethrin might be used at 1 to 10%, conveniently 2 to 4%. Other 
excipients known in the art may also be used, for example diluents, 
carriers, dyes, lubricants, stabilisers, surfactants and, in particular, 
synergists such as piperonyl butoxide. 
Formulations in accordance with the invention may be used against insect 
and acarine pests and are particularly suitable for coating surfaces such 
as wood, concrete, brickwood, paint, plaster or metal in order to provide 
a long-lasting residual action or for use in bait formulations. Surfaces 
in buildings may be treated to combat crawling insects such as cockroaches 
or ants, or flying insects, such as houseflies or mosquitoes, when they 
walk on the treated surface. Stored produce such as grain may also be 
treated. Animals such as cattle may be treated topically, for example 
sprayed, to combat biting and nuisance flies and also ticks. Formulations 
in accordance with the invention may be added to animal feed to combat 
insect larvae in the animal's dung. If the pesticide is active in the 
vapour phase, a sustained release of such vapour may be achieved to combat 
flying insects when they are flying. Crops may be treated with 
formulations of the inventions, as may stretches of water to kill larvae. 
The inclusion of non-encapsulated pesticide provides an immediate dose of 
such pesticide even before the encapsulated pesticide becomes available, 
and it has been found that careful control of specific insect populations 
can be more easily achieved. For example, a large initial dose of 
pesticide can be used to control, flush out or activate all or almost all 
of the active adult population of, say, a population of cockroaches, with 
a continued lower dose from the encapsulated material being provided 
thereafter to control immigration of adults and emergence of nymphs. 
Furthermore, two mutually incompatible pesicides may be included in the 
formulation: a less-stable non-encapsulated one, with a more stable 
encapsulated one, so that the non-encapsulated one will have been degraded 
or dispersed by the time that at least the bulk of the encapsulated 
pesticide emerges. A knock-down agent may be used as the non-encapsulated 
pesticide, with a kill agent inside the microcapsules. 
It has also been found that the presence of the pesticide outside the 
microcapsule stabilises the pesticide inside the capsule, and the capsule 
itself, particularly when the pesticides are the same, thus prolonging the 
active life of the encapsulated material. 
Formulations in accordance with the invention may take the form of dry 
granular matter or aqueous suspensions. Alternatively, a water-soluble 
wall material may be used in a non-aqueous solvent. The formulations may 
be packaged in any convenient way, for example in drums or sachets, and 
would normally be diluted before use. Conveniently, the (optionally 
diluted) formulation is sprayed onto the surface to be treated, to the 
point of "run off", by means of compression sprayers, hydraulic sprayers, 
mist blowers or the like.

The following non-limiting example illustrates a specific embodiment of the 
invention. 
EXAMPLE 1 
An oil-in-water encapsulation with a polyurea-polyamide skin represents 
production of a copolymer (strengthened by cross-linking) by interfacial 
polycondensation. Charges were prepared as follows: 
In flask: 
200 ml 0.5% aqueous "Elvanol 50-42" solution 
In 1st funnel: 
100 ml xylene 
15 ml toluene 2,4-diisocyanate 
2 ml trimesoyl trichloride (for cross-linking) 
120 g permethrin plus 50 ml "Solvesso 200" 
In 2nd funnel: 
10 g ethylenediamine 
5 g diethylenetriamine 
10 g sodium carbonate, monohydrate 
80 ml distilled water 
["Elvanol" (RTM) is a protective colloid comprising polyvinyl alcohol 
available from DuPont, Wilmington, Del.; "Solvesso 200" is a blend of 
aromatic hydrocarbons available from Exxon.] 
During the addition from the first funnel, which was rapidly effected, the 
mixture was strongly agitated to form visible droplets, the agitation 
being slowed down following completion of the first addition. Slow 
agitation was continued during the second, similarly rapid, addition. 
Contents were stirred for one hour and then filtered. Capsules of xylene 
were obtained, containing permethrin. 
The microcapsules were mixed with permethrin and "Etocas 29" surfactant (a 
castor oil derivative available from Croda Chemicals, Goole, UK) in water 
to give a 25% permethrin dilutable aqueous suspension having 20% 
permethrin inside the microcapsules and 5% outside. 
EXAMPLE 2 
The procedure of Example 1 was followed, except that the trimesoyl 
trichloride was omitted and toluene 2,6-diisocyanate was used 20/80 with 
the toluene 2,4-diisocyanate to give a total of 15 ml as before. A 
polyurea wall is thereby formed. To form an emulsifiable concentrate 
outside the capsules, a blend of 5% permethrin, 2-5% nonylphenol ethylene 
oxide condensates 2-5% calcium dodecyl benzene sulphonate and about 5% of 
"Solvesso 200" was made, the percentages, relating to the total 
formulation when the e.c. is added to the microcapsule preparation. 
EXAMPLE 3 
The procedure of Example 2 was followed, except that a wettable powder of 
deltamethrin, a diatomaceous earth and wetters was used as the 
non-encapsulated part; fenitrothion was used in place of the encapsulated 
permethrin; and the amount of isocyanate was increased to 25 ml to give a 
greater wall thickness. The final formulation had a total of 1% 
deltamethrin outside and 20% fenitrothion inside the microcapsules. 
BIOLOGICAL TEST 
The formulation of Example 1 was diluted with water 160.times. and sprayed 
onto male Blattella germanica. The time for knockdown of 50% of the 
insects (KT.sub.50) was 6.6 minutes, and all of the insects were dead 
after day 1.