Use of pheromone technology- some advice:Pheromoneresorces

Use of pheromone technology- some advice

Pheromone has been in use in India over 25 years as a monitoring tool under All India Coordinating programme for some of the crops likes cotton, groundnut and pigeon pea.  The monitoring technology is well knitted in about dozen centers in these crops.  The monitoring helps in developing forewarning systems and plan management strategies.  Unfortunately, as such efforts have not been made even at research station, the farmers are not convinced about practical utility of pheromone technology.  Some farmers use pheromone traps especially in cotton and pigeon pea eco system, as a mass-trapping tool. Surprisingly, in a recent study at the NRCG; a maximum of 1470 males/day/trap in case of Spodoptera litura was recorded showing its potentiality for mass trapping.

Even after its introduction about 25 years ago, pheromone technology in Indian Agriculture is still in its infancy. This may be attributed to defects in manufacture of the lures and traps, difficulties in installation of traps at farmers level and insect related issues.  An analysis of these issues has been made and suggestions are given to overcome the same. Then only there be actual fillip to the novel, eco-friendly pheromone technology in Indian agriculture.  

1. Defects in manufacture

v  Poor quality rubber band which is tied around the neck of the trap, can’t stand for a month time in the field condition allowing plastic sleeve to fall apart

v  Poor quality rubber band tied to bottom of the sleeve, which  escape of  trapped insects

v  The improper fixed trap tilting on one side allowing visiting insects to escape

v  Most of the available trap in the market do not have handle, so that it can be tied with single stick, warranting two pieces of stick tied to a  “t” shaped two pieces bamboo sticks

v  Poor quality dispensers (lures or delivery system) allowing quick decimation of the pheromone lasting for a week or two

v  Optimization of the gap between the lure and the mouth (clearance space), to avoid of the trapped insect

v  Improper pheromone impregnation in the lure   

v  The traps should be designed to either by using talc powder inside or tapering towards the end so that the trapped males cannot escape

v   Poor quality plastic sleeve which if run for one month becoming brittle and tear off allowing escape of the trapped males

v  Different species requires a definite type of trap

For example: Pyrallids (eg.,sugarcane borer like Early shoot borer, inter-node borer etc) is trapped in water trap only (David et al., 1985; Dr.Mukunthan and Dr. Easwaramoorthi, 2002, Sugarcnae Breeding Institute, Coimbatore- personnal communication).

Noctuids (eg., gram pod borer, tobacco caterpillar ) are efficiently trapped in sleeve trap, while Gelechidae ( groundnut leaf miner, cottom pink bollworm) are trapped in  sticky trap (Nandagopal and Soni,1993).

2. Installation of the trap and fixing of lure related issues

v  The fixing of the lures in traps are to be straight, not in  tilting position

v  The bottom of the sleeve are to be  tied with the stick

v  Very thin or damaged bamboo sticks  can not sustain the mass of trap leading to tilting of trap and thus escape of the insects attracted.

v  Farmers can not afford to store the lures in the deep fridge and lure stored openly last for a few days only, hence, community based approach wherein the  village panchayat can arrange facilities for storing the lures

3.        Insects related issues:

3.1 Pheromone specificity

Usually it is said that pheromones are speices specific, but actually it is not so for all the species. There are many components which share other insects

v  (Z)-11-Hexadecenyl acetate (Konyukhov et al.(1983) and  Nesbitt et al.(1979,1980)-Helicoverpa armigera )      

287 other species use this chemical for communication (El-Sayed,A.M.2015. ThePherobase: Database of pheromones and semiochemicals .http: //www. Pherobase)

v  Cis-8-Dodecenyl acetate attract 40 insect species (Kydonieus and Beroza, 1982)

v  Is amyl Acetate- Shares two order 1) Hymenoptera—Aphis mellifera

     2) Lepidoptera—Manduca sexta

v  Cis-14-methyle.8.hexadecenal- is shared by  many Trogoderma species

v  Cis-9, trans-12-Tetra Decadienyl acetate- Shares two different genus

1) Pyralidae—Plodia interpunctella

2) Noctuidae--Spodoptera litura

The sub-species of the main species of the sugarcane inter-node borer  shares the same pheromone. The species  Chilo sacchariphagus  is a insect of West Indies, Trinidad and Cuba etc, while the sub-species Chilo sacchariphagus indicus  is occurring in India (David et al., 1981;David et al., 1985; Brinda F. Nesbitt et all., 1986).

The pheromone components for both the species and the sub-species are  having the same two components

                        1. (Z)-13-Octadecanyl acetate 

                        2. (Z)-13-Octadecenol

3.2 Variation in pheromone blend attraction among insect

Variability in attraction for same species across the location

The ratio of blend of pheromone compounds for same species may vary for biotype, The species of Adoxophyes orana and Clepsis spectrans  in the Netherland share the two compound and (Z)-9 and (Z)-11-Tetra decanyle acetate in 9:1 and 1:3 ratio, respectively.  The biotype Ostrinia nubilalis  in Iowa, Z/E-tetradecanyle acetate is used in the ratio of 97:3 (Klun and Bindley, 1970) where as in  New york a ratio of 4:94 is morfe effective (Kochousky et al.,1975) Interestingly in Pennsylvania, both 97:3 and 2:98 ratio blends (Carde,et al., 1975).

Two sympatric species, Helicoverpa armigera and Helicoverpa assulta, use (Z)-11-hexadecenal (Z11–16: Ald) and (Z)-9-hexadecenal (Z9–16: Ald) as essential sex pheromone components but in very different ratios, 97:3 and 7:93 respectively (Wu et al.,2013).\

In India similar observation in relation to groundnut leaf miner Aproaerema modicella has been recorded.

In Tindivaram, Tamil Nadu one component (Z) - 7 - decanyl acetate or a blend of   (Z) - 7,9- decadienyl acetate (1),  (E) - 7 - decanyl acetate (2),  (Z) - 7 - decanyl acetate(3) in the ratio of 10:2:1.4 were equally effective against GLM (Hall et al., 1993). However, at Junagadh either the complete blend of the pheromone or either (Z) - 7 or (E) - 7 - decanyl acetate in combination with  with (Z) - 7,9- decadienyl acetate was only found to be effective. Similar result were also obtained in Hyderabad, A.P. excepting that (E) 9 and (Z) 7,9 combination was not so effective.

3.3 One or two related components of the blends may be attractive to the other species

eg. (our unpublished work).

Helicoverpa armigera pheromone lures attracting the pink boll worm Pectiniphora  and gossypiella

Lure: Helicoverpa armigera

Moth catch:

Components of  Helicoverpa armigera: 1 to 34 males /trap/days

1. (Z) –11-hexadecenyl acetate

2. (Z)-9- hexadecenal

Components of  Pectiniphora gossypiella: 1 to 19 males /trap/days

1. (Z,Z)-7,11-hexadecadienyl acetate

2. (E,Z)-7,11-hexadecadienyl acetate

Suggestions for improvement of the pheromone technology

For scientists:

v  There should be thorough experimentation on the trap designs to be used for various species of insects as they differ in their trapability

v  Proper ratios of the various components of the pheromone for various agro-climatic zone for a particulars species should be examined

v  There should be experimentation on the use of a particular components for more than one species  of the insects so that the multiplicity of the traps in a unit of  multi-cropping system  can be avoided

v  Durability of the traps/ sleeves and delivery system of the pheromones should be evaluated thoroughly before recommendation to large scale manufacturing by the industries

v  There should be development of standard trapping system for each insect encompassing trapability distance, trap density/unit area, minimum load of the pheromone components, placement of the trap, longevity of the lures and traps

v  The correct dispenser system should for each of the insects should be devised

v  Experimentation on the minimum distance between any two traps should be found out to minimise the number of traps to be used per unit area to avoid cost escalation

For Industries:

v  Proper quality of the materials for the manufacturing the traps should be used for using longer period in the field conditions

v  Proper fixing facilities should be provided in the trap itself so that the farmers can use it properly; Inverted ‘L” handle would be more suitable to tie the trap in a single bamboo stick, instead of ‘T’ shaped bamboo stick

v  High purity of the pheromone components should be used for actual blend of the pheromone (above 97%)

v  Proper quantity of the pheromone should be loaded in to the delivery system

v  The  cost factor is very important for the resources  poor farmers, so all the possible ways should be  found out to re3duce the cost of pheromone use

v  Supply of the pheromone traps and lures should be nearest to the farmers reach

v  Instructions with flow pictures for  proper installation of the traps and lures should be supplied along with the pheromone traps

For extension agency:

v  There should be regular training for the extension agencies on the installation and the methods adopted on the monitoring, mass trapping and communication disruption of the insects using the pheromones

v  The extension agency should explain the farmers about the proper instillations of the traps and the actual number of traps /unit area

v  Proper advise to farmers on the timing of use of the pheromone is necessary

For farmers:

v  Fresh lures should be purchased every time and lures should not be kept in room temperature, instead, if there is facilities like refrigerators, lures in a plastic bag should be kept in side the deep fridge

v  Install the actual number of traps to be used per unite area

v  The traps should be installed upright, so that the lure is in correct position and not likely to fall due to wind

v  The tying of the sleeve both at the top and at the bottom should be proper to avoid opening of the sleeve and escape of the trapped  insects

v  Do not allow the trapped insects inside the sleeve for many days as it may facilitate for slow movement and escape of few of the insects

v  At least once in a week the trap should be monitored for insects and if found, they should be killed by crushing inside the sleeve itself or  by opening the bottom of the sleeve and  killing  insects and can be removed from sleeve/trap

v   Use strong sticks so that it can withstand the weight of the moths trapped and the strong winds

v  While moving inside the field, see that any trap is loosened from its position and sleeve is detached, if found it should be rectified

v  If the crop is nearing harvest collect the traps carefully with out damaging  the fittings and the sleeves and store them properly so that the same can be used for other pest where similar trap is recommended 

v  If the neibouring farmers  are also having crops harbouring the same species, should also be encouraged to go for pheromone trapping- community approach

v  Replace the lures at least once in 25 to 30 days.