Insecticides are commonly united with acaricides(for pathogenic mites),since they have same mode of action, so this group of pesticides called insectoacaricides.The term insecticide is used as short form of insectoacaricide like fungicides and herbicides, insecticides cause harmful effect on plants which cause losses in yield and decreased the yield quality(low the gluten contents).Combination of a non pyrethroid insecticide and a repellent are used against mosquito. The development of pyrethroid resistance in mosquito vector may reduce their personal use. Mixture of repellent(DEET) and non pyrethroid insecticide propoxur is widely used. Combination of propoxur and DEET create more mortality rate and knockdown effect than deltamethrin.Unfortunately the creation of pyrethroidgot resistance in most mosquito species in tropics. Knockdown resistance creates cross resistance to DDT and pyrethroids is now creating in mosquitoes.To reduce these problems for personal protection launch an alternative way to control them is the mixture of repellent(DEET) classic synthetic repellent and non-pyrethroid(propoxur) a carbamate insecticide which have low imitant properties and high insecticidal activity against insects. The mortality rate of Bora strain (96%) when treated with DEET –propoxur.The combination of propoxur (at LC30) and DEET (at sub lethal dose) showed more imitant properties than deltamethrin (at LC100) for both LHP and Bora mosquito strains. The physiologic process cause synergistic interaction between propoxur and DEET.The mode of action of carbamate is inhibition of acetylcholinesterase but DEET is not elucidated. Effect of DEET in insects is activate the receptor system control inappropriate behavior pattern, activate the noxious odor receptor, enhance attraction signal.DEET acts not only the disturb the attraction signal but also create a physiologic perturbation in mosquitoes.The mixture of propoxure and DEET increase the personal protection against kdr resistant mosquito and good control of pyrethroid resistance. Two new insecticides spinosad and imidacloprid with dimethoate for mortality and behavioral effect on Mexican fruitfly.Anastrephaludens mixed with sugar and yellow latex paint applied to the surface of fruit mimicking biodegradeable 7cm spheres made of sugar glycerin and flour. Flies feed on it. Flies that feed on imidacloprid or dimethoate cause high mortality rate and decrease in oviposition.If baited with odour biodegradable yellow spheres treated with surface coating of imidacloprid in latex paint and sugar could have potential for suppressing Mexican fruitfly on tree.Two other insecticides methomyl and indoxacarb on adult and pupae of whitefly. These caused low mortality on pupae while methomyl efficiency is high.It produced 100% mortality on adults with fresh and 24hr old residues on leaves more as compare to indoxacarb.The harmful effect of methomyl is persisted for long time up to 60 days.The insecticide oxamyl control population of whitefly without interaction between parasitoid and insecticide on whitefly mortality.Application of insecticides against shield backed bugs decrease plant growth,transportation of photosynthesis products,in grains gluten contents and yield quality.Combination of insecticides Albit reduce this effect and increase the gluten contents up to 1.2-4.6% as compare to others.Albit is used in combinations with insecticides against shield-backed bugs in EC stages 50-69.Albit combine with thiamethoxam based insecticide for Colorado beetle did not reduce the efficiency of insecticide.Application of combine insecticides may enhance the yield due to relieving insecticide’s toxic effect on plant. So due to only insecticide yield increase 10.6% but with the combination of Albit/insecticide yield increases up to 18.5%.Insecticides based on alpha-cypermethrin,deltamethrin and beta-cypermethrin used on winter and spring canola from coming up until initiation of flowering to control blossom beetle,cabbage white butterfly,cabbage moth,bugs,red turnip beetle,turnip sawfly cabbage stem flea beetle.Combination of Albit with these insecticides does not reduce the effectiveness of insecticide,instead it enhance the oil contents in seeds and also increase the yield. With the passage of time insect pests damage cereals crops more. It is not only the mechanical loss, insects(Swedish fly aphids of cereals) are carriers the viral diseases. The combination of Albit with lambda-cyhalothrin based insecticide on barley and spring wheat against flea beetles and leaf miners.Albit decrease the yield losses responsible for diseases, and it does not reduce the efficiency of insecticide. In wheat Albit reduce the yield losses up to 30% caused by diseases and pests and 32% in barley.This amount of reduction in losses become twice if pure Albit 16-18% is applied.
In pakistan the former use the combinaton of insecticide and weedicide in the field for killing the insect and weed for saveing the time and labour cost. The combination is mostly use for vegitable crop because the have a concept of equal plant height. Some shopkeeper also give the concept to former that the combination of insecticide and weedicide of same formulation is used for killing the insect and weed.But technically it is not recommended to former as a scientist behind that there are a lot of reason some are discous below.
The insecticide have different chemical composition and weedicide have different chemical composition when these are mix togather in the spraying tank for applying in the field these chemicals interact with each other and altered in the complex chemical composition which is not give the significant result and sometime it is demage to the whole crop.Sometime former use the combination of different formulated insecticide and weedicide for exemple insecticide which is use have a systemic mode of action and weedicide have a spread sticking formulation when these are combined (mix) and applied to crop the weed which have sticking formulation sticks on the leaf and not give the chance to systemic insecticide to penetrate in the leaf for action, so former facing the problem of insect and applying the extra dose of insecticide which is very expensive for former.
The application of both insecticide and weedicide is different, insecticide is applying at the top portion of plant for killing the insects while the weedicide is use at the bottom of plant near the soil surface because weed present at the bottom of the plant, so when combination is used it is not possible to appling properly at a time and if we use it at the same height crop then we facing the problem of changing of chemical composition.The time of applying fo insecticide and weedicide is also different.
After all, we recommend to the former the use of insecticide and weedicide seperately not in a combination.
Dr. Muhammad Anjum Aqueel1,3, Dr. RashadMukhtar Balal1,2, Dr. Muhammad Adnan Shahid1,2,Mohsin Perveez1and Hafiz Muhammad AsifRaza 1
1 University College of Agriculture, University of Sargodha, Pakistan;
2 Cornell University, NY, USA
3 Imperial College London, Silwood Park Campus, Ascot, SL5 7PY, U.K.