8 Questions to Ask Before Choosing an Insecticide

Choosing an insecticide is not just a technical step in crop protection—it’s a decision that can define the health of your field, the resistance patterns of your pests, and the overall sustainability of your farming practices. With the increase in pest adaptability and market pressure for residue-free produce, farmers must ask the right questions before picking up a canister or placing an order.

Below are eight essential questions every grower should ask to ensure they make an informed, strategic, and practical choice.

What pest are you targeting, and how does it feed?

The first step in selecting an insecticide is understanding the enemy. Not all pests behave the same, and neither should your control measures. Some pests, like aphids, thrips, and whiteflies, use piercing-sucking mouthparts to feed on plant sap, often from the underside of leaves. Others, like caterpillars and beetles, chew through foliage and stems, leaving visible damage.

These differences matter because the type of feeding determines how a pesticide should act. Sucking pests typically evade surface sprays and are best controlled with systemic or translaminar insecticides that penetrate leaf tissue. Chewing pests are more exposed, making contact insecticides more effective.

If your crop is suffering from multiple pests—especially small, sap-sucking species—a dual-mode solution becomes necessary. In such cases, a balanced product like Adama’s Sigalit is ideal. Farmers aiming to control complex populations early in the crop cycle may consider purchasing Adama Sigalit Insecticide as part of an integrated approach for more reliable coverage and extended protection.

Is the insecticide’s mode of action helping you manage resistance?

Insecticides have many modes of action. Others interfere with muscle contraction, inhibit energy generation, or disturb the neurological system. These are referred to as modes of action (MoA), and the Insecticide Resistance Action Committee (IRAC) assigns them group numbers.

Resistance arises when the same MoA is used over and over again in a season, or worse, over several years. The cycle is further accelerated by resistant bugs, which proliferate more quickly and necessitate greater dosages or more sprays. For this reason, it is crucial to rotate insecticides with various MoAs.

Usually, labels display the IRAC group number. If you previously used a Group 4A neonicotinoid, think about moving on to a Group 5 spinosyn or Group 28 diamide. Always look up the active component and method of action before purchasing a product.

For detailed planning, tools from IRAC are available at IRAC’s Mode of Action resource, where you can filter insecticides by group and match them with your pest spectrum.

Are you applying at the right time in the pest's lifecycle?

Timing is critical. An effective insecticide applied too early or too late may miss the pest entirely or only partially control it. Eggs and pupae are typically less affected than larvae and nymphs, which are actively feeding and vulnerable.

In cotton, for instance, jassids need to be controlled in the early vegetative phases to prevent their widespread proliferation. On the other hand, thrips peak during periods of high humidity and become harmful right before flowering.

Farmers should schedule applications based on observed thresholds rather than the calendar when using traps and routine scouting. Forecasts based on the weather are also beneficial, particularly for pests that increase in response to changes in temperature or humidity.

In addition to risking resistance development from repeated stress on a surviving pest population, failing to time your sprays correctly could double your costs without improving control.

How long will the insecticide remain effective—and how quickly will it act?

All insecticides do not act the same way. Some knock down pests within hours, offering fast relief. Others work slowly but protect new growth over time. Understanding both speed and duration helps align product choice with pest pressure.

Pyrethroids and other contact insecticides often provide quick control but offer no long-term protection. For concealed or protected pests like mealybugs and aphids, systemic treatments are essential because they travel through plant tissues, providing internal protection.

Quick action may be necessary if you're dealing with an unexpected infestation in high-value products, such as fruits or vegetables, that're almost ready for market. However, residual management is particularly crucial when dealing with a long-term threat that spans multiple crop stages.

Selecting a product without considering these characteristics may result in gaps in control or unnecessary reapplications, which can impact both profitability and pest resurgence.

Is the product selective, can it spare beneficial insects?

The rise of ecological farming and pollinator safety regulations has made selectivity a significant concern. While eliminating the target pest, some insecticides also affect non-target species, such as bees, parasitic wasps, ladybugs, and lacewings, which help naturally control pest populations.

Consider how a pesticide will affect beneficial organisms before selecting one. This is particularly important in crops like cucurbits, when pollinators are essential, or during flowering phases. Nowadays, some formulations are designed to minimise collateral effects by reducing contact toxicity or degrading more quickly in sunlight.

Appropriate scheduling might also lessen the impact. Foraging bees are less likely to be impacted when spraying is done early in the morning or after dusk. Non-target wildlife are further protected by implementing buffer zones and avoiding flowering plants during spraying times.

Preserving ecosystem helpers can eventually lessen your dependency on chemicals and is a long-term investment in field stability, as explained by CABI's beneficial insect portal.

Will the insecticide actually reach the pest?

Placement is just as important as product. Many pests hide under leaves, within crevices, or on new shoots—areas hard to reach with broad spray coverage. Others are located at ground level or within the root zone.

Determine where your pest resides, then adjust the way your insecticide is applied to suit its behaviour. The thrips that hide behind the foliage waste a contact spray. In a similar vein, airborne pests cannot be controlled by soil-applied insecticides unless they are systemic.

Targeting protected pests requires translaminar and systemic solutions that penetrate vascular tissues or leaf layers. Several factors, including water pH, spray pressure, and nozzle type can influence the ability of an insecticide to distribute and adhere to plant surfaces.

Poor application of an effective product is no better than utilising one that is ineffective. Here, accuracy avoids waste, missed targets, and uneven insect pressure decrease throughout your field.

Is it compatible with other products or inputs?

Insecticides are rarely used alone by farmers. They frequently mix them with growth regulators, micronutrients, or fungicides. However, combining compounds without first determining their compatibility can result in phytotoxicity or ineffective sprays.

Clumps, separation, or leaf burn are symptoms of chemical incompatibility. Before combining entire batches, always perform a small jar test. Observe the label's instructions about agitation and mixing order.

Water quality is another important consideration. Many insecticides can be broken down by alkaline (high pH) water before they even get to the crop. To maintain efficacy, a buffering agent may be necessary.

When done correctly, tank mixing can save time. If not, it results in decreased control, shortened shelf life, and even plant stress, which increases the crop's susceptibility to pests.

Does it make economic sense based on your crop and market?

An insecticide is an investment rather than a cost. However, not every crop is a good fit for every investment. For instance, applying a high-end pesticide on a crop that is close to harvest or has little market value could not be profitable.

However, in order to match customer expectations, high-value commodities like grapes, tomatoes, and brinjal require control and accuracy. Even a more costly product could be more economical in these situations if it guarantees quality and lowers rejection.

In addition to the price per litre, farmers also need to figure out the cost per hectare and the possible loss avoided. The actual return on pesticide investment is further impacted by external factors, including labour expenses, the quantity of sprays, and the destination of the crop (local vs. export).

Compare value as well as price. Does the insecticide eliminate the need for a follow-up application? Does it stop the virus from spreading too soon? These elements quickly stack up in favour of the appropriate product.

FAQs

1. Can I rotate between different brands for resistance management?
   No. Rotation must be based on active ingredient or mode of action, not brand names. Always check IRAC group numbers on the label.

2. Are natural or organic insecticides better for long-term use?
   They can be useful for low pest pressure or sensitive crops but often require precise timing and higher frequency. They're best used as part of an integrated approach.

3. Is preventive spraying advisable?
   In virus-prone crops like tomato or chilli, preventive spraying against vectors (like whiteflies) may be necessary. Otherwise, rely on thresholds and scouting.

4. Do all systemic insecticides work the same?
   No. Some are root absorbed; others are foliar. Their speed and movement within the plant differ significantly.

5. How do I reduce residue in harvested produce?
   Follow pre-harvest intervals (PHIs) strictly and choose selective, short-residue products near harvest time.

Decision-Making Starts with Better Questions

Selecting an insecticide is never solely a product choice; time, biology, chemistry, ecology, and economics all play a role. You get closer to a solution that suits your particular circumstance with each inquiry you ask, which eliminates inappropriate possibilities.

Growers who ask the right questions, rather than those who use the most pesticides, get consistent outcomes in a world where pests, weather, and regulations are constantly changing. Apply these eight questions to your dealer interactions, farm planning, and field. They will help you manage pests in a more intelligent, secure, and lucrative manner.