Plant-based insecticides matrine and neemarin can be safely used alongside beneficial parasitoid wasps in integrated pest management programs, but only at lower concentrations. Research shows that at the highest dose tested (LC30), both insecticides reduced wasp lifespan by about 22% and egg production by 43-47%, but at lower doses (LC10 and LC20), they caused minimal harm to wasp populations.
Scientists tested two plant-based insecticides—matrine and neemarin—to see if they could work safely alongside a beneficial wasp that kills crop-damaging caterpillars. According to Gram Research analysis, both plant chemicals reduced how long the wasps lived and how many eggs they laid, especially at higher doses. The good news: at lower concentrations, these botanical insecticides caused only minor problems for the wasps. This research helps farmers choose safer pest control methods that don’t accidentally harm the helpful insects they rely on to protect their crops.
Key Statistics
A 2026 laboratory study published in Scientific Reports found that matrine and neemarin at high concentrations reduced parasitoid wasp lifespan from 18.35 days to 14.33-14.45 days, a reduction of approximately 22%.
According to research reviewed by Gram, both botanical insecticides decreased wasp egg production by 43-47% at the highest dose tested, dropping from 121 eggs per female to 64-69 eggs per female.
A 2026 study found that matrine and neemarin at low to medium concentrations (LC10 and LC20) had minimal adverse effects on parasitoid wasp population growth rates compared to untreated controls.
Research showed that neemarin at the highest concentration (LC30) reduced the intrinsic population growth rate of parasitoid wasps from 0.21 to 0.18 per day, while matrine maintained normal growth rates even at this dose.
The Quick Take
- What they studied: Whether two plant-based insecticides (matrine and neemarin) harm a beneficial wasp that farmers use to control crop-eating caterpillars
- Who participated: Laboratory experiments using caterpillar larvae treated with different doses of plant insecticides and exposed to parasitoid wasps
- Key finding: At low to medium doses, the plant insecticides had minimal impact on the wasps’ survival and reproduction. However, at the highest dose tested, the wasps lived shorter lives (14.3 days vs. 18.4 days in untreated controls) and produced fewer eggs (64-69 eggs instead of 121 eggs per female)
- What it means for you: If you’re a farmer using integrated pest management, these plant-based insecticides can work alongside beneficial wasps—but only if used at lower concentrations. Higher doses may backfire by harming the helpful insects you’re counting on
The Research Details
Researchers conducted controlled laboratory experiments to test how plant-based insecticides affect a beneficial wasp. They started with caterpillar larvae and exposed them to three different dose levels of matrine and neemarin—specifically the lowest dose that kills 10% of insects (LC10), 20% (LC20), and 30% (LC30). They then allowed parasitoid wasps to lay eggs in these treated caterpillars and tracked what happened to the next generation of wasps.
The scientists measured several important outcomes: how long the wasps lived, how many eggs each female produced, and population growth rates. These measurements help predict whether the wasp population can survive and thrive when exposed to the insecticides. The researchers compared all treated groups to untreated control caterpillars to see what difference the insecticides made.
This research approach is important because it tests real-world compatibility. Farmers don’t just care if an insecticide kills pests—they need to know if it will also kill the beneficial insects they use for pest control. By measuring multiple population parameters, the study reveals whether the wasps can still do their job effectively, even if the insecticides cause some harm.
This is a controlled laboratory study published in Scientific Reports, a reputable peer-reviewed journal. The researchers used standardized bioassay methods and measured multiple demographic parameters to provide a complete picture. However, laboratory results don’t always match real-world field conditions, where weather, natural predators, and other factors could change outcomes. The study focused on one parasitoid species and one pest, so results may not apply to other insect combinations.
What the Results Show
Both matrine and neemarin reduced how long the parasitoid wasps lived, particularly at the highest dose tested (LC30). Female wasps in the control group lived an average of 18.35 days, but those exposed to LC30 matrine lived only 14.33 days, and those exposed to LC30 neemarin lived 14.45 days—roughly a 22% reduction in lifespan.
Egg production dropped dramatically at high doses. Control females laid an average of 121.24 eggs each, but at LC30, matrine-exposed females produced only 68.57 eggs and neemarin-exposed females produced 63.75 eggs—a reduction of about 43-47%. This matters because fewer eggs mean fewer wasps in the next generation to control pests.
The good news: at lower concentrations (LC10 and LC20), the insecticides had minimal impact on the wasps’ ability to reproduce and grow their populations. Population growth rates remained similar to untreated controls at these lower doses. Only at the highest concentration (LC30) did neemarin significantly slow population growth.
The study found that matrine was slightly less damaging than neemarin at the highest dose. Matrine-treated wasps maintained normal population growth rates even at LC30, while neemarin at LC30 reduced the population growth rate from 0.21 to 0.18 per day. This suggests matrine might be the safer choice if farmers must use higher concentrations, though lower doses of either chemical are preferable.
This research aligns with previous findings showing that botanical insecticides generally have fewer harmful effects on beneficial insects than synthetic chemicals. However, this study demonstrates that ’natural’ doesn’t automatically mean ‘safe for all insects’—even plant-based compounds can harm helpful species at higher doses. The findings support the growing scientific consensus that integrated pest management requires careful dose selection to balance pest control with protection of beneficial insects.
The study was conducted entirely in laboratory conditions, which may not reflect what happens in actual farm fields where temperature, humidity, and other environmental factors vary. The researchers tested only one parasitoid wasp species and one pest caterpillar species, so results may not apply to other insect combinations. The study doesn’t specify the exact sample sizes used in each treatment group. Additionally, the research measured only immediate effects on the next generation of wasps; longer-term population effects over multiple generations weren’t assessed.
The Bottom Line
For farmers using integrated pest management: Use matrine and neemarin at low to medium concentrations (LC10 or LC20) when combining them with parasitoid wasps. Avoid the highest concentrations (LC30) if you’re relying on these beneficial wasps for pest control. Consider matrine as a slightly safer option than neemarin if higher doses become necessary. Confidence level: Moderate—based on controlled laboratory evidence, but field testing would strengthen these recommendations.
Farmers and agricultural professionals using integrated pest management to control Helicoverpa armigera (a major crop pest). Organic farmers seeking safer alternatives to synthetic pesticides. Pest management consultants designing spray programs. Anyone growing crops vulnerable to this caterpillar pest. This research is less relevant to home gardeners or those not using parasitoid wasps for pest control.
Effects on wasp populations would appear within one generation (approximately 2-3 weeks in laboratory conditions). In field conditions, visible impacts on pest control effectiveness might take 4-6 weeks to become apparent, as the wasp population adjusts to the insecticide exposure.
Frequently Asked Questions
Can I use plant-based insecticides if I’m relying on parasitoid wasps for pest control?
Yes, but with caution. Research shows matrine and neemarin at low to medium doses (LC10-LC20) have minimal impact on parasitoid wasps. However, at high concentrations (LC30), they reduce wasp lifespan by 22% and egg production by 43-47%, potentially compromising pest control effectiveness.
Which plant-based insecticide is safer for beneficial wasps—matrine or neemarin?
Matrine appears slightly safer. At the highest dose tested, matrine maintained normal wasp population growth rates, while neemarin reduced growth rates by 14%. Both are safe at lower concentrations, but matrine is preferable if higher doses become necessary.
How long does it take to see the effects of plant insecticides on wasp populations?
Laboratory studies show effects appear within one generation of wasps, approximately 2-3 weeks. In actual farm fields, visible impacts on pest control effectiveness may take 4-6 weeks to become apparent as wasp populations adjust to insecticide exposure.
Are botanical insecticides really safer than synthetic pesticides for beneficial insects?
Generally yes, but not automatically. This research demonstrates that plant-based insecticides like matrine and neemarin cause less harm to beneficial wasps than many synthetic chemicals, but they still cause damage at higher concentrations, requiring careful dose management.
What concentration of plant insecticide should I use if I’m using parasitoid wasps?
Use LC10 or LC20 concentrations for minimal impact on parasitoid wasps. Avoid LC30 (the highest dose tested) if you’re relying on these beneficial insects for pest control, as it significantly reduces wasp reproduction and lifespan.
Want to Apply This Research?
- Log spray applications with specific insecticide type, concentration level (LC10, LC20, or LC30), and date. Track pest caterpillar counts weekly for 6-8 weeks post-application to monitor whether pest populations remain controlled. Note any changes in beneficial wasp activity or abundance.
- If using botanical insecticides in an integrated pest management program, set a reminder to apply them at lower concentrations (LC10-LC20) rather than maximum recommended doses. Document which concentration level you’re using so you can correlate it with pest control success over time.
- Create a 6-week monitoring period after each insecticide application. Track: (1) pest caterpillar population counts, (2) visible parasitoid wasp activity, and (3) crop damage levels. Compare results between applications at different concentrations to identify the optimal dose that controls pests while preserving beneficial wasp populations.
This research describes laboratory findings on insecticide effects on parasitoid wasps and should not be considered personal medical or agricultural advice. Consult with a licensed pest management professional or agricultural extension agent before applying any insecticides to crops or gardens. Results from controlled laboratory studies may not reflect real-world field conditions. Always follow product label instructions and local regulations regarding pesticide use. Individual results may vary based on environmental conditions, crop type, and specific pest populations.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.