Sugarcane weevil management in Negros: lures and IPM

Weevils that bore into cane and banana pseudostems (Metamasius and the related banana weevil Cosmopolites) hollow out the plant from inside, where insecticide sprays struggle to reach them. Pheromone-baited bucket traps with cut cane are a monitoring and mass-trapping tool: they show where and when adults are active and remove some of them before they breed. For Negros cane growers and mixed smallholders, lure-based trapping is one part of a practical IPM program against these borers, alongside field sanitation and crop management.

Why are these weevils so hard to spray?

The damage happens out of sight. Adult weevils lay eggs at the base of the plant, and the larvae tunnel inside the stem or pseudostem, feeding in galleries that a contact insecticide cannot reach. By the time damage shows above ground, the borer is already protected inside the plant. Spraying the surface burns money and chemical while the population continues breeding internally.

Pheromone trapping sidesteps this. Instead of trying to reach larvae inside the stem, you target the adults using their own aggregation chemistry, removing breeding adults before they lay the next generation.

What has research measured for pheromone trapping?

A study of pheromone-based mass trapping of Cosmopolites sordidus and Metamasius hemipterus in commercial banana in Costa Rica (Alpizar et al. 2012) used a pheromone-baited pitfall trap for Cosmopolites and a pheromone-and-sugarcane-baited open gallon trap for Metamasius. Over 10 to 12 months, trap catches of both weevils fell by more than 75 percent, and corm damage in the trapping plots fell by 61 to 64 percent, mainly through trapping of the banana weevil Cosmopolites, which caused most of the corm damage. The study was run in banana, not sugarcane, so treat it as evidence for the method rather than a forecast for a Negros cane block.

In sugarcane, a study in a sugarcane plantation (Oehlschlager et al., 2002) compared bamboo traps baited with insecticide-laced sugarcane alone against the same traps with pheromone lures added: cane-only traps at 30 traps per hectare averaged 6 weevils per trap per week, against 66 per trap per week for pheromone-plus-cane traps at 5 traps per hectare. That is evidence that the pheromone lure greatly increases catches, not a measure of crop damage or yield.

The mechanism is the same exploit used against other plantation beetles: the pheromone makes the trap smell like an aggregation, and the cut cane adds a host-plant odour that confirms the site. Together they draw adults to the trap, where they can be counted and removed.

How do I run a trapping program in Negros cane?

The practical setup is straightforward and repeatable:

• Bait bucket traps with the aggregation-pheromone lure and pieces of fresh cut cane as the host attractant.
• Distribute traps across the field at a working density and replace the lure on schedule so release does not fade.
• Refresh the cut cane regularly, since it loses attractiveness as it dries.
• Empty traps and count the catch each week to track whether the population is trending down.
• Keep records by block so you can see which areas carry the heaviest pressure.

Why lures belong inside a full IPM program

Trapping is a monitoring and mass-trapping tool, not a stand-alone control, so use it alongside basic field hygiene. Weevils breed in crop residue and damaged stems, so cleaning up old cane, removing heavily infested stools, and managing residue reduces the breeding base that feeds the population. Combine trapping with sanitation and good crop management, and the weekly counts show whether the combined program is bringing numbers down. This combined approach, lure trapping plus sanitation, is the honest IPM position: no single tool eradicates the weevil, and the aim is to keep it below damaging levels.

Where does lure trapping fit?

Lure trapping fits Negros sugarcane under weevil pressure and mixed farms running banana alongside cane, where the related banana weevil is also a concern. For growers tired of spending on sprays that never reach the borer, a pheromone-and-cut-cane trapping program adds a measurable, lower-chemical component to IPM that you can monitor with simple weekly counts.

FAQ

Is trapping a replacement for spraying cane weevils?

No. Pheromone and cut-cane bucket traps are a monitoring and mass-trapping tool used within IPM. Sprays struggle to reach larvae inside the stem, and traps work on the adults instead, so growers use them alongside sanitation and their existing crop-protection program rather than as a stand-alone control.

What do I put in the trap?

The aggregation-pheromone lure plus fresh cut cane as a host attractant. Replace the lure on schedule and refresh the cut cane regularly, since dried cane loses its pull. Count the weekly catch to monitor the trend.

Do I still need other controls?

Yes. Trapping is one part of the program; pair it with sanitation: remove old cane, heavily infested stools, and residue that the weevils breed in. Trapping plus field hygiene is aimed at longer-term suppression rather than a one-off knockdown.

Build a weevil IPM program for your cane

Talk to us about weevil lure trapping and a sanitation routine for your Negros cane or mixed cane-and-banana farm. To get started, request a quote or message us on WhatsApp at +60 17-237 4058.

Sources

• Alpizar, D., Fallas, M., Oehlschlager, A.C. and Gonzalez, L.M. (2012). Management of Cosmopolites sordidus and Metamasius hemipterus in banana by pheromone-based mass trapping. Journal of Chemical Ecology 38(3): 245-252. https://doi.org/10.1007/s10886-012-0091-0
• Oehlschlager, A.C., Gonzalez, L., Gomez, M., Rodriguez, C. and Andrade, R. (2002). Pheromone-based trapping of West Indian sugarcane weevil in a sugarcane plantation. Journal of Chemical Ecology 28(8): 1653-1664. https://doi.org/10.1023/A:1019936831696