• Topics: Agronomy | Insects in Sugarcane (Sugarcane Handbook) | Insects | Nuessly, Gregg Stephen | Gilbert, Robert A | Lentini, Richard S | Cherry, Ronald H | Individual Insect Biology

Miscellaneous Insect Pests of Florida Sugarcane ¹

The sugarcane insect pests discussed in this report are of occasional economic importance in Florida. Because they have not historically been as important as some pests such as the sugarcane borer (Diatraea saccharalis), they have received less research interest and less is known about them. However, growers should be aware of these pests because they have the potential of becoming a problem if conditions favor their reproduction and growth.

Sugarcane Lacebug

The sugarcane lacebug, Leptodictya tabida, was first discovered in Florida in 1990. Damage to sugarcane by this bug was initially noticed in Palm Beach county. This was also the first time the insect was found on sugarcane in the mainland U.S.

The adult lacebug is about 1/8" (3.5 mm) long, flat and light-brown or straw colored (Figure 1). The forewings are semi-transparent and finely laced or netlike. Five long, erect spines are present on the head. Nymphs are flat and whitish in color with many long branched, erect spines. Eggs are laid singly into leaf tissue usually on the underside of the leaves. The tip of the egg is left outside the leaf tissue but is covered with a protective cap secreted by the adult female. A generation of lacebugs, from egg to adult, may take 20 to 30 days, with 5 nymphal molts.

Figure 1. 

Sugarcane lacebug.

[Click thumbnail to enlarge.]

In an early survey, some sugarcane plants were infested by more than 100 adult and nymphal lacebugs per leaf. More than 75 eggs were observed on some leaves. Lacebug feeding resulted in light green or yellow speckles on leaves. Some varieties developed a red russetting from the middle to the tip of the leaf as the result of moderate infestations.

Based on the condition of plants in most sugarcane fields in Florida that were infested by lacebugs during July-September, 1990, damage appeared to be minor. However, some fields had damage to the upper and spindle leaves. The lacebug may have had an economic impact on these plants.

Varietal differences in lacebug resistance have been noted in Hawaii and Florida.

Egg parasitoids of Leptodictya tabida have been found in Costa Rica and Venezuela, but natural parasite populations have not been observed in Florida.

Yellow Sugarcane Aphid

The yellow sugarcane aphid, Sipha flava, is sometimes a noteworthy insect pest of sugarcane (Figure 2). Red spots soon appear at feeding sites on susceptible cultivars. Prolonged feeding results in yellow discoloration and premature leaf death.

Figure 2. 

Yellow sugarcane aphid.

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Heavy infestations can occur almost any time during the growing season but most frequently occur during the warmer months of the dry season. Aphid feeding leads to reduced growth and tillering and subsequent yield loss of sugarcane.

There are several mechanisms of sugarcane resistance to damage by the yellow sugarcane aphid. These mechanisms are variety dependent, and include tolerance and antibiotic effects on aphid development. Winged yellow sugarcane aphids usually restrict their primary colonization to susceptible cultivars. Florida susceptible cultivars include CP61-620, CP72-1210, CP72-2086, CP80-1827 and CP89-2143.

Red imported fire ants, predatory earwigs and many species of ladybird beetles exert some control over these aphids. Heavy rains are also important in dislodging and washing aphids from the plants.

Lesser Cornstalk Borer

The larva of the lesser cornstalk borer, Elasmopalpus lignosellus, is a slender brown worm with creamy white to bluish-green bands 3/4 to 1" long when full grown (Figure 3).

Figure 3. 

Lesser cornstalk borer.

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The larvae bore into young plants at or below the soil surface and usually cause a "dead-heart" similar to the sugarcane borer or wireworms. When they feed at or below the growing point, damage above the growing point appears as rows of holes in emerging leaves. The larvae construct a tubular burrow in the soil extending outward from the cane plant. The burrow consists of soil particles which the borer webs together with silk. The larva pupates in this burrow and transforms into a small moth. The presence of these silk tubes and/or a small circular entrance hole distinguishes deadhearts caused by lesser cornstalk borers from those caused by wireworms.

The life cycle of the lesser cornstalk borer ranges from 38 to 65 days. There is considerable overlapping of generations with no sharp seasonal breaks in populations, although infestations during late summer may be uncommon.

Most damage from this pest occurs to young plants during warm, dry periods. Ratoon cane usually recovers better from lesser cornstalk borer attack than young plant cane.

Although there are parasites of the lesser cornstalk borer, the protection given by the silk tube may make these inefficient as biological control agents.

Sugarcane Delphacid

The sugarcane delphacid, Perkinsiella saccharicida, is a sugarcane pest of Australian origin (Figure 4). It was first discovered in Florida during 1982. Surveys quickly revealed that the delphacid ranged throughout the Florida sugarcane production area. To date, little economic damage has been reported by the pest. However, if a rapid population expansion were to occur, there could be serious economic damage due to its feeding and reproductive activities.

Figure 4. 

Sugarcane delphacid.

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Females deposit eggs into leaf tissue. Two to twelve eggs are laid in a cluster on either side of the leaf, mainly along the midrib, leaf sheaths, and stalk internodes. The egg is 1.0 mm by 0.35 mm, elongate-cylindrical and slightly curved. The narrow end of the egg protrudes just above the surface of the leaf and is covered with a white waxy material secreted by the female.

A female can lay up to 300 eggs during her normal 30 day life span. The incubation period varies from 2-3 weeks. The newly hatched nymph is pale, wingless, and starts feeding shortly after hatching. The nymphal period has 5 instars and lasts approximately 32 days.

Damage is caused primarily by actions of the adults and nymphs feeding on the sap of the sugarcane plant. The feeding causes yellowing and/or reddening and desiccation of the leaves. Additional damage results from impaired photosynthesis caused by growth of a sooty mold on honeydew excreted by the insects. Finally, laceration of leaf tissue by the insect's saber-like ovipositor can cause reddening and desiccation of the leaves.

There are several natural enemies of sugarcane delphacids, including predators, parasitoids and pathogens.

Historically, the sugarcane delphacid has been more important as a vector of Fiji disease than as a problem by itself.

Sugarcane Spider Mites

Spider mites, primarily Oligonychus stickneyi, have been occasional pests of importance in Florida sugarcane since the 1970's (Figure 5). These mites live and feed on the undersides of leaves. They form fine webs in which eggs are laid and young nymphs develop. Leaves infested by mites often develop a red-russetting similar to that associated with lacebugs. Severe damage by spider mites can result in leaf death.

Figure 5. 

Spider mites.

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Spider mite infestations generally occur during March - June. The lower leaves of sugarcane are usually colonized first. Damage by spider mites may often be of little consequence. However, prolonged heavy infestations accompanied by extensive damage to the middle and upper leaves of young plants may reduce growth. Predaceous mites, a predaceous thrips, and rainfall help control spider mites.

Growers should look carefully for mites if they suspect an infestation - just because a substantial amount of mite damage is present does not mean mites are still present.

West Indian Cane Weevil

The West Indian cane weevil, Metamasius hemipterous, was first found infesting cane in Florida during 1994. Sometimes referred to as the "rotten cane stalk weevil," adult weevils (Figure 6) are usually attracted to sugarcane stalks that already have some sort of injury (e.g., damage by other insects or rats). However, the weevil may be attracted to some varieties such as CP85-1382 that have growth cracks but no other obvious abnormalities.

Figure 6. 

West Indian cane weevil.

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Eggs of the West Indian cane weevil are laid into sugarcane stalks through cracks or into tissue damaged by rats, insects, wind or mechanical implements. The white, legless larvae from these eggs feed in the stalk and grow to more than an inch in length. A fibrous pupal case is usually constructed within the infested plant, although pupal cases may sometimes be found on the ground around infested stalks. The entire life cycle from egg to adult may be completed in around 8 to 10 weeks, depending on temperature. The tunnels and damage by the weevil can be so extensive that stalks may break. General observations indicate the weevil can cause large yield reductions in varieties as susceptible as CP85-1382. Damaged stalks may be unfit for use as seed.

A pheromone trapping method exists for the adult weevils that may be useful for identifying when infestations of the pest begin to develop and, consequently, when emergency control measures might be imposed to limit infestations and damage. With respect to biological control, no parasites, predators or pathogens of the rotten cane weevil have yet been observed in Florida. Growing sugarcane varieties resistant to the weevil and limiting rat and insect damage are the key management tactics. Population levels of adult weevils in an area may be reduced using pheromone traps during the summer and fall, which might help limit infestations in sugarcane.

Diaprepes Root Weevil

The Diaprepes root weevil, Diaprepes abbreviatus, is invasive to Florida and is an important pest of sugarcane in Barbados and Puerto Rico. This insect is a root weevil native to the Caribbean and one of the most economically important pests there. It was first reported in Florida during the 1960s. Since then it has spread over a large area of central and southern Florida where it is damaging to citrus, ornamental plants, and some other crops. Until 2010, although found near Florida sugarcane, sugarcane damage has not been found. In 2010, damage in Florida sugarcane by this pest was first noted. Larvae are white and look like grubs, but have no legs. Larvae feed on roots and tunnel into the stool and below ground stalks. Damage is similar to grub damage being plants turning yellow, highly stunted, and lodging. We do not know if this damage was rare or a sign of more damage that may occur.

Sugarcane Rust Mite

The sugarcane rust mite, Abacarus sacchari (Actinedida: Eriophyidae), was discovered on sugarcane in Canal Point, FL in September 2007. Though first observed in Belle Glade, FL on sugarcane in 1983, it was originally identified as Abacarus officinari. Described from Asian specimens, A. sacchari has now been recorded from Africa, Australia, India, Costa Rica, Venezuela, Brazil and Florida.

Figure 7. 

Female Abacarus sacchari on undersurface of sugar cane leaf (low temperature SEM). Photo by Gary Bauchan, USDA-ARS, Beltsville, MD.

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All stages of the mite are oval-elongate tapering toward the end of the abdomen and have two pairs of legs. Waxy growths from the body vary by environment and plant host. These mites develop through egg, larval, and nymphal stages before reaching adulthood. Development is completed in less than 7 days. The mites can be found throughout the year, but reach elevated population levels only during the mid to late summer months when temperature and humidity are both elevated.

Feeding symptoms are variety specific and range from an orange to rusty reddish-brown to purple discoloration on the underside of leaves that was originally masked by an outbreak of orange rust, Puccinia kuehnii (Basidiomycota: Pucciniales). The orange symptom color is similar to that of orange rust, but the A. sacchari feeding symptom is more uniformly distributed over the leaves and does not result in the raised pustules characteristic of rust. Beyond the range in discoloration among varieties, symptoms can be restricted to the mid vein, leaf blade, or spread across the leaf surface by variety. Leaves damaged by mite feeding display reduced photosynthesis associated with reduced chlorophyll content, transpiration, and stomatal conductance, but elevated intercellular CO₂ concentrations. Studies are currently in progress to determine whether mite feeding affects yield through reduction of sugar or tonnage.

Figure 8. 

Sugarcane rust mite symptoms on variety CP89-2143. Photo by Gregg Nuessly, University of Florida.

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Selected References

Cherry, R., and G. Nuessly. 1992. Distribution and abundance of imported fire ants (Hymenoptera: Formicidae) in Florida sugarcane fields. Environ. Entomol. 21: 767-770.

Hall, D. 1988. Insects and mites associated with sugarcane in Florida. Florida Entomol. 71: 138-150.

Mannion, C., A. Hunsberger, J. Pena, and L. Osborne. 2003. Oviposition and larval survival of Diaprepes abbreviatus (Coleoptera: Curculionidae) on select host plants. Florida Entomol. 86: 165-173.

Sandhu, H., G. Nuessly, S. Webb, R. Cherry, and R. Gilbert. 2010. Temperature dependent development of Elasmopalpus lignosellus (Lepidoptera: Pyralidae) on sugarcane under laboratory conditions. Environ. Entomol. 39: 1012-1020.

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U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, Dean.

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