Sugarcane IPM

Robert L. Meagher
USDA-ARS
Insect Attractants, Behavior and Basic Biology Research Laboratory
Gainesville, FL 32604

Introduction

photo of a field of sugarcane
Figure 1: Sugarcane

This lecture on sugarcane integrated pest management is slanted towards sugarcane production and management of insect pests in the United States (US) (Fig. 1). Major insect pests of sugarcane in the US can be divided into two groups, the stemborers (Lepidoptera: Pyralidae) and soil pests (Coleoptera: Curculionidae, Elateridae, and Scarabaeidae). This lecture will concentrate on stemborer pest management and will provide examples of different strategies used in a long-season crop ecosystem.

The lecture is divided into several sections including US sugarcane production, a brief list of the insect pests present in the sugarcane agroecosystem, and examples of chemical control, biological control, plant resistance, and cultural control strategies practiced by the sugarcane industry against stemborers.

US Sugarcane Production

photo of a field of sugarcane burned prior to harvest
Figure 2.
Sugarcane burned prior to harvest

Sugarcane (interspecific hybrids of Saccharum) is originally from southeastern Asia, possibly New Guinea, and was brought to the Western Hemisphere by Columbus. Commercial sugarcane production in the United States occurs in Florida, Hawaii, Louisiana, Texas, and Puerto Rico. Table 1 shows cane yield (tons cane/acre), sugar yield (tons sugar/acre) and sugar recovery rate for the areas that commercially produce sugarcane. Production practices differ, with mainland sugarcane harvested annually and Hawaiian sugarcane harvested on a two year cycle. All mainland sugarcane is harvested using machine harvesters, while both Hawaii and Puerto Rico use some manual labor. In many areas, sugarcane fields are burned before harvest to remove trash and debris (Fig. 2). Sugarcane fields may be ratooned, or regrown, for several years before replanting.

Table 1. Commercial sugarcane production in the United States and Puerto Rico



State/Territory

Area harvested (acres)

Number of mills

Tons cane/acre

Tons sugar/acre

Sugar recovery rate (%)

Florida

433,000

7

34.5

4.16

12.05

Hawaii

43,000

6

86.7

10.65

12.28

Louisiana

358,000

19

22.7

2.52

11.09

Texas

41,000

1

31.8

3.18

9.99

Puerto Rico

26,000

6

19.2

1.54

8.00

Adapted from USDA/ERS publication #SSSV20N2, June 1995; estimated production, 1995-1996.

Arthropod Pests

Worldwide, sugarcane as an agroecosystem contains many insect species, both in aerial (above ground) and subterranean (below ground) habitats. Important pest species that inhabit the above ground part of sugarcane are in the following orders and families: Lepidoptera (Pyralidae, Noctuidae, and Castniidae), Homoptera (Aphididae, Cercopidae, Coccidae, Delphacidae, Diaspididae, and Pseudococcidae), and Orthoptera (Acridoidea). Soil sugarcane insect pests are represented by Coleoptera (Curculionidae, Elateridae, and Scarabaeidae), Isoptera (Mastotermitidae, Rhinotermitidae, and Termitidae), Hymenoptera (Formicidae), Diptera (Stratiomyidae), Heteroptera (Cicadidae, Cydnidae, Margarodidae, and Pseudococcidae), and Orthoptera (Gryllidae and Gryllotalpidae). Readers are encouraged to refer to Williams et al. (1969) and Meagher et al. (1993) for a more thorough discussion of sugarcane pests.

Stemborer Life History and Management

photo of stem borer moths
Figure 3. Stem borers, Diatraea saccharalis (larger moths) and Eoreuma loftini

The remainder of my discussion will be focused on the life history and pest management of stemborers in sugarcane. Stemborers (Pyralidae and Noctuidae) are pests in all sugarcane growing regions of the world. Management of these pests involves many different strategies, and interested readers should further investigate research not described in this lecture. Most of my discussion will be based on two pyralids found in the US [Fig. 3, adult Diatraea saccharalis (larger moths) and Eoreuma loftini].

photo of a mature larva of the Mexican rice borer
Figure 4. Mature larva of the Mexican rice borer

The life history of sugarcane stemborers can be generalized as follows (Smith et al. 1993). Adult moths oviposit on plant leaves, stems, or cryptically in dried leaves. Eggs may be laid singly or in masses, and early instar larvae feed cryptically on leaves, whorls, or other succulent plant tissue. Older larvae (generally third instar and older) feed almost exclusively within tunnels in stems, making management by contact insecticides difficult. Tunnels within stems may be aligned vertically or horizontally, and may extend across more than one internode (Fig. 4, mature E. loftini). Some stemborers maintain clean tunnels, removing frass and debris, while others keep their tunnels filled with frass. The physical condition of stemborer tunnels has implications for natural enemy selection in biological control programs, as some parasitoids enter the tunnels to attack larvae. Pupation occurs within chambers constructed by mature larvae, often leaving an "emergence window". This structure is a thin layer of plant tissue that can be pushed open to allow the adult moth to emerge from the stem.

Sampling and Thresholds

Historical perspective

Few studies have undertaken the task of sampling for stemborer eggs and larvae. Studies conducted in the Caribbean and in Florida have shown that stemboring pyralid larvae have random or aggregated spatial patterns, depending on sample size used and field size.. Most sampling for stemborers in sugarcane involves looking for injury such as leaf feeding and tunneling within the stem.

Recent research

Sampling studies for Mexican rice borer larvae and pupae were conducted in Texas sugarcane (Meagher et al. 1996a). Population density never exceeded 1.0 larvae per stem. Ratoon fields averaged more larvae per stem than plant cane fields. There was more stem-to-stem and field-to-field variation in larval dispersion than among subdivisions within fields.

Most sampling of Mexican rice borer larvae for management decisions has documented percentage bored internodes (ratio of number of internodes with tunnels to total internodes present) as an indirect measure of larval density. However, currently there is no known relationship between larvae per stem and percentage bored internodes. This is important since the currently used action threshold for a chemical control program is 10% leaf sheath infestation by young larvae and is not correlated with an actual insect density.

Chemical Control

Historical perspective. The history of chemical use in US sugarcane production goes back to the early 1920's, when sodium fluosilicate, cryolite, and ryania were used against sugarcane borer in Louisiana. Control was usually achieved with weekly applications of these materials. Chlorinated hydrocarbons were first recommended for use in the late 1950's with the introduction of endrin. However, endrin only lasted a few years because of resistance development. The organophosphates and carbamates entered the market in the early 1960's when azinphosmethyl replaced endrin. Other organophosphate and carbamate insecticides such as monocrotophos and carbofuran were recommended through the 1960's and 1970's. Reduction in borer populations due to insecticide applications not always translated to an increase in sugar yield or quality, prompting a call for a better understanding of the relationship between sugarcane borer biology and the use of insecticides.

In Texas, modern sugarcane production began in 1972 and organophosphate insecticides, usually aerially applied, were used against sugarcane borer. These insecticides were moderately successful, producing a 60-80% reduction in bored internodes. Insecticidal suppression was the first tactic used against the Mexican rice borer, an immigrant to the lower Rio Grande Valley of Texas that was documented in 1980.

Recent research

Sugarcane plots that had weekly monocrotophos applications during different seasonal timings yielded increased sugarcane yield and quality and had reduced bored internode injury compared to untreated plots (Meagher et al. 1994). However, weekly applications exceed residue limitations and are illegal.

Studies with several insecticides, including monocrotophos and azinphosmethyl and the synthetic pyrethroid cyfluthrin, showed statistically significant reductions in percent bored internodes but rarely an increase in sugarcane yield or commercially recoverable sugar (Meagher et al. 1994). Currently, a low percentage of sugarcane acres in south Texas are sprayed with insecticides for stemborer control.

Biological Control

photo of a parasitoid asosciated with sugarcane stemborer pests

photo of a parasitoid asosciated with sugarcane stemborer pests
Figures 5 & 6.
Parasitoids associated with sugarcane stemborer pests

Historical perspective

Parasitoids - Workers have used parasitoids, predators, and nematodes as natural enemies against sugarcane pests for many years. The first parasitoid introduction in the US was the Cuban fly, Lixophaga diatraeae (Townsend) into Louisiana. This tachinid fly introduced from Cuba was released against sugarcane borer from during different intervals from1915 to the early 1970's. The Cuban fly was also released in Florida from the 1920's to the 1960's. Other parasitoids released included Alabagrus stigma (Brulle) [= Agathis stigmatera (Cresson)], introduced from Peru into Florida in the early 1930's and into Louisiana in the late 1940's and early 1950's, and had been known to be parasitizing Diatraea spp. in the Caribbean islands and South America since the 1920's (known as Microdus or Bassus stigmaterus. Other parasitoid species released in Louisiana after the original introductions included tachinids, braconids, and scelionids. Some of the above species have become established in Louisiana and Florida, but none have provided consistent stemborer population suppression.

The first non-neotropical parasitoid released in the continental US was Cotesia (= Apanteles) flavipes (Cameron). This gregarious, larval endoparasitoid native to southeast Asia was released in Florida in 1963. Recoveries were made shortly after release, but C. flavipes was not recovered the following year. C. flavipes was released and established in Texas against sugarcane borer in 1977 (Fuchs et al. 1979) and has been successful at reducing sugarcane borer populations ever since (Meagher et al., unpublished data).

The biological control program in Texas for Mexican rice borer has been extensive and has relied heavily on collection, rearing, and release of exotic natural enemies. From the period 1981-1988, 50 parasitoid species representing 12 families were imported into the quarantine facility at Texas A&M University. Over 4.6 million individuals in 15 species were released in the lower Rio Grande Valley. Eight species were recovered in at least one year, and two species were recovered in four or more years.

Recent research

Laboratory studies have investigated several features of the sugarcane borer -- C. flavipes relationship (Wiedenmann et al. 1992). Parasitoids had low attack rates, and a percentage of hosts attacked either encapsulated parasitoids or died without parasitoid progeny being produced. These results are most likely due to the new association between Old World parasitoid and New World host. Cotesia chilonis (Matsumura), a congeneric species from Japan, was compared in laboratory studies with three C. flavipes cultures to determine rates of parasitization and host encapsulation (Wiedenmann & Smith 1995). C. chilonis parasitized more hosts and was encapsulated in fewer instances that C. flavipes.

Because of a severe freeze in 1989 (a low of 15F in December), a rearing and release program for C. flavipes was initiated in 1990 that continued through 1995. C. flavipes continues to be collected from sugarcane borer larvae (Meagher et al. unpublished data).

Previous to the severe 1989 freeze, five exotic species were released against Mexican rice borer. Three species, Allorhogas pyralophagus Marsh, Macrocentrus prolificus Wharton, and Lydella jalisco Woodley, were recovered. The Jalisco fly (L. jalisco ) (Fig. 5), was collected in Ameca, Jalisco, Mexico, and rearing procedures were developed at Texas A&M (Rodriguez-del-Bosque & Smith 1996). Although initially recovered in 1989, it hasn't been recovered in recent collections (Meagher et al., unpublished data).

Since the freeze, four species are being recovered from Mexican rice borer larvae: the native species Chelonus sonorensis Cameron and Digonogastra solitaria Wharton & Quicke (Fig. 6), and the exotic species A. stigma and A. pyralophagus (Meagher et al., unpublished data). A. stigma was collected from Diatraea spp. and imported from Bolivia; A. pyralophagus was collected from E. loftini in western Mexico. Results of recent surveys have suggested that parasitism from these four species has increased (from a low of 5.6% in 1992 to over 15% in 1994), and collection of A. stigma has also increased (now over 10% of parasites collected) (Meagher et al., unpublished data).

Predators - Comparatively fewer studies have been completed determining the importance of predators in suppressing stemborer populations. In Louisiana, research results in the 1960's documented the interaction between soil insecticides, predator abundance, and sugarcane borer damage. Predator groups found to be feeding on different life stages included Formicidae, Carabidae, Forficulidae, Elateridae, Chrysopidae, and Araneae. Ecological research in the early 1980's focused on the influence of weedy habitats and foraging activity of red imported fire ant, Solenopsis invicta Buren. More extensive research documented the actual reduction in bored internodes that can be contributed by predators. In a multi-tactic management experiment where insecticidal control, varietal resistance, and predation were compared, predation due to S. invicta was shown to contribute 15.7% towards control (Bessin et al. 1990). Overwintering populations of sugarcane borer were also shown to be negatively affected by predators.

Plant Resistance

Historical perspective

Plant resistance has been an important management strategy in most sugarcane-growing regions around the world against stemboring pyralids (Mathes & Charpentier 1969). In Louisiana, plant resistance has been a component of the sugarcane IPM program against sugarcane borer for many years and has been a successful management strategy when used alone or in combination with other strategies (Bessin et al. 1990).

In Texas, the relative susceptibility of sugarcane progenitors and clones to stem injury by Mexican rice borer has been measured in field studies under natural infestation conditions. Results suggested large variability in bored internodes among progenitors such as Miscanthus floridulus (Labill) Warb., Erianthus bengalense (Retz.) Bharadw., E. trinii (Hack.), Saccharum spontaneum L., and S. officinarum L. Screening of commercial (cultivars) and noncommercial sugarcane clones showed variability in E. loftini injury (Pfannenstiel & Meagher 1991). Field evaluation of sugarcane germplasm for internodes bored by E. loftini has continued since 1989 (R.L.M. unpublished data).

Many researchers have tried to determine the factors and mechanisms of sugarcane resistance. Ovipositional resistance has been deemed not to be responsible for lower stemborer populations in sugarcane, but recently characters such as leaf pubescence was shown to confer resistance against sugarcane borer.

Larval resistance can be separated into "leaf" and "stem" components. Neonate and young larvae must be able to become established within the leaves, midribs, and leaf sheaths and obtain sufficient nutrients before entering stems. The lack of foliar establishment and mortality of neonate larvae has been described as a major factor of resistance, with leaf sheath appression, the ability of a plant to self-trash (shed lower leaves and leaf sheaths), and leaf midrib hardness documented as specific resistant characters. However, larval foliar establishment among cultivars as a resistance factor becomes important only if these differences persist until stems are invaded; if over longer periods of development, the final level of infestation is independent of initial numbers, then differences among cultivars in establishment are not important.

Stem resistance of sugarcane involves the ability of larvae to enter and become established, tunnel within the stem, and gain enough nutrition to complete development and emerge as a mature, fecund, adult. Several factors have been implicated in stem resistance, although strong correlations between a factor and resistance haven't been documented. Individual characters mentioned in conferring resistance include rind hardness, stem diameter, and physical attributes of the interior part of the stem.

Tolerance has been suggested as a resistance mechanism in the sugarcane - sugarcane borer crop system, a conclusion based on genotypes possessing high levels of injury such as bored internodes, but low levels of damage such as dead tops, adventitious shoots, secondary tillering, and cane weight loss (White 1993). Overall, breeding of sugarcane for resistance to stemborers is difficult because of hereditary characteristics of the plant and limited knowledge of specific resistant characters.

Recent research

Studies with Mexican rice borer confirm that several mechanisms of stemborer resistance, including antibiosis and nonpreference, are present across sugarcane genotypes (Meagher et al. 1996b). Larval antibiosis results of diet incorporation bioassays suggest the presence of antinutritional components or allelochemicals in some genotypes. Larvae and pupae that developed on the commercial cultivar 'NCo310' were heavier and took fewer days to develop than larvae placed on other cultivars.

Differences in adult oviposition among genotypes in laboratory, greenhouse, and field studies were slight: therefore ovipositional prefernce is probably not important in confering resistance with this pest.

Laboratory experiments indicated that differences in larval establishment could be an important resistance character. Mexican rice borer larvae showed preferences for establishment in certain genotypes, and it appears larval preference may be locationally directed among different leaf sheaths within a stem (Meagher et al. 1996b).

Cultural Control

Sugarcane stemborers appear to more severely damage stressed plants than unstressed plants. Whether this relationship is due to higher larval densities on stressed plants or the degradation of natural plant tolerance, is not known. Agronomic practices such as good plant growth management through appropriate fertilization and irrigation schedules are an obvious advantage towards improved stemborer management.

Another cultural control technique that has sparked interest is the use of pheromones for mating disruption. In Texas, the pheromone for Mexican rice borer was identified and studies were initially conducted to use it as a monitoring tool. Continued research has made available the potential use of pheromone in reducing borer populations by mating disruption (Shaver & Brown 1993). This technique is designed to permeate the area with pheromone so that males are unable to locate and mate with females. Mating disruption has had some success in the cotton and tree fruit agroecosystems.

References Cited

  • Bessin, R. T., E. B. Moser & T. E. Reagan. 1990. Integration of control tactics for management of the sugarcane borer (Lepidoptera: Pyralidae) in Louisiana sugarcane. J. Econ. Entomol. 83: 1563-1569.
  • Fuchs, T. W., F. R. Huffman & J. W. Smith, Jr. 1979. Introduction and establishment of Apanteles flavipes (Hym.: Braconidae) on Diatraea saccharalis (Lep.: Pyralidae) in Texas. Entomophaga 24: 109-114.
  • Mathes, R. & L. J. Charpentier. 1969. Varietal resistance in sugar cane to stalk moth borers, pp. 175-188. In J. R. Williams, J. R. Metcalfe, R. W. Mungomery & R. Mathes [eds.], Pests of Sugar Cane. Elsevier, New York.
  • Meagher, R. L., Jr., J. W. Smith, Jr. & K.J.R. Johnson. 1994. Insecticidal management of Eoreuma loftini (Lepidoptera: Pyralidae) on Texas sugarcane: a critical review. J. Econ. Entomol. 87: 1332-1344.
  • Meagher, R. L., Jr., L. T. Wilson & R. S. Pfannenstiel. 1996a. Sampling Eoreuma loftini (Lepidoptera: Pyralidae) on Texas sugarcane. Environ. Entomol. 25: (in press).
  • Meagher, R. L., Jr., J. E. Irvine, R. G. Breene, R. S. Pfannenstiel & M. Gallo-Meagher. 1996b. Resistance mechanisms of sugarcane to Mexican rice borer (Lepidoptera: Pyralidae). J. Econ. Entomol. 89: (in press).
  • Rodriguez-del-Bosque, L. A. & J. W. Smith, Jr. 1996. Rearing and biology of Lydella jalisco (Diptera: Tachinidae), a parasite of Eoreuma loftini (Lepidoptera: Pyralidae) from Mexico. Ann. Entomol. Soc. Am. 89: 88-95.
  • Shaver, T. N. & H. E. Brown. 1993. Evaluation of pheromone to disrupt mating of Eoreuma loftini (Lepidoptera: Pyralidae) in sugarcane. J. Econ. Entomol. 86: 377-381.
  • Smith, J. W., Jr., R. N. Wiedenmann & W. A. Overholt. 1993. Parasites of lepidopteran stemborers of tropical gramineous plants. ICIPE Science, Nairobi, Kenya.
  • White, W. H. 1993. Cluster analysis for assessing sugarcane borer resistance in sugarcane line trials. Field Crops Res. 33: 159-168.
  • Wiedenmann, R. N. & J. W. Smith, Jr. 1995. Parasitization of Diatraea saccharalis (Lepidoptera: Pyralidae) by Cotesia chilonis and C. flavipes (Hymenoptera: Braconidae). Environ. Entomol. 24: 950-961.
  • Wiedenmann, R. N., J. W. Smith, Jr. & P. O. Darnell. 1992. Laboratory rearing and biology of the parasite Cotesia flavipes (Hymenoptera: Braconidae) using Diatraea saccharalis (Lepidoptera: Pyralidae) as a host. Environ. Entomol. 21: 1160-1167.
  • Williams, J. R., J. R. Metcalfe, R. W. Mungomery & R. Mathes [eds.]. 1969. Pests of Sugar Cane. Elsevier. Amsterdam.