![](media/image1.png){width="0.75in"
height="0.5208333333333334in"}**U. S.  Department of Agriculture -
Agricultural Research Service**
![](media/image2.png){width="0.6979166666666666in"
height="0.5104166666666666in"}

**HISTORY AND IMPORTANCE OF DIAPREPES TO AGRICULTURE**

**IN THE CARIBBEAN REGION** 

[Stephen L.
Lapointe](../../../../../../../../C:%5Cfp%5Csti%5Clapointe%5Clapointe.html)\
Research Entomologist\
U. S. Horticultural Research Laboratory\
2001 South Rock Road\
Fort Pierce, FL 34945\
Telephone: (772) 462-5914\
Fax: (772) 462-5986\
E-mail:
[SLapointe@ushrl.ars.usda.gov](mailto:slapointe@ushrl.ars.usda.gov) 

The species *Diaprepes abbreviatus* was described by Carl Linnaeus as
*Curculio abbreviatus* in the tenth edition of his *Systema Naturae* in
1758 from specimens collected in the West Indies. Today, *D.
abbreviatus* is found on Puerto Rico and Hispaniola and in the Lesser
Antilles from Grenada and Barbados in the south to the Virgin Islands in
the north. Curiously, the species has not been reported from Trinidad
and Tobago nor from Jamaica (related weevils of the genera
*Exophthalmus* and *Pachnaeus* are serious pests of citrus in Jamaica).
Several species of *Diaprepes* have been described based on coloration
that have since been synonymized with *D. abbreviatus*. A questionable
species, *D. rohrii* is reported only from St. Croix, U.S. Virgin
Islands, while *D. abbreviatus* is apparently absent from that island.
*D. rohrii* may simply be another color morph of *D. abbreviatus*. By
1933, it was recognized that the various forms of Diaprepes found
throughout Hispaniola, Puerto Rico, and the Lesser Antilles were most
likely a single species, fundamentally similar both structurally and
behaviorally (Wolcott, 1933a). Puerto Rico is clearly the center of
diversity of *D. abbreviatus,* and seems the most likely center of
origin for the species because of the high degree of stable phenotypic
diversity on the island.

The Reverend N. B. Watson worked out the basic biological cycle of *D.
abbreviatus* in 1899 and 1900 on Barbados (Watson, 1903). He described
it as whitish with stripes and recalled playing with it as a youth,
thereby placing the weevil on Barbados as a common insect at least as
early as the later half of the 19^th^ century. He reported that it was
considered a minor pest until recent years but that since 1901 its
numbers had increased despite the fact that sugarcane has been
cultivated in the West Indies and Puerto Rico for close to 500 years.
Interestingly, Watson attributed the increase of Diaprepes to the
introduction of the mongoose for control of rats. Although the mongoose
failed to control its intended victims, apparently it was more effective
at destroying species of reptiles and birds that preyed on insects. *D.
abbreviatus* was a common insect on Barbados for many years prior to
1912 but only recorded as a pest of sugarcane in 1912 (Ballou, 1912). By
1921, *D. abbreviatus* was considered a serious pest of sugarcane on
Barbados and massive collection of adults by hand was recommended as a
control method (Bourne, 1921).

In 1900, Diaprepes was reported in large numbers in Puerto Rico
attacking guava and young coffee plants (Watson, 1903 citing Bulletin
No. 30, New Series of the U.S. Department of Agriculture, Division of
Entomolgy). In 1915, it was reported to be generally distributed over
the island of Puerto Rico (Jones, 1915) but causing particular damage to
sugarcane on the south coast. He noted that the *jobo* plant (*Spondias
lutea*, a species of Mombin in the Cashew Family, Anacardiaceae) was
preferred by adults. It was also noted at this time that the weevil was
found throughout the island of Puerto Rico, and that distinct phenotypes
occurred within defined geographic regions on the island. The
populations were marked by varying colors and patterns of stripes on the
elytra (wing covers). On Puerto Rico, western lowland populations of *D.
abbreviatus* tend to have whitish elytra. They are brownish in southern
and eastern lowlands including Culebra and Vieques. In the western
central mountains, there is a larger weevil often with yellow elytra and
an additional strip per elytron; in the eastern mountains, a smaller,
grayish, sometimes greenish variety prevails (Hantula et al., 1987). On
Barbados, Ballou (1912) described the weevil as pale-green with dark,
bronze stripes.

The variability of phenotypes was noted early on. Diaprepes adults are
largely black but covered with colored scales that range from ashy white
to dull orange to bright yellow. On the elytra, the length and number of
raised ridges devoid of scales varies between populations. On St. Lucia
and Puerto Rico, there is subspecific variation in color and elytral
ridges linked by intergrades. The genetic basis for this variation has
not been determined but may provide clues to the origin of Florida\'s
infestation(s).

By 1917, Hutson (1917) described the increasing importance of Diaprepes
root borer as a pest of sugar-cane, corn, limes, cotton, sweet potatoes,
onions, and ground nuts in the Caribbean. Again, he suggested collection
of adults and egg-masses as the best control method. On St. Kitts,
40,000 adults were collected in a short time in a cotton field during
April 1914. On Antigua, during the early part of 1916 some 70,000 adults
attacking limes were caught and destroyed on one estate.

From these reports and others, there is no indication of the possible
introduction of Diaprepes nor traces of possible spread from island to
island. Rather, the most parsimonious explanation of the origin of
Diaprepes is that it evolved in the Caribbean on the islands where it is
most numerous today. The greater diversity of color and elytral patterns
found on Puerto Rico argue in favor of Puerto Rico as the center of
origin although repeated genetic exchange between island populations in
recent history cannot be excluded. Any search for agents of classical
biological control must, therefore, focus on the Caribbean archipelago.

**Damage Caused**

Few efforts have been made to quantify the damage caused by Diaprepes.
Myers (1931) wrote that *D. abbreviatus* had increased to the extent
that it rivaled *Diatraea* as the most serious pest of sugar-cane in
Barbados. Apparently, the weevil, an indigenous insect, did not infest
sugarcane for centuries despite its extensive cultivation on the island.
Its attacks on sugarcane and sweet potatoes, according to Watson (1903)
were not observed prior to 1901. By 1904 it had become fairly abundant,
but not serious until 1909 (Ballou, 1912) and since that date it
increased in virulence every year. Myers (1931) cited an estimated loss
of 3.5 tons of cane per acre on Barbados in 1922.

Tucker (1929) estimated loss due to larval predation of sugarcane on
Barbados was equivalent to 5 to 6 tons of cane/acre. Tucker (1936)
reported that no parasites of any stage of *D. abbreviatus* were present
on Barbados prior to 1931. He released 22,000 *Tetrastichus haitiensis*
(an egg parasitoid) imported from Puerto Rico in 1931 and 11,000 in
1932. No parasitoids were recovered from the field on Barbados and
Tucker observed that no parasitoids were recovered from cane fields on
Puerto Rico. He concluded that *T. haitiensis* cannot attack Diaprepes
eggs when laid between leaves of sugarcane. By 1939, Tucker was
advocating a system of cash payments for collection and destruction of
adult weevils.

George Wolcott, working at the University of Puerto Rico at Rio Piedras,
observed that nurseries and young trees just set out were more damaged
that mature trees (Wolcott, 1936). He recorded oviposition, described
the life cycle, and noted the high degree of variability in development
time. Wolcott suggested that variability in development was a strategy
by the weevil to avoid parasitoids that were seasonally abundant on
Puerto Rico. He noted that parasitization of eggs was heavy in the
spring but absent the rest of the year. Eggs, however, were found
throughout the year (Wolcott, 1934). Wolcott (1933b) guessed that larval
molts and pupation are timed by sudden contact with liquid water
(rains). While this is probably accurate, it has not been sufficiently
elucidated to this day. Wolcott also described the intriguing preference
of adult females for ovipositing between strips of paper (Wolcott,
1933c).

By 1987, *D. abbreviatus* was being described as the most serious insect
pests of agriculture, horticulture, and silviculture on Puerto Rico
(Hantula et al., 1987).

**History of Efforts to Control *Diaprepes abbreviatus ***

Ballou (1912) noted that continuous cropping of cane increased damage
from Diaprepes. In 1911, school children on Barbados were enlisted to
collect and destroy adults - 30,000 were captured and destroyed on one
estate over a month. Similar efforts on St. Kitts and Antigua were
already mentioned. Adult weevils were reported from pigeon pea, sweet
potato, corn, bean, and sweet potato (considered an especially good host
for the weevil). Bourne (1921) also describes efforts to collect adults
on a massive scale and this appears to have been effective when
systematically applied over large regions. Cooperative campaigns over a
decade to reduce Diaprepes populations on Barbados were deemed
successful due to the fact that the island is small, densely populated,
and had a minimal amount of uncultivated land (Tucker, 1953). Manual
collection of newly emerged adults, especially from cane fields, was
facilitated by planting attractive host plants such as pigeon pea
(*Cajanus cajan*) or other fast-growing shrubs or trees on field borders
(Wolcott 1933a, 1933d). The toad, *Bufo marinus*, was imported to Puerto
Rico from Barbados in 1920 and again from Jamaica in 1924 to control
white grubs (*Phyllophaga* spp.) and Diaprepes. It was recommended to
plant \"gandules\" (pigeon pea, *Cajanus cajan*) or bananas along
ditches and banks to attract adult beetles that will then fall prey to
the toads (Dexter, 1932).

Nowell (1912) recommended pulling cane stumps after harvest to expose
the grubs and suggested \"a few head of poultry\" be kept on hand during
the operation. He observed that fully developed larvae disperse from the
cane stools in search of moist soil to pupate, sometimes moving a
considerable distance in the soil. Large numbers emerged after the first
heavy rains of May/June.

The interaction between larval feeding and root pathogens was noted by
Nowell (1913). He observed that rotation of cane with cotton greatly
reduced damage even though larvae survived in the soil through the
rotation. He suggested that reduction of inoculum of the pathogen
*Marasmius sacchari* reduced damage due to the complex of weevil and
pathogen.

R. G. Fennah was hired to investigate the mysterious death of lime trees
on Montserrat and of citrus in general on St. Lucia. He described
several aspects of Diaprepes biology including the preference of younger
leaves for feeding and older leaves for oviposition. He showed that
oviposition was deterred when the female\'s tarsi were covered with
various substances that destroyed the suction mechanism. He also
suggested that leaf age was detected by means of chemoreceptors on the
antennal club. Fennah described three methods of control then considered
practical for use in the Lesser Antilles: application of lead arsenate
close to the roots, the bare-root method, and growing of a repellent
cover crop between the trees. The bare root method consists of removing
the soil around the base of the cane stools, thereby exposing the most
susceptible part of the plant to the air and avoiding feeding or boring
by the grubs on the crown. In this way, damage to the most susceptible
part of the tree is avoided. Another approach was cultivation of a
repellent cover crop. Apparently, the legume *Tephrosia candida* repels
adult weevils and may be of use in deterring Diaprepes (Fennah, 1940a,
1940b, 1942). However, no reference of subsequent investigation into
this possibility could be found in the literature.

Relatively few references to chemical control of Diaprepes are to found
during the 1950\'s and 1960\'s. Para-dichlorobenzene and chlorinated
hydrocarbon insecticides were used in Jamaica as barriers to neonate
weevils (not Diaprepes) with some success (Dixon, 1954). DDT, chlordane,
barium fluosilicate, lead arsenate, aldrin, and dieldrin, were all
proposed as adulticides (Fennah, 1942; Wolcott, 1948; Wolcott, 1933a). I
suspect aldrin and dieldrin were widely used for control of both adult
Diaprepes by foliar sprays and larvae as soil insecticides during the
period when those compounds were marketed (Wolcott, 1954). On Puerto
Rico, *D. abbreviatus* attacking date palm was controlled by foliar
sprays of aldrin (Jackson, 1963). The waning of the era of persistent
insecticides coincided with the introduction of Diaprepes into the
United States. Bullock (1971) tested 24 adulticides and identified 10 as
capable of controlling adult Diaprepes. However, because of the short
residual effectiveness of foliar sprays and the prolonged period of
adult emergence, no evidence is available to indicate the value of
adulticides.

Since the introduction of Diaprepes into Florida, an increasing
awareness of the severity of the damage caused by Diaprepes and the
difficulty of controlling a long-lived subterranean insect on a tree
crop such as citrus, has stimulated considerable research into the
biology, physiology, host-plant relations, and methods for control. The
results of these efforts will be detailed in the sections that follow.

**References Cited**

1\. Ballou, H. A. 1912. Insect pests of the Lesser Antilles. Imperial
Dept. Agric., Barbados, West Indies. Pamphlet ser. 71:66-69.

2\. Bourne, B. A. 1921. Insect attacks reported or observed. Annu. Rep.
Dep. Agric., Barbados 1919-1920, pp. 12-13.

3\. Bullock, R. C. 1971. Effectiveness of foliar sprays for control of
*Diaprepes abbreviatus* (L.) on Florida citrus. Trop. Agric. 48:127-131.

4\. Dexter, R. R. 1932. The food habits of the imported toad *Bufo
marinus* in the sugarcane sections of Puerto Rico. Proc. Internat. Soc.
Sugar Cane Technologists 1935. 4th Entomol. Congress P.R., pp. 1-6

5\. Dixon, W. B. 1954. Fiddler Beetles. Natural history notes of the
Natural History Society of Jamaica No. 69:166-167.

6\. Fennah, R. G. 1940a. Rep. Dept. Agric., St. Lucia 1939, pp. 25-28.

7\. Fennah, R. G. 1940b. Observations on behaviour of citrus root-stocks
in St. Lucia, Dominica and Montserrat. Trop. Agric. 17:72-76.

8\. Fennah, R. G. 1942. The citrus pests investigation in the Windward
and Leeward Islands. B.W.I. Imp. Coll. Trop. Agric. Trinidad, 1937-1942.

9\. Hantula, J., A. Saura, J. Lokki, and N. Virkki. 1987. Genic and
color polyorphism in Puerto Rican phyllobiine weevils *Diaprepes
abbreviatus* (L.) and *Compsus maricaco* Wolcott. J. Agric., Univ. P. R.
71:391-397.

10\. Hutson, J. C. 1917. Insect notes. Some weevils of the genus
*Diaprepes* in the West Indes. The Agricultural News 16:186-187.

11\. Jackson, G. C. 1963. *Diaprepes abbreviata* Linnaeus on *Phoenix
dactylifera* L. J. Agric.**,** Univ. Puerto Rico 47:290.

12\. Jones, J. H. 1915. The sugar-cane weevil root borer (*Diaprepes
spengleri* L.). Insular Exp. Sta. (Rio Piédras, Puerto Rico) Bull.
14:1-19.

13\. Myers, J. G. 1931. A preliminary report on an investigation in the
biological control of West Indian insect pests. Empire Marketing Board
42:1-173.

14\. Nowell, W. 1912. Field investigations of beetle grubs attacking
roots of sugarcane. Rep. Local Dept. Agric., Barbados 1911-12, pp.
50-51.

15\. Nowell, W. 1913. Report of the assistant superintendent of
agriculture on the entomological and mycological work carried out during
the season under review. Rept. Local Dept. Agric., Barbados 1911-1913,
pp. 34-45.

16\. Tucker, R. W. E. 1929. Sugar-cane borers. Tropical Agric.
6:224-226.

17\. Tucker, R. W. E. 1936. Parasites introduced into Barbados for
control of insect pests. Dept. Sci. & Agric., Barbados Agric. J. 5:1-22.

18\. Tucker, R. W. E. 1953. Biological control of insect pests in
Barbados. Proc. Int. Soc. Sugarcane Tech. 8:573-581.

19\. Watson, N.B. 1903. The root-borer of sugar-cane. West Indian Bull.
4:37-47.

20\. Wolcott, G. N. 1933a. An economic entomology of the West Indes.
Entomol. Soc. P. R., San Juan. 1-688.

21\. Wolcott, G. N. 1933b. The larval period of *Diaprepes abbreviatus*
L. J. Agric., Univ. Puerto Rico 17:257-264.

22\. Wolcott, G. N. 1933c. Otiorhynchids oviposit between paper. J.
Econ. Entomol. 26:1172.

23\. Wolcott, G. N. 1933d. The changed status of some insect pests in
Puerto Rico. J. Dept. Agric. Puerto Rico 17:265-270.

24\. Wolcott, G. N. 1934. The diapause portion of the larval period of
*Diaprepes abbreviatus* L. J. Agric., Univ. Puerto Rico 18:417-428.

25\. Wolcott, G. N. 1936. The life history of *Diaprepes abbreviatus*
L., at Rio Piedras, Puerto Rico. J. Agric., Univ. Puerto Rico
20:883-914.

26\. Wolcott, G. N. 1948. The insects of Puerto Rico: Coleoptera. J.
Agric., Univ. P.R. 32:225-416.

27\. Wolcott, G. N. 1954. Residual effectiveness of insecticides against
soil-inhabiting insects. J. Agric., Univ. P. R. 38:108-114.