Scarlet lily beetle
Encyclopedia
The scarlet lily beetle (Lilioceris lilii), or red / leaf lily beetle, is a leaf beetle
that eats the leaves, stem, buds and flower of lilies
, fritillaries and other members of the family Liliaceae
. They mainly lay their eggs
on Lilium and Fritillaria species. Observed in absence of Lilium and Fritillaria species, the numbers of eggs laid were significantly less and the survival rate of eggs and larvae were lowered. It is now a pest in most temperate
climates where lilies are cultivated. Lily leaf beetles overwinter in the soil
and come out early in spring whereas adults stay in moist environments.
(harder forewings) are shiny and bright scarlet in colour. The lily beetle's underside, legs, eyes, antennae
and head are all pitch black, greatly contrasting the bright red colour of the wings. They have large eyes, a slim thorax (neck) and a wide abdomen. Their antennae are made up of 11 segments. Furthermore, they have notched eyes and two apparent grooves on their thorax.
Lily beetles are often confused with the Cardinal beetle
s as they also have a black underside and wings that are spotless and red in colour. However, the lily leaf beetles have wings that are shinier with tiny dimples on them, they are more rounded in shape compared to the dull, narrow, flattened and elongated Cardinal beetle.. Another difference between the two is their food preference. Lily leaf beetles are herbivore
s and are usually found on lily plants eating their leaves whereas the cardinal beetles are usually found on tree bark and flowers and feed on flying insects.Lastly, the cardinal beetle has a comb-like antennae.
Lily leaf beetles are fast fliers and hide very well. Additionally, when disturbed, they make a squeaky noise to deter predators. They could also be confused with unspotted ladybirds
. Lily leaf beetles however are much slimmer than ladybirds.
It has also become an invasive alien insect in the United Kingdom, where it has established itself after its introduction in 1943. It has since spread from Surrey to as far north as Glasgow.
(excrement) to make a protective shield, allowing protection from the sun and predators. However, the fecal shield is not an adequate protection against parasites - it actually acts as a chemical cue for the parasites to locate the larvae. An adult that senses danger displays a defense mechanism, thanatosis, becoming motionless, folding up its appendages and falling with its black under surface facing up, thereby helping it camouflage with the ground to get away. If unable to escape, they are also able to ‘squeak’, by rubbing two parts of their body together, which may be used to startle the attacker. This process is known as stridulation
and could even shock a bird or any other predator that may attack the lily leaf beetle.
Lily leaf beetles leave considerable damage on host plants. Managing ornamental lilies has become difficult in regions where lily leaf beetles have established. Damage to the leaves and flowers can also leave the plants weakened and susceptible to diseases such as Lily grey mold.
The Canadian Maritime provinces, especially Fritillaria and Lilium
gardens in Halifax, are largely affected by lily leaf beetles. A garden in Waverly, Nova Scotia
has reported decline of lily species and cultivar
s from 50 in 1996 to only one species in 2006. A newly discovered lily species in 2007, Lilium canadense
, has raised the concern for protection of this Canadian native lily and control of the leaf lily beetle.
, methoxychlor
, malathion
and rotenone
can prove useful in controlling populations. However, malathion
and carbaryl
, effective on adults and larvae, are toxic to bees and other insects, respectively. Products based on Neem
extracts are useful in killing very young larvae and repelling adults without comparable harm to other insects, although this option is perhaps less effective than handpicking. Neem
products should be applied every 5 to 7 days after egg hatch. Thiacloprid
is also effective. Floating row cover
has been effective in preventing the adults from feeding and laying eggs in the spring.
began testing the effectiveness of biological control of lily leaf beetle using six natural parasitoids in Europe. CAB International
Bioscience Switzerland Center has also participated in this project from 1998 till 2001.
Total parasitism rate in the last instar stage averages about 90% on wild lily Lilium martagon
, 75% in gardens and 60% in cultivated lily fields in Europe. Most of lily leaf beetle parasitoids are wasp
s that lay eggs inside the host and effectively kill all infected individuals. Parasitoid wasp, Diaparsis jucunda Holmgren (Hymenoptera
: Ichneumonidae
), dominates over 90% of the parasitoid
infections in lily leaf beetle. However, in gardens and commercial fields, Tetrastichus setifer (Hymenoptera
: Eulophidae
) and Lemophagus pulcher (Szepligeti) become the dominant parasitoids in the later season.
University of Rhode Island
experimented with release of European parasitoid wasp, Tetrastichus setifer, in Massachusetts
from 1999 to 2001 to control for the lily leaf beetle population. The experiment had shown reduction of the beetle population. Population decline was also observed at another experiment site in Rhode Island
.
In 2003, another parasitoid, Lemophagus errabundus, was also released in Massachusetts
and is now established in the region. Similar attempts of parasitoid
release have been made in Boston
with positive results.
Leaf beetle
Beetles in the family Chrysomelidae are commonly known as leaf beetles. This is a family of over 35,000 species in more than 2,500 genera, one of the largest and most commonly encountered of all beetle families....
that eats the leaves, stem, buds and flower of lilies
Lilium
Lilium is a genus of herbaceous flowering plants growing from bulbs. Most species are native to the temperate northern hemisphere, though the range extends into the northern subtropics...
, fritillaries and other members of the family Liliaceae
Liliaceae
The Liliaceae, or the lily family, is a family of monocotyledons in the order Liliales. Plants in this family have linear leaves, mostly with parallel veins but with several having net venation , and flower arranged in threes. Several have bulbs, while others have rhizomes...
. They mainly lay their eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
on Lilium and Fritillaria species. Observed in absence of Lilium and Fritillaria species, the numbers of eggs laid were significantly less and the survival rate of eggs and larvae were lowered. It is now a pest in most temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
climates where lilies are cultivated. Lily leaf beetles overwinter in the soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
and come out early in spring whereas adults stay in moist environments.
Identification
Lily beetles (Lilioceris lilii), belong to the Order Coleoptera, Family Chrysomelidae. In general, adult lily beetles are around 6 to 9 mm (¼–⅜ in) in length. The adult's elytraElytron
An elytron is a modified, hardened forewing of certain insect orders, notably beetles and a few of the true bugs ; in most true bugs, the forewings are instead called hemelytra, as only the basal half is thickened while the apex is membranous...
(harder forewings) are shiny and bright scarlet in colour. The lily beetle's underside, legs, eyes, antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
and head are all pitch black, greatly contrasting the bright red colour of the wings. They have large eyes, a slim thorax (neck) and a wide abdomen. Their antennae are made up of 11 segments. Furthermore, they have notched eyes and two apparent grooves on their thorax.
Lily beetles are often confused with the Cardinal beetle
Cardinal beetle
The cardinal beetle is a brightly-coloured red or orange beetle. It is approximately 20 mm long. It has a black face.The cardinal beetle preys on other insects and is normally found on flowers at the edges of woodland...
s as they also have a black underside and wings that are spotless and red in colour. However, the lily leaf beetles have wings that are shinier with tiny dimples on them, they are more rounded in shape compared to the dull, narrow, flattened and elongated Cardinal beetle.. Another difference between the two is their food preference. Lily leaf beetles are herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s and are usually found on lily plants eating their leaves whereas the cardinal beetles are usually found on tree bark and flowers and feed on flying insects.Lastly, the cardinal beetle has a comb-like antennae.
Lily leaf beetles are fast fliers and hide very well. Additionally, when disturbed, they make a squeaky noise to deter predators. They could also be confused with unspotted ladybirds
Coccinellidae
Coccinellidae is a family of beetles, known variously as ladybirds , or ladybugs . Scientists increasingly prefer the names ladybird beetles or lady beetles as these insects are not true bugs...
. Lily leaf beetles however are much slimmer than ladybirds.
Distribution
The lily leaf beetle is indigenous to parts of Europe and Asia. It is thought to have been introduced to North America through the import of plant bulbs around 1945. First spotted in Montreal, it has spread throughout Canada and the eastern United States within decades.It has also become an invasive alien insect in the United Kingdom, where it has established itself after its introduction in 1943. It has since spread from Surrey to as far north as Glasgow.
Life cycle
During the winter, adult lily leaf beetles rest in an undisturbed protective environment, normally shaded, cool and moist. Lily leaf beetles overwinter in soil or plant debris underneath the lily leaf plants they fed on during the previous summer and sometimes in gardens or woods quite a distance away from their host plants. In early spring, they emerge to feed on young lily leaves and mate. Females can lay up to 450 eggs each season by laying about 12 eggs on the underside of an individual lily/fritillaria leaf in irregular lines along the midrib to conceal them. Hatching of the eggs occurs in about 6 days. The larvae begin to feed underneath the leaf and working up to the rest of the plant, feeding for up to 24 days. They then burrow themselves in the ground to pupate in a cocoon formed by saliva and small particles of soil. In about 20 days, they emerge as adults and continue to feed until winter. In some cases, they are able to go through this cycle more than once in a single year.Behaviour
Not only are the eggs laid underneath the leaf to stay hidden but they are also covered with a thick sticky brown substance for further protection. As larvae, they use their own frassFrass
Frass is the fine powdery material phytophagous insects pass as waste after digesting plant parts. It causes plants to excrete chitinase due to high chitin levels, it is a natural bloom stimulant, and has high nutrient levels. Frass is known to have abundant amoeba, beneficial bacteria, and fungi...
(excrement) to make a protective shield, allowing protection from the sun and predators. However, the fecal shield is not an adequate protection against parasites - it actually acts as a chemical cue for the parasites to locate the larvae. An adult that senses danger displays a defense mechanism, thanatosis, becoming motionless, folding up its appendages and falling with its black under surface facing up, thereby helping it camouflage with the ground to get away. If unable to escape, they are also able to ‘squeak’, by rubbing two parts of their body together, which may be used to startle the attacker. This process is known as stridulation
Stridulation
Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fishes, snakes and spiders...
and could even shock a bird or any other predator that may attack the lily leaf beetle.
Human impact
The Canadian Maritime provinces, especially Fritillaria and Lilium
Lilium
Lilium is a genus of herbaceous flowering plants growing from bulbs. Most species are native to the temperate northern hemisphere, though the range extends into the northern subtropics...
gardens in Halifax, are largely affected by lily leaf beetles. A garden in Waverly, Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
has reported decline of lily species and cultivar
Cultivar
A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...
s from 50 in 1996 to only one species in 2006. A newly discovered lily species in 2007, Lilium canadense
Lilium canadense
Lilium canadense, commonly called either the Canada Lily, Wild Yellow-Lily, or the Meadow Lily, is a native of eastern North America. Flowers emerge in June, and are nodding, yellow, orange or red, with spots...
, has raised the concern for protection of this Canadian native lily and control of the leaf lily beetle.
Mechanical and chemical control
There are no registered chemicals for lily leaf beetle control, which limits options for the gardener. Although the most surefire strategy for preventing infestation by any pest is to avoid planting susceptible plants in the first place, with lily beetle this necessitates avoiding growing so many desirable cultivars of lilium, that other strategies may be preferred. Regular handpicking and crushing of eggs, larvae and adults is effective if somewhat laborious (adults can be drowned in soapy water if crushing is considered too violent). Domestic insecticides registered for general leaf beetle control containing carbarylCarbaryl
Carbaryl is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid commonly sold under the brand name Sevin, a trademark of the Bayer Company. Union Carbide discovered carbaryl and introduced it commercially in 1958...
, methoxychlor
Methoxychlor
Methoxychlor is a synthetic organochlorine used as an insecticide.-Usage:Methoxychlor is used to protect crops, ornamentals, livestock, and pets against fleas, mosquitoes, cockroaches, and other insects...
, malathion
Malathion
Malathion is an organophosphate parasympathomimetic which binds irreversibly to cholinesterase. Malathion is an insecticide of relatively low human toxicity, however one recent study has shown that children with higher levels of organophosphate pesticide metabolites in their urine are more likely...
and rotenone
Rotenone
Rotenone is an odorless chemical that is used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the roots and stems of several plants such as the jicama vine plant...
can prove useful in controlling populations. However, malathion
Malathion
Malathion is an organophosphate parasympathomimetic which binds irreversibly to cholinesterase. Malathion is an insecticide of relatively low human toxicity, however one recent study has shown that children with higher levels of organophosphate pesticide metabolites in their urine are more likely...
and carbaryl
Carbaryl
Carbaryl is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid commonly sold under the brand name Sevin, a trademark of the Bayer Company. Union Carbide discovered carbaryl and introduced it commercially in 1958...
, effective on adults and larvae, are toxic to bees and other insects, respectively. Products based on Neem
Neem
Azadirachta indica is a tree in the mahogany family Meliaceae. It is one of two species in the genus Azadirachta, and is native to India growing in tropical and semi-tropical regions. Its fruits and seeds are the source of neem oil...
extracts are useful in killing very young larvae and repelling adults without comparable harm to other insects, although this option is perhaps less effective than handpicking. Neem
Neem
Azadirachta indica is a tree in the mahogany family Meliaceae. It is one of two species in the genus Azadirachta, and is native to India growing in tropical and semi-tropical regions. Its fruits and seeds are the source of neem oil...
products should be applied every 5 to 7 days after egg hatch. Thiacloprid
Thiacloprid
Thiacloprid is an insecticide of the neonicotinoid class. Its mechanism of action involves disruption of the insect's nervous system by inhibiting nicotinic acetylcholine receptors. Thiacloprid was developed by Bayer CropScience for use on agricultural crops to control of a variety of sucking and...
is also effective. Floating row cover
Row cover
In horticulture, row cover is any material used as a protective covering to shield plants, usually vegetables, primarily from the undesirable effects of cold and wind, and also from insect damage....
has been effective in preventing the adults from feeding and laying eggs in the spring.
Biological control
There are no natural predators or parasites of lily leaf beetle in North America. In 1996, University of Rhode IslandUniversity of Rhode Island
The University of Rhode Island is the principal public research university in the U.S. state of Rhode Island. Its main campus is located in Kingston. Additional campuses include the Feinstein Campus in Providence, the Narragansett Bay Campus in Narragansett, and the W. Alton Jones Campus in West...
began testing the effectiveness of biological control of lily leaf beetle using six natural parasitoids in Europe. CAB International
CAB International
CAB International is a not-for-profit inter-governmental organisation based in the United Kingdom....
Bioscience Switzerland Center has also participated in this project from 1998 till 2001.
Total parasitism rate in the last instar stage averages about 90% on wild lily Lilium martagon
Lilium martagon
Lilium martagon is a species of lily. It has a widespread native region extending from central Europe east through northern Asia to Mongolia and Korea. Several subspecies have been named. Horticulturally it is in Division 9, It is stem-rooting, growing between 1m and 2m tall...
, 75% in gardens and 60% in cultivated lily fields in Europe. Most of lily leaf beetle parasitoids are wasp
Wasp
The term wasp is typically defined as any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor an ant. Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural control of their...
s that lay eggs inside the host and effectively kill all infected individuals. Parasitoid wasp, Diaparsis jucunda Holmgren (Hymenoptera
Hymenoptera
Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...
: Ichneumonidae
Ichneumonidae
Ichneumonidae is a family within the insect order Hymenoptera. Insects in this family are commonly called ichneumon wasps. Less exact terms are ichneumon flies , or scorpion wasps due to the extreme lengthening and curving of the abdomen...
), dominates over 90% of the parasitoid
Parasitoid
A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...
infections in lily leaf beetle. However, in gardens and commercial fields, Tetrastichus setifer (Hymenoptera
Hymenoptera
Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...
: Eulophidae
Eulophidae
Eulophidae is a large family of hymenopteran insects, with over 4,300 described species in some 300 genera . The family as presently defined also includes the genus Elasmus, which was previously treated as a separate family, "Elasmidae", and is now treated as a subfamily of Eulophidae...
) and Lemophagus pulcher (Szepligeti) become the dominant parasitoids in the later season.
University of Rhode Island
University of Rhode Island
The University of Rhode Island is the principal public research university in the U.S. state of Rhode Island. Its main campus is located in Kingston. Additional campuses include the Feinstein Campus in Providence, the Narragansett Bay Campus in Narragansett, and the W. Alton Jones Campus in West...
experimented with release of European parasitoid wasp, Tetrastichus setifer, in Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
from 1999 to 2001 to control for the lily leaf beetle population. The experiment had shown reduction of the beetle population. Population decline was also observed at another experiment site in Rhode Island
Rhode Island
The state of Rhode Island and Providence Plantations, more commonly referred to as Rhode Island , is a state in the New England region of the United States. It is the smallest U.S. state by area...
.
In 2003, another parasitoid, Lemophagus errabundus, was also released in Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
and is now established in the region. Similar attempts of parasitoid
Parasitoid
A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...
release have been made in Boston
Boston
Boston is the capital of and largest city in Massachusetts, and is one of the oldest cities in the United States. The largest city in New England, Boston is regarded as the unofficial "Capital of New England" for its economic and cultural impact on the entire New England region. The city proper had...
with positive results.