Codling moth
Encyclopedia
The codling moth is a member of the Lepidoptera
n family Tortricidae
. They are known as an agricultural
pest, their larva
being the common apple
worm or maggot. It is native to Europe and was introduced to North America, where it has become one of the regular pests of apple orchards. It is found almost worldwide. It also attacks pear
s, walnut
s, and other tree fruits.
This larva is the infamous "worm in the apple" of cartoon and vernacular fame; it is not related to the earthworm.
The codling moth is greyish with light grey and copper stripes on its wings, and has an average wingspan of 17 mm. The females lay eggs on fruit or leaves and the black-headed yellow larvae attack the fruit immediately upon hatching. Each larva burrows into the fruit, eats for around three weeks, then leaves the fruit to overwinter and pupate elsewhere. Most nourishment is obtained by feeding on the proteinaceous seeds.
The codling moth is bivoltine
in most regions of the USA — in the Pacific Northwest there is a partial third generation.
s. Successful synthesis of codlemone, the codling moth female sex pheromone blend, has led to behavior-based monitoring and management. Pheromone
traps are used to capture male moths for monitoring and setting biofix, which is the time of first flight for codling moth. Biofix is used with weather data to run degree day
models (see below) which predict with excellent accuracy the phenology of the population in the field, thereby allowing growers to time their management actions to target codling moth when they are most susceptible. A kairomone
, which is a feeding attractant, can be used to capture males and females (DA lure). Mating disruption
can be used to effectively manage codling moth populations in many cases. Mating disruption involves the use of a pheromone-impregnated release device, typically made of plastic or rubber. Dispensers are distributed throughout the orchard and emit female pheromone at a high, relatively constant rate. The mechanism by which mating disruption affects males is poorly understood; it may increase the time required for males to find females, thus reducing fecundity, or it may simply mask the position of females to searching males, reducing mating substantially. The codling moth is not a great candidate for biological pest control
, as the larvae are well protected within the fruit for the majority of development. However, their eggs are susceptible to biological control by Trichogramma
wasps. The wasps deposit their eggs into codling moth eggs, and the developing wasp larvae consume the moth embryo inside. Another method for control and sampling, 'trunk banding', consists of wrapping a corrugated cardboard strip around the tree trunk. Larvae making their way down the tree to pupate after exiting the infested fruits will use bands as pupation sites. Bands may then be removed and burned.
The most common biological control of codling moth is the application of codling moth granulosis virus (CMGV)in a water based formulation including the granulosis virus, Occlusion Bodies (OBs). CMGV occurs naturally in all major pome fruit growing regions around the world. CMGV is widely used in the commercial and organically grown orchards of Europe and North America. A widely used brand is Virosoft CP4. CP4 is the region of Quebec where the CP4 strain was originally isolated. The CMGV is applied at initiation of egg hatch. The codling moth larvae consume the OB. Next the OB is degraded by the alkaline gut of the Codling moth larvae. Then the virus infests the gut membrane linings and reproduces within the larvae. The larvae then stop feeding and eventually die within 3-7 days.
Recent trials of nontoxic kaolin clay-based sprays indicate an effective alternative means of codling moth suppression may be on the horizon. Codling moths and other pests find leaves and fruit covered in kaolin clay unfit for laying eggs. Tiny particles of the clay tend to attach to their bodies, disturbing and repelling them. In addition, trees covered in kaolin clay can make them less recognizable as habitat to codling moths. Full coverage of trees is necessary to achieve effective suppression. If used only at the beginning of the fruit growing season, kaolin clay often comes off by itself due to wind and rain attrition, leaving fruit clean at harvest time.
The prime difficulty in dealing with codling moth infestations seems to lie with appropriate timing. The method of calculating 'degree-days' is often used by orchardists to approximate when a particular pest will reach a particular stage of development during a given season. Since stages of insect development are triggered by the accumulation of a certain amount of heat over time, this calculation involves careful tracking of changes in daily temperature. In the case of codling moths, adults emerging from pupae in bark and other overwintering spaces will mate and begin laying eggs soon after petal fall. For a given moth, this migration can take place within a mere two to three hours. Effective control using any method, therefore, depends crucially on identifying when decisive moments such as these occur.
Lepidoptera
Lepidoptera is a large order of insects that includes moths and butterflies . It is one of the most widespread and widely recognizable insect orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...
n family Tortricidae
Tortricidae
Tortricidae is a family of moths, commonly known as tortrix moths, in the order Lepidoptera. Tortricidae is a large family with over 9,400 species described, and is the sole member of the superfamily Tortricoidea. Many of these are economically important pests. Olethreutidae is a junior synonym...
. They are known as an agricultural
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
pest, their larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
being the common apple
Apple
The apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
worm or maggot. It is native to Europe and was introduced to North America, where it has become one of the regular pests of apple orchards. It is found almost worldwide. It also attacks pear
Pear
The pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....
s, walnut
Walnut
Juglans is a plant genus of the family Juglandaceae, the seeds of which are known as walnuts. They are deciduous trees, 10–40 meters tall , with pinnate leaves 200–900 millimetres long , with 5–25 leaflets; the shoots have chambered pith, a character shared with the wingnuts , but not the hickories...
s, and other tree fruits.
This larva is the infamous "worm in the apple" of cartoon and vernacular fame; it is not related to the earthworm.
The codling moth is greyish with light grey and copper stripes on its wings, and has an average wingspan of 17 mm. The females lay eggs on fruit or leaves and the black-headed yellow larvae attack the fruit immediately upon hatching. Each larva burrows into the fruit, eats for around three weeks, then leaves the fruit to overwinter and pupate elsewhere. Most nourishment is obtained by feeding on the proteinaceous seeds.
The codling moth is bivoltine
Voltinism
Voltinism is a term used in biology to indicate the number of broods or generations of an organism in a year. The term is particularly in use in sericulture, where silkworm varieties vary in their voltinism....
in most regions of the USA — in the Pacific Northwest there is a partial third generation.
Control
Codling moth infestations are often managed with pesticidePesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s. Successful synthesis of codlemone, the codling moth female sex pheromone blend, has led to behavior-based monitoring and management. Pheromone
Pheromone
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...
traps are used to capture male moths for monitoring and setting biofix, which is the time of first flight for codling moth. Biofix is used with weather data to run degree day
Growing degree day
Growing degree days , also called growing degree units , are a heuristic tool in phenology. GDD are a measure of heat accumulation used by horticulturists, gardeners, and farmers to predict plant and pest development rates such as the date that a flower will bloom or a crop reach...
models (see below) which predict with excellent accuracy the phenology of the population in the field, thereby allowing growers to time their management actions to target codling moth when they are most susceptible. A kairomone
Kairomone
A kairomone is a semiochemical, emitted by an organism, which mediates interspecific interactions in a way that benefits an individual of another species which receives it, without benefiting the emitter. This "eavesdropping" is often disadvantageous to the producer...
, which is a feeding attractant, can be used to capture males and females (DA lure). Mating disruption
Mating disruption
Mating disruption is a pest management technique designed to control certain insect infestations. Specifically, mating disruption involves the use of synthesized sex pheromones to disrupt the reproductive cycle of insects.- Mechanism:...
can be used to effectively manage codling moth populations in many cases. Mating disruption involves the use of a pheromone-impregnated release device, typically made of plastic or rubber. Dispensers are distributed throughout the orchard and emit female pheromone at a high, relatively constant rate. The mechanism by which mating disruption affects males is poorly understood; it may increase the time required for males to find females, thus reducing fecundity, or it may simply mask the position of females to searching males, reducing mating substantially. The codling moth is not a great candidate for biological pest control
Biological pest control
Biological control of pests in agriculture is a method of controlling pests that relies on predation, parasitism, herbivory, or other natural mechanisms...
, as the larvae are well protected within the fruit for the majority of development. However, their eggs are susceptible to biological control by Trichogramma
Trichogramma
The wasps of genus Trichogramma, commonly known as "stingless wasps", are some of the most widely-studied agents of biological control in the field of entomology. Trichogramma wasps are tiny Hymenopteran insects, measuring 1 millimeter in length or less, that parasitize the eggs of many types of...
wasps. The wasps deposit their eggs into codling moth eggs, and the developing wasp larvae consume the moth embryo inside. Another method for control and sampling, 'trunk banding', consists of wrapping a corrugated cardboard strip around the tree trunk. Larvae making their way down the tree to pupate after exiting the infested fruits will use bands as pupation sites. Bands may then be removed and burned.
The most common biological control of codling moth is the application of codling moth granulosis virus (CMGV)in a water based formulation including the granulosis virus, Occlusion Bodies (OBs). CMGV occurs naturally in all major pome fruit growing regions around the world. CMGV is widely used in the commercial and organically grown orchards of Europe and North America. A widely used brand is Virosoft CP4. CP4 is the region of Quebec where the CP4 strain was originally isolated. The CMGV is applied at initiation of egg hatch. The codling moth larvae consume the OB. Next the OB is degraded by the alkaline gut of the Codling moth larvae. Then the virus infests the gut membrane linings and reproduces within the larvae. The larvae then stop feeding and eventually die within 3-7 days.
Recent trials of nontoxic kaolin clay-based sprays indicate an effective alternative means of codling moth suppression may be on the horizon. Codling moths and other pests find leaves and fruit covered in kaolin clay unfit for laying eggs. Tiny particles of the clay tend to attach to their bodies, disturbing and repelling them. In addition, trees covered in kaolin clay can make them less recognizable as habitat to codling moths. Full coverage of trees is necessary to achieve effective suppression. If used only at the beginning of the fruit growing season, kaolin clay often comes off by itself due to wind and rain attrition, leaving fruit clean at harvest time.
The prime difficulty in dealing with codling moth infestations seems to lie with appropriate timing. The method of calculating 'degree-days' is often used by orchardists to approximate when a particular pest will reach a particular stage of development during a given season. Since stages of insect development are triggered by the accumulation of a certain amount of heat over time, this calculation involves careful tracking of changes in daily temperature. In the case of codling moths, adults emerging from pupae in bark and other overwintering spaces will mate and begin laying eggs soon after petal fall. For a given moth, this migration can take place within a mere two to three hours. Effective control using any method, therefore, depends crucially on identifying when decisive moments such as these occur.