Insect Pheromone in Forest Pest Management

Insect Pheromone in Forest Pest Management
In the process of pest control in forestry, the use of various chemical
pesticides tends to induce stronger pest resistance, significantly hindering the
control and development of forestry. The advent of insect pheromone has
opened up an effective way of pest control. After insects mature, they release a
trace chemical substance with a special smell, and such chemical substances
can lure the same species of insects to mate. Insect pheromone has been
highly valued by scholars at home and abroad and is becoming one of the
main measures in integrated pest control, with broad application and
development prospects.
The mechanism and transmission methods of pheromone
At present, extended research has been accomplished on studying the
pheromone of Lepidopteran insects. Some insects secrete pheromone through
their wings, while others secrete pheromone on the back of their thorax or the
first two thorax segments. There are two major ways of transmitting
pheromones: one relies on airflow, which is transmitted from the upper wind
to the lower wind, forming a pheromone belt, then insects follow this belt to
reach the odor source and resulting in a faster transmission fashion. The
second way to transmit pheromones relies on the free movement of the prime
molecules diffusing around, which is a slower transmission method.
Insect pheromone components
In 1959, a chemist spent nearly 20 years extracting the pheromone –
Bombykol from the glands of 500,000 female silkworms. The composition
and content of pheromone released by different insects also hold different
degrees. For example, the chemical structures of pheromones of Lepidopteran
insects are mostly long-chain unsaturated alcohols and esters, which are
composed of aldehydes, ketones, alcohols, and esters with 10 to 21 carbons.
Factors affecting the release of pheromone by insects
Studies have shown that the physiological process of insect secretion and
release of pheromone is controlled and dominated by external environmental
factors and the lateral body. In some Coleopteran insects, the secretion of
pheromones stops when the lateral pharynx is removed. In addition,
temperature and photoperiod directly affect the release of pheromones.
Application of pheromone in monitoring and forecasting
The traditional monitoring and forecasting of insect situations are mainly
carried out by methods such as manual surveys and black light trapping. For
pests with secret lifestyles, weak phototaxis, low insect population densities,
as well as forests of complex terrain, the traditional pest monitoring and

forecasting strategies were greatly limited, resulting in an enlarged deviation
of the survey data and affecting the overall accuracy. Now pheromones can be
widely used in insect monitoring and forecasting to predict the occurrence
period, damage location, and even the number of pests.
Applications of pheromone in pest control
In forest land located in high mountains and sparsely populated, it is
unsuitable to use pesticides for pest control. Insect pheromone would be a
good choice due to the fact that it could be used in combination with biological
agents. Moreover, insect pheromone has benefited the overall efficacy
duration for prevention and control; hence, it is used directly for pest trapping
and killing.
Classification of insect pheromones
According to functions, pheromones have been classified into 8 categories:
aggregation pheromones, alarm pheromones, oviposition-deterrent
pheromones, home recognition pheromones, sex pheromones, trail
pheromones, recruitment pheromones, and royal pheromones. Based on
different compositions, pheromones can be grouped as the
ketone-functionalized pheromone, aldehyde-functionalized pheromone,
carboxyl-functionalized pheromone, epoxy-functionalized pheromone,
ester-functionalized pheromone, and alcohol-functionalized pheromone.