CONTROL OF THE GIANT LOOPER
Y. Izhar & M. Wysoki
The giant looper Boarmia
(Ascotis) selenaria Schiff. is known throughout the world as a serious
pest of various crops : citrus in Sicily and South Africa, tea in Formosa and
India, mulberry in Japan, teak trees in Burma, alfalfa in Hungary, coffee in
Kenya and Tanzania and peanuts in Madagascar.
B. selenaria has been
reported in Israel since 1937. The first record of damage caused in Israel by
this pest was reported in 1964 on apple and later on avocado and pecan.
In the later 1960s and early 1970s, aerial spray of cotton fields adjacent to avocado orchards upset the biological equilibrium in the groves. As a result, severe pests appeared, such as the long-tailed mealybug, the honeydew moth, and later B. selenaria causing extensive damage to foliage and fruit in Israel.
The giant looper causes
extensive damage to foliage and fruits in avocado orchards in Israel.
The biology of the looper : Boarmia selenaria has
5 generation in a year. The female adult lives for a short time, 5-6 days, during
which it lays up to 3000 eggs. The eggs are laid on all parts of the tree.
After a few days, in the spring and summer time, the larva hatches. The larva
reaches its biggest size of 6 cm after 4 weeks and pupates in the upper part of
the soil.
The heavy outbreak of the
population of Boarmia selenaria in avocado orchards was a result of an
upset in the biological equilibrium caused by aerial sprays in a near cotton
fields. Since biological control of pests in avocado orchards was decided upon,
Bacillus turingiensis like Dipel or Turiside is being used against the pest.
Only young caterpillars (up to 1.5 cm) in length are sensitive to these
preparations, and hence a monitoring system was developed.
The monitoring consists on
hanging traps. Fluctuation of the male population of Boarmia (Ascotis) selenaria
was estimated by male captures using traps baited with virgin females.
Those traps are used for monitoring purposes to control the pest population by
Bacillus thuringiensis preparations. The first peak of males was noted in
March, with additional peaks in June-July and September-October. Capture of
males in November and December pointed to the possibility that they may
overwinter as adults or emerged from pupae when the temperatures were suitable. Some differences
were noted between regions where the traps are situated (Western Galilee, Hefer
valley and Centeral Coastel Plain).
Because of the Appearance of
B. selenaria male peaks in each year in another period, even in short
time differences (of 2 weeks) and connected with the appearance of the young
caterpillars in the orchard (which are only in this stage sensitive to Bacillus
thuringiensis preparations), make the use of virgin traps still necessary for
monitoring purpose and are important items to improve the control of the pest.
At the beginning of this investigations the traps were put out in the avocado
orchards for a long period (some times a year) and sprays were performed with
or shortly after the appearance of the moth. At present, the traps are in the
avocado orchards only from February to June, and the control is directed
against young larva of the first or second generation through B. thuringiensis
applied on aerial sprays. The traps are hung in march and are controlled during
spring and summer. Once a week the virgin females in the traps are changed and
the observation of the traps is done every second day. When the level of 10
male butterfly is observed we search for caterpillars on the leaves and fruits.
When we have 5-10 caterpillars per tree we spray B.T. preparation and sticker
by helicopter crosswise.
The advantages of using B. T. are:
1) its long residual effect (up to 6 weeks).
2) harmlessness to parasitic wasps and honey bees.
3) non phytotxicity.
4) effectiveness against another avocado pest like
honeydew moth.
KEYWORDS: Boarmia (Ascotis) selentria - Virgin
females-baited traps - Pheromones - Population dynamics - Bacillus
thuringiensis - Avocado.