Some Important Insect Predators
The first known use of the tactic of biological insect pest suppression was in china around 300 A.D. where in ants were used to protect orange groves from developing wormy fruit. The red wood ants are considered important in maintaining forest insect pest population in balanced condition in 12th century. Their food consists of stages of Lepidopterous caterpillars. This is an example to be quoted for efficient facultative predator. The mired Cyrtorhinus modulus has been proved as an effective predator on the eggs of the sugarcane leaf hopper. Its first release was made in 1920 from Australian stock and late from Fiji and by 1923 the sugarcane leaf hopper was suppressed.
1) Vedalia beeytle, Rodolia Cardinalis Mulsant
This is probably the most frequent mentioned predator in classical biological control literature. It has been thoroughly reviewed by Debauch(1974). The successful story of the Vedalia beetle against cottony cushion scale, Icerya purchasein California on citrus has already been outlined in C. V. Riley campaign. Like success in California, it has been repeated in 30-50 countries around the world where this beetle has been released.
Adults of Vedalia beetle male and have a pre-oviposition period of 3-4 weeks in the summer and 1-3 weeks in the winter. The eggs are laid singly or in small cluster. Oviposition lasts on as average of 75 days (11-170 days) and the average number of eggs laid by a female is 341 eggs. The females deposit eggs on the egg sacs of their prey. The predatory eggs hatch in 6 days. Larval stage lasts for 22 days, during which it moults 4 times. Pupal stage lasts for 8 days. The total life cycle from egg to adult is completed on an average of 35 days. The adult female live for an average of 70 days and adults males 81 days and it completes 6-7 generations per year. The larva and adult eat cottony cushion scales. The mated egg producing female eats more prey than virgin females or males.
2) Cryptolaemus montrouzieri Mulsant
The mass production and periodic release of C. montrouzieri against various mealy bugs pests of citrus has been going on for several years. The major pest against which it is employed is the citrus mealy bugs Planococcus citri and grape vine mealy bugs Maconellicoccus hersutus. The life cycle of C. montrouzieri takes about 30-35 days at temperature between 23 and 26.7 ̊C. Colonies of 30-40 adult coccinellids may be placed in each tray when mealy bugs are 8 days old. They deposit their eggs on the sprouts and trays. After 12 days, their adults are removed for liberation. As predator larvae feed and mature, seek pupation site 18 days after the parent stock is removed their adult progeny first appear. The emerging beetles are collected for about 21 days. Adults can be hold in the vials for 12-18 hours prior to release if cooled to 15.6 ̊C. The adult predator beetles are released at approximately 20 adults/citrus tree.
3) Green lacewing: Chrysoperla carnea
(Neuroptera : Chrysopidae)
This is one of the most important chrysopid in biological insect pest suppression programmes. The eggs are characteristically stalked and take an average of 9.5 days (7-15 days) to hatch. The newly emerged larvae carry no reserve of foods and thus must crawl down the stalk and began to search for pray immediately. The larvae develop through 3 instars in 12-28 days. The pe-pupal and pupal stages lasts for average of 19.2 days (11-21 days) and 6-48 days, respectively. The total period from egg to adult is 37-70 days. The pupa emerges from the cocoon and shortly casts its skin to become an adult. Mating takes place shortly after adult mergence and repeated copulation is necessary for continuous reproduction. The females capable of laying 500-700 eggs. The number of annual generations range from 2-7. Winter is usually passed in protected situations by the adult stage. The adult feeds on aphids and other small insect. The larvae feed nearly all gardens certain ignite, and eggs of thrips, moths, leaf hoppars etc.
The life cycle or life history observed at College of Agriculture, Nagpur within 10 years from 1993 to 2002, all year round for both is as follows.
(i) Chrysoperla carnea and
(ii) Mallada beninensis
3 days in rainy season and summer season
5 days in winter season
7 days to 10 days in rainy and summer season
10 to 17 days in winter season
7 days in rainy season
7 to 10 days in summer
10 to 15 days in winter season
30 to 35 days in rainy
35 to 50 days in winter for both males and females.
200 eggs to 700 eggs.