Search

Chelonus blackburni (Cameron) that parasitizes eggs of potato tuber moth is widely distributed and occurs commonly in potato fields throughout the country. Studies on its biology and ovipositional performance were carried out on both hosts i.e. Phthorimaea operculella and Corcyra cephalonica in laboratory conditions. Average number of eggs laid per female was found to be 210.9 ± 16.62 on P. operculella and 118.4 ± 7.49 on C. cephalonica. Incubation period of the parasitoid on P. operculella was 24.5 ± 1.62 hours on an average, while on C. cephalonica, it was found as 25.2 ± 1.33 hours. Total larval duration was 14.5 days and 19.2 days on P. operculella and C. cephalonica, respectively. Pupal period was 10.6 ± 0.70 days on P. operculella, whereas it was slightly higher on C. cephalonica (13 ± 0.57 days). The average life span was observed to be 6.8 days on P. operculella and 7.7 days on C. cephalonica.

Biology and feeding potential of a chrysopid, Mallada boninensis Okamoto, recorded by us for the first time from Gujarat, were studied under laboratory conditions. The predator laid stalked eggs in groups usually of 11 to 20. The larvae with the habit of carrying trash on its back passed through three Instnrs, the durations of which were 4.11, 4.11 and 4.63 days at a constant temperature of 25.26 ± 2.2 °C and 59.90% RH. The short prepupal and pupal periods averaged 5 to 7 and 13.79 days respectively. The female was slightly bigger than male. The sex ratio of male:female was 1:1.5 with 81.40 per cent emergence of adults. Pre oviposition, oviposition and post-oviposition periods averaged 9.90 ± 1.60, 36.90 ± 4.41 and 18.00 ± 12.24 days respectively. The total number of eggs laid by the female averaged 431 ± 38.62 eggs. The average longevity of females and males were 64.8 ± 15.97 and 27.36 ± 8.03 days respectively. The larva consumed on an average 628.75 eggs of Corcyra cephalonica Stainton and 453 nymphs of white flies.

An experiment was conducted in the laboratory on effect of Corcyra cephalonica (Stainton) density on six biological parameters of Chrysoperla carnea (Stephens). The result revealed that the maximum eggs (53.29 per day) were consumed in the density of 125 eggs/day, which also recorded minimum larval and pupal periods of 8.04 and 9.17 days, respectively. Whereas in the density of 100 eggs/day, maximum pupal weight (8.42 mg), highest fecundity (350.75 eggs/female) and maximum adult longevity (46.5 days) was observed.

The natural occurrence of Heterorhabditis bacteriophora Poinar, 1976 in a forest soil from Burliar, Tamil Nadu, India, is reported along with the dimensions of this population. The life cycle of this isolate was completed in eight days at laboratory temperatures of 23.0°C (minimum) and 30.2°C (maximum) on larvae of Corcyra cephalonica Stainton (Galleridae: Lepidoptera). Under experimental conditions, it infected larvae of certain Elaterldae (Coleoptera), Noctuidae, Papilionidae and Nymphalidae (Lepidoptera) and adults of Acrididae (Orthoptera). The LC50 for fourth-instar larvae of Spodoptera litura (Fabricius) (Noctuidae: Lepidoptera) was 19.14 dauers per larva at room temperatures of 22.3°C (minimum) and 30.0°C (maximum).

Campoletis chlorideae Uchida an early larval parasitoid of Helicoverpa armigera (Hiibner) was successfully reared on Corcyra cephalonica Stainton. The comparative biology of C. chlorideae was also studied on C. cephaionica, H. armigera and Spodoptera litura (Fabricius).

An experiment conducted in the laboratory on the effect of host, Corcyra cephalonica on the development of Chrysoperla carnea (Stephens) revealed that the maximum eggs (53.29 per day) were consumed in the treatment of 125 eggs/day which also recorded minimum larval and pupal periods of 8.04 and 9.17 days, respectively. Whereas, the treatment 100 eggs/day noted maximum pupal weight (8.42 mg) and the highest fecundity (350.75 eggs/female) as well as the maximum adult longevity (46.50 days). The food offered as 25 eggs/day has shown the adverse effect on the development of predator.

Different cereal grains viz, maize, rice, sorghum and wheat were evaluated as food at various concentrations i. e., 500, 1000, 1500 and 2000 eggs per kg for the mass production of Corcyra cephalonica (Stainton). The aim was to find an alternative to sorghum, which is costly and to arrive at the optimum quantity of eggs per unit of food material. It was found that the Iife-cycle of C. cephalonica was shorter and fecundity and female progeny production were higher when reared on maize. Charging one kg of food material (maize) with of 1500 eggs of C. cephttlonica was observed to be optimum for successful mass production.

Fecundity and adult longevity of both the sexes in Rhynocoris marginatus (Fabricius) were maximal while total developmental period was minimal when this reduviid predator was reared on larvae of Spodoptera litura (Fabricius) in place of Earias vittella (Boisduval) or Corcyra cephalonica (Stainton). Its intrinsic rate of increase and net reproductive potential were of the highest order if the predator always fed on caterpillars of S. litura.

Since Goniozus nephantidis (Muesebeck) is found to have strong parental care for its progeny, the influence of different densities of G. nephantidis and its host, Corcyra cephalonica (Stainton) on the behaviour ecology of the parasitoid was studied. Interaction between different densities of the host and parasitoid revealed that a ratio of 1:1 was significantly superior to all other ratios resulting in maximum parasitism (9.0 larvae / female), fecundity (93.2/female) and number of progenies (75.2/female). Exposing more than one C. cephalonica larva did not significantly increase the parasitizing efficiency, fecundity and progeny produced. Conversely, exposing a single C. cephalonica larva to several female parasitoids adversely affected the biological attributes of the parasitoid. Increasing the densities of either host insects or parasitoids had an inverse relationship with oviposition behaviour, parasitism efficiency and progeny production of the parasitoid establishing the important and significant role played by host-parasitoid density.

Laboratory studies on parasitizing efficiency of Trichogmmmatoidea bactrae Nagaraja and bioassay of Bacillus thuringiensis Berliner, and field evaluation of these bioagaents alone and in combination were carried out against diamondback moth, Plutella xylostella (Linnaeus) on cabbage. The results indicated that the parasitism of T. bactrae was higher in the eggs of Corcyra cephalonica Stainton (91.36%) than P. xylostella (82.46%) while the adult emergence was more from parasitized eggs of P. xylostella (92.16%) than C. cephalonica (91.40%). The estimated LC50 value of B. thuringiensis formulation Dipel 8L was 0.043 per cent. Field studies revealed that inundative releases of T. bactrae @50,000 adults/ha/release five times at weekly interval with two intermittent sprays of B. thuringiensis @ 1 litre/ha at 10 days interval commencing from 30 days after transplanting of cabbage resulted in minimum of 0.45 mean surviving larvae of DBM with 84.16 per cent reduction in larval number and maximum yield of 380.2 q/ha marketable cabbage heads, and proved to be the most effective.

Corcyra cephalonica (Stainton) is a laboratory host for mass production of Trichogramma spp. and other biocontrol agents. In the present study for rearing Corcyra, three diets were used as broken maize alone, broken maize + yeast (2%) and broken maize + protinex (2%). Maize + yeast combination gave the best results in terms of mean total adults emergence (2211), mean total females (985), mean fecundity (397.85) and mean duration of moths emergence (52.31 days), while average developmental period was lowest (36 days) when compared with other two diets. The effect of egg laying on parasitization by T. chilonis revealed that highest mean per cent parasitization of 51.96 (mean of 1st to 6th day laying) was obtained on eggs laid by moths reared on maize + yeast diet. The highest mean per cent parasitization (73.9) was obtained on 2nd day egg laying.

Biology and feeding potential of an anthocorid predator, Blaptostethus pallescens Pop pius were studied on the eggs of alternate host, Corcyra cephalonica (Stainton). Approximately 100 UV irradiated C. cephalonica eggs are required for rearing one nymph throughout its nymphal period of about 16 days (4-11 eggs per day) and 630 eggs for an adult throughout its longevity (3-19 eggs per day). Adult females had a greater feeding potential (943 eggs per adult) in comparison to males (381 eggs per adult). Utilising 9cc of C. cephalonica eggs, 1000 B. pallescens could be produced. The lab-reared adults had a very high longevity (38- 78 days) and fecundity (110-203 nymphs/female), indicating the suitability of C. cephalonica eggs for mass production.

Laboratory evaluation of Trichogrammatoidea bactrae Nagaraja reared on Corcyra cephalonica (Stainton) as an egg parasitoid of Plutella xylostella (Linnaeus) was carried out at 26±1°C and 50-80 percent relative humidity. From each parasitized egg of C. cephalonica, up to 2 parasitoids emerged and there were almost equal chances of getting 1 or 2 parasitoids. Each female parasitized a mean of 4.6 and 6.4 eggs of P. xylostella and C. cephalonica during its mean survival of 1.7 and 2.3 days, respectively, and mean fecundity was 6.3 and 9.1 with a female biased sex ratio (64.6 and 68.6 percent females). The parasitoid failed to emerge from 45.9 and 38.9 percent parasitized eggs of P. xylostella and C. cephalonica. During post-embryonic development, 38.1 and 31.9 percent mortality was observed and maximum mortality was in the pupal stage.

To determine the suitable food media for the mass production of Corcyra cephalonica (Stainton), eleven types of food media viz., sorghum, pearlmillet, maize, coarse rice, wheat bran, rice husk, sorghum + rice husk (9:1), pearl millet + rice husk (9:1), pearl millet + rice husk + wheat bran (5:1:1), maize + rice husk (9:1) and rice + rice husk (9:1) were used for rearing. Observations were taken on average development period, percentage of moth emergence and weight of eggs. Food efficiency index (FEI) was calculated by dividing the product of percent emergence and egg weight by average development period. The FEI was highest in case of sorghum followed by pearlmillet, maize, pearlmillet + rice husk + wheat bran, sorghum + rice husk, wheat bran and rice, while in other food media it was extremely low.

Studies on Trichogrammatoidea bactrae Nagaraja were carried out with the objective of determination of storage conditions conducive for holding the parasitiod. From parasitized eggs of Corcyra cephalonica (Stainton), stored after 3-7 days of parasitization for 5 days at 10°C, above 50 per cent adult emergence Occurred and eggs could not be stored for more than 7 days. However, at 15°C, storage could be extended up to 18 days but with low emergence (17.2%), In another experiment, exposure of eggs to 10 and 15°C for 5, 10 and 15 days after 3, 5 and 7 days of parasitization, provided satisfactory adult emergence from eggs stored at 15°C for 5 days after 5 and 7 days of parasitization (72.3 and 72.1%) and for 10 days after 5 days of parasitization (69.8%). Occasionally from the eggs stored for more than 5 days at 15°C after 7 days of parasitization adult emergence occurred in storage. In eggs without adult emergence hole, mortality often occurred in the pupal stage (55.9 and 61.6% after 3 and 5 days of parasitization, respectively), followed by larval (21.3 and 6.6%, respectively) and adult stage (22.8 and 31.7 %, respectively). Thus storage at 15°C for 10 days after 5 days of parasitization will be the right choice.

Effeet of egg density of Corcyra cephalonica (Stainton) on parasitism and adult emergence in Trichogramma chilonis Ishii was investigated under two systems of rearing in the lahoratory. In nucleus culture maintenance system, 150 eggs/two females and under mass production system, 500 adults to 1 cc of eggs (about 15,000 eggs) were found most optimum for efficient utilization of eggs and females. The highly significant regression coefficients obtained for relation between egg density and number of egg parasitised, and per cent parasitisation and number of adults indicated the usefulness of prediction model.

A machine for making Corcyra egg cards was designed, fahricated and evaluated for labour efficient mass production of Trichogramma egg cards. The machine could paste on an average 9.97 ml of eggs per minute compared to 0.7 ml in the manual method. The number of eggs pasted per 0.25 sq cm of the card varied from 32 to 145 eggs with an average of 73 eggs for machine made cards whereas the corresponding values for manually made cards were 45, 118 and 76.65, respectively. The average number of egg cards produced per hour in the machine operated system was 14.3 times higher when compared to the manual system. The machine is provided with an in-built UV chamber for the sterilization and inactivation of the host eggs. The cost of the machine works out to be about Rs.20, 000 per unit and this is the first report of a machine developed for host egg card preparation from India.

Four insecticides commonly used in the management of cotton pests were field tested for their deleterious effects on an effective egg-parasitoid, Trichogramma chilonis Ishii. Endosulfan (0.05%) proved to be safer than quinalphos (0.05%), monocrotophos (0.04%) and fenvalerate (0.04%). Both, the emergence and parasitism of T. chilonis decreased gradually as the time increased from 12 to 72h in all treatments including control.

Experiments were carried out to improve the Culturing technique of the mirid bug Cyrtorhinus lividipennis for the biological control of hoppers in rice. Corcyra cephalonica eggs pasted on the rice pseudostem and the rice seedlings served as food and oviposition substrate, respectively, for the mirid. The results indicated an increase in the culturing efficiency to a tune of about 10 to 25 per cent over Bentur and Kalode's method.

The life table and intrinsic rate of increase of Acanthaspis pedestris Stal (Heteroptera: Reduviidae) a predator of lepidopteran insect pests viz., Spodoptera litura (Fabricius), Earias vittella (Fabricius) and Corcyra cephalonica (Stainton) are discussed. The intrinsic rates of increase were 0.039, 0.032 and 0.028 per female per day on S. litura, E. vittella and C. cephalonica, respectively. The population multiplied 44.44, 24.79 and 19.36 times in the cohort generation time of 115.19,121.82 and 133.19 days on S. litura, E. vittella and C. cephalonica, respectively.