Trichogramma Chilonis Research Articles

Olfactory Response of Trichogramma chilonis to Capsicum annuum

Olfactory attraction of an egg parasitoid, Trichogramma chilonis, to the hot pepper ( Capsicum annuum) and other host plants of its host insect species, Helicoverpa assulta, was studied in laboratory experiments. T. chilonis was attracted more to the hot pepper than the tobacco ( Nicotiana tabacum), eggplant ( Solanum melongena), carrot ( Daucua carot var. sativa), or clean air flow. A higher attraction of T. chilonis was observed in combined leaf and green fruit of the hot pepper plant than leaf or fruit alone, and its red fruit had the least attractivity. But the combination of pepper odor and H. assulta sex pheromone did not attract more than the pepper odor or sex pheromone alone.

Physical and chemical plant characters inhibiting the searching behaviour of Trichogramma chilonis

AbstractSeveral plant characters are known to affect the searching behaviour and parasitization efficiency of Trichogramma spp. (Hymenoptera: Trichogrammatidae). In this study, plant characters contributing to the low Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) egg parasitism levels on pigeonpea (Cajanus cajan (L.) Millspaugh) were investigated. The efficiency of T. chilonis on pigeonpea was dependent on the plant structure on which the host eggs were found. In a cage experiment, more than 55% of eggs placed on leaves were parasitized, while 1% of eggs on calyxes and no eggs on pods were parasitized. In a filter paper bioassay, parasitoids were deterred by acetone and hexane surface extracts from pigeonpea pods but showed no response to water extract. The searching behaviour of the parasitoids was not affected by different solvent extracts from the surface of pigeonpea leaves. In a four‐armed airflow olfactometer, T. chilonis was repelled by volatiles from pigeonpea pods but showed no response to volatiles derived from hexane extract of pod surfaces. Volatile infochemicals and hexane surface extracts from pods of two wild Cajanus species, C. scarabaeoides (L.) Thours and C. platycarpus (Bentham) van der Maesen, were similarly deterrent to T. chilonis. The movement of the parasitoids on pigeonpea pods and calyxes was inhibited by long trichomes and wasps were trapped by sticky trichome exudates. Parasitoids walked significantly faster on leaves than on pods. The walking speed on both pods and leaves increased significantly after washing with hexane. The results presented in this paper show that the plant growth stage and the plant structures preferred by H. armigera for oviposition are the least suitable for T. chilonis, contributing to the low parasitoid efficiency on pigeonpea.

Constraints on the use of Trichogramma Egg Parasitoids in Biological Control Programmes in India

The use of Trichogramma (Hymenoptera: Trichogrammatidae) egg parasitoids for the biological control of several insect pests, including the pod borer Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae), is being promoted in India. Several companies supply these parasitoids to farmers, but no evaluation of product quality has been made. Low product quality is recognized as being one of the most important reasons for the failure of these biocontrol agents. In this study, Trichogramma chilonis Ishii egg-cards were obtained from eight producers in southern India. Product quality was evaluated using the following parameters: number of eggs/card, percentage parasitism, percentage emergence, progeny sex ratio and percentage of deformed females. In addition, producers were asked for the average values of these parameters in their production systems and for their recommendations for the use of T. chilonis to control H. armigera in cotton. The quality of the egg-cards was highly variable and was much lower than that stated by the producers. The recommended frequency and interval of releases, and the number of parasitoids to be released, differed greatly among producers. The low product quality results in up to 85% fewer parasitoids being released than is recommended by the producer. The effect of the low product quality and the highly variable release recommendations on applied biological control programmes is discussed. Suggestions for more effective use of Trichogramma spp. are given.

Saturated hydrocarbons as kairomonal source for the egg parasitoid, Trichogramma chilonis Ishii (Hym., Trichogrammatidae)

Abstract: Studies on the effect of saturated hydrocarbons on parasitization by the egg parasitoid Trichogramma chilonis Ishii were carried out in the laboratory and net house. Bioassay of 11 hydrocarbons, viz. pentadecane, heptadecane, ecosane, heneicosane, docosane, tricosane, tetracosane, pentacosane, hexacosane, octacosane and hexatriacontane, were carried out under controlled conditions in the laboratory. These were also tested on potted maize plants in a net house. Among the saturated hydrocarbons, octacosane recorded the highest parasitoid activity index followed by docosane and tricosane. However, tricosane caused the highest percentage of parasitization, which was at par with octacosane and docosane. A positive correlation was found between concentration and kairomonal activity only in case of tricosane. In the net house, tricosane recorded the highest parasitization. Response of the parasitoid to egg cards treated with hydrocarbons decreased with increase in distance between the release point and host eggs. No parasitization was observed in host eggs placed at 8 m and 10 m away from the point of release except in the case of tricosane and pentacosane.

Effects of host-egg age on the parasitism by Trichogramma chilonis Ishii (Hymenoptera : Trichogrammatidae), an egg parasitoid of the diamondback moth

Eggs of Plutella xylostella (DBM), 0, 1, 2, 2.5 and 3 days old, were offered to female Trichogramma chilonis in a laboratory experiment. Females oviposited on host eggs of all ages tested. However, the percentage of oviposition was highest on the l-day-old host eggs, and decreased as the host egg became younger or older than the 1-day-old host. Parasitized host eggs did not hatch. The emergence rate was high on the 1-day-old eggs but did not differ among other host ages, except the 3-day-old host. A T. chilonis progeny failed to complete development on the 3-day-old DBM eggs. Hind tibia length of the emerging parasitoid female progeny also tended to decrease as the host egg became older than 2 days. Host age had no significant effect on development time. A method of utilization of the parasitoid in a biological control program against DBM is also discussed based on the effect of DBM egg age on the parasitism of the parasitoid.

Acceptance and suitability of ultraviolet‐irradiated Helicoverpa armigera (Hühner) (Lep., Noctuidae) eggs for Trichogramma chilonis Ishii (Hym., Trichogrammatidae)

AbstractHelicoverpa armigera (Hbn.) eggs were irradiated with a 30 W ultraviolet (UV)‐lamp from a distance of 30 cm. Egg mortality increased with duration of exposure to the UV‐light source; exposure for 48 min was sufficient to kill 98% of the eggs. Survival of the egg parasitoid Trichogramma chilonis Ishii was lower on eggs irradiated for 60 and 90 min than on untreated control eggs. Clutch size and sex ratio of the parasitoid progeny were similar in irradiated and control eggs. The lower suitability of irradiated host eggs was not recognized by female wasps as they accepted irradiated and control eggs equally in a choice test. The higher parasitoid mortality in irradiated eggs may be a result of morphological changes in the host egg chorion. Supporting this hypothesis, it was observed that the duration of drilling by the parasitoid was significantly shorter on irradiated eggs than on control eggs.

Recycling of spent larval food of Corcyra cephalonica for fuel gas production

Commercial production of the egg parasitoid, Trichogramma chilonis Ishii (Trichogrammatidae: Hymenoptera) needs a continuous egg supply of Corcyra cephalonica Stainton (Pyralidae: Lepidoptera). Larvae of C. cephalonica are reared in pearl millet grains in commercial laboratories and the disposal of accumulated spent larval medium (90 days after usage) poses a problem. Experiments conducted to recycle the biowaste indicated that anaerobic digestion of spent larval medium with cow dung slurry at 1:3 and 3:1 ratio produced higher total biogas and fuel methane output equal to cow dung slurry alone. Spent larval medium alone, however, resulted in minimum biogas and methane output.

Studies on the Comparative Efficacy of Three Species of Trichogramma for the Control of Cotton Bollworms

The comparative efficacy of Trichogramma aehaeae Nagaraja and Nagarkatti, Trichogramma brasiliensis Ashmead and Trichogramma chilonis Ishii (8 releases @ 1,50,000 parasitised eggs/ha) was studied. Of the three species, T.achaeae was the most effective with 18.7% boll infestation, 51.8 bolls/plant and 14.3 q/ha seed cotton yield, followed by T.chilonis with 23.5% boll infestation,48.4 bolls/plant and 12.8 q/ha yield and T.brasiliensis with 27.7% boll infestation,43.2 bolls/plant and 11.4 q/ha seed cotton yield, Control had 32.3 % boll infestation, 30.6 bolls/plant and 7.6 q/ha seed cotton yield which were significantly lower than in different treatments.

Discrimination between Parasitized and Unparasitized Hosts in an Egg Parasitoid, Trichogramma chilonis ISHII (Hymenoptera: Trichogrammatidae)

Discrimination between Parasitized and Unparasitized Hosts in an Egg Parasitoid, Trichogramma chilonis ISHII (Hymenoptera: Trichogrammatidae)

Movement of Introduced Biological Control Agents onto Nontarget Butterflies, Hypolimnas spp. (Lepidoptera: Nymphalidae)

Since 1911, over 100 species of exotic organisms have been deliberately introduced for biological control of various pests on Guam. Of these, 27 species were released against seven lepidopterous pests including one butterfly and one skipper. Recently, concern has mounted about the negative effects of these introduced biocontrol agents on nontarget species, particularly endemic island species. Guam may have suffered extinction of as much as 20–25% of its butterfly fauna. To determine the extent of movement and possible impacts of biocontrol agents on nontarget butterflies, mortality factors affecting juvenile stages of Hypolimnas anomala (Wallace) and Hypolimnas bolina (L.) were studied. Both species were attacked by the same parasitoids and predators, which included native, accidentally introduced, and deliberately introduced species. Parasitoids killed 2.4% of the eggs of H. anomala , and ants removed about 25% of the eggs. Parasitization was about 40% in H. bolina , and ants killed about 35% of the eggs. One species introduced for biological control, Trichogramma chilonis Ishii, was found parasitizing the eggs, but it caused little mortality. No larval parasites were reared for either species. H. anomala suffered heavy mortality from a disease. Both species were attacked by ants and two exotic, self-introduced predators. The major pupal parasite was Brachymeria lasus (Walker), a deliberate biological control introduction. B. lasus parasitized 24.6% of the pupae of H. bolina and 2.9% of those of H. anomala . Ants attacked 17% of H. anomala pupae and 7% of those of H. bolina. B. lasus and T. chilonis are polyphagous parasitoids that have the potential to affect a variety of nontarget species. This type of parasitoid, and highly polyphagous predators like ants, should require more intensive evaluation and review for use in classical biological control programs than more specialized species.

Superior Strain Selection of the Egg Parasitoid Trichogramma chilonis Ishii - Biological Parameters

To select superior strains of the egg parasitoid Trichogramma chilonis Ishii, collections were made from cotton ecosystems of six different agroclimatic zones of the country viz. , Anand (Gujarat), Ludhiana (Punjab), Coimbatore (Tamil Nadu), Bangalore (Karnataka), Rajahmundry (Andhra Pradesh) and Nagpur (Maharashtra). These ecotypes are referred as BioC1, BioC2, BioC3, BioC4, BioC5, and BioC6 respectively. Mean fecundity during F1, F20, and F40 generations in the laboratory was significantly more in BioC1, BioC2, and BioC6 than in others. Longevity of males was 4.0, 4.0 and 4.2 days and that of females was 7.0, 7.4 and 7.3 days respectively in BioC1, BioC2 and BioC6 strains, which was higher than in the other three ecotypes. Net reproductive rate (Ro) and rate of increase per female per generation (λ) was higher in BioC1 and BioC2. There was no difference in emergence pattern and sex-ratio amongst six ecotypes. Results thus, indicated that BioC1 and BioC2 are superior to other ecotypes.

Indigenous and Exotic Trichogrammatids (Hymenoptera: Trichogrammatidae) Evaluated for Biological Control of Eoreuma loftini and Diatraea saccharalis (Lepidoptera: Pyralidae) Borers on Sugarcane

Investigations were conducted to determine relative suitability of eggs of sugarcane pests Eoreuma loftini (Dyar) and Diatraea saccharalis (F.) for parasitization by indigenous and exotic trichogrammatids. The eight species of trichogrammatids tested (three collected locally, the others from elsewhere) successfully developed on eggs of both hosts, with number of eggs parasitized per female ranging from 14.0 to 36.6 for E. loftini and from 0.1 to 21.5 on D. saccharalis. The most successful species on E. loftini and D. saccharalis were Trichogramma retorridum (Girault) and Trichogramma fuentesi Torre, respectively. In addition, exposure of E. loftini egg masses concealed in paper substrata or in dry leaf material demonstrated differences among parasite species in proportion of eggs attacked, ranging from 92.0% for T. retorridum to 18.0% for Trichogramma chilonis Ishii. Results indicate that although all eight species developed on E. loftini in the laboratory, the concealed location of E. loftini egg masses in the field may place limits on parasitization by trichogrammatids.

Density supression effects of some cabbage defoliators by released Trichogramma chilonis in the autumn

Density supression effects of some cabbage defoliators by released <i>Trichogramma chilonis</i> in the autumn

Intercropping maize and sweet potatoes, effects on parasitization of Ostrinia furnacalis eggs by Trichogramma chilonis

Trichogramma chilonis is the most important natural enemy attacking Ostrinia furnacalis on Guam, but it does not keep O. furnacalis below the economic threshold. O. furnacalis normally does not attack maize on Guam until about the 4th week after planting, when it appears in high numbers. To see if populations of T. chilonis could be augmented so that they were high when high when the borer appeared, we provided an alternate host for the parasite to build up on by intercropping maize with sweet potato. Sweet potato is a host for Agrius convolvuli, whose eggs are also attacked by T. chilonis. Parasitization rates of O. furnacalis eggs by T. chilonis tended to be higher on maize intercropped with sweet potatoes at a spacing of 3 rows maize to 1 row potatoes 936% parasitized), compared to a maize monoculture (27% parasitized), but the difference was not significant. T. chilonis parasitized between 70 and 100% of the eggs of A. convolvuli, but less than 20% of O. furnacalis eggs were attacked.

Sex allocation and effects of superparasitism on secondary sex ratios in the gregarious parasitoid, Trichogramma chilonis (Hymenoptera: Trichogrammatidae)

The role of sex-controlling behaviour at oviposition in generating primary sex ratios, and the effect of larval competition on secondary sex ratios, were studied in the gregarious endoparasitoid, Trichogramma chilonis. The production of a fertilized (female) egg is indicated by the incorporation of a pause in abdominal movements during oviposition, while the absence of it indicates the production of an unfertilized (male) egg. During each ovipositional bout, the first male egg is deposited at the second oviposition, and thereafter at intervals of about eight eggs. This simple pattern enables the wasps to adjust their progeny sex ratios under local male competition to a wide range of host size. Inexperienced wasps do not distinguish between parasitized and healthy hosts. Immature mortality is not significantly different between the sexes when a host is attacked by a single wasp, while females suffer higher immature mortality than males when superparasitism occurs.

Recovery of two exotic parasites,Trichogramma brasiliensis [Hym.: Trichogrammatidae] andEucelatoria bryani [Dip.: Tachinidae] fromHeliothis armigera [Lep.: Noctuidae] in tomato fields

Heliothis armigera (Hubner) is a major pest of several crops especially tomato and pulses in India. Indigenous natural enemies likeCarcelia illota Curr.,Campoletis chlorideae Uchida,Trichogramma chilonis Ishii andHexamermis sp are unable to exert adequate control ofH. armigera in tomato. Field trials were conducted with 2 exotic parasites,Trichogramma brasiliensis (Ashmead) andEucelatoria bryani Sabrosky in tomato fields around Bangalore. Both the parasites were recovered fromH. armigera in tomato fields. Field parasitism inH. armigera byT. brasiliensis ranged from 34.6 to 51.3%. WithE. bryani, the parasitism ranged from 0.0 to 8.0%.