Impact of Spodoptera littoralis (Boisd.) and Agrotis ipsilon (Hufn.) larval frass on oviposition of conspecific insects

Ethanolic extracts of larval frass of the cotton leaf worm and the black cutworm were prepared and tested to deter the eggs lay of the adults of the same insects. Two different types of food were used for larval feeding. Extracts fractions were identified using gas chromatography–mass spectrometry analysis. High concentrations were more deterrent to oviposition than low. Extracted frass of fed larvae on semi-artificial diet was more effective than others fed on natural host. Sensitivity of the black cutworm adult females to the cotton leaf worm frass extract was clearly observed at high tested concentration of L_1–3 and L₄ frass extracts which resulted completely oviposition deterrent. Several fatty acids were identified qualitatively and quantitatively in frass extracts of different larval instars of both target insects. Type and quantity of fatty acid depends mainly on larval food source and larval instar, except palmitic acid which recorded at all larval instars and food sources. Oleic acid and ethyl 9-hexadecaenoic acid were found when semi-artificial diet used as a food source while myrisitic acid was observed only in extracted frass of fed larvae on castor oil leaves.     

Beneficial effect of supplementing an artificial diet for Amblyseius swirskii with Hermetia illucens haemolymph

Artificial diets have been developed to sustain the mass rearing of a wide range of arthropod natural enemies, with varying success. In some cases, such diets can be optimized using insect‐derived materials, such as haemolymph. In this study, we examined the effect of supplementing haemolymph of the black soldier fly, Hermetia illucens, to a basic artificial diet for the phytoseiid mite Amblyseius swirskii. The survival, development and reproduction of the predatory mite were assessed when fed on artificial diets composed of honey, sucrose, tryptone, yeast extract and egg yolk, supplemented with 5%, 10%, or 20% of H. illucens pre‐pupal haemolymph. Developmental time from larva to adult was shorter for males and females offered artificial diets supplemented with 20% haemolymph vs. the basic diet. The oviposition rate and total fecundity of females reared on the basic diet were substantially lower than those of females supplied with the enriched diets. The intrinsic rate of increase was highest on the diet containing 20% haemolymph, followed by those containing 10% and 5% haemolymph. In a subsequent diet‐switching experiment, mites fed on the basic diet in their juvenile stages were switched upon adulthood to diet enriched with different concentrations of H. illucens haemolymph. The females that were fed with the enriched diets from the adult stage on had higher oviposition rates and fecundities than those maintained on the basic diet, but their reproductive parameters were not significantly affected by the concentration of the haemolymph in the artificial diet. In conclusion, supplementing artificial diets with black soldier fly haemolymph significantly improved their nutritional value for A. swirskii. Our findings indicate the potential of using H. illucens as a cheap source for haemolymph in artificial diets, as the fly can be cost‐effectively produced at a large scale on organic waste materials.     

Host Location of Hyssopus pallidus, a Larval Parasitoid of the Codling Moth, Cydia pomonella

The effectiveness of parasitoids as biological control agents depends largely on their host location behavior. In this study we describe the host-searching behavior of Hyssopus pallidus (Askew), a larval parasitoid of the codling moth Cydia pomonella L. We observed parasitoid behavior on mature apples (a potential host patch) and elucidated some of the stimuli which determine host location. Female wasps showed more complex and intensive searching on infested apples than on mechanically damaged or noninfested apples. Wasps were able to enter infested apples through the calyx or the tunnel made by the host larvae and parasitize them. Area-restricted searching was observed on infested apples, in particular on areas contaminated with host frass. In a further bioassay, we confirmed that host frass contains a host location kairomone. The kairomone appears to be produced by the host independently from its diet, even though frass produced by hosts fed on an apple are more attractive than frass produced by hosts fed on a fruit-devoid artificial diet. The capability of H. pallidus to locate its host inside apples makes the foraging strategy of this species potentially useful as a biological control agent.     

Turbulence, trees and semiochemicals: wind-tunnel orientation of the predator, Rhizophagus grandis, to its barkbeetle prey, Dendroctonus micans

Abstract. Insects apparently responding to the visual stimulus offered by a tree or other object may also be responding to the variety of physical effects caused by the obstruction, including turbulence, a reduction in wind velocity and eddies. The relative importance of prey odour associated with the bark beetle Dendroctonus micans (Kugelann) (Scolytidae), prey-host-tree odour, silhouette, and physical barrier to the wind, in the orientation and landing behaviour of a predatory beetle, Rhizophagus grandis Gyllenhall (Rhizophagidae), were investigated. R. grandis responded very positively to the frass of its prey when presented on a 'tree' but not to the same quantity of frass presented alone. Frass on black plastic uPVC pipes was significantly more attractive than frass on real host tree logs, suggesting that host-tree volatiles do not enhance the attractiveness of prey frass.
The beetles responded to 'transparent' Mylar three-dimensional cylinders in the same way as they did to the black plastic pipes. Beetles were also tested with frass and two-dimensional stimuli offering a visual stimulus or physical barrier alone or in combination. Frass with a two-dimensional visual stimulus was no better than frass alone: few insects landed. Significantly more insects were attracted to the same two-dimensional visual stimulus with a hidden upwind barrier producing turbulence, but a similar number were attracted to the frass in front of a hidden barrier alone. As many plants are similar in size to the logs used in these experiments, comparable effects might influence the behaviour of other phytophagous insects, their predators and parasitoids.     

Development ofTrichogramma australicum (Hym.: Trichogrammatidae) at low and high population density in artificial diet

We compared the development ofTrichogramma australicum Girault in artificial-diet filled artificial “eggs” containing 10–15 (low density) or 35–50 (high density) immature parasitoids. The size of low- and high-densityT. australicum eggs at 1, 15, 30 and 36 h was not significantly different. Also, incubation time of low- and high-density eggs in artificial diet was similar. Appearance of urate bodies in larvae developing low and high density occurred at the same time (100–108 h). Size of immatureT. australicum in low density significantly increased after the urate bodies had appeared. Black deposits appeared on the surface ofT. australicum prepupae soon after all diet had been consumed (at 108–120 and 144–168 h in low and high density, respectively). We concluded that the appearance of the black deposits was an indication of the onset of the prepupal stage. The pupal size was significantly larger at low density than high density. Mortality of prepupae and pupae was significantly higher at low density than at high density. Proportion of larvae at high density developed to abnormal and normal wasps. Wasps did not emerge from larvae reared at low density.     

Differential utilization of ash phloem by emerald ash borer larvae: ash species and larval stage effects

• 1 Two experiments were performed to determine the extent to which ash species (black, green and white) and larval developmental stage (second, third and fourth instar) affect the efficiency of phloem amino acid utilization by emerald ash borer (EAB) Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) larvae.
• 2 EAB larvae generally utilized green ash amino acids more efficiently than those of the other two species. For example, the concentrations of only six (two essential) and seven (two essential) amino acids were lower in frass from EAB that fed upon black and white ash than in the corresponding phloem, respectively. By contrast, concentrations of 16 (eight essential) amino acids were lower in the frass from EAB that fed upon green ash than in the phloem. In addition, in green ash, the frass : phloem ratios of 13 amino acids were lower than their counterparts in black and white ash.
• 3 The concentrations of non‐essential amino acids glycine and hydroxylproline were greater in frass than in phloem when EAB fed on black ash, although not when EAB fed on green or white ash.
• 4 The concentration of total phenolics (a group of putative defensive compounds to EAB, expressed as antioxidant activity of acetone extraction) was high in EAB frass but even higher in the phloem samples when the data were pooled across ash species and EAB larval stages. This suggests EAB larvae may eliminate phenolics through a combination of direct excretion and enzymatic conversion of phenolics to nonphenolics before excretion. Because the ratio of frass total phenolics to phloem total phenolics in white ash was lower than the ratios in black and green ash, the ability to destroy phenolics or convert them to nonphenolics was greater when EAB larvae fed on white ash.
• 5 Fourth‐instar EAB extracted phloem amino acids, including threonine, more efficiently than third‐instar EAB. The different larval developmental stages of EAB did not differ in their apparent ability to destroy phenolics or convert them to nonphenolics.

     

Behavioural responses of bethylid parasitoid species of the coffee Berry borer to chemicals cues from host and non-host dust/frass

The bethylid wasps Cephalonomia stephanoderis Betrem and Prorops nasuta Waterston are parasitoids of the coffee berry borer, Hypothenemus hampei (Ferrari), the most serious insect pest of coffee worldwide. Recent studies on the host location behaviour of these parasitoids have shown that females are attracted to volatile compounds released by immature stages and dust/frass of H. hampei. Also, these studies have reported that the locomotory behaviour of parasitoids is influenced by contact chemical cues from host dust/frass. In this study, we investigated the responses of females of both species to volatiles and contact cues from dust/frass from different sources. Volatiles from dust/frass from H. hampei-infested coffee and maize infested with Sitophilus sp were attractive to P. nasuta females. In contrast, C. stephanoderis females were only attracted to the volatiles from dust/frass from H. hampei-infested coffee. Volatiles from an artificial diet used for rearing H. hampei were not attractive to females of both species. The effect of methanolic extracts from dust/frass from different sources on the patch-searching time of parasitoids was analysed using the Ethovision software. P. nasuta females spent more time in the patches treated with extracts of dust/frass from H. hampei-infested berries, artificial diet, and from maize infested with Sitophilus sp than on patches treated with dry coffee extract or solvent control. C. stephanoderis females spent more time on patches treated with dust/frass extracts from H. hampei-infested berries and artificial diet than on patches treated with an extract of dust/frass from maize infested with Sitophilus sp, an extract of dry coffee, and methanol control.     

How the oligophage codling moth Cydia pomonella survives on walnut despite its secondary metabolite juglone

Besides apple, its primary host, the codling moth Cydia pomonella uses walnut as a secondary host. Abundance of toxic naphthoquinones, among which juglone prevails, does not restrain this economically important pest insect from infesting walnut, but processes underlying the suitability of this host were yet unknown. Larvae feeding on an artificial diet supplemented with juglone at naturally occurring concentrations survived to adulthood at a similarly high proportion as those in the juglone-devoid control. However, their development time was prolonged, their weight gain was reduced, and adult sex ratio was distorted. Results from the natural system with walnut and apple fruits were in line with data gained on artificial diet. Remarkably, a twofold increase of the maximal juglone content reported from the walnut husk was lethal to the larvae. Chemical analyses showed that larvae feeding on the artificial diet supplemented with juglone concentrations present in walnut contained 1,4,5-trihydroxynaphthalene and excreted it in their frass, whereas the hemolymph contained neither detectable amounts of juglone nor the product of its reduction. Hence, effective metabolism of juglone in the intestinal system of the larvae underlies their survival on host plants containing this defensive compound.     

Esterification of cholesterol and cholestanol in the whole body,tissues, and frass of Heliothis zea

The quantity of free and esterified sterols in the whole body, intestine, hemolymph, fat body, and frass of 6th-instar larvae of H. zea, fed cholesterol or cholestanol, was measured in order to determine if there was a difference in the utilization of these two molecules. The principal sterol in the tissues of the larvae was cholestanol or cholesterol, when they were fed diet containing these two molecules, respectively; there was little, if any, metabolism of dietary cholestanol to cholesterol. There was little or no difference in the amount of total sterol in the whole body, tissues, or frass of larvae fed the two different diets, indicating that the absence of a Δ⁵-bond in cholestanol does not prevent the uptake or distribution of this sterol to various tissues. However, the relative percentage of steryl ester was significantly higher in prepupae reared on a diet containing cholestanol instead of cholesterol (6–7-, 4-, 13-, 4-, and 2-fold increase, for the whole body, intestine, hemolymph, fat body, and frass, respectively). The average percentage of total sterol that was esterified in the tissues was greater in the fat body (10.8 ± 15.4 and 44.2 ± 12.3%, respectively, for larvae fed cholesterol and cholestanol) than in the hemolymph (0.5 ± 0.1 and 6.3 ± 0.8%) and intestine (1.2 ± 0.1 and 4.7 ± 1.1%). The percentage of sterol that was esterified in the frass of larvae was large (26.9 ± 3.7 and 48.2 ± 0.5%, respectively, for larvae fed cholesterol and cholestanol). Therefore, the fact that larvae of H. zea fed cholestanol, instead of cholesterol, contain this saturated molecule as their principal tissue sterol and preferentially esterify it may explain, at least in part, why their rate of growth on cholestanol is slower than on cholesterol.     

Effect of rearing Cactoblastis cactorum on an artificial diet on the behaviour of Apanteles opuntiarum

Cactoblastis cactorum's unintended arrival to Florida and its expansion in North America represent a threat to Opuntia-based agriculture and natural ecosystems in the United States and Mexico. Apanteles opuntiarum attacks C. cactorum and is a potential biocontrol agent due to its specificity, wide distribution and occurrence. Laboratory rearing methods using excised cladodes for C. cactorum as host larvae of A. opuntiarum were developed, but require a continuous supply of cactus with a risk of microorganisms compromising the rearing. Host cues —including odour of host metabolic subproducts like faeces and chemicals emitted by the attacked plant— are the most important signals that help a parasitoid locate a host. Little attention has been paid to behavioural differences of parasitoids in the presence of hosts reared on artificial diet. Thus, the aims of the present work were to determine the effect of meridic diet for C. cactorum on parasitoid behaviour and to determine whether prior experience (previous exposure to stimuli) influences the response of A. opuntiarum towards hosts. Parasitism rates were assessed using cladodes or meridic diet as larvae food source. Behavioural experiments also evaluated the effect of prior experience (larvae or frass from larvae fed on cactus or diet) on host searching, encounter and attack of different stimulus (larvae or frass from larvae fed on cactus or diet). Parasitism behaviour of A. opuntiarum was negatively affected by the use of meridic diet to feed host larvae. Presenting parasitoids with larvae rather than their frass influenced excitatory behavioural responses in terms of contact, probing and stinging in A. opuntiarum females, whereas the effect of prior experience on the behaviours was not quite consistent. For laboratory mass-rearing procedures of A. opuntiarum, we recommend previous contact of females with frass from cactus-fed larvae and a piece of cactus, which showed enhanced parasitism rates.     

Forage collection,substrate preparation,and diet composition in fungus‐growing ants

1. Variation and control of nutritional input is an important selective force in the evolution of mutualistic interactions and may significantly affect coevolutionary modifications in partner species. 2. The attine fungus‐growing ants are a tribe of more than 230 described species (12 genera) that use a variety of different substrates to manure the symbiotic fungus they cultivate inside the nest. Common ‘wisdom’ is that the conspicuous leaf‐cutting ants primarily use freshly cut plant material, whereas most of the other attine species use dry and partly degraded plant material such as leaf litter and caterpillar frass, but systematic comparative studies of actual resource acquisition across the attine ants have not been done. 3. Here we review 179 literature records of diet composition across the extant genera of fungus‐growing ants. The records confirm the dependence of leaf‐cutting ants on fresh vegetation but find that flowers, dry plant debris, seeds (husks), and insect frass are used by all genera, whereas other substrates such as nectar and insect carcasses are only used by some. 4. Diet composition was significantly correlated with ant substrate preparation behaviours before adding forage to the fungus garden, indicating that diet composition and farming practices have co‐evolved. Neither diet nor preparation behaviours changed when a clade within the paleoattine genus Apterostigma shifted from rearing leucocoprinous fungi to cultivating pterulaceous fungi, but the evolutionary derived transition to yeast growing in the Cyphomyrmex rimosus group, which relies almost exclusively on nectar and insect frass, was associated with specific changes in diet composition. 5. The co‐evolutionary transitions in diet composition across the genera of attine ants indicate that fungus‐farming insect societies have the possibility to obtain more optimal fungal crops via artificial selection, analogous to documented practice in human subsistence farming.     

Oviposition deterrents in larval frass of the cotton boll worm, Helicoverpa armigera (Lepidoptera: Noctuidae): chemical identification and electroantennography analysis

Oviposition deterrents in the frass of cotton bollworm (CBW), Helicoverpa armigera larvae fed on an artificial diet (FA) and on cotton Gossypium hirsutum leaves (FC) were investigated by behavioral bioassays and electroantennography analyses in the laboratory. It was found that a water suspension or a hexane extract of the frass FA or FC, in contrast to the corresponding foods, significantly deterred oviposition of conspecifics. When hexane extracts of the frass FA and FC were further partitioned into polar and neutral lipid fractions, two polar fractions significantly reduced oviposition. The neutral fraction from frass FC also exhibited significant deterrence, although the activity was much lower than that of the corresponding polar fraction. The polar lipid fractions contained several fatty acids, mainly palmitic and oleic acid at the ratio nearly 1:1. A blend of authentic fatty acids of the same composition found in frass FA or FC mimicked the deterring effect. Moreover, these fatty acids and their blend at the ratio found in frass FA or FC elicited significant electroantennogram responses and typical dose-response curves. Thus, it is suggested that CBW larvae may deploy two types of oviposition deterrents: a non-specific and a specific one. The former is a blend of fatty acids, independent of food and plays an important role in oviposition deterrence, whereas the latter may be produced only when the larvae feed on cotton leaves. The possible explanations of this deployment have also been discussed.     

Larval diet influence on oviposition behaviour inSpodoptera littoralis

Females ofSpodoptera littoralis Boisd. (Lepidoptera: Noctuidae) with different feeding experiences during their larval development were tested for their ovipositional response to methanol extracts of larval frass and semisynthetic diets. The effect of the following frass, diet and diet component extracts was tested: (a) frass fromS. littoralis orAgrotis segetum larvae fed on a potato-based diet; (b) frass fromS. littoralis larvae fed on a wheat germ-based diet; (c) potato and wheat germ-based diets; and (d) potatoes and wheat germ. Ovipositing females without prior experience of the potato diet were deterred by extracts of: (1) larval frass from either species fed on potato diet; (2) the potato-based diet; (3) potato. Also females with experience of the potato diet during only a part of their larval development were deterred from oviposition by frass of larvae reared on the potato diet and by the diet itself. However, for females reared on the potato diet for their entire larval development, oviposition was no longer deterred by either of the three extracts listed above. Extracts of: (1) frass from larvae of either species reared on wheat germ diet: (2) the wheat germ diet; or (3) wheat germ did not significantly affect oviposition. Females with ablated antennae were still deterred by frass extracts from larvae fed on potato diet, when they had been reared on the wheat germ diet. In feeding experiments, larvae of larval stage one and of larval stage three-four reared on either of the two diets preferred to feed on the wheat germ diet. However, the preference was significantly stronger for larvae with no prior contact with the potato diet. The effect of larval experience on the loss of oviposition-deterring activity by extracts of larval frass, diets and diet components is discussed in view of induction and selection.     

Identification and origin of host-associated volatiles attractive to Prorops nasuta, a parasitoid of the coffee berry borer

Previous studies have shown that prepupae/pupae and dust/frass from Hypothenemus hampei (Ferrari) reared on coffee berries were attractive to its parasitoid Prorops nasuta Waterston, while the same biological materials obtained from an artificial diet were not. In this study, we identified the volatiles from prepupae/pupae and dust/frass from H. hampei reared on Coffea canephora Pierre ex Froehner berries and artificial diet by gas chromatography coupled with mass spectrometry (GC?CMS), evaluated their behavioural activity, and investigated the possible origin of the kairomones in the H. hampei dust/frass attractive to P. nasuta. The GC?CMS analysis indicated that 24 peaks were consistently present in the headspace volatiles of dust/frass from H. hampei reared on coffee berries, 18 of these peaks were identified. Nineteen compounds were found in the dust/frass from H. hampei reared on an artificial diet. The compounds 1-octen-3-ol, limonene, n-tridecane, n-tetradecane, longifolene, n-pentadecane and n-heptadecane were common in dust/frass from H. hampei reared on coffee berries and artificial diet. Parasitoids were more attracted to 3-octanone, limonene, longifolene and n-dodecane compared to clean air. In contrast, P. nasuta preferred clean air to n-tetradecane. The rest of the compounds did not influence the behaviour of parasitoids. Two compounds were released by prepupae/pupae from H. hampei obtained from coffee berries, whereas six compounds were emitted by prepupae/pupae from the artificial diet. The compounds n-hexadecane and n-heptadecane were found in both types of prepupae/pupae. Parasitoids were more attracted to n-hexadecane than to clean air. In contrast, females did not show any preference for n-heptadecane or clean air. Among the compounds identified from dust/frass from H. hampei attractive to P. nasuta, only longifolene was found in the healthy C. canephora berry volatiles. Four species of fungi were isolated from the dust/frass of H. hampei, including Fusarium solani (Mart.) Sacc., Penicillium crustosum Thom, Aspergillus aculeatus lizuka and Mucor sp. Among the compounds identified in the dust/frass from H. hampei attractive to P. nasuta females, only 3-octanone was detected in the volatiles from F. solani and P. crustosum.     

Discrimination of previously searched,host-free sites byMicroplitis croceipes (Hymenoptera: Braconidae)

The ability of free- ranging parasitoids to discriminate between previously visited and unvisited sites containing host kairomone (caterpillar frass) but not hosts was tested. Females of Microplitis croceipes,a host specialist and plant generalist larval parasitoid of Helicoverpa (Heliothis) zea,were allowed to fly freely in a simulated plant patch in a flight chamber. Wasps spent less time searching frass sites previously searched by themselves or by conspecifics than unsearched frass sites. In addition to chemical marking, spatial memory of visual cues was implicated as a mechanism for discriminating against self-visited, host-free sites.     

Temporal and spatial relationships between an herbivorous lady beetleEpilachna niponica and its predator,the earwigAnechura harmandi

The relationships between egg predation of an herbivorous lady beetle Epilachna niponica (Lewis ) and its predator, the earwig Anechura harmandi (Burr ), were examined in both time and space. In spite of little annual, changes in egg densities, egg mortality due to predation varied considerably. There was no, clear relationship between the earwig density and the proportionate predation over the five years. The seasonal occurrence of earwig nymphs on thistle plants, however, was closely synchronized with that of egg predation. Predator attacks on the beetle occurred in a time-restricted manner. Thus, later cohorts mostly escape from heavy predatory pressure. No spatially density-depent egg predation was detected at the level of either thistle plants or thistle patches. Furthermore, there was no indication of aggregative behaviour of the earwig in response to local egg density. The earwig density was more likely to be associated with particular localities with sandy deposits available for its nest site.     

低含水量饲料对黑水虻生长发育的影响

【目的】了解低含水量饲料对黑水虻Hermetia illucens生长发育的影响。【方法】在27℃、RH 80%、光周期14L∶10D的饲养条件下,以含水量70%人工饲料饲养黑水虻为对照,比较饲料含水量降为30%和50%时黑水虻幼虫的存活率、幼虫体重、雌雄成虫体长、羽化率以及不同发育阶段持续时间等生物学参数与对照组的差异。【结果】30%和50%含水量饲料饲养幼虫平均体重与对照幼虫相比显著降低（P<0.05）,30%和50%含水量两个处理间体重亦有显著差异（P<0.05）。黑水虻幼虫不能在含水量30％的人工饲料中发育至预蛹,大部分幼虫至13 d时死亡。50%含水量饲料饲养幼虫比对照延迟5 d出现预蛹,滞后14 d结束预蛹,预蛹过程耗时18 d,比对照延长8 d;50%含水量饲料饲养雌雄虫比对照成虫体长显著缩短（P<0.05）,雌雄成虫羽化时间亦比对照延后5 d,雌雄成虫羽化历期均为18 d,比对照增加5 d;50%含水量饲料饲养黑水虻自卵孵化至蛹全部羽化为成虫所需时间比对照延长10.67 d,所需时间为55.67 d,而对照仅需45.00 d;但是50%含水量饲料饲养幼虫存活率和成虫羽化率与对照相比差异均不显著（P>0.05）。【结论】含水量低于70%的人工饲料不利于黑水虻的生长发育。     

The proof is in the poo: Non-invasive method to detect endoparasitic infection

Almost every animal trait is strongly associated with parasitic infection or the potential exposure to parasites. Despite this importance, one of the greatest challenges that researchers still face is to accurately determine the status and severity of the endoparasitic infection without killing and dissecting the host. Thus, the precise detection of infection with minimal handling of the individual will improve experimental designs in live animal research. Here, we quantified extracellular DNA from two species of endoparasitic worm that grow within the host body cavity, hairworms (phylum Nematomorpha) and mermithids (phylum Nematoda), from the frass of their insect host, a cave wētā (Orthoptera: Rhaphidophoridae) and an earwig (Dermaptera: Forficulidae), respectively. Frass collection was done at two successive time periods, to test if parasitic growth correlated with relative DNA quantity in the frass. We developed and optimized two highly specific TaqMan assays, one for each parasite-specific DNA amplification. We were able to detect infection prevalence with 100% accuracy in individuals identified as infected through post-study dissections. An additional infection in earwigs was detected with the TaqMan assay alone, probably because some worms were either too small or degraded to observe during dissection. No difference in DNA quantity was detected between sampling periods, although future protocols could be refined to support such a trend. This study demonstrates that a noninvasive and minimally stressful method can be used to detect endoparasitic infection with greater accuracy than dissection alone, helping improve protocols for live animal studies.     

Diet factors responsible for the change of the glucose oxidase activity in labial salivary glands of Helicoverpa armigera

We investigated the change of the glucose oxidase (GOX) activity in labial salivary glands of Helicoverpa armigera larvae fed with the artificial diet or host plant tobacco and the major factors responsible for such a change. Throughout larval development, the labial salivary GOX activities in caterpillars reared on the artificial diet were remarkably higher than those fed with the plant. After fifth-instar plant-fed caterpillars were transferred to the artificial diet, their labial salivary GOX activity increased quickly, which was closely correlated with the time spent feeding on the artificial diet. The total sugar content of the artificial diet was 68 times higher than that of the tobacco leaves. We hypothesized that sugars and secondary metabolites are the possible causes of induction of GOX activity. When fifth-instar caterpillars were fed with tobacco leaves coated with glucose or sucrose, their labial salivary GOX activity was significantly higher than those fed with leaves without sugar coating. Following native PAGE, 1 single band of the labial salivary GOX was observed in all the caterpillars fed with different diets, implying that only the activity of the isoenzyme was changed in response to different diets. Furthermore, the labial salivary GOX activity was determined after caterpillars were fed with artificial diets containing chlorogenic acid, rutin, and quercetin. The results showed that all these phenolic compounds had no effect on the GOX activity. We conclude that sugar in diets was a major factor influencing the labial salivary GOX activity of the larvae. Arch. Insect Biochem. Physiol. 2008.     

Influence of predator density,diet and living substrate on developmental fitness of Orius laevigatus

Mass rearing of Orius laevigatus on non‐insect foods could substantially increase the cost‐effectiveness of the production of this biological control agent which is largely based on the use of expensive eggs of the Mediterranean flour moth Ephestia kuehniella. In this study, the effect of substrate quality and predator density on nymphal development of O. laevigatus fed on E. kuehniella eggs, honeybee pollen or an egg yolk based artificial diet was assessed using several types of substrates as shelter materials in the rearing containers (wax paper, bean pod or no extra substrate). In general, E. kuehniella eggs proved to be a nutritionally superior food compared to pollen and artificial diet. Pollen supported nymphal development of O. laevigatus better than the artificial diet. Overall, increasing nymphal density resulted in higher mortality, which may be due in part to cannibalism. The addition of a bean pod compensated for the nutritionally suboptimal artificial, but had a negative effect when O. laevigatus was fed on pollen. The non‐insect foods tested could not adequately replace lepidopteran eggs as a food source for O. laevigatus but they may be useful as an alternative food or in a part of the rearing process.