Fecundity and egg hatchability of Dastarcus helophoroides adults fed on different types of artificial diets

Both fecundities and egg hatchabilities were compared among three populations of Dastarcus helophoroides Fairmaire adults（Coleoptera： Bothrideridae） fed on three types of artificial diets（Diet of formula 1 composed of silkworm pupa powder, dried yeast powder,sucrose, peptone, egg yolk powder and poplar branch powder. Diet of formula 2 composed of silkworm pupa powder, dried yeast powder, sucrose, egg yolk powder,poplar branch powder, cricket powder, benzoic acid and distilled water. Diet of formula 3 composed of pine bark powder and Monochamus alternatus larva powder）. for90 days. The three diets showed no significant difference regarding the average number of eggs deposited by all D. helophoroides females（16622.3–23874.7）; the average number of eggs per female（1278.6–1836.5）; and the average number of eggs per female per day（14.2–20.4）.The number of eggs one cluster contained mainly（82.06–82.66 %） lied in 1–100 eggs, and the average number of eggs per cluster ranged from 61.7 to 63.1. In the first 10-day period, the number of eggs deposited by all females fed on formula 1 was significantly larger than that on formula 3. The eggs deposited in the last four 10-day periods were more than in the former five 10-day periods,on formula 3. There were no significant differences in hatchability of total eggs among the three artificial diets,and the average corrected egg hatchability ranged from82.85 to 84.78 %. No significant differences in the adult mortality and mean weight gain of D. helophoroides were found after feeding on three artificial diets. Our results suggest that D. helophoroides adults were not specialized on the diet, and the diet types might have little effect on fecundity and egg hatchability in D. helophoroides, as long as sufficient nutrition was supplied.

A Practical Artificial Diet for the Diamondback Moth

A new artificial diet for the diamondback moth,Plutella Xylostella(L), had been selected out successfully. The diet contained the following constituents: soybean powder, wheat germ, wheat bran powder, brewer's yeast and other constituents. So far, the diamondback; moth had been reared on this artificial diet for 25 generations and still mantained its normal biological characteristics. Under 25±1℃ and 60%￣75%RH with 12 h PH,the results of rearing the diamondback moth on the diet as follows:egg hatch,81. 3%￣94. 7 %; survival from eggsto pupae, 55. 0% ￣ 76. 7 % 1 pupal survival, 79. 7 % ￣ 100 % ; adult emergence, 80% ￣ 100 %; fecundity 94. 7￣ 144.4 eggs/ ;pupal weight, 90. 4￣110. 8 mg/20 pupae; average days to adult: , 10. 2; 13. 1. The diet is not only simpler on the constituents but also have better r-earing results and more rearing generations.

Effect of Feeding on Fresh(wet)Housefly Maggots(Musca domestica)with or without Artificial Diet on Water Quality and Growth Rates of African Catfish(Clarias gariepinus Burchell,1822)Fry under Laboratory Conditions

No or little information on the use fresh(wet)housefly maggots(Musca domestica)in African catfish(Clarias gariepinus)fry feeding.Therefore,this study was conducted to investigate the effect of feeding on fresh(wet)housefly maggots with or without artificial diet on water quality,growth performance,survival percentage and feed utilization of African catfish fry under laboratory conditions.Housefly maggots produced from a mixture of poultry droppings and foods wastes,it was used to replace artificial feed at 0,50 and 100% levels.Catfish were fed artificial diet alone(Feed 1),fresh(wet)housefly maggots alone(Feed 2),and 50% fresh housefly maggots with 50% artificial diet(Feed 3)were prepared and tested on triplicate groups of African catfish fry(initial weight of 0.25±0.02 g)for 60 days.Results showed that final weight(g/fish)was significantly(P≤0.05)higher in fish fed on feed 3(6.03±0.08),followed by fish fed feed 2(4.62±0.27),followed by fish fed feed 1(3.15±0.68).Specific growth rate(%/day)was also significantly higher in fish fed on feed 3(5.31±0.10),followed by fish fed feed 2(4.86±0.03),followed by fish fed feed 1(4.18±0.24).The same trend was observed with total weight gain,percentage weight gain,daily growth rate and relative growth rate.Feed intake and protein intake were significantly(P≤0.05)higher in fish fed on feed 3 and fish fed on feed 2,followed by fish fed feed 1.While,feed conversion ratio(FCR)and protein efficiency ratio were not significantly(P>0.05),but the improvement in FCR recorded in catfish fry fed feed 3 and feed 2 under the experimental conditions.Survival percentage was within the range 55-75%,with insignificant differences(P>0.05)among treatments.The water quality parameters such as temperature,pH,dissolved oxygen,total ammonia,nitrite and nitrate were not significantly(P>0.05)between the treatments and were tolerable for Catfish culture.Accordingly,use of the 50% fresh(wet)housefly maggots with 50% artificial diet in African catfish fry feeding had positive effect on growth performance and reduce of the feed cost.

Development of an Artificial Diet for Effective Oral Delivery of dsRNA to Soybean Pod Borer,Leguminivora glycinivorella(Lepidoptera:Tortrici-dae)

RNA interference(RNAi)technology is a promising crop protection strategy against agricultural pests.The soybean pod borer(SPB),Leguminivora glycinivorella(Mats.),is a serious pest of soybean in northeastern Asia.The neonate larvae of SPB are endophagous,initially feeding on the inner layer of the pod and then on the immature soybean seeds,a behavior that makes them difficult to rear.Therefore,a suitable artificial diet is desirable to facilitate RNAi research.Seven artificial diets and soybean pods were used for rearing SPB neonate larvae.The survival and mean weight of the larvae reared on artificial diet 6(A6,included 2 g soybean flour and 10 g R3 immature soybean pod powder)were found to be significantly higher than those for larvae reared on all other diets.Subsequently,A6 diet was prepared in DEPC-treated water to obtain a RNase-free artificial diet(RF).The survival and mean weight of the larvae were not significantly different between A6 and RF diets.Feeding neonate larvae with RF-SpbP0 dsRNA(ribosomal protein P0)silenced SpbP0 gene,resulting in arrested development and increased mortality.The results of this study suggested that the newly developed A6 or RF diets could rear SPB neonate larvae and help towards developing an effective method for oral delivery of dsRNA to SPB larvae.

Impact of numerous larval diets on the biology of pink bollworm Pectinophora gossypiella(Saunders)(Lepidoptera:Gelechiidae)under laboratory conditions

Background Pink bollworm,Pectinophora gossypiella(Saunders)(Lepidoptera:Gelechiidae)has become a poten-tial pest of cotton by causing substantial yield losses around the world including Pakistan.Keeping in view the facts like limited research investigations,unavailability,and high cost of artificial diet’s constituents and their premixes,the present research investigations on the dietary aspect of P.gossypiella were conducted.The larvae of P.gossypiella were reared on different diets that were prepared using indigenous elements.The standard/laboratory diet com-prised of wheat germ meal 34.5 g,casein 30.0 g,agar–agar 20.0 g,sucrose 10.0 g,brewer’s yeast 5.0 g,α-cellulose 1.0 g,potassium-sorbate1.5 g,niplagin 0.5 g,decavitamin 0.01 g,choline-chloride 0.06 g,maize-oil 3.30 g,honey 2.0 g,and water 730.0 mL.Alternatives to cotton bolls and wheat germ meal were okra seed sprouts,okra fruit,cottonseed meal,and okra seed meals,which were included in the study to introduce an efficient and economic mass-rearing system.Results The larval development completed in 19.68d±0.05 d with a weight of 20.18mg±0.20 mg at the fourth instar fed on the cottonseed meal-based diet instead of wheat germ meal based diet.On the same diet,84.00%±4.00%,17.24 mg±0.03 mg,and 7.76d±0.06 d were recorded as pupae formation,pupal weight,and pupal duration,respectively.Adult emergence,76.00%±1.00%was recorded from pupae collected from larvae raised on cottonseed meal-based diet.These male and female moths lived for 40.25d±0.10 d,and 44.34d±0.11 d,respectively.Females deposited 21.28±0.04 eggs per day with the viability of 65.78%±0.14%.The larval mortal-ity at the fourth instar was 37.20%±1.36%and malformed pupation of 12.00%±1.41%was recorded.Replacement of wheat germ meal with that of local meals(cottonseed and okra seed)in the standard laboratory diet has saved 463.80 to 467.10 PKR with 1.62 to 1.63 cost economic returns,respectively.Conclusion This research is of novel nature as it provides a concise and workable system for the economic and suc-cessful rearing of P.gossypiella under laboratory conditions.

Growth and Reproduction of Artificially Fed Cnaphalocrocis medinalis

The growth and reproduction of rice leaffolder,Cnaphalocrocis medinalis,fed on an artificial diet were studied.The results showed that the larvae were able to grow and pupate on the artificial diet.The durations of larvae and pupas of C.medinalis on the artificial diet were 28.1 d and 10.1 d,postponed 4.9 d and 1.7 d respectively,compared with those reared with rice leaves.The number of ovipositions was 41.6 per female,26.2% higher than that fed on rice leaves.Survival rate curve of larvae was a descent function of mortality-age,with no significant differences from the curve of larvae fed on rice leaves.The net reproductive rate （Ro）,intrinsic rate of increase （rm） and finite rate of increase （λ） of the population fed on diet were 17.6928,0.0884 and 1.0924,respectively,and the mean generation time （T） and double time （td） were prolonged 4.9 d and 1.3 d in comparison with the treatment of rice leaves.Population trend index （I） was 3.26,indicating a growing number of the population of C.medinalis fed on artificial diet.

The Use of Cyanobacteria Arthrospira platensis and Cladoceran Daphnia magna as Complementary Protein and Lipid Sources in Transitional Diet for Common Carp (Cyprinus carpio L.) Nursery

This study was conducted to evaluate the use of cyanobacteria Arthrospira platensis and cladoceran Daphnia magna biomass as complementary protein and lipid sources in diet supplementation for common carp (Cyprinus carpio L.) nursery. Three experimental diets containing A. platensis and D. magna meal at different concentrations were compared to the commercial (control) diet. Each experimental diet (ED) was set to contain D. magna and A. platensis meal at a specific combination: 2% and 5%, 2% and 7%, and 4% and 5% for ED1, ED2 and ED3, respectively. The protein and lipid content of the experimental diets ranged from 43.20% to 44.60% dry weight (DW) and 10.64% to 13.42% DW, respectively;while the protein and lipid content of the control diet were 43.00% DW and 6.72% DW, respectively. After 20 days of feeding period, ED3 group obtained the highest final body weight (BW) (58.18 ± 35.24 mg), total biomass (1936 ± 1625 mg), food conversion rate (1.34 ± 0.04), and specific growth rate (12.86 ± 0.03% BW day–1) among all treatment groups (P > 0.05);while ED1 group obtained the highest survival (75.5% ± 7.47%) among all treatment groups (P > 0.05). The total bacterial count and total pathogenic Aeromonas sp. in the culture water of the treatment groups (ranged from 2.00 to 2.65 × 105 CFU mL–1 and 3.50 to 4.12 × 103 CFU mL–1, respectively) were lower compared to the water of the control group fed (3.73 × 105 and 4.70 × 103 CFU mL–1, respectively). No significant differences in physicochemical water quality parameters were observed among treatments (P > 0.05). The current study suggests that the combination of A. platensis and D. magna biomass can be used as complementary protein and lipid sources in diet supplementation for common carp larvae and can result in a comparable fish growth, survival and feed utilization in common carp culture at the nursery phase.

Fitness and predation potential of Macrolophus pygmaeus reared under artificial conditions

The biological parameters of Macrolophus pygmaeus Rambur afler prolonged rearing in the absence of plant materials were compared with those of conventionally plant-reared predators. When eggs of Ephestia kuehniella Zeller were provided as food, developmental and reproductive fitness of M. pygmaeus reared for over 30 consecutive generations using artificial living and oviposition substrates was similar to that of predators kept on tobacco leaves. Plantless-reared fifth instars of the predator also had similar predation rates on second instars of the tobacco aphid, Myzus persicae nicotianae Blackman, as their peers maintained on plant materials. In a further experiment, predation on aphid prey by fifth instar M. pygmaeus fed one of two egg yolk-based artificial diets was compared with that of nymphs fed E. kuehniella eggs. Despite their lower body weights, preda- tors produced on either artificial diet killed similar numbers of prey as their counterparts reared on lepidopteran eggs. Our study indicates that artificial rearing systems may be useful to further rationalize the production of this economically important biological control agent.

Tier-1 assays for assessing the toxicity of insecticidal proteins produced by genetically engineered plants to non-target arthropods

In assessing an insect-resistant genetically engineered （IRGE） crop before its commercialization, researchers normally use so-called ＂Tier-1 assays＂ as the initial step to determine the effects of the crop on non-target organisms. In these tests, the insecticidal proteins （IPs） produced by the IRGEs are added to the diets of test organisms in the laboratory. Test organisms in such assays can be directly exposed to much higher concentrations of the test IPs than they would encounter in the field. The results of Tier-1 assays are thus more conservative than those generated in studies in which the organisms are exposed to the IPs by feeding on IRGE plant tissue or in the case of predators or parasites, by feeding on invertebrate prey or hosts that have fed on IRGE plant tissue. In this report, we consider three important factors that must be considered in Tier-1 assays： （i） methods for delivery of the IP to the test organisms; （ii） the need for and selection of compounds used as positive controls; and （iii） methods for monitoring the concentration, stability and bioactivity of the IP during the assay. We also analyze the existing data from Tier-1 assays regarding the toxicity of Bt Cry proteins to non-target arthropod species. The data indicate that the widely used Bt proteins have no direct toxicity to non-target organisms

Suppressing tawny crazy ant (Nylanderia fulva) by RNAi technology

A bstract The tawny crazy ant(Nylanderia fulva)is a new invasive pest in the United States.At present,its management mainly relies on the use of synthetic insecticides,which are generally ineffective at producing lasting control of the pest,necessitating alternative environmentally friendly measures.In this study,we evaluated the feasibility of gene silencing to control this ant species.Six housekeeping genes encoding actin(NfActin),coatomer subunit β (NfCOPP),arginine kinase(NfArgK),and V-type proton ATPase subunits A(NfvATPaseA),B(NfvATPaseB)and E(NfvATPaseE)were cloned.Phylogenetic analysis revealed high sequence similarity to homologs from other ant species,particularly the Florida carpenter ant(Camponotus floridanus).To silence these genes,vector L4440 was used to generate six specific RNAi constructs for bacterial expression.Heat-inactivated,dsRNA-expressing Escherichia coli were incorporated into artificial diet.Worker ants exhibited reduced endogenous gene expression after feeding on such diet for 9 d.However,only ingestion of dsRNAs of NfCOPfi(a gene involved in protein trafficking)and NfArgK(a cellular energy reserve regulatory gene in invertebrates)caused modest but significantly higher ant mortality than the control.These results suggest that bacterially expressed dsRNA can be orally delivered to ant cells as a mean to target its vulnerabilities.Improved efficacy is necessary for the RNAi-based approach to be useful in tawny crazy ant management.

Probing behavior of aposymbiotic green peach aphid persicae） on susceptible Solanum tuberosum and resistant Solanum stoloniferum plants

The green peach aphid, Myzuspersicae Sulzer （Hemiptera： Aphididae） is one of the potato important pests; it is the most efficient vector of potato viruses. Myzuspersicae harbors the endosymbiotic bacteria Buchnera aphidicola which supplements their diet. There is increasing evidence that B. aphidicola is involved in plant-aphid interactions and we previously demonstrated that B. aphidieola disruption （aposymbiosis） affected the probing behavior ofM. persicae on radish plants, delaying host plant acceptance. In this work, we evaluated the effect of aposymbiosis on the probing behavior of M. persicae on 2 Solanum species with different compatibility with M. persieae, Solanum tuberosum （susceptible） and Solanum stoloniferum （resistant） with the electrical penetration graph technique （EPG）. To disrupt B. aphidicola, rifampicin was administered to aphids through artificial diets. Aposymbiotic aphids, on both plant species, showed increased pathway activities, mechanical problems with the stylets, and delayed salivation in the phloem. The extended time in derailed stylet mechanics affected the occurrence of most other probing activities; it delayed the time to the first phloem phase and prevented ingestion from the phloem. The effect of aposymbiosis was more evident in the compatible interaction of M. persicae-S, tuberosum, than in the incompatible interaction with S. stoloniferum, which generated the M. persicae--S, tuberosum interaction to become incompatible. These results confirm that B. aphidicola is involved in the plant-aphid interaction in relation to plant acceptance, presumably through a role in stylets penetration in the plant.

Effect of Maruca vitrata （Lepidoptera： Crambidae） host plants on life-history parameters of the parasitoid Apanteles taragamae （Hymenoptera： Braconidae）

The effect of four host plant species of the herbivore Maruca vitrata Fabri- cius （Lepidoptera： Crambidae） on development time, longevity, fecundity and sex ratio of the parasitoid Apanteles taragamae Viereck （Hymenoptera： Braconidae） was investi- gated under laboratory conditions. The larvae were parasitized when in the second instar. Maruca vitrata larvae were fed with flowers of four legumes, that is, Vigna unguiculata （cowpea）, Sesbania rostrata, Lonchocarpus sericeus and Pterocarpus santalinoides, or an artificial diet both before and after parasitization. The parasitoid did not develop in hosts feeding on L. sericeus or E unguiculata at 25℃, or on P. santalinoides at 25℃ or 29℃. Apanteles taragamae had the shortest development time on artificial diet at both 25℃ and 29℃ while the longest development time was recorded on L. sericeus at 29℃. Female wasps took longer to develop compared to males at the two temperatures, regardless of the feeding substrate of their host. The longevity of the wasps at 25℃ varied among feeding substrates, but not at 29℃. Survival rate of parasitized larvae depends on the feeding sub- strate. Moreover, infection of host larvae with Maruca vitrata multi-nucleopolyhedrovirus （MaviMNPV） killed larger proportions of parasitized larvae at 25℃ than at 29℃, which was likely caused by the difference in parasitoid developmental rate. The proportion of female parasitoids was lowest on L. sericeus. The daily fecundity showed a nonlinear trend regardless of the feeding substrate, indicating that A. taragamae is a pro-ovigenic species. The data support the slow growth-high mortality hypothesis.