3rd Instar Nymphs Research Articles

Temperature and host age effects on the life history of Tamarixia radiata, a dominant parasitoid of citrus psyllid Diaphorina citri

The Asian citrus psyllid, Diaphorina citri, is the primary vector for the bacterium Candidatus Liberibacter asiaticus, the causal agent of Citrus Huanglongbing. In this study, we investigated the effects of temperature and psyllid host age on the biology of Tamarixia radiata, the species-specific dominant nymphal parasitoid of D. citri in South China. Both temperature and host age significantly affected the fecundity, parasitism, and development of T. radiata. For the temperature effects, the averaged fecundity and parasitism of T. radiata was significantly increased with temperatures between 18 and 26 °C. The highest averaged fecundity (15.6 eggs/female) and parasitism (78%) were recorded at 26 °C. The developmental time of T. radiata on the 4th and 5th instars nymphs averaged 19.6 days at 18 °C, 13.4 days at 26 °C, and 10.2 days at 34 °C. The optimal temperatures for the development and survival of T. radiata was in the range of 26–30 °C. For the age effects, the development time from egg to adult parasitoid of T. radiata increased with the age of host nymph, 11.5 days in the 3rd instar, 12.3 days in the 4th instar, and 13.4 days in the 5th instar at 26 °C. Moreover, citrus psyllid host age also affected the sex ratio of T. radiata, with 42.78%, 60.66%, and 76.56% females developing from 3rd, 4th and 5th instar nymphs, respectively. These findings may prove to be helpful toward the development of biological control strategies targeting D. citri.

Data on the ecology of Kermes echinatus Balachowsky (Hemiptera, Coccomorpha, Kermesidae) on Quercus ilex (Fagaceae) in Greece

The Phenology and natural enemies of the scale insect Kermes echinatus Balachowsky (Hemiptera: Kermesidae), which infests the holly oak Quercus ilex (Fagaceae), were studied between November 2015 and November 2017, in southern Greece (Kalamata, Peloponnese). Kermes echinatus is a univoltine, oviparous and biparental species. It overwinters as 1st instar nymphs, settling on the branches of the trees. The second instar nymphs appear by the middle of April, followed by 3rd instar nymphs until the end of May. The male larvae and pupae were recorded from the end of April to the end of May. Mature females, pre-ovipositing and ovipositing adults, were recorded during May and June. The newly hatched crawlers appeared by the end of June, which remained at this stage, settled on branches during the rest of summer and winter periods till next April. The parasitoid species Metaphycus gennaroi Guerrieri & Noyes and the hyperparasite Cheiloneurus claviger Thomson (Hymenoptera: Encyrtidae) were recorded on the colonies of the scale. The parasitism level of the scale reached to 21%. The predator Chilocorus bipustulatus L. (Coleoptera: Coccinellidae) was also recorded on the colonies of the scale.

Role of ABC transporters White, Scarlet and Brown in brown planthopper eye pigmentation.

The brown planthopper ATP-binding cassette (ABC) proteins White (W), Scarlet (St) and Brown (Bw) belong to the ABC transporter superfamily and are responsible for the transportation of guanine and tryptophan precursors of eye pigments. In the present study, the brown planthopper White (NlW), S t(NlSt) and Bw (NlBw) genes were cloned, and subsequent phylogenetic analysis showed that these genes are clustered with their respective homologues, with a genetic relationship observed between NlW and its Bemisia tabaci homologue having the highest similarity. Sequence alignments showed that these three proteins have a highly conserved Walker A domain, an ABC "signature sequence" and a Walker B domain. QRT-PCR demonstrated that W, St and Bw are highly expressed in the head of long-winged males and are highly expressed in both egg and male. Adult eye colour was altered after the downregulation of NlW, NlSt and NlBw in the 1st to 3rd instar nymph. The eye colours of emerged adults became white, dark and red after injection of dsNlW, dsNlSt and dsNlBw, respectively. The eye pigment content assay revealed that xanthommatin and pteridine were significantly decreased after the injection of dsRNAs, and the range of variation was inversely correlated with nymph age. The present study provides a theoretical basis for understanding the function of ABC transporters at the molecular and biochemical levels.

Sublethal effects of buprofezin on development, reproduction, and chitin synthase 1 gene (SfCHS1) expression in the white-backed planthopper, Sogatella furcifera (Hemiptera: Delphacidae)

Abstract The white-backed planthopper, Sogatella furcifera (Horvath) (Hemiptera: Delphacidae), is a major rice pest in some Asia-Pacific countries. Buprofezin is an insect growth regulator with relatively low mammalian toxicity but high efficacy to many rice pests. In this study, we estimated the toxicity of buprofezin against 3rd-instar nymphs of S. furcifera using the rice-stem dipping method. The results showed that the LC50 of buprofezin to 3rd-instar nymphs were 0.89 mg/L. When 3rd-instar nymphs were exposed to the LC10 and LC25 (0.10 and 0.28 mg/L) of buprofezin, the duration of juvenile development was significantly prolonged in the F0 and F1 generations. The fecundity (eggs per female) of the F1 females was reduced by 5.29% and 12.34%, respectively, in addition to the survival rate, emergence rate, copulation rate, and hatchability were decreased by treatment with buprofezin at LC10 and LC25, compared with the control group. The relative fitness of S. furcifera in LC10 and LC25 treatments was reduced by 47% and 63%, respectively. Furthermore, real-time quantitative PCR analyses revealed increased the expressions of SfCHS1 and its two variants following the exposure of nymphs to buprofezin. Increased these genes mRNA levels associated with reduced chitin biosynthesis may result from the inhibition of chitin synthase activity, and thereby leading to a higher mortality of S. furcifera. Overall, sublethal concentrations of buprofezin suppressed the population growth of S. furcifera.

Infection of tomato by Tomato Yellow Leaf Curl Virus alters the foraging behavior and parasitism of the parasitoid Encarsia formosa on Bemisia tabaci

Abstract Encarsia formosa Gahan is a solitary endoparasitoid that is commercially reared and released for augmentative biological control of whiteflies including Bemisia tabaci (Gennadius). Bemisia tabaci biotypes B and Q are two most invasive species that greatly reduce crop yields in China by feeding on plant sap and by transmitting Tomato Yellow Leaf Curl Virus (TYLCV). The effects of TYLCV infection of tomato on E. formosa foraging on B. tabaci B and Q are unknown. In Y-tube olfactometer assays in the present study, E. formosa significantly preferred TYLCV-infected tomato plants over TYLCV-free plants. The wasp females also significantly preferred TYLCV-infected tomato plants infested with 3rd-instar nymphs of B. tabaci biotype Q over TYLCV-free plants with biotype Q nymphs. However, no significant differences were observed when B. tabaci biotype B was infested on tomato plants. The oviposition bioassays confirmed that TYLCV infection on tomato plants resulted in the recruitment of parasitoids. These results indicate that TYLCV-infection of tomato increase the foraging of E. formosa on B. tabaci, as differs on the B and Q biotypes.

PENGGUNAAN CENDAWAN ENTOMOPATOGEN Beauveria bassiana (BALSAMO) VUILLEMIN DAN Lecanicillium lecanii (ZIMM) ZARE & GAMS UNTUK MENGENDALIKAN Helopeltis antonii SIGN (HEMIPTERA: MIRIDAE) The Use of Entomopathogenic Fungi Beauveria bassiana (Balsamo)Vuillemin

Helopeltis sp. has been known as one of major pests on tea, cacao and cashew plantation. Recently, genus Helopeltis is also reported attack Acacia plantation in Sumatra and Kalimantan. For such extensive plantation, low cost biocontrol agents like entomopathogenic fungi are choosen because of the simplicity for mass production. The objective of this study was to measure the effectiveness of Beauveria bassiana and Lecanicillium lecanii against Helopeltis sp. Both fungi that were used in this study were obtained from IPB Insect Pathology Laboratory. The tested insect, Helopeltis sp. was collected from Gunung Mas tea plantation. The insects were reared in laboratory. Four level of conidial density, 109, 108, 107, 106 conidia/ mL were applied to Helopeltis adult (B. bassiana) and 3rdinstar nymph (L. lecanii). Daily mortality was observed until seven days post treatment. The result showed that L. lecanii at 106 conidia/mL caused 96.25% mortality of 3rd instar nymph of Helopeltis sp. with the LC50 value at two days observation was 1.03 x 106 conidia/ mL, LT50 was 1.198 days and LT95 was 5.25 days. On the other hand, B. bassiana at 106 conidia/ mL caused 81.25%. mortality of adult Helopeltis sp. while 100% mortality could be attained by using 108 conidia/ mL. The LC50 of B. bassiana was 3.2 x 104 conidia/ mL, at four days observation and LT50 was 4.214 days. The two fungi were thus judged effective against Helopeltis sp. in this bio assay.Key words: Beauveria bassiana, conidia, density, Helopeltis sp., Lecanicillium lecanii, mortality.

Effect of the Insect Growth Regulator “ Lufox” on Some Biological Aspects of the Soft Tick Argas persicus (Oken)

Lufox interfered with the reproduction and development of Argas persicus when fed adult female and second nymphal instar were topically treated with a single dose (10 ul/tick) of Lufox at three different concentrations (10, 50, and 150 ppm). Generally, the effects of Lufox were dose- dependent, increased by increasing dose concentration, and temporally dependent on the physiological state of the treated tick. Lufox treatment of the adult female A. persicus at different periods of its reproductive cycle reduced fecundity and fertility of the female tick by decreasing the number and percent hatching of the deposited eggs, respectively. Lufox treatment prolonged the pre-oviposition, oviposition, and the egg incubation periods. The effects were most prominent when females were treated during vitellogenesis (3rd day after feeding). Lufox was toxic to A .persicus, induced mortality of the treated newly moulted fed second nymphal instar to reach 100% at 150 ppm. Application of Lufox prolonged the premoulting periods of the treated 2nd and the resulted 3rd nymphal instars, delayed, and reduced adult emergence. Also, Lufox treatment led to production of different deformities in legs and inability to shed exuvia of the resulted 3rd instar nymphs and an inhibition of adult emergence. The probable physiological bases of the observed effects of Lufox on adult female and nymphs were discussed.

Dynamic changes in energy metabolism and electron transport of photosystem II in Nicotiana tabacum infested by nymphs of Bemisia tabaci (Middle East-Asia Minor 1)

Bemisia tabaci Middle East-Asia Minor 1 (MEAM1) infestation adversely affected photosynthesis of host plants. In the current study, chlorophyll a fluorescence was measured to determine the effects of MEAM1 nymph infestation of tobacco local and systemic leaves on energy metabolism and electron transport of photosystemII(PSII). The results showed that the density of PSII reaction centres per excited cross section (CS) (RC/CS) of infested and systemic leaves was reduced at 14 and 20 days. In systemic leaves, the number of PSII closed reaction centres (1-qP) increased significantly at 14 and 20 days. Absorption flux per QA− reducing PSII reaction centre (RC) (ABS/RC), trapped energy flux per RC (TRo/RC), and electron transport per RC (ETo/RC) of infested and systemic leaves increased with MEAM1 nymph infestation. The most obvious increase in absorption flux per CS (ABS/CSo) and trapped energy flux per CS (TRo/CSo) of infested and systemic leaves occurred at 14 days. MEAM1 nymph infestation significantly reduced the energy required for PSII QA to be completely reduced (Sm) in tobacco leaves. These results suggested that MEAM1 nymph infestation caused changes in light-harvesting antenna system and deactivation of the reaction centre, resulting in the reduction of photons absorbed by reaction centres per unit area. MEAM1 nymph infestation, particularly the 3rd instar nymphs, decreased light utilization ability and increased excess excitation energy in tobacco leaves. With MEAM1 nymph infestation, the relative electron transport capacity of the entire electron transport chain decreased, and more light energy was used to reduce QA.

Sublethal effects of Beauveria bassiana sensu lato isolate NJBb2101 on biological fitness and insecticide sensitivity of parental and offspring generations of brown planthopper, Nilaparvata lugens

Entomopathogenic fungi such as Beauveria bassiana sensu lato (s. l.) have been developed for biological control of sucking insect pests such as Nilaparvata lugens. However, the sublethal effects of B. bassiana s. l. on N. lugens remain unclear, and were investigated in the present study. N. lugens 3rd instar nymphs were inoculated with a sublethal concentration of B. bassiana s. l. isolate NJBb2101 conidia and then reared until they developed into adults. The resultant adults (parental generation) were paired to generate offspring. Life parameters in both the parental and the offspring generations were examined: nymph survival rate, emergence rate, nymph duration, sex ratio, copulation rate, fecundity, hatching rate and adult female longevity. Compared with the control, NJBb2101-treated N. lugens exhibited lower fitness indices such as low female ratio and fecundity, with the relative fitness of offspring being only 0.28. Both generations of NJBb2101-treated N. lugens were much more susceptible to three test insecticides with susceptibility increasing by 12.7–23.3-fold in parental females and 3.8–8.4-fold in the offspring (4th instar nymphs and females). The results suggest that sublethal effects of entomopathogenic fungi on N. lugens can reduce insect growth and development and increase insecticide susceptibility. The findings are of practical interest for pest insect management in terms of combining entomopathogenic fungi with chemical insecticides.

Effects of Aschersonia aleyrodis on the life table and demographic parameters of Bemisia tabaci

The present study reports the sublethal effects of the entomopathogenic fungus, Aschersonia aleyrodis (Webber) on Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). A fungal suspension of A. aleyrodis isolate Aa005 containing 1×107 conidia mL−1 was sprayed against B. tabaci on eggplant leaves under greenhouse conditions. The effects of fungal application on survival as well as life table parameters of the whitefly were observed at different post inoculation periods. The results indicated that A. aleyrodis can significantly affect the survival of 1st, 2nd, and 3rd nymphal instars of B. tabaci. Developmental periods of different instar nymphs were not affected by fungal application. A. aleyrodis spores persisted well and significantly affected the survivorship of young instar nymphs of B. tabaci at different post incubation periods. Life table results suggested that A. aleyrodis has no impact on general fecundity and longevity of B. tabaci. When the pathogen was exposed to the open environment and maintained for a relatively longer period, a reduction in the reproductive rate and intrinsic rate of increase was caused by the fungal spores, though the sublethal effects were not as good as the control treatment. The results suggest that the ability of spores to suppress an increase in whitefly population persists well after incubation of spores to the external environment (up to 9 days).

Reproductive performance of spiralling whitefly on guava and impact of weather parameters on its immature stages

The study was conducted to know the reproductive performance of spiralling whitefly on guava. Number of colony, eggs, 1st instar, 2nd instar, 3rd instar and 4th instar nymphs per five leaves ranged from 6 to 15, 8 to 32, 0 to 44, 0 to 22, 0 to 45 and 0 to 28, respectively. Maximum number of adults and nymphs were found in the month of January. Highest longevity of Aleurodicus dispersus (21.5 days) was recorded in adult while the lowest was in 2nd instar nymph (6.4 days). The number of colony/leaf and number of 3rd and 4th instar nymphs of A. dispersus had significant positive correlation with minimum and maximum temperature while non-significant positive correlation is observed between the number of egg/colony, the number 1st and 2nd instar nymphs with minimum and maximum temperature. A. dispersus showed nonsignificant positive correlation with minimum and maximum relative humidity regarding number of colony/leaf, 2nd instar nymph while nonsignificant negative correlation with 4th instar nymph.SAARC J. Agri., 15(2): 207-214 (2017)

Effect of mating combinations on the host parasitisation and sex allocation in solitary endoparasitoid, Aenasius arizonensis (Hymenoptera: Encyrtidae)

ABSTRACTAenasius arizonensis (Girault) is an important solitary endoparasitoid of Phenacoccus solenopsis Tinsley. To optimise the mass production of high-quality females, it is important to assess the influence of mating regimes on the progeny fitness and sex allocation. We, therefore, hypothesise that mating combinations in A. arizonensis adults emerged from different host instars may influence parasitism and sex allocation in the subsequent generation. Therefore, we compared three nymphal instars (1st, 2nd and 3rd) and adults host stages of P. solenopsis for parasitism and sex allocation by A. arizonensis. Further, F1 female progeny of the parasitoid emerged from different host instars was henceforth evaluated for its fitness in six mating combinations. A. arizonensis females parasitised all the host stages except the 1st instar nymphs. The parasitised 2nd instar nymphs yielded only males, while the sex ratio in the later host instars was strongly female-biased. The parasitoid females preferred 3rd instar nymphs with respect to higher parasitism (74.0–84.0%) and produced more females in the F1 progeny as compared to other host stages. F1 females that emerged from 3rd instar nymphs produced significantly higher parasitism (74.0–79.0%). These mating combinations also yielded more female progeny in the F2 generation. However, parasitism by F1 females was significantly lower (9.0–12.0%) when mated with males that emerged from 2nd instar P. solenopsis nymphs. Moreover, latter combinations yielded only male progeny in F2 generation. These findings can be used in laboratory mass rearing of this parasitoid vis-à-vis biological control of P. solenopsis.

Influence of some Insecticides on the Biological Attributes of Orius albidipennis (Reuter) (Hemiptera: Anthocoridae)

Effect of direct application of five bio- and conventional insecticides Dipel2x, Radiant, Proclaim, Aphox andCoragen) at three different concentrations on the biological attributes of immature (1st, 3rd and 5th nymphal instars) andadult stages of Orius albidipennis (Reuter) (Hemiptera: Anthocoridae) were evaluated. Procalim, Aphox and Coragenhad harmful effect and caused significant reduction in the tested stages of O. albidipennisas compared to Dipel 2x andRadiant insecticides, irrespective of tested concentrations. Also, the direct impact of those insecticides on immaturestages was higher than that recorded for adult stage. Insecticide-treated immature stages of O. albidipennis had negativeimpact on developmental periods. However, the longevity, fecundity rates and hatchability percentages of obtainedadults from insecticide-treated immature and insecticide- treated adult stages were differed from those of untreated(control).

Virus-Infected Plants Altered the Host Selection of Encarsia formosa, a Parasitoid of Whiteflies.

The sweetpotato whitefly Bemisia tabaci (Gennadius) is one of the most invasive pest species worldwide. Q and B biotypes are the two most devastating species within the B. tabaci complex. Bemisia tabaci can vector hundreds of plant viruses that seriously threaten crop production. Endoparasitoid, Encarsia formosa Gahan, is widely used to control whiteflies, however, little is known about the effects of virus-infected plants on E. formosa parasitism of B. tabaci. Here, we reported that tomato, which was infected with Tomato Yellow Leaf Curl Virus (TYLCV), altered the host selection of E. formosa between B. tabaci Q and B biotypes. On healthy tomato plants, parasitism and host selection by E. formosa did not differ between the 3rd-instar nymphs of B. tabaci Q and B biotypes. On TYLCV-infected tomato plants, however, B. tabaci Q biotype were significantly more attractive to E. formosa than B biotype. When TYLCV-infected tomato plants were infested with B. tabaci Q or B biotype, volatile profiles differed quantitatively but not qualitatively. Olfactometer assays suggested that the preference of E. formosa to Q over B biotype was associated with an elevated level of β-Myrcene, β-Ocimene, β-Caryophyllene, and α-Humulene from TYLCV-infected tomato plants.

English

Gomaa KFS, Bashir MO. 2017. Evaluation of five pearl millet ecotypes susceptibility to the nymphal instars of migratory locust. Trop Drylands 1: 57-63. The present study was carried out biological control unit of Insectary Laboratory, Department of Crop Protection, Faculty of Agriculture, University of Khartoum, Shambat, Sudan. The study lasted from during the beginning of May 2014 to January 2015. The experiments were undertaken under semi-field (cage-experiment) conditions. The primary objective of the study was to detect the most preferred food variety on the development of nymphal instars (3rd & 4th instars) of the locust. Five different experiments with five ecotype varieties of Pearl millet Pennisetum glaucum var. were setup. Each experiment with three replications was applied topically on the 3rd and 4th nymphal instars. Each experiment lasted for four days. We grew the Millet in ground basin and plastic cup to feed the locusts and for experiment application techniques. Observed variables were recorded daily after 24 hours from the start of experiments until the fourth day. The food preference and ecotype susceptibility evaluation were based on the amount of food intake in gram, weight of food ingested and digested in gram, percentages, and amount of weight of feces in gram. The results showed a significant difference of susceptibility of five ecotypes of pearl millet. The susceptibility of feeding by 3rd and 4th nymphal instars was observed in all ecotypes. The study results showed that the preference of ecotypes by nymphs was increased according to increasing of application time. The highest one was Bayouda-late maturing compared to four other ecotypes. During the experiments, we noticed that the preferences of five ecotypes were elevated in the first and third readings of experiments. However, we discovered in the study that the susceptibility of five pearl millet ecotypes was according to the remaining amount of feces in any ecotype variety. The least amount of reminder feces was in Bayouda-late maturing ecotype, which means that most of the food intake was ingested, digested and assimilated as with the four other ecotypes. The greater percentages of ingested amount of food consumption for five ecotypes of pearl millet, with 3rd and 4th instars of African migratory locust, ranked as mentioned above. The research concludes that further works on evaluation of susceptibility of pearl millet varieties with different pest, particularly in migratory locust is recommended to detect the palatable target variety as a trap in pest management control.

Identification and virulence characterization of entomopathogenic fungus Lecanicillium attenuatum against the pea aphid Acyrthosiphon pisum (Hemiptera: Aphididae)

An entomopathogenic fungal strain was originally isolated on artificial medium from the corpse of a pea aphid (Acyrthosiphon pisum Harris) collected at Jingzhou, China (N30°21′18.15″, E112°08′41.63″). Based on tests of the morphological, physiological and biochemical characteristics and analysis of internal transcribed spacer (ITS) sequences, it was considered to be a strain of Lecanicillium attenuatum Zare & W. Gams. Therefore, the strain was designated L. attenuatum YZU 151121. The activity of the biological agents under study was determined at 26 °C and 90% relative humidity. The number of A. pisum killed was increased by increasing the concentration of L. attenuatum. The results demonstrated that L. attenuatum YZU 151121 showed a high efficacy against 3rd-instar nymphs (LC50 = 2.91 ± 0.365 × 105 conidia/ml) and adults (LC50 = 3.12 ± 0.398 × 106 conidia/ml) after 6 days of exposure. Crude extract from this strain was tested for contact toxicity and showed high activity in 3rd-instar nymphs and adults, with LC50 values of 251.34 ± 49.54 and 315.46 ± 87.66 mg/l, respectively. In addition, crude extract at a concentration of 200 mg/l could significantly reduce fecundity in adults. These results revealed that the strain YZU 151121 may be useful in biopesticides for controlling pea aphid.

GROWTH THRESHOLD AND DEGREE DAYS REQUIREMENT FOR DEVELOPMENT AND GROWTH OF CITRUS MEALYBUG Planococcus citri (Risso), HEMIPTERA : PSEUDOCOCCIDAE

Laboratory studies was conducted in Biocontrol unit- Faculty of Agriculture- University of Baghdad in order to determine the impact of different temperatures 15, 20, 25, 30 and 35 ±2 C° on the development and growth rate of different stages of mealy bug P.citri. The results showed that the total developmental time from (egg - adult)of the mealy bug were 24.0, 28.08, 39.67 and 73.31 days respectively. With significant rearing differences on temperatures 15, 20, 25 and 30 ±2 C° respectively, while no development and growth rate on temperature 35±C°. the developmental threshold for the mealy bug stages eggs, crawlers, 2nd and 3rd nymphal instars as well as the duration of the egg to adult were different, being 7.1, 7.26, 7.08, 7.12 and 7.15C° respectively, while 116.27, 136.98 and 172.4 thermal units for degree days required for growth and development while the thermal constant for the period from egg to adult was 526.31. Optimum temperature was 27.85C ͦ while Upper threshold was 33.64 C° for P.citri Which refers to the lack of suitable high temperature for growth and development .

GROWTH THRESHOLD AND DEGREE DAYS REQUIREMENT FOR DEVELOPMENT AND GROWTH OF CITRUS MEALYBUG Planococcus citri (Risso), HEMIPTERA : PSEUDOCOCCIDAE

Laboratory studies was conducted in Biocontrol unit- Faculty of Agriculture- University of Baghdad in order to determine the impact of different temperatures 15, 20, 25, 30 and 35 ±2 C° on the development and growth rate of different stages of mealy bug P.citri. The results showed that the total developmental time from (egg - adult)of the mealy bug were 24.0, 28.08, 39.67 and 73.31 days respectively. With significant rearing differences on temperatures 15, 20, 25 and 30 ±2 C° respectively, while no development and growth rate on temperature 35±C°. the developmental threshold for the mealy bug stages eggs, crawlers, 2nd and 3rd nymphal instars as well as the duration of the egg to adult were different, being 7.1, 7.26, 7.08, 7.12 and 7.15C° respectively, while 116.27, 136.98 and 172.4 thermal units for degree days required for growth and development while the thermal constant for the period from egg to adult was 526.31. Optimum temperature was 27.85C ͦ while Upper threshold was 33.64 C° for P.citri Which refers to the lack of suitable high temperature for growth and development .

Effects of temperature on the growth, development and reproduction of Dysmicoccus neobrevipes Beardsley (Hemiptera: Pseudococcidae).

In recent years, Dysmicoccus neobrevipes Beardsley (Hemiptera: Pseudococcidae) is found as one of important alien species in China. For the alien pest, temperature always is a crucial factor on constructing stable population. In this study, the development and reproduction of D. neobrevipes population of pumpkin under different temperatures were investigated. The developmental duration, developmental rate, survival rate and fecundity of D. neobrevipes were compared in the laboratory under the conditions of 17, 20, 23, 26, 29 and 32 ℃, photoperiod 14L:10D, RH (75±5)%, and the life table of the laboratory population was constructed. The results showed that in 20-29 ℃, the developmental durations of every stage of D. neobrevipes all decreased with the increasing temperature; under 20 ℃, both female and male nymph D. neobrevipes had the longest duration, being 46.95 and 50.26 d, respectively. The female and male nymph D. neobrevipes grew most fast under 29 ℃ (20.28 d) and 32 ℃ (20.70 d). The relationship between the developmental rate and temperature for each stage could be simulated by the quadratic regression. In addition, we found that the temperature could impact the survival rate of D. neobrevipes. The highest survival rate of D. neobrevipes was recorded at 29 ℃ for both female (70.3%) and male (69.3%) nymphs. The developmental threshold temperature of female and male was 13.80 ℃ and 11.61 ℃, and the accumulated temperature of female and male was 491.50 and 388.85 day-degrees, respectively. Both pre-oviposition duration and adult longevity decreased with increasing temperature, and the highest fecundity per female was 442.2 eggs at 29 ℃, and the lowest 111.8 eggs at 20 ℃. The population trend indexes under 20 ℃ and 29 ℃ were 19.1 and 168.2, respectively. At 17 ℃ and 32 ℃, D. neobrevipes of the 1st instar nymphs and 3rd instar nymphs were found to stop growth, suggesting that excessively high or low temperature was unfavorable to the growth of D. neobrevipes. In conclusion, temperature could significantly affect the growth and development, survivorship, reproduction and population increasing of D. neobrevipes, and the most suitable temperature range for this pest is from 23 ℃ to 29 ℃.

Effect of different diets on growth and development of the two-spotted cricket, Gryllus bimaculatus (Orthoptera: Gryllidae)

Many insects have gained increasing attention as an alternative protein for humans. Among those, the two-spotted cricket, Gryllus bimaculatus (Orthoptera: Gryllidae), was recently approved as a general food ingredient by the Korean Ministry of Food and Drug Safety. For industrial utilization of G. bimaculatus , mass rearing techniques and production system should be standardized first. In this study, we investigated the effects of five different feeds on the growth and development of G. bimaculatus. Feed is the one of the key factors that has considerable effects on rearing insects. With five different kinds of feed on 1st, 3rd, and 5th instar nymphs, the change of survival rate, body weight were monitored up to eight wk after hatching. We concluded that 50% of soybean flour, 20% of corn powder, 10% of rice bran, 9% of milk serum, 10% of rice flour, 0.5% of microorganisms, and 0.5% of multivitamins and minerals (diet C) was the best mix for promoting growth and development of 3rd instar nymphs compared to the control diet.