Relative Abundance of Carsonella ruddii (Gamma Proteobacterium) in Females and Males of Cacopsylla pyricola (Hemiptera: Psyllidae) and Bactericera cockerelli (Hemiptera: Triozidae)

Carsonella ruddii (Gamma Proteobacterium) is an obligate bacterial endosymbiont of psyllids that produces essential amino acids that are lacking in the insect’s diet. Accurate estimations of Carsonella populations are important to studies of Carsonella-psyllid interactions and to developing ways to target Carsonella for control of psyllid pests including pear psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae) and potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae). We used two methods, namely fluorescence in situ hybridization and quantitative polymerase chain reaction (qPCR), to estimate relative abundance of Carsonella in bacteriocytes and whole bodies of psyllids, respectively. Using these two methods, we compared Carsonella populations between female and male insects. Estimations using fluorescence in situ hybridization indicated that Carsonella was more abundant in bacteriocytes of female C. pyricola than in those of males, but Carsonella abundance in bacteriocytes did not differ between sexes of B. cockerelli. Analyses by qPCR using whole-body specimens indicated Carsonella was more abundant in females than in males of both psyllids. Neither fluorescence in situ hybridization nor qPCR indicated that Carsonella populations differed in abundance among adults of different ages (0–3 wk after adult eclosion). Using fluorescence in situ hybridization, Carsonella was observed in ovarioles of newly emerged females and formed an aggregation in the posterior end of mature oocytes. Results of our study indicate that female psyllids harbor greater populations of Carsonella than do males and that sex should be controlled for in studies which require estimations of Carsonella populations.     

Thermal Biology of Liorhyssus hyalinus (Hemiptera: Rhopalidae) and Nysius simulans (Hemiptera: Lygaeidae), Fed on the Milky Stage of Maize Grains

When quinoa, Chenopodium quinoa Willd., is cultivated in South America outside of its Andean origin, the heteropterans Liorhyssus hyalinus (Fabricius) and Nysius simulans Stål may emerge as important pests. Here we studied the development and reproduction of both species at different constant temperatures in the laboratory. Egg and nymphal development were investigated at 18, 22, 26, 30, 34, and 36°C. For both species, egg incubation time significantly decreased as the temperature increased. Nymphs did not successfully develop at 18°C and the total nymphal time significantly decreased as the temperature increased from 22 to 36°C. Based on a linear day-degree (DD) model, the lower developmental threshold (LDT) temperatures for eggs and nymphs were estimated to be 16.0 and 17.9°C for L. hyalinus, and 16.1 and 19.7°C for N. simulans, respectively. Thermal requirements for egg and nymphal development were 68.6 and 114.8 DD for L. hyalinus, and 77.7 and 190.3 DD for N. simulans, respectively. Reproduction and adult longevity were studied at 22, 26, 30, and 34°C. For both species preoviposition time decreased as temperature increased, and the oviposition period was longest at 26°C. The highest fecundity and egg viability were observed at 30°C, whereas longevities were higher at 22–26°C than at 30–34°C. As the lowest tested temperatures were not suitable to both heteropterans and 30°C was found to be the optimal temperature for development and reproduction, peak densities are expected in warm areas and seasons.     

Chemical control of sorghum head bugs (Hemiptera: Miridae)

Eight contact and three systemic insecticides, and an enriched neem extract were tested for the control of sorghum head bug, Calocoris angustatus Leth. at the ICRISAT Center. The insecticides were applied at the complete-anthesis and milk stages (at 500 1/ha) with a knapsack sprayer. On the basis of effectiveness of head bug control, grain yield and 1000-grain mass, carbaryl (at 500 g a.i./ha) was the most effective insecticide followed by fenvalerate (at 50 g a.i./ha), and chlorpyrifos (at 250 g a.i./ha). Among the systemic insecticides, demeton-S-methyl (at 250g a.i./ha), was the most effective. Demeton-S-methyl and dimethoate were also effective for the control of other head bug species—Eurystylus bellevoyei Put. and Reut. and Campylomma sp. Plots sprayed with demeton-S-methyl gave higher grain yields than those treated with carbaryl, which was the best contact insecticide. Two sprays of carbaryl (at 500g a.i./ha) applied at the complete-anthesis and milk stages have been found to be effective for head bug control. Dichlorvos, fenitrothion and monocrotophos were highly phytotoxic and resulted in burning and drying of entire leaves. Dimethoate resulted in a slight drying of leaf tips and margins.     

Insecticide-induced increase in the protein content of male accessory glands and its effect on the fecundity of females in the brown planthopper Nilaparvata lugens Stål (Hemiptera: Delphacidae)

The brown planthopper Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) is a classical resurgent rice pest induced by insecticides. The past focus on resurgence mechanisms has been on the stimulation of the reproduction of adult females induced by insecticides. To date, the role that males play as a resurgence of N. lugens has not been investigated. The present study examined changes in protein levels in both male accessory glands and female ovaries induced by the insecticides triazophos and deltamethrin as well as the stimulating effect of treated males on the fecundity of adult females via mating following foliar sprays of the insecticides. For adults that had been exposed as nymphs to treated rice plants, the protein content in both the male accessory glands and in the female ovaries of N. lugens were significantly affected by male mating status, insecticide and insecticide concentration. There was a higher protein content in male accessory glands when males were exposed to triazophos as third instars compared to fifth instars, and there was a higher protein content before mating compared to after mating. In addition, the protein levels in male accessory glands after mating for individuals exposed to high doses of the two insecticides as 3rd and 5th instars were significantly lower than untreated control except for exposed to triazophos as 3rd instar, indicating that treated males transferred more male accessory gland protein to adult females via mating. The protein content was also affected by different combinations of treated mating pairs. Adult males (♂_t) developed from third instar nymphs treated with triazophos stimulated the fecundity of the female significantly via mating (♂_t × ♀_ck) with untreated females (♀_ck) (control females), increasing the reproductive rate by 43.5% as compared to the mating (♂_ck × ♀_ck) of untreated males and females. Also, the fecundity of the females after the mating (♂_t × ♀_t) of treated males and females was significantly higher than that after the mating (♂_ck × ♀_t) of untreated males with treated females. These findings indicated that the reproductive effects of insecticide on males can be transferred to females via mating. The present findings provide valuable information for understanding the potential role that males play in the pesticide-induced resurgence of N. lugens.     

桑小头木虱Paurocephala sauteri Enderlein生物学特性研究

近年在海南各植桑区均发现桑小头木虱（Paurocephala sauteri Enderlein）严重为害,桑园被害株率达100%。在我国,该木虱仅记录于台湾省,为我国大陆新入侵害虫。本研究在实验室条件下[(27±1)℃、RH (70±5)%、12L∶12D],采用45日龄桑树扦插苗和离体叶片饲养,对桑小头木虱的发育与繁殖特性及各虫态的形态特征开展观察。结果表明,桑小头木虱生活史包括卵、1~5龄若虫和成虫期。各龄期主要形态特征为：卵呈水滴形,带短的卵柄,端部具细长的端丝,初产时乳白色,待孵化时可见淡红色眼点;1龄若虫头、胸部乳白色,复眼和腹部橘黄色,无翅芽;2~5龄若虫黄绿色,随着龄期增加,体长增加,翅芽随之变化。2龄翅芽出现,稍突起;3龄翅芽较小,呈三角形;4龄和5龄翅芽长椭圆形,其中5龄超过腹部第1节。各龄若虫和初羽化成虫均可分泌白色球形蜡质。雌雄成虫以两性生殖方式繁殖后代,羽化3 d后体色由黄绿色逐渐变为黄褐色并开始交配,交配时间为0.5~3 h,结束交配18~21 h后开始产卵,产卵量为20~42粒。卵单个散产于叶片背面叶脉处,偶尔可见产于新抽嫩叶正面边缘,5~7 d后孵化,孵化率为98.19%,雌性百分率为70.44%。若虫期12~18 d,完成一代的时间为18~24 d。本研究将为桑小头木虱的准确识别与监测,以及防控策略的制定提供前提条件和理论依据。     

Resistance of Selected Potato Genotypes to the Potato Psyllid (Hemiptera: Triozidae)

The characterization of resistance of selected potato, Solanum tuberosum L., breeding clones to the potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae) was investigated. Antixenosis was assessed in choice tests in which a single plant of each genotype was placed inside a rearing cage, where 60 female psyllid adults were released and the number of adults and eggs on each genotype was counted 24 h later. Antibiosis was evaluated in no-choice tests in which adults (five males and five females) were confined in a cage fixed to the upper side of leaves. After 4 h of exposure, adults were removed and the number of eggs counted. The developmental time and survival of offspring were recorded until all insects became adults. All the resistant genotypes showed strong antibiotic effects to B. cockerelli. These results show promise for incorporation into an IPM program against B. cockerelli.     

木槿曼粉蚧生物学特征的初步研究

木槿曼粉蚧是我国南方大豆上的一种新害虫。为了明确其各个虫态识别特征及其在大豆上的生活史及主要生物学特征,在室内恒温条件下[温度(25±1)℃,相对湿度70%±5%,光周期为L∶D=12∶12],观察描述了雌雄不同虫态的形态特征及其个体生活史、各虫态主要习性和危害特征等。结果表明:木槿曼粉蚧具有典型的性二型现象。雌虫包括卵、1龄若虫、2龄若虫、3龄若虫和雌成虫。雄虫包括卵、1龄若虫、2龄若虫、预蛹、蛹和雄成虫。若虫期各龄期体长、体宽、触角节数等形态结构具有明显差异,可作为区分龄期的依据。在25℃条件下,以大豆为寄主的雌性个体若虫期为33.34 d,成虫期19.03 d,平均产卵269.6粒;雄性个体若虫期24.60 d,预蛹期2.27 d、蛹期3.33 d,成虫寿命仅3.83 d。     

Monitoring and action threshold determination for the obscure mealybug Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae) using pheromone-baited traps

The absence of effective pest monitoring has resulted in an increase in populations of the obscure mealybug Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae) in pome fruit orchards in the Western Cape Province of South Africa recently. The sex pheromone for P. viburni was recently identified and synthesized. Flight activity of adult male P. viburni was monitored by placing and servicing three, evenly spaced pheromone-baited traps per orchard in three pome fruit growing regions used for the study. Fortnightly fruit sampling was done by randomly picking three fruits per tree for the duration of each fruit season, dissecting and noting mealybug infestation. The biweekly male P. viburni trap catch information and fruit infestation data collected over two seasons were correlated. There was a positive and significant relationship between the fruit infestation and number of P. viburni adult males caught in pheromone-baited traps (r² = 0.454, P < 0.001). The action threshold level was estimated to be 2.5 male P. viburni caught per trap per fortnight at an economic threshold of 2% fruit infestation. This monitoring method was less labor intensive, more accurate and quicker than the current visual sampling and monitoring techniques.     

A Molecular Approach for Detecting Stage-Specific Predation on Lygus hesperus (Hemiptera: Miridae)

A molecular gut analysis technique is described to identify predators of Lygus hesperus (Knight), a significant pest of many crops. The technique is unique because it can pinpoint which life stage of the pest was consumed. Sentinel egg masses designed to mimic the endophytic egg-laying behavior of L. hesperus were marked with rabbit serum, while third instar and adult L. hesperus were marked with chicken and rat sera, respectively. Then, the variously labeled L. hesperus life stages were introduced into field cages that enclosed the native arthropod population inhabiting an individual cotton plant. After a 6-h exposure period, the predator assemblage, including the introduced and native L. hesperus population, in each cage were counted and had their gut contents examined for the presence of the variously marked L. hesperus life stages by a suite of serum-specific enzyme-linked immunosorbent assays (ELISA). The whole-plant sampling scheme revealed that Geocoris punticpes (Say) and Geocoris pallens Stal (Hemiptera: Geocoridae) and members of the spider complex were the numerically dominant predator taxa in the cotton field. The gut content analyses also showed that these two taxa appeared to be the most prolific predators of the L. hesperus nymph stage. Other key findings include that Collops vittatus (Say) (Coleoptera: Melyridae) and Solenopsis xyloni McCook (Hymenoptera: Formicidae) appear to be adept at finding and feeding on the cryptic L. hesperus egg stage, and that L. hesperus, albeit at low frequencies, engaged in cannibalism. The methods described here could be adapted for studying life stage-specific feeding preferences for a wide variety of arthropod taxa.     

Interactions between Metopolophium festucae cerealium (Hemiptera: Aphididae) and Barley yellow dwarf virus (BYDV-PAV)

Interactions between an invasive aphid, Metopolophium festucae (Theobald) subsp. cerealium, and Barley yellow dwarf virus (BYDV-PAV) were studied under laboratory conditions. M. festucae cerealium is an economic pest of wheat and barley that has recently been found in high population densities in wheat in the Pacific Northwest of the United States. BYDV-PAV is the most prevalent and injurious species of BYDV worldwide and in the Pacific Northwest. Although M. festucae sensu stricto (Theobald 1917) has been reported previously as a vector of some BYDV isolates, there is no confirmed transmission of BYDV by M. festucae cerealium. Two experiments examined the ability of M. festucae cerealium to transmit BYDV-PAV. The first used single aphids caged to indicator plants of a BYDV-susceptible winter wheat cultivar and the second used multiple aphids on each test plant. M. festucae cerealium did not transmit BYDV-PAV in either experiment, whereas transmission by a known BYDV vector, Rhopalosiphum padi L., was consistently high (≥93%). A third experiment compared the intrinsic growth rate, days until first reproduction and daily reproduction by M. festucae cerealium on sham-inoculated and BYDV-PAV-infected wheat, but detected no differences. The findings are reviewed in light published data on M. festucae species, BYDV transmission, and the potential pest status of this new invading aphid.     

Insecticides applied to soil of transplant plugs for Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae) management in broccoli

Chemical control with insecticides, typically applied as foliar sprays or chemigation, is the primary tactic used to manage Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae). We evaluated the efficacy of 14 insecticides, including both systemic and non-systemic insecticides, against B. hilaris applied as a seedling tray drench. Experiments were conducted in both greenhouse and field settings. In all experiments, we used the maximum label rate of insecticides and calculated dose per seedling based on this rate and standard plant density per hectare. Each seedling in the tray received 2-mL insecticide solution, and the seedlings were then exposed to B. hilaris adults after transplanting in cages for greenhouse experiments or natural B. hilaris populations in the field experiments. A scale system (0–4) was used to evaluate the severity of B. hilaris feeding injury on leaves where 0 = no injury and 4 = >75% of the leaf margins with B. hilaris feeding injury. We evaluated damage using the rating system, percentage of damaged leaves, number of feeding injury sites, as well as plant height, leaf width, and fresh and dry weight. In the greenhouse experiment, percentage of injured leaves, number of injury sites, and damage rating were significantly lower for transplants treated with acetamiprid, clothianidin, dinotefuran, imidacloprid, and thiamethoxam, and cyclaniliprole compared with the untreated. There was a relationship between feeding injury sites and plant height, leaf width, fresh and dry weight (R² > 0.5) in both 2015 field experiments. Similarly, the transplants treated with acetamiprid, clothianidin, dinotefuran, imidacloprid, thiamethoxam, thiamethoxam + chlorantraniliprole, imidacloprid + β-cyfluthrin and cyclaniliprole had significantly lower damage ratings than those treated with chlorpyrifos, bifenthrin, tolfenpyrad, flonicamid, cyantraniliprole, spinetoram and the untreated control. For transplanted broccoli, treatment of transplant plugs with neonicotinoid insecticides prior to planting can be an effective method for controlling B. hilaris.     

Population Dynamics of Wolbachia in the Leafhopper Vector Yamatotettix flavovittatus (Hemiptera: Cicadellidae)

Wolbachia (Rickettsiales: Alphaproteobacteria) infections induce abnormalities in the reproductive system and affect various biological traits of the host insects. The density of Wolbachia is one of the major parameters that influence induced phenotypes and interactions with the hosts. Wolbachia occurs naturally in populations of the leafhopper Yamatotettix flavovittatus Matsumura (Hemiptera: Cicadellidae), which transmits phytoplasma that cause white leaf disease in sugarcane. However, the quantity and dynamics of Wolbachia in this leafhopper are not well understood. In the current study, we estimated the number of Wolbachia by absolute quantification of the copy number of wsp, which encodes the outer surface protein, using real-time quantitative polymerase chain reaction (PCR). This investigation was performed using natural populations and laboratory colonies from three lineages of leafhoppers (designated as UD, KK, and SK). There was no significant difference in the number of wsp copies in most of field-collected adults. During the immature developmental stages, there were differences in the dynamics of Wolbachia infection between the UD lineage and the other two lineages. However, the number of wsp copies increased in the early instar and plateaued in the later nymphal instars. Sex had no influence on the number of Wolbachia within the same lineages. The number of Wolbachia was relatively constant during the adult stage in the UD lineage but fluctuated in the other two lineages. In conclusion, the present data provide a framework for exploring the relationship between Wolbachia and the leafhopper and could facilitate future research into management strategies using Wolbachia.     

Characterization and Phylogenetic Analysis of the Mitochondrial Genome Sequence of Nisia fuliginosa (Hemiptera: Fulgoroidea: Meenoplidae)

We explored characterization of the mitochondrial genome (mitogenome or mtGenome) and phylogenetic analysis between 32 Fulgoroid species by sequencing and analyzing the mitogenome of Nisia fuliginosa Yang and Hu, 1985 (Hemiptera: Fulgoroidea: Meenoplidae), thereby making it the first determined mitogenome from the family Meenoplidae. The mitogenome was found to be 15,754 bp in length and contained 13 protein-coding genes (PCGs), 22 tRNA genes, two ribosomal RNA genes (rRNAs), and a control region. All PCGs started with typical ATN codons, except for nad1, which used GTG as the start codon. Canonical TAA termination codons were found in 10 PCGs and the remaining three genes (cox2, nad6, and nad1) had incomplete stop codons T. All tRNAs could fold into typical cloverleaf secondary structures, with the exception of trnC, trnV, and trnS1. Additionally, we compared the AT and GC skews of 13 PCGs of 32 Fulgoroidea mitogenomes, on the L-strand, the AT and GC skews were negative and positive, respectively. However, on the H-strand, the AT skew could be positive or negative and the GC skew was always negative. Phylogenetic results showed that the eight families of Fulgoroidea were divided into two large groups. Delphacidae formed a monophyletic group sister to a clade comprising Meenoplidae and other six families (Fulgoridae, Ricaniidae, Flatidae, Issidae, Caliscelidae, and Achilidae). Meenoplidae was located near the clade of Delphacidae, and Fulgoridae was located near the clade of Meenoplidae. Furthermore, Caliscelidae, Issidae, Ricaniidae, and Flatidae are closely related and they collectively formed a sister group to Achilidae.     

Effect of photoperiod on development and reproduction of Megacopta cribraria(Hemiptera:Plataspidae)

Megacopta cribraria (Hemiptera: Plataspidae) continually outbreaks due to suitable photoperiod in recent years. Effect of photoperiod on growth, development and reproduction of M. cribraria were assessed in this study. Results indicated that developmental duration, nutrient accumulation efficiency, and adult fecundity of M. cribraria were significantly different under 6 photoperiodical conditions. Developmental duration of nymph stage gradually tended to be shorter as day time increase. Body weights of 5th instar nymphs for 16 h and 4 h day time photoperiods were 5.2 mg and 4.6 mg, respectively. Moreover, longevity of adults tended to be longer as day time increase. However, for the short day photoperiod (4 L:20 D and 8 L:16 D), population showed no reproductive behaviors. Index of population trend increased with photoperiod extension and adults showed stronger reproductive capacity and longer longevity. This research identified the favorable photoperiodical conditions before outbreak. It may provided reference for ecological adaptability of M. cribraria, and contribute to the scientific basis for forecasting and controlling of M. cribraria.     

Spatiotemporal Distribution of Chinavia hilaris (Hemiptera: Pentatomidae) in Peanut-Cotton Farmscapes

The green stink bug, Chinavia hilaris (Say) (Hemiptera: Pentatomidae), is a pest of cotton in the southeastern United States, but little is known concerning its spatiotemporal distribution in agricultural farmscapes. Therefore, spatiotemporal distribution of C. hilaris in farmscapes where cotton fields adjoined peanut was examined weekly. Spatial patterns of C. hilaris counts were analyzed using SADIE (Spatial Analysis by Distance Indices) methodology. Interpolated maps of C. hilaris density were used to visualize abundance and distribution of C. hilaris in crops. For the six peanut-cotton farmscapes studied, the frequency of C. hilaris in cotton (94.8%) was significantly higher than in peanut (5.2%), and nymphs were rarely detected in peanut, indicating that peanut was not a source of C. hilaris into cotton. Significantly, aggregated spatial distributions were detected in cotton. Maps of local clustering indices depicted patches of C. hilaris in cotton, mainly at field edges including the peanut-to-cotton interface. Black cherry (Prunus serotina Ehrh.) and elderberry (Sambucus nigra subsp. canadensis [L.] R. Bolli) grew in habitats adjacent to crops, C. hilaris were captured in pheromone-baited stink bug traps in these habitats, and in most instances, C. hilaris were observed feeding on black cherry and elderberry in these habitats before colonization of cotton. Spatial distribution of C. hilaris in these farmscapes revealed that C. hilaris colonized cotton field edges near these two noncrop hosts. Altogether, these findings suggest that black cherry and elderberry were sources of C. hilaris into cotton. Factors affecting the spatiotemporal dynamics of C. hilaris in peanut-cotton farmscapes are discussed.     

Spatiotemporal Distribution of Chinavia hilaris (Hemiptera: Pentatomidae) in Corn Farmscapes

The green stink bug, Chinavia hilaris (Say) (Hemiptera: Pentatomidae), is a pest of cotton in the southeastern United States but little is known concerning its spatiotemporal distribution in corn cropping systems. Therefore, the spatiotemporal distribution of C. hilaris in farmscapes, when corn was adjacent to cotton, peanut, or both, was examined weekly. The spatial patterns of C. hilaris counts were analyzed using Spatial Analysis by Distance Indices methodology. Interpolated maps of C. hilaris density were used to visualize abundance and distribution of C. hilaris in crops in corn–peanut–cotton farmscapes. This stink bug was detected in six of seven corn–cotton farmscapes, four of six corn–peanut farmscapes, and in both corn–peanut–cotton farmscapes. The frequency of C. hilaris in cotton (89.47%) was significantly higher than in peanut (7.02%) or corn (3.51%). This stink bug fed on noncrop hosts that grew in field borders adjacent to crops. The spatial distribution of C. hilaris in crops and the capture of C. hilaris adults and nymphs in pheromone-baited traps near noncrop hosts indicated that these hosts were sources of this stink bug dispersing into crops, primarily cotton. Significant aggregated spatial distributions were detected in cotton on some dates within corn–peanut–cotton farmscapes. Maps of local clustering indices depicted small patches of C. hilaris in cotton or cotton–sorghum at the peanut–cotton interface. Factors affecting the spatiotemporal dynamics of C. hilaris in corn farmscapes are discussed.     

Combining reflective mulch and host plant resistance for sweetpotato whitefly (Hemiptera: Aleyrodidae) management in watermelon

A study was conducted to evaluate the use of reflective mulch and host plant resistance for the management of the sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), in watermelon [Citrullus lanatus var. lanatus (Thunberg) Matsum & Nakai]. Whitefly abundance data were collected under both greenhouse (caged and uncaged) and field conditions. Consistently, a reflective mulch (also called silver or metallic) treatment resulted in a lower incidence of adult whiteflies as compared with a standard black mulch treatment. Moreover, two whitefly resistant Citrullus colocynthis (L.) Schrad genotypes, which are wild relatives of cultivated watermelon, reduced whitefly populations as compared with standard watermelon. There was generally no interaction between the mulch and genotype variables. No effect of mulch color was observed on sticky card capture of Delphastus catalinae (Horn), a whitefly predator, or on capture of an Eretmocerus sp. whitefly parasitoid in caged trials, which suggests no adverse effect on these natural enemies when using reflective mulch. Overall whitefly populations were relatively low during four seasons of field trials (2006–2009). Results from this study suggest that a combination of using reflective mulch and host plant resistance can additively suppress whitefly infestations, which have particular importance in the fast-growing organic vegetable production industry.     

Characterizing the Feeding Injury Caused by Phylloscelis rubra (Hemiptera: Dictyopharidae) to Cranberries

Due to changes in pest management practices, farmers’ reports of severe feeding injury to cranberries, Vaccinium macrocarpon Aiton Ericales: Ericaceae, caused by the cranberry toad-bug, Phylloscelis rubra Ball, have increased in recent years in New Jersey (United States). Currently, however, limited information is available on the effects of P. rubra feeding or density of individuals needed to cause injury to cranberry vines and fruit. In 2015‒2017, we conducted studies to characterize injury to cranberry at a range of P. rubra densities by using cages in a screen-house and field, to establish a correlation between P. rubra density and crop injury in an open field experiment, and to measure the effects of P. rubra injury on the nutritional content (i.e., amounts of macro- and microelements) of cranberry vines. Phylloscelis rubra feeding on cranberry vines produced typical injury symptoms at relatively low densities (i.e., 2 individuals per vine in field cages or <10 individuals per sweep net sample in open fields), which included discolored (yellowish or reddish) or dead (brown) vines. This vine injury could lead to reductions in fruit mass and total fruit number. However, P. rubra injury to cranberry vines did not alter their nutritional composition. In general, this study highlights the ability of P. rubra to cause substantial injury to cranberry vines even when population densities were relatively low, which could result in declines in fruit production (quality and quantity). Therefore, infestations by P. rubra in cranberries must be considered when making pest management decisions in regions where this insect is present.     

Temperature-dependent development of Ascotis selenaria (Lepidoptera: Geometridae) and its stage emergence models with field validation

Temperature-dependent development of Ascotis selenaria (Denis et Schiffermüller) was studied in the laboratory. Time to egg eclosion decreased with increasing temperature and ranged from 17.4 d at 16 °C to 5.0 d at 30 and 32 °C. Total development times of larvae decreased from 54.7 d at 16 °C to 17.3 d at 32 °C. The development time of pupae ranged from 29.7 days at 16 °C to 10.2 days at 30 and 32 °C. Eggs, larvae and pupae did not develop successfully to the next stage at 12 and 35 °C. The estimated lower temperature thresholds were 10.4, 9.3, and 9.8 °C for eggs, larvae, and pupae, respectively. Thermal constants of egg, larvae, and pupae were 88.5, 370.4, and 188.7 DD, respectively. Stage emergence models for eggs, larvae, and pupae of A. selenaria were constructed by using the development rate model (Lactin 2 function) and development distribution model (three-parameter Weibull function), which simulate the proportion of individuals shifted from one stage to the next. Pearson's correlation coefficients between actual observations in the field and model outputs were statistically significant with 0.99, 0.68 to 0.87 and 0.96 to 0.98 for egg, larval and pupal stage emergence model, respectively. The egg stage emergence model could be used to facilitate spraying time as it successfully predicted the first instar larval population. Predictability of the pupal stage emergence model was greatly improved when the physiological age of overwintering pupae was assumed to be in various state. The stage emergence models developed here should be useful to construct an A. selenaria population model.