Insect Population Levels Research Articles

Economic Damage Levels of the Green Shield Bug (Palomena prasina, Hemiptera: Pentatomidae) in Türkiye Hazelnut Orchards

The green shield bug (GSB) (Palomena prasina, Hemiptera: Pentatomidae) is one of the most important pests of hazelnut in Turkish hazelnut orchards. This harmful insect causes serious yield and quality losses by feeding directly on fruits every year. Their feeding on hazelnut fruits may result in nut abortion (empty nuts) in early season and cause shriveled and corked kernels in kernel expansion period. Insect pest management must be decided by depending on insect population level in field according to integrated pest management concept. Economic injury level (EIL) and economic threshold (ET) are the main essential points that must be considered in decision for insect pest control. Thus, it can be possible to protect the natural environment from unnecessary pesticide applications and the growers from high production costs. Therefore, determining of economic decision levels for controlling pests is critical. This is especially important for hazelnuts, which are grown on hundreds of thousands of hectares of land in Türkiye, and for the GSB, a serious pest that requires a couple of chemical applications per year. The economic decision levels vary mainly due to insect species and their damage potential, crop value in the market and control costs which can change over years and countries. This study aimed to calculate the EIL and ET values for GSB control action in hazelnut orchards in Türkiye using new economic market data. Based on previous research, the authors calculated the yield loss caused by one individual of GSB in this study. Direct yield loss, as well as quality and quantity losses from damaged kernels, were calculated separately and then totaled. The data, including crop value and control costs necessary for calculation was updated from free market sources. In the calculation of EIL/ET, the most common formula (EIL= C/ VxbxK) was used. As a result, the economic threshold for a single insecticide application was determined to be3.8 insect/da (=0.1 ha) for K=1 value and 4.76 insect/da for K=0.8 value, for single insecticide application. When ET values were converted in traditional Turkish approach that is special for hazelnut orchards; ET values for K=1 and K=0.8 were 0.76 insect/ 10 “hazelnut “ocak” (traditional growing of hazelnut plants together) and 0.95 insect/ 10 “ocak” respectively. If 2 applications per year for GSB were considered, ET values were doubled up and calculated to be 7.6 and 9.47 insect/da for K=1 and K=0.8 value respectively, and thusly 1.52 and 1.9 insect/ 10 “ocak” for Türkiye. For practical reasons, the ET value for GSB was recommended as 10 insect/da and 2 insects/10 “ocak”, for Türkiye, with consideration of 2 chemical applications and K= 0.8.

Effect of Pheromones, Plant Volatiles and Spinosad on Mating, Male Attraction and Burrowing of Cadra cautella (Walk.) (Lepidoptera: Pyralidae).

Simple SummarySex pheromones used at higher concentrations than their availability in insects have been successful in decreasing the insect population. Furthermore, botanical oils have also had negative impacts on the insect population level. In the first study, we investigated the combined effect of sex pheromones and plant oils on mating of almond moth. The second study sought the burrowing ability of almond moth larvae through different flour media. Mating declined on the presence of pheromones and botanical oils, whereas burrowing ability differed with flour type. Exposure to spinosad affected both mating success and larval penetration through flour media. The findings of this study reveal that various applications of sex pheromones, plant oils and spinosad ensure the better protection of cereal-based agricultural produce from insect infestation during storage.Mating disruption of Cadra cautella (Walk.) (Lepidoptera: Pyralidae) using its sex pheromone components, (Z, E)-9,12-tetradecadienyl acetate (ZETA) and (Z)-9-tetradecadien-1-yl acetate (ZTA), is successful in its population management. In addition, botanical oils have extensively been investigated in stored product pest management, but the effect of synthetic sex pheromones on the mating of C. cautella in the presence of plant volatiles is still unknown. Spinosad is used in food facilities as a contact insecticide but, if C. cautella larvae burrow into food, they may escape from spinosad. Importantly, the impact of spinosad on burrowing ability of C. cautella remains unknown. Therefore, the objectives of this study were to determine the effects of sex pheromone components ZETA and ZTA in the presence of botanical oils on the mating of C. cautella and the burrowing ability of C. cautella larvae in different types of flour treated with spinosad. In the first study, male and female moths were introduced into the cubicle having botanical oils and pheromone components. The mating status of female moths and male moth attraction to the trap was determined. The control experiments had only the botanical oils or pheromones. In the second study, burrowing ability of C. cautella larvae through different flour types was evaluated over 10 d. The flour was sprayed with spinosad (treatments) or water (controls). The mating success was higher with botanical oils alone but declined with exposure to pheromone either alone or combined with botanical oils. No differences in male attraction to traps were observed in botanical only, pheromone only or pheromone + botanical oil treatments. The burrowing of C. cautella larvae differed with flour type and spinosad altered burrowing ability. Thus, we conclude that the mating and burrowing of C. cautella is influenced by its pheromone and by exposure to botanicals and spinosad.

Impact of weeds on Auchenorrhyncha incidence and species richness in citrus orchards

Due to the risk posed by the imminent invasion of Xylella fastidiosa in Mediterranean countries, scientific focus has shifted towards studies on the ecology of the bacteria’s potential vectors belonging to the Auchenorrhyncha suborder. In order to gain knowledge regarding the management of this pest,it is essential to evaluate the potential impact of Auchenorrhyncha weed hosts and their population composition on the ecology of these species. Under this light, the relationship between Auchenorrhyncha species abundance and composition and wild plant species of a citrus orchard in central Greece (Attica) was studied. The orchard was divided in two sections based on weed management treatments: one with weeds being removed by mowing and the other without any weed treatment. Yellow sticky traps, replaced in a weekly basis, were installed in each orchard section while a migration Malaise trap was installed in the border of the two sections. Additional sampling from different weed species and citrus trees using an entomological net was carried out weekly. Results showed that the presence of weeds (especially those belonging to the Poaceae family), affected both auchenorrhynchan insect diversity and population levels. A marked preference of insects for weed plants compared with citrus trees was observed with the later plants usually being visited only after weed removal. The implications of the above observation on weed management as a means of controlling potential Xylella fastidiosa vectors belonging to the auchenorrhynchan species was discussed.

A comparison of integrated pest management and traditional practices for bagged maize stored in Nigeria

In grain markets in Nigeria, stored product insects can cause significant losses in quality and quantity of stored grains. Insect infestations in storehouses are usually controlled by the unilateral use of chemical insecticides, which have unintended adverse effects. In this study, approximately 15 MT of well-dried, Aflasafe™-treated maize was procured from a local farm settlement in January 2016. It was subsequently fumigated, mechanically cleaned and placed in 100-kg polypropylene bags for storage. The study was conducted during February–December 2016, to compare the effectiveness of traditional storage practice (TSP) with integrated pest management (IPM) practice. IPM for warehouse facilities focuses on adequate drying, inspection and cleaning of storehouses and their surroundings and regular examination of grain (IPMD). Traditional storage practice generally has little or no sanitation of the facility or regular examination of grain (monitoring) for insect pests. Study locations were markets in Ibadan, Oyo and Ilorin towns in Southwest and Northcentral Nigeria, respectively. Each market had two storehouses where TSP or IPMD was assigned; each storehouse had twenty-five bags of maize, which were sampled monthly to assess the effects of the two practices on stored maize insect populations and quality. Generally, from October to December, there tended to be more insects of all species in TSP than IPMD. Percent insect damaged kernels (%IDKNB) and weight loss (%WL) were also higher in TSP than IPMD during the October–December period. Percent germination in December was higher in IPMD (96.3%) than in TSP (85.3%). Aflatoxin levels in both TSP and IPMD did not exceed 1.9 ppb. Data from this study show that IPMD results in lower stored-product insect population levels and better maize quality than TSP. Thus, IPMD practice needs to be more widely adopted in storehouses in Nigeria and the rest of sub-Saharan Africa.

Economic injury level and action thresholds for Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in maize crops

Spodoptera frugiperda (J.E. Smith) is the pest insect that produces the highest losses in maize production in the tropics and neotropics. Its control in Colombia comprises about 10% of the total production costs. The aim of this study was to determine the economic injury level (EIL) and define action thresholds (ATs) for this insect pest in the maize hybrids 30F35R and 30F35HR (with Cry1F protein) in Espinal, Colombia. In two sowing cycles, a completely randomized design was established for each maize hybrid to measure their yield response at four insect population levels (a control without any applications of insecticides and applications at 2, 5, and 10 larvae per 10 plants). For 30F35R, an inverse relationship was found between levels of infestation and yields; meanwhile, for 30F35HR, only during the first cycle this relationship was found. The EIL calculated for 30F35R showed an average of 2.6 and 1.9 larvae per 10 plants in the first and second cycles, respectively, and 2.8 for 30F35HR in the first cycle. Two ATs were established, one in the period from 0 to 20 days after emergence (DAE) and another from 20 to 40 DAE. The threshold for 30F35R from 0 to 20 DAE showed an average of 1.8 larvae per 10 plants in both cycles, while, from 20 to 40 DAE, it was 2.0 and 1.7 in the first and second cycles, respectively. In 30F35HR, the thresholds were 2.1 and 2.5 larvae per 10 plants on average for both periods of the first cycle, respectively. These results can be considered as a tool within integrated pest management that also includes biological and cultural control strategies.

Spatial patterns of within-treeEnaphalodes rufulus(Coleoptera: Cerambycidae) attacks during outbreak conditions in the Ozark National Forest in Arkansas, United States of America

AbstractEnaphalodes rufulus(Haldeman) (red oak borer; Coleoptera: Cerambycidae) is a native wood borer that colonises and develops in oaks (QuercusLinnaeus; Fagaceae) across southeastern Canada and the eastern United States of America. It is rarely considered a pest because it normally occurs at low population density levels in stressed or dying oak trees. In the late 1990s and early 2000s there was a large, historically unique outbreak ofE.rufulusin the Ozark mountains of Arkansas and Missouri, United States of America. This outbreak provided an opportunity to investigate within-tree spatial distribution of attacks during unusually high insect population levels. Fifty trees from northern Arkansas were felled and destructively sampled. The locations of attack sites by femaleE.rufuluswere standardised across varying heights and diameters for comparison across trees. Attack sites showed a significant clustered pattern within trees. Attack sites were aggregated towards the lower and middle bole, and on the south-facing side of trees. This pattern has been seen in other insects, including wood borers, and is potentially related to differences in temperature. These patterns of ovipositional behaviour in outbreak situations have implications forE.rufulusresource partitioning and facultative intraguild predation among larvae.

Oxygen Consumption and Acoustic Activity of Adult Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae: Bruchinae) during Hermetic Storage.

Acoustic monitoring was applied to consider hermetic exposure durations and oxygen levels required to stop adult Callosobruchus maculatus activity and economic damage on cowpea. A 15-d study was conducted with six treatments of 25, 50, and 100 C. maculatus adults in 500 and 1000 mL jars using acoustic probes inserted through stoppers sealing the jars. Acoustic activity as a result of locomotion, mating, and egg-laying was measured by identifying sound impulses with frequency spectra representative of known insect sounds, and counting trains (bursts) of impulses separated by intervals of <200 ms, that typically are produced only by insects. By the end of the first week of storage in all treatments, oxygen levels declined to levels below 4%, which has been demonstrated to cause mortality in previous studies. Concomitantly, insect sound burst rates dropped below an acoustic detection threshold of 0.02 bursts s−1, indicating that the insects had ceased feeding. Statistically significant relationships were obtained between two different measures of the acoustic activity and the residual oxygen level. Based on the experimental results, a simple equation can be used to estimate the time needed for oxygen to decline to levels that limit insect feeding damage and thus grain losses in hermetic storage containers of different insect population levels and various volumes.

Impacts of insect outbreaks on tree mortality, productivity, and stand development

AbstractThe impacts of insect outbreaks on tree mortality, productivity, and stand development in Canada are reviewed, emphasising spruce budworm (Choristoneura fumiferana(Clemens), Lepidoptera: Tortricidae) and mountain pine beetle (Dendroctonus ponderosaeHopkins, Coleoptera: Curculionidae). Reduced growth and survival are a function of insect population and defoliation level. It is feasible to make short-term (annual) predictions of insect population and defoliation based upon sampling, but long-term, multi-year predictions are problematic. Given the historical record, it is expected that outbreaks will occur with relatively predictable frequency and basic host relationships and abiotic constraints will not change dramatically. However, the precision of predictions at fine scales is variable and reduced over time. Relationships between tree growth reduction, survival, and cumulative defoliation or beetle population level are available for major insect species. Understanding insect outbreak effects hinges on mortality, changes in interspecies competition, regeneration, and succession. Altered stand dynamics caused by insects can be interpreted for indicators such as wildlife habitat, old forest, riparian buffer cover, viewscapes, and connectivity. Anthropogenic changes are altering impacts via range expansions, northward shifts, and changes in forest composition. We can better understand effects of insect outbreaks and how best to ameliorate damage through a combination of empirical permanent plot studies, modelling, and manipulative experiments.

Effects of Salt Water and Elevation of the Corpse on the Rate of Decomposition and Subsequent Insect Succession

The post-mortem decomposition and corresponding insect succession is a continuous process, which commences from the moment of death, until skeletonisation. Many studies have been carried out looking at these processes, and what may have an effect upon them. The effect of salinity levels in water and elevation have on a corpse is very rarely touched upon at all. With the field of forensic entomology growing in popularity with law enforcement agencies all the time, more studies need to be undertaken. This study is designed to investigate the effects that elevation of the corpse and salinity level have on decomposition rates, whilst comparing insect biodiversity and population levels of insects on the individual corpses. So far no research has been carried out in this particular area of the field. Three pig corpses were left to decompose in the open air and therefore exposed to the insect population. One corpse was elevated, limiting its contact with the ground. A second corpse was soaked in a salt water solution, whilst a third corpse was used as a control. Insects were sampled and pictures were taken for a 43-day period during the months of March and April, in Leicestershire, England. The results indicate that insect succession and the rate of decomposition are both affected respectively with regards to salinity and elevation level.

Predicting population level of Delphacodes kuscheli, vector of Mal de Río Cuarto virus, and climate risk in the Argentine Pampas using meteorological models.

The planthopper Delphacodes kuscheli Fennah (Hemiptera: Delphacidae), principal insect vector of Mal de Rio Cuarto virus on corn in Argentina, produces severe disease outbreaks when migration of large macropterous populations coincides with early corn growth stages. Linear models based on winter environmental variables were developed to explain variation of macropterous populations accumulated on oat until November 30 (1993-2001) in La Aguada (department of Rio Cuarto, Cordoba, Argentina). Using daily records of maximum and minimum temperatures and precipitation, variables were generated and processed in different periods from June 1 to September 20. The best bivariate model (R2=0.97) had the lowest mean square error, was selected by Stepwise procedure, and its validation was highly satisfactory. It included the variable DDTxn, which accumulates mean temperature values exceeding 10°C on days with maximum and minimum temperature >24.5°C and 11°C, respectively, and DPr, which counts days with precipitation (>0mm). These variables were processed from July 1 to September 19. Using this model (correctly validated against independent observations in Chajan, Sol de Mayo and Espinillo -department of Rio Cuarto- for 2, 3 and 7 years, respectively), climate risk in the Pampas region was evaluated relative to insect population levels in the endemic area.

Effects ofBacillus thuringiensisCry1Ab and Cry3Aa endotoxins on predatory Coleoptera tested through artificial diet-incorporation bioassays

Traditional approaches to studying the effects of genetically modified (GM) crops on beneficial insects involve either field assays, comparing insect population levels between control and GM crops or tritrophic bioassays with contaminated insects - usually larvae or eggs of Lepidoptera - as preys. Here, we report the results of a bioassay using an artificial diet, suitable for predatory Coleoptera, to supply Bacillus thuringiensis (Bt) solubilized Cry1Ab and Cry3Aa as well as trypsin-activated Cry1Ab to Atheta coriaria and Cryptolaemus montrouzieri adults and young larvae of Adalia bipunctata. Water, solubilization buffer and trypsin-treated solubilization buffer were used as controls. In total, 1600 insects were assayed. Assays showed a relatively low mortality rate in the controls, ranging from as low as 7% after 15 days (C. montrouzieri) to about 15-20% after five days (A. bipunctata) or 15 days (A. coriaria). For all three predators, there were no statistical differences between the mortality recorded in any of the treatment groups and the corresponding controls. These results indicate a lack of short- (A. bipunctata) and long-term (A. coriaria and C. montrouzieri) mortality associated with oral ingestion of Cry1Ab and Cry3Aa at the high dose tested (50 microg ml-1). We discuss the relevance of these findings for the ecology of beneficial Coleoptera and compatibility with Bt and GM Bt crops.

Fungal flora associated with Ips typographus: frequency, virulence, and ability to stimulate the host defence reaction in relation to insect population levels

This study was aimed at determining the composition of Ips typographus L. (Coleoptera: Scolytidae) associated fungal flora in France, its virulence, and its ability to stimulate host defence reactions. The relationship between these parameters and the beetle population levels was also considered. The study was conducted in 2001, 2002, and 2003 in Norway spruce (Picea abies (L.) Karst.) stands, with different bark beetle damage levels. In each stand, the frequency of association between fungi and I. typographus was determined. The virulence of the most frequent species was assessed through mass inoculations on living spruce trees. The ability to stimulate the host defence reactions was estimated with low-density inoculations. The most frequent species, Ophiostoma bicolor Davids. &amp; Wells, Ophiostoma piceaperdum Rumbold, and Ophiostoma tetropii Mathiesen, were all pathogenic. Ophiostoma piceaperdum also induced intense defence reaction zones, suggesting that it could play a role in I. typographus population establishment on living trees. However, significant correlations between fungal frequencies and damage of the current year were observed only with O. tetropii or O. bicolor, and no relationships between damage of the previous year and fungal frequencies were found. The effects of some fungal species on beetle population dynamics was suggested, but selection of species during epidemic condition was not confirmed.

Field Trials Measuring the Effects of Ultraviolet-Absorbing Greenhouse Plastic Films on Insect Populations

Field studies were conducted to compare insect population levels in greenhouse crops covered with plastics that block the transmission of UV light in two wavelength ranges. Crops grown in greenhouses under a plastic that blocked UV light at wavelengths of 380 nm and below had lower numbers of aphids and thrips compared with a plastic that blocked UV light at wavelengths of 360 nm and below. This is consistent with the results found for thrips in previous studies using small, completely enclosed tunnels with no plant material. The effects were not as dramatic in the commercial greenhouses, perhaps due to unfiltered light entering through the open sides of those greenhouses. There was no reduction in greenhouse whitefly, Trialeurodes vaporariorum Westwood, populations under the <380 UV-absorbing plastic compared to <360 nm UV-absorbing plastic in these field trials. This is inconsistent with results found in small, completely enclosed tunnels, where sticky traps caught a significantly higher proportion (95 +/- 2%) of released greenhouse whiteflies inside tunnels covered with <360 nm absorbing plastic compared with the <380 nm absorbing plastic. The results of these studies suggest that the type of greenhouse plastic used in a structure can affect population levels of some insect species, and may be useful tools in developing integrated pest management programs for insect management. The design of the greenhouse and amount of unfiltered light that enters the system appear to be important factors in determining the level of effect.

Sweetpotato Insect Management in North Carolina

The 199 sweetpotato growing season was one of extremes: early high temperatures, cool temperatures at planting, drought early and extended, and then hurricane floods. Insect species and population levels were highly variable. Thrips early and armyworms late. Insect control tactics and management strategies were used and include the following. Insect presentations and handouts were made at field days, annual meeting and at several county meetings. A sweetpotato insect field guide was prepared to assist fieldmen with insect scouting. Insect scouting schools were held in several counties to show insects, their damage, and traps to use in detecting their presence and numbers over time. Control studies with insecticide formulations and rates along with timing studies were conducted and prepared for the annual report. Spintor and Admire received registations for worms late and for early season insect control. Aphid vector studies centered on aphid suction traps, yellow sticky traps, and aphid identifications. Foliar and soil insecticides were discussed as to their use and impact. Insecticides of the future were presented and discussed. Cooperative studies and long term plans were discussed.

Insects on Trees: Population and Individual Response to Fertilization

We review the literature dealing with the effect of soil fertilization on phytophagous insects and mites on trees. Most published studies focus on nitrogen fertilization. The results of different experiments are often contradictory. In this review we attempt to facilitate the interpretation of the experimental results by distinguishing between direct effects on insect individuals and population level effects, and by grouping insects according to their feeding mode. By making these distinctions it is possible to explain at least some of the ostensibly contradictory results, such as where a fertilization-induced improvement in food quality from an individual point of view does not positively affect population growth. Enhanced nitrogen availability usually benefits individual herbivores by improving the nutritional quality of the host plant. However, except for aphids where a positive response to nitrogen fertilization is usually found, the effects of nitrogen fertilization on insects at the population level are often nonsignificant or even negative. The reason for this might be that fertilization also affects higher trophic levels in the ecosystem, i.e. predators and parasitoids, which control herbivore populations, and the effects mediated by community structure override the effects mediated by the improved quality of the host tree.

Evaluation of Chlorpyrifos-Methyl and Chlorpyrifos-Methyl plus Methoprene as Protectants of Stored Corn: Small Bin Tests

Chlorpyrifos-methyl applied at 6 ppm and a combination of 6 ppm chlorpyrifos-methyl + 1 ppm methoprene were evaluated as protectants of stored corn ( Zea mays L.) against a standard malathion application of 8 ppm and an untreated control. Corn was treated in October 1987, placed in 10-, 19-, and 76-bu bins, and infested at selected intervals with red flour beetle, Tribolium castaneum (Herbst); flat grain beetle, Cryptolestes pusillus (Schonherr); maize weevil. Sitophilus zeamais Motschulsky; and Indianmeal moth, Plodia interpunctella (Hiibner). Indianmeal moths did not establish populations on treated or untreated corn. Beetle populations in untreated controls were not abundant until June 1988 (8 mo after application). After 12 mo, red flour beetle and flat grain beetle populations were significantly greater in corn treated with malathion than in corn treated with either chlorpyrifos-methyl or chlorpyrifos-methyl + methoprene. Maize weevil populations were not significantly different among the three chemical treatments. Moisture content was not significantly different between treated and untreated corn or among the chemical treatments. Dockage and weight loss were significantly greater in untreated than in treated corn after 8 mo. After 12 mo, weight loss was significantly greater in malathion-treated corn than in corn treated with either chlorpyrifos-methyl or chlorpyrifos-methyl + methoprene. Insect population levels or insect damage did not differ significantly between the latter two treatments.

Goal programming for estimating initial influx of insect pests

A method is presented to estimate the initial number of insect pests entering a field by using a goal programming routine coupled with an insect population dynamics simulation model. In this method, the observed insect population levels during the season are used as goals and the coupled routine and simulation model are used to estimate the initial emergence pattern. Enhancements to the method are described including weighting certain goals and allowing goals to be represented by ranges. An algorithm is presented by which entomological expertise can be utilized in an interactive mode.

Insect conservation and the disturbance landscape

Long-term changes in climate and topography influence the physical appearance of the landscape. In medium-term historical times, agriculture has dramatically and increasingly rapidly changed the landscape. It has contributed to heterogeneous partitioning of the land surface and multiplied the number of small patches and line corridors. Inclement weather can have a short-term relatively instantaneous influence, causing fine tree fall, landslips, avalanches, mud deposition, etc. These various influences all have an impact upon insect population levels and distribution. Inclement weather has a major but transient detrimental effect upon insect populations, both directly and indirectly by changing the landscape. Even apparently innocuous conditions, such as dew, can be inclement to small insects, but insect populations usually recover rapidly from such disturbances. In contrast, landscape disturbance by man has a major and fairly permanent effect upon overall insect population levels and distribution. Wholesale equatorial forest removal is clearly harmful to biotic diversity, while it is also well known that the character of the landscape has an important influence upon economically important noxious insects as well as beneficial biocontrol agents. Less well known is the part played by agricultural elements such as herbaceous ecotones and farm dams in Mediterranean and sub-tropical areas as refugia for certain insects of conservation status.

Control of Greenbug, 1988

Abstract The previous year’s crop was soybeans. The experiment was arranged in a randomized complete block design with 4 replicates. Plots were 4 rows wide (30-inch spacing) and 30.8 ft long and were planted 19 May. The 2 center rows were used for data collection. Banded planting-time application of granules was made by applying a preweighed amount of granules (1.2 oz [AI]/1,000 row-ft) from a V-belt seeder into a bander mounted just in front of the planter presswheel. In-furrow planting-time application of granules (1.2 oz [AI]/1,000 row-ft) was made by applying a preweighed amount of granules from a V-belt seeder into the granule delivery tube mounted on the planter behind the seed tube. Emerged plants were counted 8 Jun. Insect population levels were determined by examining 5-10 plants on the stated dates. The heads were counted 26 Sep. Plots were harvested 19 Oct with a Massey 35 combine.

Sorghum Greenbug Control, 1985

Abstract This experiment was conducted in Clay County, Nebr. The previous year's crop was soybeans. The experiment was arranged in a randomized complete block design with 5 replications. Plots were 4 rows wide (30-inch spacing) and 30.2 ft long. The 2 center rows were used for insect counts and yield. In-furrow planting-time application of granules was made by applying a preweighed amount of granules from a V-belt seeder into the granule delivery tube mounted on the planter behind the seed tube. Foliar applications were applied on 25 Jul with a CO2-pressurized unit mounted on a bicycle-wheeled plot sprayer. Three nozzles/row were used—1 from each side and 1 over the row. Spraying Systems TX8 hollow-cone tips were used at 40 psi with spray output of 22.5 gal/acre. The number of emerged plants in the 2 center rows of each plot was counted on 20 Jun. Insect population levels were determined by examining 10 plants in the 2 center rows on the stated dates. Plots were harvested on 25 Oct with a Massey 35 combine.