Infestation Of Crops Research Articles

Review of Farm Level Adaptation Strategies to Climate Change in Africa

Climate change poses social, economic and environmental problems on a global scale. It is a threat to agricultural development, as it has multitude manifestations among which include increased infestation of crops by pest and diseases, increased rural-urban migration, increased biodiversity loss, frequent drought and flood. These evident consequences of climate change however, can be reduced through adaptation. The review revealed that farmers practiced various adaptation strategies peculiar to the impact of climate change in their localities. These include mixed cropping, early planting, use of new crop varieties and soil management techniques among others. Inadequate inputs, lack of information on climate change forecast and poverty were the constraints to climate change adaptation among crop farmers as reviewed by this study. It is recommended that more campaign need to be carried out to sensitize farmers on the dangers and consequences of climate change and need for adaptation. Farmers need to be empowered economically through access to loans for them to procure adaptation inputs.

High spectral and spatial resolution hyperspectral imagery for quantifying Russian wheat aphid infestation in wheat using the constrained energy minimization classifier

The effects of insect infestation in agricultural crops are of major ecological and eco- nomic interest because of reduced yield, increased cost of pest control and increased risk of environmental contamination from insecticide application. The Russian wheat aphid (RWA, Diuraphis noxia) is an insect pest that causes damage to wheat (Triticum aestivum L.). We pro- posed that concentrated RWA feeding areas, referred to as hot spots, could be identified and isolated from uninfested areas within a field for site specific aphid management using remotely sensed data. Our objectives were to (1) investigate the reflectance characteristics of infested and uninfested wheat by RWA and (2) evaluate utility of airborne hyperspectral imagery with 1-m spatial resolution for detecting, quantifying, and mapping RWA infested areas in commercial winter wheat fields using the constrained energy minimization classifier. Percent surface reflec- tance from uninfested wheat was lower in the visible and higher in the near infrared portions of the spectrum when compared with RWA-infested wheat. The overall classification accuracies of >89% for damage detection were achieved. These results indicate that hyperspectral imagery can be effectively used for accurate detection and quantification of RWA infestation in wheat for site-specific aphid management. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10.1117/1.JRS.8.083661)

Morphological and genetic characteristics of Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae) infesting potato crops in Korea

The pea leafminer fly, Liriomyza huidobrensis (Blanchard), was found infesting and damaging Korean potato crops during a 2012 field survey. Localized outbreaks of L. huidobrensis were observed in Miryang and Goryeong counties in the south of the Korean Peninsula. This paper describes the morphological and genetic characteristics of the Korean population of L. huidobrensis. The dorsal color pattern on the abdomen, and an array of microsetae on the thorax, were the main diagnostic characteristics of this species. On the basis of an analysis of a partial mitochondrial cytochrome c oxidase subunit 1 (COI) DNA sequence, we found that intraspecific variation in L. huidobrensis was negligible, and that the distance between L. huidobrensis and a closely related species, L. trifolii, was estimated to be 7.4–7.6 K2P. This is the first report of the infestation of field crops by the invasive leafminer L. huidobrensis in Korea.

De Novo Assembly and Characterization of the Transcriptome of the Parasitic Weed Dodder Identifies Genes Associated with Plant Parasitism

Parasitic flowering plants are one of the most destructive agricultural pests and have major impact on crop yields throughout the world. Being dependent on finding a host plant for growth, parasitic plants penetrate their host using specialized organs called haustoria. Haustoria establish vascular connections with the host, which enable the parasite to steal nutrients and water. The underlying molecular and developmental basis of parasitism by plants is largely unknown. In order to investigate the process of parasitism, RNAs from different stages (i.e. seed, seedling, vegetative strand, prehaustoria, haustoria, and flower) were used to de novo assemble and annotate the transcriptome of the obligate plant stem parasite dodder (Cuscuta pentagona). The assembled transcriptome was used to dissect transcriptional dynamics during dodder development and parasitism and identified key gene categories involved in the process of plant parasitism. Host plant infection is accompanied by increased expression of parasite genes underlying transport and transporter categories, response to stress and stimuli, as well as genes encoding enzymes involved in cell wall modifications. By contrast, expression of photosynthetic genes is decreased in the dodder infective stages compared with normal stem. In addition, genes relating to biosynthesis, transport, and response of phytohormones, such as auxin, gibberellins, and strigolactone, were differentially expressed in the dodder infective stages compared with stems and seedlings. This analysis sheds light on the transcriptional changes that accompany plant parasitism and will aid in identifying potential gene targets for use in controlling the infestation of crops by parasitic weeds.

Influence of weather parameters on the population dynamics of black bug, (Cavelerius sweetiSlater & Mugomoto) in sugarcane in Haryana, India

In autumn planted, sugarcane, (Saccharum officinarum) crop the correlation coefficient showed non significant but positive trend with minimum and maximum temperature. The effect of minimum and maximum relative humidity with black bug population showed a negative correlation. In ratoon crop the highest black bug population 7.2/tiller was recorded during the 4th week of May at minimum temperature, maximum temperature, minimum relative humidity, maximum relative humidity, 22.9°C 40.9°C 32.0% 46.0% and 9.4 sun shine hours respectively. The Cavelerius sweeti population was significant and positively correlated with minimum and maximum temperature. While minimum and maximum relative humidity was correlated negatively the population of black bug but it was positively correlated with sun shine hours. The regression coefficient for minimum and maximum temperature, minimum and maximum relative humidity and sun shine hours were 0.361, -0.162, -0.054, 0.029 and -0.867 in autumn planted crop and 0.014, 0.610, –0.075, 0.644 and -0.989 in ratoon crop of sugarcane, respectively. The ratoon crop of sugarcane was more vulnerable to C. sweeti attack in comparison to autumn planted sugarcane crop. The weather factors viz., minimum and maximum temperate, minimum and maximum relative humidity and sun shine hours were 22.9°C, 40.9°C 32.0 per cent, 46.0 per cent and 9.4 respectively found optimum for the fast multiplication of the black bug population as well as infestation in ratoon crops.

Effects of the penetration of Artemisia vulgaris L. into maize crops as a result of the use of reduced tillage

In recent years, a significant increase in weed infestation of agricultural crops with <em>Artemisia vulgaris </em>has been observed in the south-western region of Poland. The ease of migration of this expansive species results from the fact that it does not face competition from segetal weeds and therefore poses a great threat to the ecological balance. During the period 2008–2011, a floristic study was carried out using the Braun-Blanquet method in an abandoned field adjacent to a maize monoculture grown under two tillage systems: plough and ploughless tillage. These observations allowed an evaluation of the actual risk of spread of <em>Artemisia vulgaris </em>depending on tillage system. The vicinity of the abandoned field had a significant effect on the penetration of <em>Artemisia vulgaris </em>into maize crops. Higher numbers of individuals of this species were found under ploughless tillage compared to plough tillage, regardless of the distance from the field edge, and its increased competitive effects on <em>Viola arvensis </em>L. and <em>Veronica persica </em>L. could be observed. The lowest grain yield was obtained under ploughless tillage where the strong competitive effects of <em>Artemisia vulgaris </em>were observed even in the plot most distant from the abandoned field adjacent to the maize crop.

A Simple Method for Estimating Instantaneous Levels of Endoparasitism ofPlutellaxylostella(Linnaeus) (Lepidoptera: Plutellidae) by Hymenoptera in the Field

Although endoparasitoids are widely used for biological control of Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) throughout the world, current methods do not allow for easy estimation of parasitism levels. I investigated the potential of using ratios of parasitoid cocoons to infestations to develop a simple and practical method of estimating parasitism levels in the field. Crop infestations by the pest and densities of its endoparasitoids' cocoons were recorded at weekly intervals over six consecutive years on unsprayed cabbage. In order to establish if there was a relationship between parasitism levels and ratios of parasitoid cocoons to infestations, samples of host larvae and pupae were collected every week during scouting for rearing in the laboratory. The majority of parasitoid cocoons belonged to the larval endoparasitoid Cotesia vestalis (Haliday) (Hymenoptera: Braconidae), which was the major mortality factor of P. xylostella. Total parasitism levels were positively related to ratios of parasitoid cocoons to infestations. Crop infestation by P. xylostella was low during periods of high parasitism (≥50 %) than during low parasitism (< 50 %), and 50 % parasitism corresponded with 20 % ratio of parasitoid cocoons to infestations. This study shows that ratios of parasitoid cocoons to infestations can be used to estimate background parasitism levels.

A Comparison of the Infestation ofAproaerema simplexella(Walker) on Groundnut and other Known Hosts forAproaerema modicella(Deventer) (Lepidoptera: Gelechiidae)

A groundnut pest occurring in South Africa and widely reported as Aproaerema modicella (Deventer) has recently been identified by mtDNA CO1 analysis as Aproaerema simplexella (Walker), a strain native to Australia. Two experiments were conducted during 2011–2012 growing season at five sites in South Africa. The first experiment examined the preference of A. simplexella between groundnut, soya bean, lucerne, pigeon pea and lablab (common known host crops for A. modicella). The second experiment examined the effect of cypermethrin on the control of the pest on soya bean and groundnut at two sites. Among the host crops tested, soya bean was the most preferred by the pest followed by groundnut at all sites. The pest was also observed on pigeon pea at all sites, but the infestation was very low. Lucerne was observed as the less preferred host for this species. No infestation was observed on lablab bean across the sites. Spraying cypermethrin in groundnut and soya bean reduced infestation in both crops to very low levels. In the unsprayed plots, the high infestation levels significantly reduced crop yields.

Farm‐scale dispersal of Bactericera cockerelli in potato crops measured using Bt mark‐capture techniques

AbstractNatural populations of Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), also known as tomato/potato psyllid, were marked in potato [Solanum tuberosum L. (Solanaceae)] crops using Bacillus thuringiensis Berliner (Bt) to investigate the impact of dispersal on crop infestation and management of potential insecticide resistance in New Zealand. The technique was adapted from previous studies that used conventional spray applications of Bt to mark Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), and identified marked individuals with selective microbiological assays and identification of characteristic crystal inclusions. Initially, marking rates of B. cockerelli were improved by using ultra‐low volume applications of undiluted Bt, but this result was not consistent. Several other pests and natural enemies were also marked. In mark‐capture studies, marked B. cockerelli were captured over 3 days on yellow sticky traps in small trap plots of potatoes at 60, 120, 180, 250, and 350 m from the sprayed crop. Bactericera cockerelli flight activity occurred throughout daylight hours with evidence of bimodal diurnal peaks. Significantly greater numbers of B. cockerelli were captured in downwind traps. The combined dispersal curve derived from two mark‐capture experiments estimated a mean dispersal distance for B. cockerelli of 100 m in 3 days and indicated that 10% of the population dispersed further than ca. 250 m. Over the period of a growing season, this level of dispersal suggests that B. cockerelli can disperse throughout a vegetable‐growing region, with implications for crop infestation and management of potential insecticide resistance.

Scientific Opinion on the risks to plant health posed by Bemisia tabaci species complex and viruses it transmits for the EU territory

The Panel on Plant Health conducted a pest risk assessment for Bemisia tabaci and the viruses it transmits, including an evaluation of risk reduction options and an assessment of the effectiveness of the special requirements linked to B. tabaci and the viruses listed in Council Directive 2000/29/EC. B. tabaci and a large number of viruses transmitted by this polyphagous insect occur in subtropical and tropical climates around the world. Five entry pathways for B. tabaci and associated viruses were identified, with the plants for planting pathway being most significant and rated for entry of insects and viruses as likely and moderately likely, respectively. The most invasive B. tabaci species and several of its associated viruses responsible for severe diseases in major European food crops are established outdoors in coastal Mediterranean regions. Because of similar climate requirements and host plant preferences, B. tabaci and associated viruses currently not present in Europe are likely to establish within the temperature limits set for B. tabaci. Trade between European Member States allows B. tabaci to reach greenhouses in northern Europe, including those in areas with protected zone status. Because of the cool climate, establishment and spread outdoors of B. tabaci is rated unlikely for northern Europe. This situation is likely to continue even under a climatic scenario with an increase in temperature of +2 °C. B. tabaci -transmitted viruses cause severe diseases with major negative impact on crop production when risk reduction measures are not used. Risk reduction options will also apply to B. tabaci and viruses new to Europe. Risk reductions options are evaluated in terms of reducing B. tabaci populations, crop infestations, virus incidence and the impact of diseases. © European Food Safety Authority, 2013

Features of weed component formation in spring wheat crops upon the introduction of No-Till technology

Data on changes in the weed infestation of spring wheat crops during transition to No-Till technology under conditions of the forest steppe zone of Western Siberia are provided. The features of formation of a weed component are revealed depending on the predecessor and the level of agrochemicalization.

Weed infestation of field crops in different soils in the protective zone of Roztocze National Park. Part II. Root crops

The study on weed infestation of root crops in different soils in the protective zone of Roztocze National Park was conducted in the years 1991-1995. As many as 240 phytosociological records, made with the use of Braun-Blanquet method, were taken in potato and sugar beet fields. The number of weed species in sugar beet and potato in the area depended on the soil and type of root crop. In the same environment conditions. the iiuinber of weed species was higher in potato than in sugar beet. The most difficult weed species iii all types of soil were: &lt;i&gt;Chenopodium album, Stellaria media&lt;/i&gt; and &lt;i&gt;Convolvulus arvensis&lt;/i&gt;. Podsolic soils were highly infested by two acidophylic species: &lt;i&gt;Spergula arvensis&lt;/i&gt; and &lt;i&gt;Raphanus raphanistum&lt;/i&gt;. Potato in loess soil and brown soil made of loamy sands were highly infested by &lt;i&gt;Echinochloa crus-galli, Equisetum arvense&lt;/i&gt; and &lt;i&gt;Galinsoga parviflora&lt;/i&gt;. Root crop plantations in brown soils formed from gaizes of granulometric loam texture and limestone soils were infested by: &lt;i&gt;Galium aparine, Sonchus arvensis, Sinapis arvensis&lt;/i&gt; and &lt;i&gt;Veronica persica&lt;/i&gt;.

Nisza ekologiczna chwastów w odmianach zbóż jarych uprawianych po rzepaku ozimym

The environmental conditions and ecological niches for weed survival and development in cereals crops are diversified. They are conditioned by biotic and abiotic factors of the environment and natural factors including quantitative rations between species of agrophytocenosis. The object of the studies carried out in 2009–2012 was to determine the weed species composition and infestation in crops of spring cereal species. Two cultivars were taken into consideration for each cereal species. The observations were done on the control (untreated) plots of a field experiment on evaluation of herbicide biological efficacy. The obtained results revealed that regardless of cereal species and cultivar, the weed species composition was similar, however the number of weeds and their biomass were different. The smaller weed biomass and their number were correlated with a higher competitiveness of cultivated cereal plants in relation to weeds. The rye cultivar Bojko showed the highest competitivenes, while the wheat cultivar Tybalt was the least competitive. The highest weed infestation was recorder for wheat in contrast to the lowest one in barley and rye crops. A proper selection of cereal species and cultivars with high competitive abilities should be taken into consideration by organic farms. Warunki życia chwastów i nisze ekologiczne w zasiewach rożnych gatunków zbóż nie są jednakowe. Zależą one od zespołu biotycznych i abiotycznych czynników środowiska i całokształtu czynników przyrodniczych, w tym od stosunków ilościowych pomiędzy różnymi gatunkami tworzącymi agrofitocenozę. W badaniach wykonanych w latach 2009–2012 określono skład florystyczny i stopień zachwaszczenia w 5 gatunkach zbóż jarych, przy czym w każdym gatunku uwzględniono 2 odmiany. Obserwacje przeprowadzono w obiektach kontrolnych doświadczeń z oceną skuteczności biologicznej herbicydów. Uzyskane wyniki wskazują, że niezależnie od gatunku i odmiany liczba występujących taksonów kształtowała się podobnie, natomiast ich liczebność i biomasa ulegała dużemu zróżnicowaniu w zależności od uprawianych gatunków i odmian zbóż jarych. Im mniejsza była liczba i biomasa chwastów, tym większa była konkurencyjność uprawianych roślin w stosunku do chwastów. Największą konkurencyjnością charakteryzowało się żyto odmiany Bojko, a najmniejszą pszenica odmiany Tybalt. Największe zachwaszczenie wyrażone zarówno ogólną liczbą chwastów i biomasą odnotowano w pszenicy a najmniejsze w jęczmieniu i w życie. Wybór do uprawy gatunków i odmian zbóż jarych o większej zdolności konkurencyjnej powinien być uwzględniany w gospodarstwach ekologicznych.

Weed infestation of crops in different soils in the protective zone of Roztocze National Park. Part I. Winter and spring cereals

The study on weed infestation of crops in different soils in the protective zone of RPN was conducted in the years 1991-1995. The characterization of weed infestation of winter and spring cereals was based on 306 phytosociological records. made with the use of Braun-Blanquet method. The degree of weed infestation in the fields in the protective zone of RPN depended on environment conditions. Both winter and spring cereals in majority of soils were most infested by: &lt;i&gt;Cenaturea cyanus, Apera spica-venti&lt;/i&gt; and &lt;i&gt;Vicia hirsta&lt;/i&gt;. In the lightest podsolic soils, made of loose sand and slightly loamy sand. winter and spring cereals were additionally infested by &lt;i&gt;Equisetum arvense&lt;/i&gt; and two acidophylic species: &lt;i&gt;Seleranthus annuus&lt;/i&gt; and &lt;i&gt;Spergula arvensis&lt;/i&gt;. The crops in brown loess soil were infested by &lt;i&gt;Matricaria maritima&lt;/i&gt; subsp. &lt;i&gt;inodora&lt;/i&gt;. The most difficult weed species in brown soil formed from gaizes and limestone soil were: &lt;i&gt;Convolvulus arvensis, Papaver rhoeas&lt;/i&gt; and &lt;i&gt;Galium aparine&lt;/i&gt;. Moreover winter cercals in limestone soil showed high or medium infestation with &lt;i&gt;Consolida regalis, Aethusa cynapium, Lathyrus tuberosus&lt;/i&gt; and low infestation with &lt;i&gt;Apera spica-venti&lt;/i&gt; and &lt;i&gt;Centaurea cyanus&lt;/i&gt;. Spring cereals were less infested than winter cereals. &lt;i&gt;Apera spica-venti&lt;/i&gt; and &lt;i&gt;Centaurea cyanus&lt;/i&gt; were less common with spring cereals than with winter cereals. Also, spring cereals showed high or medium infestation with &lt;i&gt;Convolvulus arvensis&lt;/i&gt;. Spring cereals in some soil units were infested by &lt;i&gt;Chenopodium album&lt;/i&gt; and &lt;i&gt;Stellaria media&lt;/i&gt;. There was also higher infestation of spring cereals in limestone soils with &lt;i&gt;Avena fatua, Veronica persica, Sinapis arvensis&lt;/i&gt; and &lt;i&gt;Sonchus arvensis&lt;/i&gt;, compared to winter cereals in limestone soils.

FORAGE PRODUCTIVITY AND WEED INFESTATION OF ANNUAL EARLY–SPRING MIXTURE UNDER DIFFERENT SOWING DATES

During the 2011–2012 periods in the Research Institute of Mountain Stockbreeding and Agriculture (RIMSA) in Troyan (Bulgaria) the effect of sowing time on some bio– productive indicators (green mass and dry matter yields, weed infestation) of the forage from annual early–spring cereal–legume mixture from oats and field pea was performed. As variants the following periods of sowing were studied: 1. 10–20 March (Standard); 2. 21–30 March; 3. 1– 10 April; 4. 11–20 April. It was established that the optimum time for sowing of annual early spring pea and spring oats mixed crop was the period from 10 to 20 March. Then was received most plant production (1.84 t.ha green mass and 0.41 t.ha dry matter), which exceeded the other sowing periods from 7.07% (21–30 March) to 27.72% (11–20 April) and from 1.6 to 8.13%, respectively. In the different sowing times the weed infestation of crops varied and was a highest in early spring sowing (10–20 March)–from 8.40 to 9.26%.

Scientific Opinion on the risk to plant health posed by Tomato spotted wilt virus to the EU territory with identification and evaluation of risk reduction options

The Panel on Plant Health conducted a pest risk assessment for Tomato spotted wilt virus (TSWV) including the identification and evaluation of risk reduction options. The plants for planting pathway is considered the most important one and rated as likely, with medium uncertainty. TSWV, reported in many Member States, has one of the widest host range for plant viruses and has three widely distributed thrips vector species in the risk assessment area. For countries falling under the provisions of 2000/29/EC Annex IIAII legislation, the probability of establishment is rated as very likely, with low uncertainty. For Finland and Sweden, protected zone under the 2000/29/EC Annex IB legislation, the probability of establishment is rated unlikely to moderately likely. Spread can occur through the activity of thrips vectors and through trade of infected hosts. The probability of spread in Member States under Annex IIAII provisions is evaluated as likely, with low uncertainty. In Finland and Sweden, spread is rated as unlikely to moderately likely, with medium uncertainty. Since TSWV may cause both yield and quality losses in a wide range of hosts, a major impact is predictable in the absence of appropriate control measures, with medium uncertainty. The risk reduction options evaluated by the Panel are those addressing either the sanitary status of the propagation material (including the provisions of 2000/29/EC Annex IIAII and Annex IB, statutory certification system and the use of voluntary industry standards) or those addressing the control of TSWV epidemic development through actions directed at the virus or at its vectors (including cultural methods to reduce crop infestation and chemical or biological control of thrips vectors). Limitations of the current measures and the potential consequences of repealing the current legislation are discussed.

Stem borer infestation of cereal crops in Jere, the Sudan-Sahelian savanna region of Nigeria

Field data collected during the rainy season of two years, 2010 and 2011, were used to determine the per cent plant infestation and stem borer abundance on cultivated cereal crops grown by farmers' in Jere or the Sudan-Sahelian savanna ecological region of Nigeria. Stem borers were recovered using destructive sampling. Mean total per cent plant infestation and stem borer abundance per farmers' field were significantly higher on millet (40% and 25 individuals, respectively) and sorghum (30% and 21 individuals, respectively) than on maize (19% and 13 individuals, respectively). Of the five stem borer species found in this study, Coniesta ignefusalis (Lepidoptera: Pyralidae) (3.5)/Chilo sp. nr. aleniellus (Lepidoptera: Crambidae) (2), Busseola fusca (Lepidoptera: Noctuidae) (3.1)/Sesamia calamistis (Lepidoptera: Noctuidae) (2.4) and S. calamistis (2.9), with significantly higher number of individuals per plant, tended to be more important pests on millet, sorghum and maize crops, respectively. Although, mean total per cent plant infestation and abundance of stem borers in this study were generally moderate, further studies on the effects of different types of cereals intercropping (locally practiced) on stem borer infestation and abundance should ascertain the true importance of these pest species in the Sudan-Sahelian savanna ecological region of Nigeria.

Bats Track and Exploit Changes in Insect Pest Populations

The role of bats or any generalist predator in suppressing prey populations depends on the predator's ability to track and exploit available prey. Using a qPCR fecal DNA assay, we document significant association between numbers of Brazilian free-tailed bats (Tadarida brasiliensis) consuming corn earworm (CEW) moths (Helicoverpa zea) and seasonal fluctuations in CEW populations. This result is consistent with earlier research linking the bats' diet to patterns of migration, abundance, and crop infestation by important insect pests. Here we confirm opportunistic feeding on one of the world's most destructive insects and support model estimates of the bats' ecosystem services. Regression analysis of CEW consumption versus the moth's abundance at four insect trapping sites further indicates that bats track local abundance of CEW within the regional landscape. Estimates of CEW gene copies in the feces of bats are not associated with seasonal or local patterns of CEW abundance, and results of captive feeding experiments indicate that our qPCR assay does not provide a direct measure of numbers or biomass of prey consumed. Our results support growing evidence for the role of generalist predators, and bats specifically, as agents for biological control and speak to the value of conserving indigenous generalist predators.

Habitat, Body Size and Reproduction of the Leafhopper,Dalbulus elimatus(Hemiptera: Cicadellidae), during the Winter Dry Season

Although the Mexican corn leafhopper Dalbulus elimatus (Ball) is an important vector of maize pathogens, little is known about its biology in natural conditions, particularly about its overwintering habitats. Winter populations are a source of infestation of crops and are responsible for efficient distribution of offspring in the new habitat that in this case is maize cultivated in the rainy season (Jun–Oct). This study was conducted in the habitats were D. elimatus adults have green food available during the Mexican winter (dry) season (Nov– May) in central Mexico, such as on senescent maize, green wild grasses that grow on the edges of maize fields, and volunteer maize and maize seedlings. Dalbulus elimatus adults were found in Nov on senescent maize, in Dec on green wild grasses, and in Apr on volunteer maize. These results suggest that adults can overwinter locally. Moreover, a sudden appearance of D. elimatus adults occurred in Jul when maize was planted, at the onset of the rainy season. These immigrant adults are mainly females that exhibit larger body size (wing length and head width) and carry higher numbers of mature eggs than females collected during the winter season.

Development of cell lines from the cactophagous insect: Cactoblastis cactorum (Lepidoptera: Pyralidae) and their susceptibility to three baculoviruses

The unintentional introduction of the cactus moth, Cactoblastis cactorum, a successful biological control agent formerly employed in the control of invasive prickly pear cactus species (Opuntia spp.) in Australia, Hawaii, South Africa, and various Caribbean islands, has posed great concern as to the possible threat to native, endangered species of cactus in the southeastern USA as well as with the potential to cause a major infestation of commercial and agricultural cactus crops in Mexico. A number of control measures have been investigated with varying degrees of success including, field exploration for cactus moth-specific parasitoids, insecticides, fungal, bacterial, and nematode agents. Current tactics used by the USA-Mexico binational program to eradicate cactus moth from Mexico and mitigate its westward movement in the USA include host plant removal, the manual removal and destruction of egg sticks and infected cacti stems, and the Sterile Insect Technique. One other approach not taken until now is the development of a cactus moth cell line as a tool to facilitate the investigation of baculoviruses as an alternative biocontrol method for the cactus moth. Consequently, we established C. cactorum cell lines derived from adult ovarian tissue designated as BCIRL-Cc-AM and BCIRL-Cc-JG. The mean cell population doubling time was 204.3 and 112 h for BCIRL-Cc-AM and BCIRL-Cc-JG, respectively, with weekly medium change, while the doubling time was 176.6 and 192.6 h for BCIRL-Cc-AM and BCIRL-Cc-JG, respectively, with a daily change of medium. In addition, the daily versus weekly change in medium was reflected in the percentage viability with both cell lines showing higher levels with a daily medium change. Of the three baculoviruses tested, only the recombinant AcMNPV-hsp70Red and GmMNPV at a multiplicity of infection (MOI) of 1.0 were able to demonstrate significant production of extracellular virus (ECV) in each of the cell lines, whereas both cell lines were refractive to an HzSNPV challenge at an MOI of 10. In this study, we have demonstrated both the successful development of a C. cactorum cell line and its ability to support a complete baculovirus infection. The potential is also there to pursue further investigations to determine the susceptibility of the cactus moth cell line to other viruses. Additionally, the availability of a cactus moth cell line will facilitate the analysis of viruses prior to using the more expensive bioassay test. Finally, it is hoped with the knowledge presented here that baculoviruses may also be considered as an alternative biocontrol method for the cactus moth.