Laboratory studies were carried out on the effects of an emulsifiable concentrate (EC) formulation of Azadirachtin (AZ) (6 g a.s./l EC) on four major cotton pests in Senegal: Spodoptera littoralis Boisduval (Lepidoptera: Noctuidae), Helicoverpa armigera Hϋbner (Lepidoptera: Noctuidae), Aphis gossypii Glover (Homoptera: Aphididae) and Tetranychus urticae Koch (Acari: Tetranychidae). In both S. littoralis (SL) and H. armigera (HA), larval weight loss was observed 48 h after treatment. Appreciable weight gain was only observed in SL larvae at dosages of 0.05 and 0.1 g a.s. /l AZ, 72 h after treatment. In both SL and HA, there was a significant difference (p < 0.05) between the control larvae and those treated with 0.1 to 1.5 g a.s. /l AZ. At a dosage of 1.5 g a.s./l, AZ caused 60% mortality in SL and 0% mortality in HA, 72 h after treatment. The treatment with AZ at dosages of 0.05 and 1.5 g a.s./l resulted in 50 and 30% malformation in SL and HA pupae respectively. The duration of development from the IV instar larva to pupa in both lepidopterans increased progressively with AZ dosage. SL was more susceptible to AZ than HA. No growth disrupting effects were observed in A. gossypii (AG) and T. urticae (TU) where EC50 values of 1.49 and 1.36 g a.s./l AZ respectively were obtained. The implications of the effects of AZ on further field trials against cotton pests are discussed.
The species Halyomorpha halys (Stål), which is endemic in East Asia, was first detected in North America in 1996 and was probably introduced into Europe in 2008. The species is polyphagous. It consumes over 170 host plant species and significantly impacts crop production. In Greece the first recording of its presence was in 2014, when it was reported as a nuisance in houses in the region of Athens. The present study describes the systematic spread and damage of this invasive pest, including the first recorded identification in peach and olive cultivations in the prefecture of Imathia in central Macedonia, Greece. Sampling was carried out in representative peach and olive farms during July and August, 2018 and 2019 in which significant levels of fruit damage were recorded, especially during 2018. The population of the species was recorded throughout the winter seasons of 2018 and 2019 in which overwintering adults were systematically recorded in shelters and other constructions near fruit orchards. Given the dynamics of the species and its destructive impact on a wide range of host species, H. halys is expected to be a major pest. Additionally, considering that the prefecture of Imathia is the most important peach growing area of Greece, further studies of the presence and population dynamics of this species along with the establishment of particular management actions to control the population is imperative for the future protection of horticultural production in Greece.
Pest mites of the family Tetranychidae are commonly reported in several legumes. However, reports of their occurrence in lima beans are insipient, especially in Brazil. The objective of this research was to record the occurrence of mites in lima bean plants and to describe their damage in this Fabaceae. Tetranychus neocaledonicus André and Mononychellus planki McGregor were found in lima bean plants, Phaseolus lunatus (Fabaceae or Leguminosae). The lima bean plants, when infested by these mites, initially exhibit small whitish spots in the leaflets, which with increasing population density rapidly evolve into chlorotic patches, followed by silvering, and may dry out and fall due to their overfeeding. The extent of the damage caused to lima bean plants and the adaptability of the mite to warm and dry conditions indicate that T. neocaledonicus has greater potential as a lima bean pest than M. planki in northeastern Brazil. This is the first record of these mites associated with P. lunatus.
The population of spider feeding on insect pests of cotton was observed throughout the growth period of the crop, being maximum in the month of July. Chrysoperla was observed from second fortnight of June to harvesting of the crop being maximum in November. The incidence of coccinellids was recorded from the middle of August to middle of September and remained till harvesting of the crop being maximum in the first fortnight of November. A positive significant effect of maximum and minimum temperature on spider and negative significant effect on population of chrysoperla and coccinellids was recorded. Evening RH exerted positive significant effect on spider and negative significant effect on coccinellids.
The aim of the study carried out during 2002–2004 was to assess the effects and economic effectiveness of application of fungicides and insecticides in winter triticale crops. Its leaves were attacked by pathogenic fungi in 43.2% to 52.2% and the damage to leaf blade surfaces by cereal leaf beetle (Oulema spp.) ranged from 23.6% to 34.4%. The effectiveness of applied fungicides ranged from 44.7% to 90.8%, and that of insecticides was within 70.1% and 94.4%. The saved crops were evaluated for PLN 198 to 1 171 per ha. The cost coverage ratio ranged from 0.7 to 9.9 and the treatment profitability index ranged from 0.9 to 7.4. Cost index in percentage ranged from 0.8 to 8.5, with its average value of 4.2.
The whitefly, Bemisia tabaci, an insect of the order Hemiptera which attacks more than 600 species of plants, is one of the most important agricultural pests around the world. The insecticidal Cry proteins from Bacillus thuringiensis (Bt) are useful biological pesticides, and some are toxic to Hemipteran insects. In this study, Colombian native isolates of Bt were functionally characterized at molecular and biological levels. The strains contained between one and five different crystal shapes: round, triangular, amorphous, bipyramidal and squared. The strains presented between three to seven bands of proteins in their electrophoretic pattern that were organized into six groups according to their possible biological activity on insect pests. Cry1Aa, cry1Ab, cry1Ac, cry1B and cry1C genes were identified for PCR in the different Bt isolates. Bioassays were performed on tomato leaves whose surface was spread with 3 μg · ml−1 crude extract of Bt toxins. Second instar larvae of whitefly, which were placed on top of leaves and exposed to the toxins for 7 days, exhibited mortalities from 18 to 69%. The lethal concentration 50 (LC50) of ZBUJTL39, Bt kurstaki HD1 and ZCUJTL9 strains were 1.83, 1.85 and 2.16 μg · ml−1, respectively (p < 0.05). These results show that the native Bt strain ZBUJTL39, which contained the genes cry1Aa, cry1Ab, cryCa and cryBa could eventually be used for the development of an integrated management program together with other tools for the control of B. tabaci.
Soybean [Glycine max (L.)], one of the most important crops in Argentina, is commonly infected by Colletotrichum truncatum, the causal agent of anthracnose. Tagetes filifolia essential oil (EO) is presented as a natural approach to minimize the dose of chemical fungicides applied to the crop. The fungus Trichoderma harzianum is used as a biocontrol agent because of its ability to produce secondary metabolites that destroy cell walls of phytopathogenic fungi. However, its performance can be affected when it is exposed to chemical fungicides. The objective of this work was to evaluate the antifungal activity of T. filifolia EO both individually and combined with chemical fungicides against C. truncatum, and its effect on T. harzianum. Fungi were isolated from soybean crops. The following pesticides were assessed: carbendazim (F1), difenoconazole (F2) and trifloxystrobin + cyproconazole (F3). The EO was obtained from native plants and its chemical composition was analyzed by gas chromatography–mass spectrometry (GC–MS). The minimum fungicide concentration (MFC) was determined for each compound. Fungicides were combined with the EO to look for combinations that allowed a reduction of pesticide doses. Among fungicides, F1 showed the strongest antifungal activity against C. truncatum (MFC = 0.25 μl ⋅ l–1) and T. harzianum (MFC = 1.5 μl ⋅ l–1). The sensitivity of both fungi to the EO was lower than to fungicides. The EO presented MFCs of 6,000 and 9,000 μl ⋅ l–1 against C. truncatum and T. harzianum. The EO and F1 affected the growth of T. harzianum at concentrations that controlled C. truncatum (31 and 10%). Eight combinations of fungicides and the EO allowed fungicide concentration reductions of up to 80%, although the growth of the biocontrol strain was also affected. The results demonstrated that T. filifolia EO can be used to control anthracnose and reduce doses of chemical fungicides applied to soybean crops. Its effect on T. harzianum should be considered in the design of integrated pest management strategies.
Development and demography of Adalia decempunctata L. were studied under laboratory conditions at seven constant temperatures (12, 16, 20, 24, 28, 32 and 36°C). First instar larvae failed to develop to second instar at 12°С and no development occurred at 36°C. The total developmental time varied from 47.92 days at 16°C to 15.94 days at 28°C and increased at 32°C. The lower temperature thresholds of 11.05 and 9.90°C, and thermal constants of 290.84 day-degree and 326.34 day-degree were estimated by traditional and Ikemoto-Takai linear models, respectively. The lower temperature threshold (Tmin) values estimated by Analytis, Briere-1, Briere-2 and Lactin-2 for total immature stages were 11.99, 12.24, 10.30 and 10.8°C, respectively. The estimated fastest developmental temperatures (Tfast) by the Analytis, Briere-1, Briere-2 and Lactin-2 for overall immature stages development of A. decempunctata were 31.5, 31.1, 30.7 and 31.7°C, respectively. Analytis, Briere-1, Briere-2 and Lactin-2 measured the upper temperature threshold (Tmax) at 33.14, 36.65, 32.75 and 32.61°C. The age-stage specific survival rate (sxj) curves clearly depicted the highest and lowest survival rates at 16 and 32°C for males and females. The age-specific fecundity (mx) curves revealed higher fecundity rate when fed A. gossypii at 24 and 28°C. The highest and lowest values of intrinsic rate of increase (r) were observed at 28 and 16°C (0.1945 d–1 and 0.0592 d–1, respectively). Also, the trend of changes in the finite rate of increase (λ) was analogous with intrinsic rate of increase. The longest and shortest mean generation time (T) was observed at 16 and 28°C, respectively and the highest net reproductive rates (R0) was estimated at 24 and 28°C. According to the results, the most suitable temperature seems to be 28°C due to the shortest developmental time, highest survival rate, and highest intrinsic rate of increase.
The shipment of cut flowers from Colombia and Ecuador to the United States, the biggest importer of this product in the world, has doubled in the last 20 years. One of the main constraints in cut roses production is the gray mold disease caused by the fungus Botrytis cinerea, which can destroy the flowers, in the crop, during storage and/or shipping. Since the resistance of the fungus to conventional fungicides has been increasing, as well as the health effects in rose growers, alternative approaches for controlling the disease are needed. The effect of UV-C light on the gray mold development in cut roses was studied. Irradiation with 2,160; 1,080 and 540 J ⋅ m–2 UV-C, every 24 h for 5 days in a humid chamber, did not harm the roses. Instead, as seen by image analysis, a highly significant reduction of the area of the lesions by the disease and of the fungus germination was obtained at 1,080 J ⋅ m–2. The addition of a 4-h dark period to the irradiation did not improve the effect of UV-C on the disease. The results of this work potentiate the use of UV-C light in the agro-industry as a low-cost and non-invasive alternative method to control diseases. They also reflect the application of optical approaches as image analysis in the evaluation of important agricultural features.
The rose flea beetle, RFB (Luperomorpha xanthodera Fairmaire 1888) is a new flower pest in Europe. In 2012, it was brought accidentally to central Poland. To search for this introduced species in the area adjacent to the site of the first finding, 29 plant species belonging to five botanical families (Lamiaceae, Brassicaceae, Asteraceae, Plantaginaceae, Crassulaceae) were monitored over a 3-year-long study (2016−2018). RFB were found on 11 herbaceous/ ornamental plant species (Lamiaceae, Brassicaceae, Asteraceae) along with feeding damage to the flowers. White mustard (Sinapis alba L., Brassicaceae), hyssop (L.), and Monarda spp. (Lamiaceae) were its most preferred host plants. In each season, RFB females preferred host plants which bloomed abundantly and vividly. However, among the examined plant species there was a large variation in the year-to-year RFB abundance. Over the examined period the RFB extended its abundance exponentially, and its population survived and established itself in the area. The general sex ratio of the beetles was strongly female biased. In the female pool, females with conspicuously swollen abdomens predominated. The results of our study provide more insight into RFB behaviour, its establishment and spreading into new areas. To support the evidence for the RFB risk factor as an agricultural/ horticultural pest, further research should focus on the beetles’ biology, reproductive tactics, larval host plant preference, larva-inflicted damage and harmfulness, the impact of the RFB on the native fauna, as well as its further local and distant migration propensity. Presently our knowledge about these aspects is still fragmentary.