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.