In this paper, we analyzed the occurrence of motifs (modules) in empirical food-webs from different ecosystem types. Differently from previous studies, our analysis did not relied on randomized networks with specific a priori assumptions, which has been demonstrated to produce inconsistent patterns. We aimed to evaluate the interplay between population dynamics and food-web topology, and its consequences to module occurrences in complex food-webs. We evaluated 13 arrangements of three-species modules and 199 arrangements of four-species modules. For each module, we assembled, a corresponding Jacobian predation matrix, and evaluated the arrangements expected to persist after a disturbance in the equilibrium of the populations dynamics (local stability). Our general results were that (1) a limited set of stable arrangements occurs most frequently; (2) the omnivory module is the only three-species module expected to occur both in the stable and unstable region; (3) connectance and omnivory affects the proportion of stable modules; and (4) the type of ecosystem influence the proportion of stable modules. Further, we demonstrated that food-web topology and population dynamics influenced module occurrences in natural communities; presented a function for the ways that local stability increases the probability of module occurrence; and highlighted the use of omnivory degree to access the effect of feeding at more than one trophic level on food-web stability.

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Phosphites (Phi) are inorganic salts of phosphorous acid that have been used as resistance elicitors to activate mechanisms underlying plant defence. This study assessed the effectiveness of manganese phosphite (MnPhi) for the management of rust (Hemileia vastatrix) on coffee seedlings. The effect of this compound on the induction of resistance was also measured by the expression of defence‐related genes such as POX (peroxidase), CAT (catalase), GLU (β‐1.3‐glucanase) and PAL (phenylalanine ammonia‐lyase) and by the activity of defence enzymes such as ascorbate peroxidase (APX), superoxide dismutase (SOD) and polyphenol oxidase (PPO). Foliar sprayings of MnPhi on coffee seedlings provided 63% control of rust severity. This compound induced defence responses in seedlings with increased transcription of genes POX, CAT, GLU and PAL in non‐inoculated plants and increased activity of APX, SOD and PPO enzymes in plants inoculated with H. vastatrix and in non‐inoculated plants. It is suggested that MnPhi can induce resistance in coffee seedlings.

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The aim of this study was to investigate the effectiveness of potassium phosphites for the control of anthracnose and the mode of action of these products on common bean plants against Colletotrichum lindemuthianum, comparing it with the standard resistance inducer acibenzolar‐S‐methyl. The protection of plants against anthracnose was evaluated in greenhouse after treatment with potassium phosphites (Phosphite A and B, 5.0 ml/L), acibenzolar‐S‐methyl (0.25 g/L), or no treatment (control). Two sprayings of the treatments were performed, respectively, at V4 stage (three trifoliate leaves) and at the R5 stage (flower buds present). The inoculation with C. lindemuthianum was performed 5 days after the first spraying. Phosphite formulations A and B reduced the severity of anthracnose by 68.7% and 55.6%, respectively, and the presence of phosphites in the leaf tissues were detected at concentrations between 1 and 3 mm by 7 days after spraying. These same concentrations of phosphites reduced the mycelial growth of C. lindemuthianum in vitro by 15.0% to 25.7%. In addition, the activities of defence enzymes and the levels of phenolic compounds and lignin were assessed. Phosphite treatments enhanced the activity of various enzymes, including superoxide dismutase, peroxidase, chitinase, and β‐1,3‐glucanase, and increased the lignin and a small increase in the levels of soluble phenolics. This study provides evidence that phosphite treatments control anthracnose by acting directly on C. lindemuthianum and by inducing the production of defence responses.

Black rot of crucifers, (Xanthomonas campestris pv. campestris) is the principal yield-limiting and destructive pathogen of cruciferous crop worldwide. In order to validate a bio-based control alternative for this disease, whey, lime sulfur, biofertilizer, Bordeaux mixture or raw milk were applied to kale (Brassica oleracea var. acephala) plants. The disease control was achieved by most of the tested products. Milk-based products (raw milk and whey) and biofertilizer reduced the severity by 44 and 56% in the field. Antioxidants, crude fibber, crude protein and lipid contents and kale yield were verified in the five treatments on the leaves with and without X. campestris pv. campestris inoculation. In the absence of the pathogen (non-inoculated), lime sulfur and Bordeaux mixture improved plant nutritional value compared to organic treatments, nevertheless milk-based products and biofertilizer improved the evaluated variables more than the control. However, on leaves inoculated with X. campestris pv. campestris raw milk increased antioxidant activity, crude protein and fiber contents, whereas biofertilizer increased kale yield, lipid and antioxidant contents. Milk-based products and biofertilizer were further evaluated in greenhouse trials to determinate the activity of defense-related enzymes and lignin content. Biofertilizer treatment resulted in increased phenylalanine ammonia lyase, catalase, peroxidase activities and lignin content. Hence, the application of milk-based products and biofertilizer are promising to control black rot of crucifers and also improves food quality by boosting nutritional values and antioxidant activity.

The morphometric analysis of parasitoids may contribute to biological control programs by providing information on development of insects and relationships among sizes of morphological characters. Furthermore, it can infer about the impact of insecticides on morphological characters and fitness. We evaluate the morphometry, allometry, and fluctuating asymmetry of the egg parasitoid Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) with and without influence of the growth-regulating insecticides teflubenzuron and lufenuron. Trichogramma pretiosum had significantly larger wings and tibiae in treatments with insecticides. We found no effects of insecticides on asymmetry in T. pretiosum and conclude that this insect is very close to isometry. This study emphasizes the importance of evaluating the size of parasitoids destined to biological control programs.

1. The intensity of community interactions and the structure of food webs can be associated with an organism's body size. However, little is known about how interactions among species in multitrophic communities determine the body size of individuals exploiting the same resource.2. This study evaluates the effects of resource size, fruit infestation, and parasitism on tibia length, a proxy measure of body size, of insects exploiting the same resource. The three most abundant seed-feeding species of Senegalia tenuifolia (Fabaceae: Mimosoideae) were selected, and the relationship between their tibia length and the interactions within the food web was estimated. The selected species were the beetles Merobruchus terani and Stator maculatopygus, and the braconid wasp Allorhogas vulgaris.3. The body sizes of 531 specimens were measured and it was found that tibia length of each species responded differently to the interactions, demonstrating that functionally similar species may respond differently to multitrophic effects. The body size of Merobruchus terani, the most abundant species in the food web, was negatively affected by the presence of A. vulgaris, but there was a positive relationship with seed biomass and its own abundance in the fruits. The other two species were less abundant and more plastic in their responses, as a strong negative effect of M. terani presence on A. vulgaris body size was observed, as well as a strong negative effect of Coleoptera parasitism rate on S. maculatopygus body size. 4. It is concluded that morphological traits can provide information on how interactions affect species body size.