A four-year field study (2013–2016) was conducted to screen Indian sugarcane hybrids together with two susceptible checks against internode borer Chilo sacchariphagus indicus (Kapur) (Lepidoptera: Crambidae) in endemic locations of Tamil Nadu State, India. Each year, borer incidence on cane basis and intensity on internode basis were assessed at harvest to eliminate susceptible entries. Of the total 535 hybrids screened, only Co 293 emerged as resistant at the end of fourth year trial which was confirmed in tests under controlled conditions with artificial infestation. A modified relative resistance ratio computed using incidence and intensity also confirmed its resistance to the borer. In laboratory oviposition choice tests with excised leaves of the resistant Co 293 and susceptible hybrids Co 86032 and Co 1060, percent of leaf bits oviposited, egg masses laid, and egg numbers deposited were significantly lowest in Co 293. Also, an oviposition preference index computed for both egg mass number and egg number was significantly lowest for Co 293 which suggested antixenosis. Larval survival was significantly lowest in Co 293 with 5 to 10-fold higher neonate mortality than in the two susceptible hybrids. Prolonged larval development period and lower fecundity were observed when the borer was reared on Co 293 which indicated antibiosis. A relative suitability ratio developed from larval and pupal durations also indicated lower suitability of Co 293. Among the plant morphological characters examined, leaf length and cane thickness positively influenced borer incidence; loose sheath-clasp was associated with higher borer incidence. Among 12 shoot phenolics quantified, eight were present in higher quantities in Co 293 suggesting their role in antibiosis. Co 293 identified as resistant hybrid in the present study has the potential to be used as a parent in breeding programs for C. sacchariphagus indicus resistance.

The use of nematophagous fungi is an alternative for the biological control of nematodes in ruminants. In this study, the compatibility of joint growth of the fungi Monacrosporium sinense and Pochonia chlamydosporia and the joint nematicidal activity of these fungal isolates on bovine infective larvae were evaluated. For that, tests of direct confrontation, the effect of volatile compounds and antibiosis were conducted. In order to carry out the tests, the fungi were inoculated in potato dextrose agar culture medium and, after the incubation period, the growth of the colonies, the formation of an inhibition halo and the effect of volatile metabolites were verified. The compatibility between fungi isolates M. sinense and P. chlamydosporia was confirmed and the nematicidal evaluation proved the best effectiveness was when both were used together, with a 98.90% reduction in the number of bovine nematode infective larvae under in vitro conditions. It was concluded that M. sinense and P. chlamydosporia presented synergistic action, suggesting that the joint application of the fungi increases the effectiveness of biological control of bovine infective larvae.

The cabbage aphid, Brevicoryne brassicae L. (Hem: Aphididae), is one of the most serious pests of canola worldwide. In this research, the effects of Pseudomonas putida, salicylic acid (SA), and integrated application of both inducers were studied on the resistance of canola to B. brassicae. In free-choice situation, the number of B. brassicae attracted on canola plants under treatments containing P. putida and SA was significantly lower compared to control plants. In the life table study, pre-adult survival, longevity, reproductive period, and fecundity of this aphid were lowest on plants treated with P. putida + SA. The net reproductive rate (R0), intrinsic rate of population increase (r), and finite rate of increase (λ) of B. brassicae decreased significantly in the following order: control (47.19 offspring, 0.293 and 1.340 day−1), P. putida (16.7 offspring, 0.238 and 1.269 day−1), SA (6.37 offspring, 0.163 and 1.178 day−1), and P. putida + SA (3.24 offspring, 0.112 and 1.119 day−1). Moreover, the beneficial effect of the integrated application of P. putida and SA on plant growth parameters was significantly evident in our study. The highest values of glucosinolates, total phenol, and flavonoids were recorded in P. putida + SA treatment. We concluded that canola plants treated with P. putida + SA are more resistant to the cabbage aphid. These findings demonstrated that SA integrated with P. putida on canola plants act effectively for reducing the population of B. brassicae and can be used in integrated management programs of this pest.

Nematophagous fungi are used in the biological control of the parasitic helminths of animals and plants. The association of ovicidal and predator nematophagous fungi may present a complementary and increased action on the biological control of helminths. Joint growth compatibility and predation tests were carried out on infective larvae of nematode parasites of bovines with the nematophagous fungus ovicide Pochonia chlamydosporia and the nematophagous fungus predator Arthrobotrys cladodes. The tests of antagonism in direct confrontation, antibiosis and the effect of volatile metabolites between the isolates of P. chlamydosporia and A. cladodes indicated the viability of joint growth of these fungi. The association of the fungi P. chlamydosporia and A. cladodes presented a higher predatory capacity of infective larvae of the parasitic nematodes of bovines when compared to the predation of the fungi used alone. Therefore, under laboratory conditions, the fungi studied presented growth compatibility and the association of these increased the nematicidal activity against parasitic helminths of cattle.

The cabbage aphid, Brevicoryne brassicae L. (Hem: Aphididae), is an important pest of canola that can considerably limit profitable crop production either through direct feeding or via transmission of plant pathogenic viruses. One of the most effective approaches of pest control is the use of biostimulants. In this study, the effects of humic acid, plant growth-promoting rhizobacteria (PGPR), and integrated application of both compounds were investigated on life table parameters of B. brassicae, and the tolerance of canola to this pest. B. brassicae reared on plants treated with these compounds had the lower longevity, fecundity, and reproductive period compared with control treatment. The intrinsic rate of natural increase (r) and finite rate of increase (λ) were lowest on PGPR treatment (0.181 ± 0.004 day−1 and 1.198 ± 0.004 day−1, respectively) and highest on control (0.202 ± 0.005 day−1 and 1.224 ± 0.006 day−1, respectively). The net reproductive rate (R0) under treatments of humic acid, PGPR and humic acid + PGPR was lower than control. There was no significant difference in generation time (T) of B. brassicae among the tested treatments. In the tolerance test, plants treated with PGPR alone or in integrated with humic acid had the highest tolerance against B. brassicae. The highest values of total phenol, flavonoids, and glucosinolates were observed in treatments of PGPR and humic acid + PGPR. Basing on the antibiosis and tolerance analyses in this study, we concluded that canola plants treated with PGPR are more resistant to B. brassicae. These findings could be useful for integrated pest management of B. brassicae in canola fields.

The corn leaf aphid, Rhopalosiphum maidis (Fitch) (Hemiptera: Aphididae), is an important pest of corn, but no corn genotypes resistant to R. maidis are commercially available. Although the ability of silicon to induce plant resistance against some insects is known, the effect of silicon on R. maidis and in corn hybrids with different levels of constitutive resistance is still unknown. This study sought to determine the constitutive resistance of corn hybrids to R. maidis and silicon resistance induction in hybrids with different degrees of constitutive resistance. Field experiments with natural infestations of aphids were conducted in three locations in Brazil (Patos de Minas, Araguari, and Tupaciguara). Greenhouse trials were also used to evaluate the effect of varietal resistance on aphid population growth and identify resistant and susceptible genotypes. Aphid resistance induced by silicon was determined with resistant and susceptible corn hybrids. In the field, the corn hybrids BM8850, AS1625PRO, and DKB310PRO had the greatest proportion of plants infested by R. maidis in all three localities. The hybrids P30F53H, STATUS VIP, BM9288, DAS2B587HX, DKB175PRO, AS1633PRO, and DKB390PRO2 were the least infested in Patos de Minas and Araguari, and P30F53H was the least infested in Tupaciguara. When antibiosis effects were evaluated by aphid population growth, the hybrids AG7088PRO3 and DKB310PRO2 were susceptible, while P30F53YH was resistant. When natural aphid infestation was evaluated, wherein the effects of antibiosis and non-preference could not be discriminated, soil applications of silicon-induced resistance to R. maidis in both susceptible and constitutively resistant corn hybrids.

Rhynchophorus ferrugineus, known as the Red Palm Weevil (RPW), is reported as a pest of up to 40 palm species. However, the susceptibility degree and the defense mechanisms of these species against this weevil are still poorly known. In Europe, the RPW is a major pest of Phoenix canariensis while other palm species, including the congeneric Phoenix dactylifera, seem to be less suitable hosts for this insect. The aim of our study was to compare the defensive response of P. dactylifera, Chamaerops humilis and Washingtonia filifera against R. ferrugineus and try to define the mechanisms of resistance that characterize these species. Bioassays were carried out to evaluate the mortality induced on RPW larvae by extracts from the leaf rachis of the studied palm species. Tests at semi-field scale were also conducted, based either on forced palm infestation, with larvae of RPW, or on natural infestation, with adult females. Rachis extracts from C. humilis and W. filifera caused 100% larval mortality after 2 days of exposure, while extracts of P. dactylifera did not impair larval survival. Independently of the effect of the leaf extracts, the weevils were unable to naturally infest the three palm species, although larval survival was high after forced infestation of the plants. We concluded that the observed lack of infestation of P. dactylifera by RPW is due to factors other than antibiosis. In W. filifera and C. humilis, although the presence of antixenosis mechanisms cannot be excluded, resistance to R. ferrugineus seems to rely on the presence of antibiosis compounds.

Symbionts in sponges must interact with the host immune system, and this can be mediated by immunomodulators. As the bases of the immune system in sponges resemble those of higher metazoans, it is possible that compounds from this microbiota show similar effects in other phyla. It is also known that several antibiotics, in special macrolides, can modulate many components of the immune response and sponges and their associated microorganisms are a rich source of these compounds. Therefore, we tested the immunosuppressive capacity of antibiotic substances produced by bacterial and fungal strains isolated from the Amazon freshwater sponge Metania reticulata. Fourteen bacterial and six fungal strains were obtained from samples of M. reticulata collected in the Negro River (Amazon Central Basin region), during the dry season. These cultures were monitored for natural antimicrobial activity, and two Bacillus strains (MERETb.761 and MERETb.762) and one fungus (MERETf.010) were selected. One Bacillus strain, MERETb.762, showed strong and specific antibiosis on Staphylococcus aureus and two fractions of its extract inhibited the degranulation of RBL–2H3 cells. The predicted formulas of these fractions were C12H6N4O8 and C25H4N2O6, both corresponding to nitroaromatic compounds.

The capitate glandular trichomes of wild sunflowers (Helianthus spp.) are considered to be effective defence components that act against some herbivorous insects, but cultivated sunflowers are reportedly deficient in glandular trichomes. To investigate whether glandular trichomes have a role in the protection of cultivated sunflowers against insects, in the present study, Helianthus annuus L. accessions were grown to quantify glandular trichome density in wild and cultivated germplasm types and assess potential anti-insect effects of terpenoids in the glandular trichomes of cultivated sunflowers. Evaluation revealed that capitate glandular trichomes are often abundant in cultivated sunflowers; relative to wild H. annuus, inbred maintainer (HA) lines have similar numbers of glandular trichomes per floret, while commercial hybrids have only ≈ 20% fewer trichomes when compared with wild sunflowers. In the laboratory assay, it was found that glandular trichome extracts increased the mortality rates of sunflower moth, Homoeosoma electellum (Hulst), larvae exposed from the neonatal stage to 9 d. In the surviving larvae, the extracts significantly reduced larval mass and head capsule width. Though there are limitations to the value of glandular trichomes for host plant resistance, the feeding deterrent or toxic effects of sesquiterpene lactones and diterpenes in sunflower glandular trichomes are not limited to sunflower moth larvae, suggesting a potential for resistance to other sunflower insect pests. Additional research is required to understand the inheritance and value of glandular trichomes in commercial sunflower germplasm and how the composition of terpenoids in the glandular trichomes of wild H. annuus may differ from that in cultivated material.

Resistance mechanisms to the pod-sucking bug (PSB) Clavigralla tomentosicollis Stäl, in cowpea genotype IT86D-716, were studied in field and laboratory. Non-preference was evaluated on three cowpea varieties (IT86D-716, Moussa local and KVx396-4-5-2D) through measuring differences in population parameters and extent of damage under field and laboratory conditions. Antibiosis was evaluated based on development parameters of C. tomentosicollis when reared on pods of the aforementioned varieties. The variety IT86D-716 consistently exhibited both non-preference and antibiosis resistance mechanisms to C. tomentosicollis. A chemical analysis of the pods was conducted to identify compounds conferring antibiosis. Several compounds including cyanogenic heterosides, flavonoids, tannins and trypsin inhibitors were present in pods of IT86D-716. Evidence suggests that antibiosis due to these compounds may contribute to the resistance to PSB. In the case of antibiosis, 5-day long exposures were adequate to observe nymphal mortality. Based on this finding, a fast, reliable and low-cost screening of pods can be carried out in the laboratory for identification of lines that are C. tomentosicollis resistant.

Cacao genotypes of various origins were evaluated for resistance to the cocoa mirid (Sahlbergella singularis (Haglund)) based on field damage, antixenosis, antibiosis and tolerance. Field damage was assessed by scoring recent and cumulative damage by the mirid to the major genetic groups of cacao. Antixenosis assessment was based on the number of feeding lesions on twig segments using a choice test. Antibiosis was measured through survival of young mirid nymphs on shoots and pods, whereas tolerance was assessed through the reaction of the twigs to mirid feeding punctures. Among the genetic groups of cocoa, the Upper Amazon, the materials from Guiana and hybrid genotypes were the least damaged by the mirids, both for recent and cumulative damage. The Catongo group was, by far, the most susceptible group with more than 50% of the canopy showing both recent dieback and cumulative canker damage. With regard to antixenosis, antibiosis and tolerance, significant differences (P < 0.05) were found between the genotypes. The least preferred clones sustained between 2 and 3 lesions compared with the most preferred ones with 6–8 lesions per twig segment. Clones UPA402, T79/501 and IMC67 gave the lowest rate of mirid nymph survival, indicating that they exhibit antibiosis. The clones PA107, SCA6 and C151-61 sustained high numbers of mirid feeding lesions and relatively high levels of shoot death, but have a good ability for re-growth and can be considered as tolerant genotypes.

The antibiotic effects of 12 different cotton genotypes on Bemisia tabaci (Gennadius) were studied during June–July and August–September 2003, with the objective to determine the biological parameters which are important to study the mechanism of antibiosis and to identify the genotypes in which antibiosis is operating. The detailed biology of whitefly, i.e. developmental period, survival, fecundity, longevity and sex ratio were studied under ‘no choice’ conditions, by confining the whiteflies in leaf cages. The study revealed that incubation period, nymphal developmental time, total developmental time, nymphal survival, total survival, fecundity and female longevity are the most important biological parameters for detecting the presence of antibiosis in resistant cotton genotypes against whiteflies. On the other hand, pupal period and survival, male longevity and sex ratio do not seem to play important roles in antibiosis. The combined effect of these parameters indicated that Gossypium arboreum genotype PA 183 was the most resistant while Bt 6304, TX Maroon 2–78 and F846 were the most susceptible ones. Other genotypes with moderate resistance include Supriya and LD 694.

The demographic statistics of the ladybird Exochomus flaviventris Mader (Coleoptera: Coccinellidae) were investigated under laboratory conditions on the cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Homoptera: Pseudococcidae), reared on four host plants with different levels of antibiotic resistance to the mealybug: two cassava (Manihot esculenta Crantz, Euphorbiaceae) varieties, Incoza and Zanaga, Faux-Caoutchouc (FC) (hybrid of M. esculenta × M. glaziovii Muel. Arg.) and water weed (Talinum triangulare Jack, Portulacacae). Preimaginal mortality, mean oviposition time and total fecundity of female ladybirds were strongly affected by the host plant even though there was no linkage with antibiotic resistance. The net reproduction rates R0 of the predator were 1.5,1.7 and 2.4 times higher on Zanaga than on water weed, Incoza and FC respectively, and the generation time (T) was significantly longer on Zanaga than on the other three plants. The intrinsic rate of increase rm was not modified by the antibiotic resistance of the host plants. With the two cassava varieties, Incoza and Zanaga, it was found that antibiosis significantly affected the life history parameters of the ladybird without modifying its fitness, and provided better cassava mealybug control.

Background and objective It is claimed that local anaesthetics have antimicrobial properties. Our aim was to investigate the antimicrobial effects of different concentrations of ropivacaine, bupivacaine, lidocaine and prilocaine on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans.

Methods All local anaesthetic dilutions were exposed to microorganisms for 0, 30, 60, 120, 240 min at room temperature. The inoculums taken from diluted suspensions were reinoculated on blood agar and incubated for 18–24 h at 35°C and then the colonies were counted.

Results Ropivacaine did not inhibit any of the microorganisms tested. Bupivacaine reduced the viable cells of P. aeruginosa at 0.5% and 0.25% solutions. Lidocaine 5% and 2% and prilocaine 2.0% dilutions reduced the viable cells of all microorganisms tested. Prilocaine 1.0% reduced the viable cells of E. coli, S. aureus and P. aeruginosa. Lidocaine 1% reduced only the viable cells of P. aeruginosa and prilocaine 0.5% reduced only E. coli.

Conclusion Ropivacaine had no antimicrobial effect on microorganisms tested. Bupivacaine showed poor antimicrobial effectiveness. Lidocaine and prilocaine had more powerful antimicrobial effects than the other two local anaesthetics.

The defoliating beetle Mesoplatys ochroptera Stål (Coleoptera: Chrysomelidae) has become a serious pest of the tropical legume Sesbania sesban (L.) Merrill in agroforestry systems in eastern and southern African countries. In this study, 32 accessions of Sesbania spp. collected from eastern and southern Africa were screened for resistance to M. ochroptera at Msekera, Zambia. Two mechanisms of resistance—antixenosis and antibiosis—were indicated in the different accessions. Accessions of Sesbania bispinosa, S. leptocarpa and S. macrantha were found to be more preferred by the insect compared to S. sesban and S. rostrata accessions. Preference of accessions was negatively correlated with leaf-hair density and positively correlated with the number of leaves per seedling and plant height. Under the conditions of eastern Zambia, some accessions of S. sesban from Kenya, Malawi and Ethiopia were found to be comparable to the Zambian accessions in survival, growth and biomass production. Four accessions of S. sesban—Kakamega (ex Kibwezi) and Kisii 2 from Kenya, Zwai 090 from Ethiopia and Rumphi from Malawi—appeared to compensate well for M. ochroptera damage.

A study was conducted to elucidate the effects of protein fractions isolated from maize (Zea mays L.) seeds on the development and survival of the Mexican bean weevil, Zabrotes subfasciatus (Boh.) (Coleoptera: Bruchidae). Maize seeds were fractionated into albumins, globulins, prolamins, glutelins and a residue and the bruchids reared on artificial seeds composed of susceptible background bean flour enriched with the different protein fractions. Survival (as indicated by LD50) and development (as indicated by WD50) of 20-day-old larvae of the bruchid were negatively affected by most of the fractions. The albumins and globulins were the most detrimental to Z. subfasciatus, significantly affecting both its survival and development.

The aim of the present study was to determine, by a field experiment, whether the seasonal variations in the levels of cyanide and rutin in the phloem, secondary compounds potentially implicated in cassava resistance to the cassava mealybug (Phenaccocus manihoti), could be influenced by different kinds of soil fertilisation (manure, NPK, KC1, lime, mulch). It was found that mean cyanide and rutin contents varied significantly with season, soil treatments and infestation. For each soil treatment, the highest contents of these compounds on uninfested plants was registered in the main dry season (Jul-Aug) for cyanide and at the end of the dry season (Jul-Aug) and beginning of the rainy season (Oct-Nov) for rutin. The infestation factor induced an increase in cyanide and rutin contents for 43 combinations of period and soil treatment among 48 in total. For cyanide content (phagostimulant function in mealybug), this increase appeared significant at the end of the rainy season (Apr-May) and in the main dry season (Jul-Aug) for control and KC1 fertilisation. For rutin content (an unfavourable substance for the insect) significant increase was induced by infestation in each period for manure and mulch and especially in the main dry season (Jul-Aug) and at the beginning of the rainy season (Oct-Nov) for other soil treatments. Concerning the seasonal variations in the level of rutin, these results showed that mulch and manure are the best fertilisers to increase cassava resistance against mealybugs.

Cassava varieties resistant to the cassava green mite, Mononychellus tanajoa (Bondar) ( Acari:Tetranychidae) have been reported in many parts of Africa where the pest has been introduced. However, the resistance mechanisms have not been identified. Laboratory studies on biology and feeding behaviour of cassava green mite were carried out at the International Institute of Tropical Agriculture (IITA), in order to determine whether this resistance is mainly due to pubescence.

Cassava pubescence was found to have no antibiotic effect; both pubescent and non-pubescent varieties were preferred by the mite for oviposition, food and shelter. In addition, pubescence does not afford a mechanical barrier to cassava against green mite infestation.

This study was conducted to identify the individual biochemical factors involved in the resistance observed in a few Mexican bean accessions against the bean weevil, Acanthoscelides obtectus (Say) (Coleoptera: Bruchidae). Soluble proteins from different bean genotypes were separated by fractionated acetone precipitation. Insects were reared on artifical seeds composed of a susceptible background bean flour enriched with the different protein fractions. At low doses (2% w/w), the 0–20% and 20–40% acetone fractions of the resistant bean accessions G 12954 and G 12880 inhibited larval growth of the bean weevil, but not of a related species, the Mexican bean weevil, Zabrotes subfasciatus (Boheman). The 0–20% fraction caused the highest mortality of first instar larvae. The 60–80% acetone fraction contains general resistance factors, like α-amylase and protease inhibitors, which when enriched in artifical seeds led to a strong depression of insect growth for resistant and susceptible bean accessions alike. These factors should also be taken into account in breeding for multigenic, durable resistance, in order to exploit the synergism between general and specific resistance factors.

Cowpea, Vigna unguiculata (L.) Walp., is susceptible to a wide spectrum of insect pests from seedling to harvest as well as in storage. Insecticide use has been the most commonly adopted method for the control of cowpea pests. However, due to the deleterious effects of insecticides on man, livestock and the environment, research over the years has been focused mainly on developing resistant/tolerant cultivars as a vital component in the integrated management of cowpea pests. This approach has, however, recorded varying degrees of success, due in part to the multiple and often overlapping pest complex attacking at different phenological growth stages of the crop.

In spite of the progress in the utilisation of insect-resistant cowpea varieties, the use of resistance as a control tactic has by no means been fully realised. There are many important cowpea insect pests for which resistant varieties are not yet available for commercial cultivation. Where resistant varieties are available for a given insect, these varieties may not be widely planted because of their unsuitability to local conditions.

In this paper, the status of host plant resistance research in cowpea is reviewed and some novel approaches aimed at solving its seemingly intractable pest problem are proposed, based on the state-of-the-art scientific and crop biotechnological development. The proposed framework for orientation of cowpea resistance research should ensure yield stability and sustainability for the resource-poor, smallscale farmers in Africa.