Vector-borne plant pathogens often change host traits to manipulate vector behavior in a way that favors their spread. By contrast, infection by opportunistic fungi does not depend on vectors, although damage caused by an herbivore may facilitate infection. Manipulation of hosts and vectors, such as insect herbivores, has not been demonstrated in interactions with fungal pathogens. Herein, we establish a new paradigm for the plant-insect-fungus association in sugarcane. It has long been assumed that Fusarium verticillioides is an opportunistic fungus, where it takes advantage of the openings left by Diatraea saccharalis caterpillar attack to infect the plant. In this work, we show that volatile emissions from F. verticillioides attract D. saccharalis caterpillars. Once they become adults, the fungus is transmitted vertically to their offspring, which continues the cycle by inoculating the fungus into healthy plants. Females not carrying the fungus prefer to lay their eggs on fungus-infected plants than mock plants, while females carrying the fungus prefer to lay their eggs on mock plants than fungus-infected plants. Even though the fungus impacts D. saccharalis sex behavior, larval weight and reproduction rate, most individuals complete their development. Our data demonstrate that the fungus manipulates both the host plant and insect herbivore across life cycle to promote its infection and dissemination.

Some pathogens can manipulate their host plants and insects to optimize their fitness, increasing the attraction of insects to the infected plant in ways that facilitate pathogen acquisition. In tropical American sugarcane crops, the fungus Colletotrichum falcatum, the red rot causal agent, usually occurs in association with the sugarcane borer Diatraea saccharalis, resulting in large losses of this crop. Considering this association, we aimed to identify the effects of C. falcatum on D. saccharalis host preference and performance as well as the effect of this insect on C. falcatum sugarcane infection. Here, we show that the fungus C. falcatum modulates D. saccharalis behavior to its own benefit. More specifically, C. falcatum-infected sugarcane plants showed a dramatic increase in VOCs, luring D. saccharalis females to lay eggs on these plants. Therefore, sugarcane infection by the fungus C. falcatum increased in cooccurrence with insect herbivory, benefiting the pathogen when associated with D. saccharalis.

The long-lived polygynandrous ladybird beetle Tenuisvalvae notata (Mulsant) found in Brazil was evaluated in the laboratory for the effects of multiple mating and aging on its reproductive performance. This species is native to South America and is an important predator of mealybugs. Specifically studied were partner choice, female reproductive success, adult longevity, male virility, and offspring development. Young (5-10 days old) and older virgin females (95-100 days old) were subjected to either a single mate or multiple mating with the same or different males of various mating status (virgin or previously mated once, twice, and thrice). Results revealed a preference in both genders to mate with previously known partners. Additionally, younger females had higher fecundity and greater longevity when mated only once in comparison to those mated multiple times. Fecundity, fertility, and offspring development were similar across the treatments regardless of the number of mating or male mating history. Fecundity and fertility decreased throughout the oviposition period regardless of mating treatment.

The predatory ladybird beetle Tenuisvalvae notata (Coleoptera: Coccinellidae) (Mulsant) is a polygamous species and its morphology, as well as the storage capacity of seminal fluid in the spermatheca, may affect its reproductive performance. Thus, the present study evaluates the spermatheca morphology of virgin and mated T. notata females using light and scanning microscopy. The results show that the spermatheca of T. notata is kidney shaped and consists only of the receptacle and spermathecal duct, being morphologically similar in virgin and mated females. There is no secretion in the spermathecae of virgin females and, in mated females, only once it was not possible to observe the presence of spermatozoa. By contrast, females mate multiple times it is possible to observe spermatozoa in the lumen of the spermatheca surrounding the secreted material. Polygamy in T. notata might be related to the maintenance of viable spermatozoa in the spermatheca, in which case the female would prefer to copulate more times during its adult life than to store spermatozoa for a longer period of time.

In robusta coffee, Coffea canephora, the black twig borer Xylosandrus compactus (Eichhoff) (Coleoptera: Curculionidae) causes considerable damage. Although this has been reported in many crops for years in Brazil, recently, the injury caused by X. compactus in coffee has been ignored. This present study aimed to report the current status of X. compactus in Brazil, and to investigate its attack frequency in different robusta coffee genotypes. In this study, we reported the occurrence of X. compactus in robusta coffee plants in the state of Rondônia for the first time. We also evaluated the occurrence of this pest in different robusta coffee genotypes in the state of Espírito Santo. In all plants, the plagiotropic branches were attacked; however, the genotypes G2, G6, G8, G20, G48, G50, G51 and G52 showed a high number of attacked plagiotropic branches, whereas the genotypes G24 and G41 showed a low attack frequency. Thus, these can be promising candidates for pest resistance studies. Moreover, it was reported that Almeidea rubra, Alseis floribunda, Plinia grandifolia and Casearia Sylvestris can serve as hosts of X. compactus. Thus, our findings suggest that X. compactus is a threat to coffee production, and that future studies are necessary to find appropriate tools for its management.

Cyclocephalini beetles of the genus Cyclocephala (Coleoptera: Melolonthidae: Dynastinae) use flowers of some plants as food, shelter, and mating sites. However, little is known about floral scent chemistry involved in this interaction. Here we show that a sesquiterpene alcohol mediates attraction of Cyclocephala paraguayensis Arrow, on bottle gourd flowers, Lagenaria siceraria (Cucurbitaceae). Both males and females started to aggregate on the flowers at twilight; after that, mating began and remained for the entire night. GC-FID/EAD analysis of the L. siceraria floral scent collected in the field revealed that only the major constituent of the airborne volatiles elicited electroantennographic responses on male and female antennae of C. paraguayensis. This compound was identified as (3S,6E)-nerolidol, which was tested in two field trapping trials in Brazil. In the first bioassay, traps baited with nerolidol (mix of isomers) captured significantly more adult C. paraguayensis than control traps. In the second field trial, catches in traps baited with a mixture of isomers or enantiopure nerolidol were significantly higher than captures in control traps, but the treatments did not differ significantly. Analysis from the gut content of adult C. paraguayensis showed the presence of pollen, suggesting that they also use bottle gourd flowers for their nourishment. Taken together, these results suggest that (3S,6E)-nerolidol plays an essential role in the reproductive behavior of C. paraguayensis by eliciting aggregation, mating, and feeding.

No abstract

The tomato is a crop of great importance for Brazilian agriculture. Among the most damaging pests, the small tomato borer, Neoleucinodes elegantalis Guenée (Lepidoptera: Crambiadae) has caused great losses, since they directly reach the fruits to be commercialized, being used for its handling a large volume of insecticides. In this way, the use of alternative techniques that help in the management of this pest becomes of great importance. Among them, the use of the egg parasitoid Trichogramma spp. has been promising. Thus, the present study aimed to evaluate the performance of Trichogramma species and/or strains in N. elegantalis by selection of strains. The selection was made based on four lineages maintained in the Nucleus of Scientific and Technological Development in Phytosanitary Management of Pests (NUDEMAFI), being three strains of the species T. pretiosum and one of T. galloi species. The parameters evaluated were percentage of parasitized eggs, egg viability, number of individuals per eggs, sex ratio and number of Trichogramma spp. to be released. The T. galloi (T. g1) showed the best parameters for selection of the strain. Estimating the optimal number of T. g1 in eggs of small-fruit-borer was 82 individuals per egg parasitoid. Therefore, this strain was selected for the management of the small tomato-borer, whose eggs presented favorable physicochemical characteristics for the development of the parasitoid.