Vespula germanica is a social wasp and an opportunistic predator. While foraging, these wasps learn and integrate different kinds of cues. They have successfully invaded many parts of the world, including native Nothofagus and Lophozonia forests located in the Andean-Patagonian region, where they forage on native arthropods. Perzelia arda, a lepidopteron defoliator of Lophozonia obliqua, uses the foliage to hide in and feed on. The purpose of this work is to study whether V. germanica use olfactory cues when foraging on P. arda. To do this, we used a Y-tube olfactometer and established three treatments to compare pairs of all combinations of stimuli (larvae, leaves with larval traces, and leaves without larval traces) and controls. Data were analysed via two developed models that showed decisions made by V. germanica and allowed to establish a scale of preferences between the stimuli. The analysis demonstrates that V. germanica wasps choose P. arda as larval prey and are capable of discriminating between the offered stimuli (deviance information criterion (DIC) null model = 873.97; DIC simple model = 84.5, n = 152). According to the preference scale, V. germanica preferred leaves with traces of larvae, suggesting its ability to associate these traces with the presence of the prey. This may be because, under natural conditions, larvae are never exposed outside their shelters of leaves and therefore V. germanica uses indirect signals. The presence of V. germanica foraging on P. arda highlights the flexible foraging behaviour of this wasp which may also act as a positive biological control, reducing lepidopteran populations.

Since 2008, several outbreaks of yellow fever and dengue occurred in Abidjan, the economic capital of Côte d'Ivoire. A better knowledge of the biology of Aedes aegypti populations, the main vector of yellow fever and dengue viruses, is necessary to tailor vector control strategies implemented in the city. This study was designed to determine some biological parameters, occurring during the life cycle of two morphological phenotypes of Ae. aegypti larvae. Mosquitoes were sampled in a suburb of Abidjan (Treichville) using the WHO layer-traps technique. Biological parameters were studied in laboratory under standard conditions of temperature (27°C ± 2°C) and relative humidity (80% ± 10%). Our results indicated that the mean eggs laid by females from ‘brown larvae’ (BL) (85.95, 95% confidence interval (CI 95%) 78.87–93.02) was higher than those from ‘white larvae’ (WL) (64.40%, CI 95% 55.27–73.54). The gonotrophic cycle was 3 and 4 days in females from BL and WL, respectively. The overall yield of breeding mosquitoes from BL (63.88%, CI 95% 62.61–65.14) was higher compared with those of mosquitoes from WL (59.73%, CI 95% 58.35–61.12). The sex ratio (male/female) was 0.95 and 1.68 in Ae. aegypti populations from BL and WL, respectively. Females from BL lived slightly longer than those from WL (t = −2.332; P = 0.021). This study shows that Ae. Aegypti populations from BL and WL present different biological parameters during their life cycle. This could have an implication on their ability to transmit human disease viruses such as dengue and yellow fever. Further molecular studies are needed to determine genetic divergence between these Ae. aegypti populations.

Helicoverpa gelotopoeon, the South American bollworm, is a polyphagous pest of the Heliothinae complex that causes damage to soybean, cotton, and chickpea crops. Some species within this complex have developed resistance to genetically modified crops and insecticides, which has led to increased interest in their genetic diversity and population structure. The objective of this study was to characterize biological and reproductive parameters of two populations of H. gelotopoeon collected in two different provinces of Argentina. Intra- and inter-population crosses revealed that H. gelotopoeon populations from both regions of Argentina did not present evidence of pre-zygotic and post-zygotic incompatibility, suggesting that Tucumán and Córdoba populations of H. gelotopoeon belong to a single wide-ranging species. Our data support the occurrence of substantial gene flow between H. gelotopoeon populations, probably due to the widely documented, long-range migratory capacity of Heliothinae species.

In this study, we investigated resistance traits to the sugarcane borer Diatraea saccharalis Fab. (Lepidoptera: Crambidae) in the leaves and stalks of six sugarcane cultivars in a series of greenhouse and laboratory assays. Investigation of plant factors and infestation rates to better discriminate stalk damage by the sugarcane borer indicated that infestation of 7-month-old, single plants with 20 larvae at the third or fourth instar per plant was suitable to assess tunneling length. Three cultivars (i.e. SP803280, RB928064, and RB835486) had lower stalk damage (i.e. tunnel length) than cultivar SP891115, which exhibited relatively greater susceptibility to tunneling by the borer. The time required for the larvae to enter the sugarcane stalk was longer for cultivar SP803280, indicating resistance traits on the stalk surface, which correlated with lower stalk damage. Larvae feeding on SP813250 stalks had the lowest weight gain, indicating that this cultivar has resistance traits to larval development within its stalks. Cultivars RB867515 and SP891115 resulted in the highest mortality of early-stage larvae feeding on leaves, indicating the presence of resistance factors in their leaves. Multi-trait cluster and principal component analyses placed the cultivars into three and four clusters, respectively. The cultivars placed in different groups that exhibited resistance to leaf feeding, stalk entrance, and tunneling by the sugarcane borer could be used for crossings in sugarcane breeding programs with the goal of obtaining higher levels of resistance to D. saccharalis.

The Artocarpus fruit fly, Bactrocera umbrosa (Fabricius) (Diptera: Tephritidae), is an oligophagous fruit pest infesting Moraceae fruits, including jackfruit (Artocarpus heterophyllus Lamarck), a fruit commodity of high value in Malaysia. The scarcity of fundamental biological, physiological and ecological information on this pest, particularly in relation to behavioural response to phytochemical lures, which are instrumental to the success of many area-wide fruit fly control and management programmes, underpins the need for studies on this much-underrated pest. The positive response of B. umbrosa males to methyl eugenol (ME), a highly potent phytochemical lure, which attracts mainly males of many Bactrocera species, was shown to increase with increasing age. As early as 7 days after emergence (DAE), ca. 22% of males had responded to ME and over 50% by 10 DAE, despite no occurrence of matings (i.e. the males were still sexually immature). Male attraction to ME peaked from 10 to 27 DAE, which corresponded with the flies’ attainment of sexual maturity. In wind-tunnel assays during the dusk courtship period, ME-fed males exhibited earlier calling activity and attracted a significantly higher percentage of virgin females compared with ME-deprived males. ME-fed males enjoyed a higher mating success than ME-deprived males at 1-day post ME feeding in semi-field assays. ME consumption also promotes aggregation behaviour in B. umbrosa males, as demonstrated in wind-tunnel and semi-field assays. We suggest that ME plays a prominent role in promoting sexual communication and enhancing mating performance of the Artocarpus fruit fly, a finding that is congruent with previous reports on the consequences of ME acquisition by other economically important Bactrocera species.

Thrips palmi and Frankliniella occidentalis (order Thysanoptera) are thrips species that represent major plant pests. They are polyphagous insects capable of adversely affecting crop production. As such, in the European Union, these thrips species should be regulated as quarantine organisms. T. palmi and F. occidentalis can cause considerable damage to susceptible plants by feeding on them and transmitting several viruses responsible for serious plant diseases. Successful pest control strategies are based on an early, fast, and reliable diagnosis, which precedes the selection of appropriate steps to limit the effects of harmful organisms. We herein describe a novel diagnostic approach that enables the sensitive and species-specific detection (and differentiation) of these pests in a duplex polymerase chain reaction assay, which was adapted for both standard and real-time quantitative assays. Our method is based on the amplification of a 5.8S-internal transcribed spacer 2 ribosomal DNA fragment that is conserved between T. palmi and F. occidentalis.

Ceratovacuna lanigera Zehntner is a major leaf pest of sugarcane. Widely distributed, it affects both the yield and quality of sugarcane in China. This study aimed to assess real yield and sugar yield losses, and the effect of C. lanigera damage on emergence of newly planted and ratoon cane under current production levels. Field experiments were carried out from 2014 to 2016 in Yunnan Province China. At maturity, plants were harvested and weighed to determine yield, and the effect on sugarcane quality and sucrose content analyzed. Real yield decreased by average of 46,185 kg hm−2 (range: 37,545–61,845 kg hm−2) in damaged versus undamaged areas, with an average yield loss rate of 35.9% (28.5–45.7%). Juice yield decreased by an average of 3.01% (2.4–4.13%) and sucrose content by 6.38% (5.48–8.16%). Juice brix decreased by an average of 7.66°BX (6.95–9.05°BX) and juice gravity purity by 12.35% (8.43–19.97%). In contrast, the reducing sugar content increased by an average of 1.21% (1.01–1.3%). Emergence rates of newly planted cane decreased by an average of 26.0% (24.7–27.3%). The emergence number of ratoon cane decreased by 66,834 hm2 (57,429–76,238 hm−2) and relative emergence loss rates of ratoon cane decreased by an average of 57.8% (57.6–58.0%). These findings confirm that C. lanigera damage severely affects sugarcane yield and quality in Yunnan Province. The results will help the implementation of effective control measures, thereby supporting sustainable development of the Chinese sugar industry.

The purpose of this study was to investigate and compare root morpho-anatomical traits and physiological responses of susceptible (SP81–3250) and resistant (H. Kawandang) sugarcane genotypes exposed to the attack by nymphs of spittlebug Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae). Two experiments were conducted to compare the damage caused by spittlebug nymphs on fresh and dry biomass weight; lignin content in stalks; root anatomy; chlorophyll content; photosynthetic rate (A); carboxylation efficiency (A/Ci); stomatal conductance (gS) and transpiration rate (E) of these genotypes. SP81–3250 consistently obtained significantly higher damage scores than H. Kawandang in both experiments, confirming the previously observed level of resistance in each genotype. Attack by spittlebug nymphs had a much higher effect on both fresh and dry biomass weight, chlorophyll content, A, A/Ci, gs and E of SP81–3250, than that on H. Kawandang. Anatomical studies indicated the presence of aerenchyma tissue in the root cortex of SP81–3250, a feature which may facilitate penetration of the nymph's stylet into the vascular cylinder. In contrast, roots of H. Kawandang are characterized by having more dense and compact parenchyma cells. In addition, infested plants of this genotype contained an unidentified mucilaginous compound in the vascular cylinder of the roots. We conclude that resistance of H. Kawandang to spittlebug is related to the ability of this genotype to maintain normal chlorophyll content, as well as stomatal conductance and photosynthesis, thus, allowing for biomass accumulation under spittlebug attack, in contrast to SP81–3250. In addition, the presence of more compact and denser parenchymal cells, as well as that of an induced mucilaginous compound in the root's vascular cylinder, are likely to hinder host-feeding activity in nymphs, causing higher nymph mortality and therefore, reduced damage in plants of this genotype.

Disentangling trophic interactions among species is important for elucidating mechanisms underlying ecosystem functioning and services. Carabid beetles are an important guild of predators that may regulate pest populations in arable landscapes, but their generalist feeding behavior hinders predictions about their actual contribution to pest control. In order to assess carabids’ potential for pest control, we simultaneously analyzed the carbon and nitrogen stable isotope ratios of a community of 45 co-occurring species in wheat and oilseed rape fields. With the expectation to identify distinct trophic groups based on the mean and the variance of carabid isotopic signatures, we observed a high degree of overlap in trophic positions between species. However, we also observed that species could be successfully categorized into two groups according to whether or not their carbon signatures varied independently from variations in the crop baseline. We interpret these results as differential primary resource uptake or by differential mobility aptitude in foraging. Accordingly, we propose that the isotopic signal can inform us on the presence/absence of links between generalist predators and cultivated plants through the trophic networks they belong to, and consequently on their potential role as pest natural enemies. We therefore suggest the complementarity of stable isotope analysis for obtaining a time-integrated assessment of carabid trophic behavior that may be combined with more direct molecular diet analysis allowing the simultaneous quantification of specific trophic links within agricultural landscapes.