Attraction of the Mosquitoes Aedes aegypti and Aedes albopictus (Diptera: Culicidae) to a 3-Part Phytochemical Blend in a Mesocosm

Aedes aegypti (L.) and Aedes albopictus (Skuse) mosquitoes of both sexes were attracted to a 3-part volatile synthetic phytochemical blend but differed according to their component ratios, 7:3:2 or 1:1:1, and their initial concentrations. These arbovirus vectors were presented with the blends as baits in paired baited and blank CFG traps in a large greenhouse mesocosm. Ae. aegypti attraction was highest at a 7:3:2 blend ratio, but at a concentration half that found most effective for an anopheline mosquito species in outdoor screenhouses. Both lower and higher concentrations yielded substantially lower attraction scores for Ae. aegypti. By contrast, the few tests conducted on Ae. albopictus showed that it was not as sensitive to concentration, but again it was more responsive to the 7:3:2 ratio of components than to the 1:1:1 ratio. The two sexes of both species were represented equally in the trap catches, indicating the potential value of this and similar attractive blends for population surveillance and control of Aedes mosquitoes.

Population Dynamics of Rice Insect Pests through Light Trap Catches and Its Relation to Abiotic Factors in High Altitude Tribal Zone of Seethampeta in Andhra Pradesh, India

Studies were carried out at Agricultural Research Station, Seethampeta in Andhra Pradesh during the kharif season for three consecutive years starting from 2017 to 2019 on the population dynamics of insect pests occurring in paddy and also to assess the influence of weather parameters on insect pests. The insect pests observed in the light trap catches were, Yellow stem borer, Gall midge, Leaf folder, Green leafhopper, Plant hopper (BPH/WBPH) and Grasshoppers. The light trap catches of rice insect pests were recorded at weekly interval during 32nd Standard Meteorological Week (SMW) to 52nd Standard Meteorological Week (SMW) and the data were correlated with the weather parameters. The results revealed that more number of adults of Yellow stem borer were noticed during the year 2019 from 45th to 48th SMW and the correlation studies revealed that that maximum temperature, minimum and maximum relative humidities had significant positive influence and regression value of R2 (743, 638 and 726 during 2017, 2018 & 2019). The population of gall midge was negligible during the year 2017 and 2018. Whereas, in 2019 peak was notice during 38th SMW (15 No’s) maximum relative humidity has positive relation with increase in the gall midge population. Leaf folder adults were trapped more in the light traps during the year 2019 with peak catches of 11.00 No’s on 42nd SMW and were positively correlated with maximum temperature, minimum and maximum relative humidities. Similarly, leafhopper, brown leaf hopper, grass hoppers were positively correlated with the relative humidity.

Evaluation of different traps for the invasive leaf miner, Liriomyza huidobrensis in potato (Solanum tuberosum) fields of the Nilgiris district, Tamil Nadu, India

Potatoes are currently threatened by the pea leaf miner (Liriomyza huidobrensis Blanchard), an exotic, exceedingly polyphagous, and chemically resistant pest that attacks a wide range of crops, ornamental plants, and weeds. The present work was conducted to study the attractiveness of various traps to Liriomyza leaf miner, one of the invasive pests recently observed in potato fields of Kotagiri and Ooty in Nilgiris district of Tamil Nadu. A trial was conducted at these two different locations, the Nilgiris district, in 2021. The results revealed that among different traps tested for their efficacy in attracting the leaf miner, L. huidobrensis, yellow sticky trap was found to be more efficient in attracting adult leaf miner flies with the mean trap catches of 40.49 and 36.64 adult flies/ 10 cm2 areas at Kotagiri and Ooty respectively. The peak population of leaf miners was recorded in the last week of April (45.67 adult flies/ 10 cm2 areas) at Ooty and during the 3rd week of June (52.33 adult flies/ 10 cm2 areas) at Kotagiri. The correlation study revealed a significant positive correlation of the trap catches with maximum temperature, diurnal variation (DV) and growing day degrees (GDD). Multiple regression equation was also developed, where the abiotic factors contributed 46.1% and 65.5% to the Liriomyza leaf miner population fluctuation in the potato ecosystem. The trappers may be used to determine the initial presence of a leaf miners’ population and in projecting their future population through pest management models and management decisions.

Windfield related light-trap catches of Nephotettix spp. (N. virescens Distant and N. nigropictus stål), vectors of rice tungro virus in West Bengal

ABSTRACT. Regular peak catches of rice green leafhoppers, Nephoteltix virescens (Distant) and N. nigropictus (Stal) are usually obtained in a light-trap 60 ± 14 days after the peak monsoon rains in August in West Bengal. In 1986, in addition to this peak catch, very high catches were obtained on two different dates, 17 September and 10 November. The high catch on 17 September was probably due to the increase of the effective trap radius caused by the overcast sky and by the presence of a resident population. The high catch on 10 November was due to the transport of the insects by cyclonic winds and deposition in a zone of light and variable winds (at a convergence) real the trapping site. Trajectory analysis indicates that these insects may have been brought from the north-east, upto about 280 km away from the trapping site.

Mating Disruption of the Olive Moth Prays oleae (Bernard) in Olive Groves Using Aerosol Dispensers

The olive moth (OM), Prays oleae (Bern.) (Lepidoptera: Yponomeutidae), is a major olive grove pest worldwide; however, until now, very few studies have investigated the effectiveness of mating disruption (MD) techniques against this pest. Experiments were carried out for two successive years (2019 and 2020) in three different olive groves in Andalucía (Southern Spain) to evaluate mating disruption’s efficacy in controlling the OM from the first to the third generation. The effectiveness of MD formulations against the three generations of OM was assessed by determining the percentage of infested olive fruits, the reduction of pheromone trap catches, and the number of affected inflorescences in both MD-treated and untreated control olive groves. The number of release points (one or two aerosol devices per ha) was also evaluated. In all years and trials, the mean number of males caught in traps placed in the MD-treated plots was significantly lower than untreated sites. Mating disruption registered a high suppression of male captures (>75%) in treated plots for two consecutive seasons. Concerning infested olive fruits, substantial reductions (about 80%) were observed in the MD plots of locations B and C, and a reduction of about 40% was detected in location A, compared to the control plot. Results showed that the installation of two aerosol devices/ha reduced fruit damage below 20% of infested olive fruits except for one site where a reduction of about 71% in the MD plot was recorded in 2019. Although few significant differences were associated with OM male catches and infested olive fruits between plots treated with one aerosol/ha and two aerosols/ha in most of the comparisons, significant differences in the number of olive inflorescences infested by P. oleae were found, suggesting a similar performance between the two tested aerosol densities. Results of two-year field trials in Andalucía demonstrated the potential of Mister P X841 aerosol devices as an effective tool for controlling the olive moth, P. oleae.

Impact of abiotic factors on population dynamics of Bactrocera dorsalis Hendel and Bactrocera zonata (Saunders) at different ecological zones in NW Plains of India

In India, fruit flies have been identified as one of the ten most serious problems of agriculture because of their polyphagous nature and the huge economic loss it causes to the fruits and vegetables (2.5 to 100%). Study was carried to determine the population dynamics of fruit flies (Bactrocera dorsalis and Bactrocera zonata) and establish the correlation with abiotic factors in guava and citrus fruits crops in two agro ecological zones of North West India. Fruit flies population was recorded by installation of pheromone traps in different fruit crop ecosystems during the fruiting season of this zone. The data of trap catches of both the locations was correlated with the significantly influencing abiotic parameters. The peak fruit fly incidence varied between 31st to 34th standard weeks in guava ecosystem at both the locations. In citrus ecosystem, the incidence was highest during 35th and 39th standard weeks coinciding with the ripening of the fruits. At both the locations, trap catches of guava ecosystem were positively correlated with all the weather parameters, while under citrus ecosystem minimum temperature and rainfall showed negative correlation, but relative humidity was positively correlated. Information may be utilized in targeting suitable pest management techniques for respective zones.

Forewarning of incidence of Spodoptera litura (Tobacco caterpillar) in soybean and cotton using statistical and synoptic approach

A study on the effect of weather parameters on the the population dynamics of Spodoptera litura (S.litura) in soybean and cotton during kharif season using six years pest data (pheromone trap catches) at Niphad and Rahuri in Maharashtra showed that rainfall two weeks prior, Tmax and Tmin during the week of incidence signifiantly contributed towards the occurrence of S.litura in soybean. Maximum temperature and morning humidity during the week and one week prior were found to be favourable for the incidence of S. litura in cotton. Temperature (maximum: 26-27°C & minimum: 21-22°C), morning relative humidity (above 90%) and rainfall during one week prior were found to be congenial weather parameters for the outbreak of the pest in soybean. Similarly, maximum temperature around 32-33°C, minimum temperature around 22-23°C, morning relative humidity around 90 per cent, sunshine hours about 4 hrs day-1 and rainfall during the previous 2 weeks favoured heavy incidence of S.litura in cotton crop during flowering to boll formation stages. It is also shown how the incidence of S.litura in soybean and cotton can be predicted well in advance using the observed relationship of the pest with weather parameters as well as weather forecast.

Aposematic Coloration of Moths Decreases Strongly along an Elevational Gradient in the Andes

On tropical mountains, predation pressure decreases with elevation. Accordingly, one expects an elevational decay in the prevalence of costly defensive traits such as aposematic coloration. Using light-trap catches of Arctiinae moths (353 species, 4466 individuals), assembled along a forested gradient in the megadiverse tropical Andes of southern Ecuador, we show that the incidence of aposematic coloration decreases strongly between 1040 and 2670 m asl. While over 60% of Arctiinae moths were warningly colored at lowest sites, this fraction decreased to less than 20% in montane forest, yet increased slightly again at the highest sites in the very open Purdiaea nutans forest. In parallel, the incidence of hymenopteran mimics and of species that mimic chemically defended beetles decreased with elevation. Hymenopteran mimics accounted for less than 5% of Arctiinae moths at sites above 2100 m, and beetle mimics were essentially lacking at high elevations. These patterns coincide with a change in gross taxonomic composition of Arctiinae ensembles and with an increase in average body size towards higher elevations. Representatives of Euchromiina and Ctenuchina became scarce with altitude, whereas the prevalence of Lithosiinae increased. Our findings suggest that the variable selective pressures along the elevational gradient favor warning coloration primarily at lower sites, whereas cryptic appearance of adult moths dominates in the tropical upper montane forest.

Modelling diapause termination and phenology of the Japanese beetle, Popillia japonica

We developed a mechanistic, stage-structured model simulating the phenology of Popillia japonica. The model simulates the influence of soil temperature on the larval diapause termination and on the development rate function of post-overwintering larvae and pupae. Model parameters are estimated based on literature evidence for pupae development and on a parameterisation process that allows estimating parameters for larval diapause termination and for the development rate function (and the related uncertainty) of post-overwintering larvae. Data used for model parameterisation and validation refer to time-series adult trap catches collected during the P. japonica monitoring programme performed by the Phytosanitary Service of Lombardy Region within the infested area in Lombardy (Italy) from 2015 to 2019. A total of 12 randomly selected locations are used to estimate biologically realistic model parameters (parameterisation dataset). We applied a Jackknife nonparametric resampling procedure on the parameterisation dataset to quantify uncertainty associated with parameters’ estimates. Parameterised model is then validated on time-series adult trap catches data referring to a different set of 12 randomly selected locations (validation dataset) surveyed in Lombardy. The model successfully predicted the beginning of adult emergence and the overall curve of adult emergence in the validation dataset. The model presented can support the definition of the best timing for the implementation of monitoring and control activities for the local and the area-wide management of P. japonica.

Monitoring an invasive coconut rhinoceros beetle population using pheromone traps in Honiara, Solomon Islands

An invasive population of the coconut rhinoceros beetle (Oryctes rhinoceros; CRB) was discovered in Honiara, Guadalcanal, Solomon Islands in 2015. The beetle has caused severe damage to coconut palms in the outbreak area and its continued spread threatens the food security and livelihood of thousands of smallholder farmers in the region. Spread and abundance of the beetle were monitored using bucket traps baited with the aggregation pheromone, ethyl-4 methyloctanoate. Beetles were collected from traps approximately bi-weekly for two periods; one during 2017–18 and the other during 2019–2020. Trap catches showed that CRB was present throughout the whole survey region with significantly higher numbers of female CRB trapped than males. Results indicate a significant 1.5-fold increase in CRB trap catch numbers from 2017–2018 to 2019–2020 despite control efforts. The number of CRB adults trapped also varied between sites and months during both time periods but with no clear patterns. Removal of breeding sites along with strong local quarantine should remain the top priority of the local government to contain CRB expansion within Solomon Islands and beyond.