Babasaheb B. Fand

Temperature Impacts the Development and Survival of Common Cutworm (Spodoptera litura): Simulation and Visualization of Potential Population Growth in India under Warmer Temperatures through Life Cycle Modelling and Spatial Mapping

The common cutworm, Spodoptera litura, has become a major pest of soybean (Glycine max) throughout its Indian range. With a changing climate, there is the potential for this insect to become an increasingly severe pest in certain regions due to increased habitat suitability. To examine this possibility, we developed temperature-based phenology model for S. litura, by constructing thermal reaction norms for cohorts of single life stages, at both constant and fluctuating temperatures within the ecologically relevant range (15–38°C) for its development. Life table parameters were estimated stochastically using cohort updating and rate summation approach. The model was implemented in the geographic information system to examine the potential future pest status of S. litura using temperature change projections from SRES A1B climate change scenario for the year 2050. The changes were visualized by means of three spatial indices demonstrating the risks for establishment, number of generations per year and pest abundance according to the temperature conditions. The results revealed that the development rate as a function of temperature increased linearly for all the immature stages of S. litura until approximately 34–36°C, after which it became non-linear. The extreme temperature of 38°C was found lethal to larval and pupal stages of S. litura wherein no development to the next stage occurred. Females could lay no eggs at the extreme low (15°C) and high (> 35°C) test temperatures, demonstrating the importance of optimum temperature in determining the suitability of climate for the mating and reproduction in S. litura. The risk mapping predicts that due to temperature increase under future climate change, much of the soybean areas in Indian states like Madhya Pradesh, Maharashtra and Rajasthan, will become suitable for S. litura establishment and increased pest activity, indicating the expansion of the suitable and favourable areas over time. This has serious implication in terms of soybean production since these areas produce approximately 95% of the total soybeans in India. As the present model results are based on temperature only, and the effects of other abiotic and biotic factors determining the pest population dynamics were excluded, it presents only the potential population growth parameters for S. litura. However, if combined with the field observations, the model results could certainly contribute to gaining insight into the field dynamics of S. litura.

Temperature-Based Phenology Modeling and GIS-Based Risk Mapping: A Tool for Forecasting Potential Changes in the Abundance of Mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae)

Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is a highly invasive and a polyphagous pest of worldwide importance. Its recent outbreak and rapid spread in Indian cotton growing belt caused large scale devastation. A study was undertaken with a basic assumption that the future distribution and abundance of P. solenopsis will be affected seriously by temperature alterations due to global climate change, which might further aggravate the yield losses. The population growth potential of P. solenopsis was estimated at six constant temperatures ranging from 15 to 40 °C. The phenology models established using best fitting functions in a rate summation and cohort up-dating approach were employed in a geographic information system for mapping population growth potentials according to real-time or interpolated temperature data, for both current and future climate to predict the impact of climate change. The risks for population establishment and survival, average numbers of generations and potential population increase/year were computed using interpolated daily minimum and maximum temperatures at a spatial resolution of 10 arc minutes obtained from worldclim database (www.worldclim.org). The real-time weather station data from two selected locations across India were used to analyze within-year variation of pest population increase due to seasonal climate fluctuations. The model predicted favorable temperature range for P. solenopsis development, survival, and reproduction within a range of 20–35 °C with maximum population growth potential and shorter generation length at 30 °C. The findings revealed significant changes in P. solenopsis activity under climate change scenario, including expansion of a geographical distribution range at higher latitudes and altitudes, marked increase in the number of generations/year and increased abundance and damage activity in present distribution range in India. The study generated knowledge on temperature-dependent population dynamics and growth potential of P. solenopsis crucial for undertaking agroecoregion specific management strategies.

Phenology Modelling and GIS Applications in Pest Management: A Tool for Studying and Understanding Insect-Pest Dynamics in the Context of Global Climate Change

Intensification of agricultural yield losses due to pest aggravation in the context of global climate change has been the key focus of ecological research. In this regard, interest in forecasting models is now days growing radically among entomologists to predict the environmental suitability for new and invading agricultural insect pests. This chapter describes the approaches for development of temperature-based phenology models that helps in understanding insect behaviour and physiology under diverse environmental conditions. A few suitable illustrations are provided on how phenology models can be used for simulating variability in insect development times through stochastic and deterministic simulation functions with inclusion of temperature as a main predictor of insect development. Further, discussions were also included on linking of phenology models with geographic information systems (GIS) for mapping pest population growth potentials according to real-time or interpolated temperature data, as a tool for pest risk assessments in different agro-ecological regions and to support the development of management strategies. The concepts and approaches underlying simulation of age-stage-structured populations using cohort-updating and rate summation principle and the use of geostatistical algorithms integrated in GIS for risk mapping are described briefly.

Record of six Pteromalid parasitoids from the soybean stem fly Melanagromyza sojae Zehntner with the description of a new species of Sphegigaster Spinola (Hymenoptera: Chalcidoidea) from Maharashtra, India

Abstract Field surveys were carried out in Pune area of Maharashtra state in India during June–September of 2014 and 2015 to determine the parasitoid species associated with stem fly Melanagromyza sojae Zehntner infesting soybean. Ten species of parasitoid wasps emerged from the collected materials and included six species of Pteromlaidae, and one species each from the families Eurytomidae, Figitidae (= Eucoilidae), Braconidae and Eulophidae. Six pteromalid parasitoids recorded were: Chlorocytus amaravathicus, Colotrechnus melghaticus, Halticoptera propinqua, Syntomopus carinatus, Syntomopus nigrus and Sphegigaster punensis sp. nov. Sureshan, Fand & Nikhil. Among pteromalids, S. punensis was dominant parasitoid during the mid-season, whereas C. amaravathicus, C. melghaticus, H. propinqua, S. carinatus and S. nigrus were present in low number towards the end of the season. Whilst S. carinatus constitute an already reported parasitoid species from M. sojae, this study reports for the first time M. sojae as a new host for the parasitoid species viz., C. amaravathicus, C. melghaticus and S. nigrus. For H. propinqua, this is the first record of the genus and species from M. sojae whereas, Sphegigaster punensis sp. nov. Sureshan, Fand & Nikhil is described for the first time as a new pteromalid species. Keys to the pteromlaid parastioids of M. sojae in general and species of Sphegigaster in particular are provided. http://zoobank.org/urn:lsid:zoobank.org:pub:A9C5E4C0-1251-458D-82CD-2741C4F43A93

First report of the Invasive Mealybug, Phenacoccus parvus Morrison Infesting Naga King Chili and its Colonization Potential on Major Host Plants in India

The lantana mealybug, Phenacoccus parvus Morrison (Hemiptera: Pseudococcidae), although had made its entry in continental India since 2012, however, was hitherto not reported to occur in northeast India. The present study reports first record of P. parvus invasion on Naga King chili, Capsicum chinense Jacquin (Family: Solanaceae) plants in the Meghalaya state of India. During the surveys, the infested plants were found stunted, withered and did not bear flowers. In case of severe infestation, 100% mortality of young plants and seedlings was observed. Being an economically important crop, biological knowledge about P. parvus in relation to C. chinense is highly imperative for devising effective management strategy against this invasive mealybug. We studied basic biological attributes of P. parvus like development times, survival and fecundity on C. chinense and other potential host plants under in vitro conditions. The biological parameters studied on the five test host plants were on par with each other with less significant differences. Developmental time of P. parvus was found to be significantly higher on Solanum tuberosum L. (Family: Solanaceae) (26.40±0.75 days) and Lycopersicon esculentum L (Family: Solanaceae) (26.60±0.51 days) compared to C. chinense (24.00±0.55 days), Callistephus chinensis (L.) Nees (Family: Asteraceae) (23.20±0.58 days) and Lantana camara L. (Family: Verbenaceae) (20.60±2.20 days). Overall results revealed that, P. parvus has a potential to cause significant damage to all the host plants tested in this study. The information generated in this study helps in undertaking timely management options for P. parvus prior to its incidence reaches alarming proportions.