Integrating temperature-dependent life table data into Insect Life Cycle Model for predicting the potential distribution of <em>Scapsipedus icipe</em> Hugel &amp; Tanga

Scapsipedus icipe Hugel and Tanga (Orthoptera: Gryllidae) is a newly described edible cricket species. Although, there is substantial interest in mass production of S. icipe for human food and animal feed, no information exists on the impact of temperature on their bionomics. Temperature-dependent development, survival, reproductive and life table parameters of S. icipe was generated and integrated into advanced Insect Life Cycle Modeling software to describe relative S. icipe population increase and spatial spread based on nine constant temperature conditions. We examined model predictions and implications for S. icipe potential distribution in Africa under current and future climate. These regions where entomophagy is widely practiced have distinctly different climates. Our results showed that S. icipe eggs were unable to hatch at 10 and 40°C, while emerged nymphs failed to complete development at 15°C. The developmental time of S. icipe was observed to decrease with increased in temperature. The lowest developmental threshold temperatures estimated using linear regressions was 14.3, 12.67 and 19.12°C and the thermal constants for development were 185.2, 1111.1- and 40.7-degree days (DD) for egg, nymph and pre-adult stages, respectively. The highest total fecundity (3416 individuals/female/generation), intrinsic rate of natural increase (0.075 days), net reproductive rate (1330.8 female/female/generation) and shortest doubling time (9.2 days) was recorded at 30°C. The regions predicted to be suitable by the model suggest that S. icipe is tolerant to a wider range of climatic conditions. Our findings provide for the first-time important information on the impact of temperature on the biology, establishment and spread of S. icipe across the Africa continent. The prospect of edible S. icipe production to become a new sector in food and feed industry is discussed

Advances in crop insect modelling methods—Towards a whole system approach

A wide range of insects affect crop production and cause considerable yield losses. Difficulties reside on the development and adaptation of adequate strategies to predict insect pests for their timely management to ensure enhanced agricultural production. Several conceptual modelling frameworks have been proposed, and the choice of an approach depends largely on the objective of the model and the availability of data. This paper presents a summary of decades of advances in insect population dynamics, phenology models, distribution and risk mapping. Existing challenges on the modelling of insects are listed; followed by innovations in the field. New approaches include artificial neural networks, cellular automata (CA) coupled with fuzzy logic (FL), fractal, multi-fractal, percolation, synchronization and individual/agent based approaches. A concept for assessing climate change impacts and providing adaptation options for agricultural pest management independently of the United Nations Intergovernmental Panel on Climate Change (IPCC) emission scenarios is suggested. A framework for estimating losses and optimizing yields within crop production system is proposed and a summary on modelling the economic impact of pests control is presented. The assessment shows that the majority of known insect modelling approaches are not holistic; they only concentrate on a single component of the system, i.e. the pest, rather than the whole crop production system. We suggest system thinking as a possible approach for linking crop, pest, and environmental conditions to provide a more comprehensive assessment of agricultural crop production.Peer reviewe

Effects of endophyte colonization of Vicia faba (Fabaceae) plants on the life-history of leafminer parasitoids Phaedrotoma scabriventris (hymenoptera: braconidae) and Diglyphus isaea (hymenoptera: eulophidae).

Effects of the fungal endophytes Beauveria bassiana (isolates ICIPE 279, G1LU3, S4SU1) and Hypocrea lixii (isolate F3ST1) on the life-history of Phaedrotoma scabriventris and Diglyphus isaea, parasitoids of the pea leafminer Liriomyza huidobrensis, were studied in the laboratory. Parasitoids were allowed to parasitize 2(nd) and 3(rd) instar L. huidobrensis larvae reared on endophytically-inoculated faba bean, Vicia faba. In the control, parasitoids were reared on non-inoculated host plants. Parasitism, pupation, adult emergence and survival were recorded. No significant difference was observed between the control and the endophyte-inoculated plants in terms of parasitism rates of P. scabriventris (p = 0.68) and D. isaea (p = 0.45) and adult' survival times (p = 0.06). The survival period of the F1 progeny of P. scabriventris was reduced (p<0.0001) in B. bassiana S4SU1 to 28 days as compared to more than 40 days for B. bassiana G1LU3, ICIPE 279 and H. lixii F3ST1. However, no significant difference (p = 0.54) was observed in the survival times of the F1 progeny of D. isaea. This study has demonstrated that together, endophytes and parasitoids have beneficial effects in L. huidobrensis population suppression

Effects of endophyte colonization of Vicia faba (Fabaceae) plants on the life

The effects of fungal endophytes Beauveria bassiana isolates ICIPE 279, G1LU3, S4SU1 and Hypocrea lixii isolate F3ST1 on the life-history of Phaedrotoma scabriventris and Diglyphus isaea, parasitoids of the pea leafminer Liriomyza huidobrensis, were studied in the laboratory. Parasitoids were allowed to parasitize 2nd-3rd L. huidobrensis larvae reared on endophytically-inoculated Vicia faba. In the control, parasitoids were reared on non-inoculated host plants. Parasitism, pupation, adult emergence and survival were recorded. No significant difference was observed between the control and the endophyte-inoculated plants in terms of parasitism rates of P. scabriventris (p = 0.68) and D. isaea (p = 0.45) and adult' survival times (p = 0.06). The survival period of the F1 progeny of P. scabriventris was reduced (p < 0.0001) in B. bassiana S4SU1 to 28 days as compared to more than 40 days for B. bassiana G1LU3, ICIPE 279 and H. lixii F3ST1. However, no significant difference (p = 0.54) was observed in the survival times of the F1 progeny of D. isaea. This study has therefore demonstrated the beneficial effects of both endophytes and parasitoids in L. huidobrensis population suppression

Dispersal behavior of Tetranychus evansi and T. urticae on tomato at several spatial scales and densities: implications for integrated pest management.

Studying distribution is necessary to understand and manage the dynamics of species with spatially structured populations. Here we studied the distribution in Tetranychus evansi and T. urticae, two mite pests of tomato, in the scope of evaluating factors that can influence the effectiveness of Integrated Pest Management strategies. We found greater positive density-dependent distribution with T. evansi than T. urticae when assayed on single, detached tomato leaves. Indeed, T. evansi distribution among leaflets increased with initial population density while it was high even at low T. urticae densities. Intensity and rate of damage to whole plants was higher with T. evansi than T. urticae. We further studied the circadian migration of T. evansi within plant. When T. evansi density was high the distribution behavior peaked between 8 am and 3 pm and between 8 pm and 3 am local time of Kenya. Over 24 h the total number of mites ascending and descending was always similar and close to the total population size. The gregarious behavior of T. evansi combined with its rapid population growth rate, may explain why few tomato plants can be severely damaged by T. evansi and how suddenly all the crop can be highly infested. However the localisation and elimination of the first infested plants damaged by T. evansi could reduce the risk of outbreaks in the entire crop. These findings suggest also that an acaricide treated net placed on the first infested plants could be very effective to control T. evansi. Moreover circadian migration would therefore accentuate the efficiency of an acaricide treated net covering the infested plants

Expression of Resistance in Amaranthus spp. (Caryophyllales: Amaranthaceae): Effects of Selected Accessions on the Behaviour and Biology of the Amaranth Leaf-Webber, Spoladea recurvalis (Lepidoptera: Crambidae)

Spoladea recurvalis F. is a major pest moth of amaranth (Amaranthus spp.) flowers worldwide, with a potential of causing complete foliage loss under severe outbreaks. Chemical insecticides are uneconomical for resource-poor farmers and pose health and environmental risks. Host plant resistance (HPR) to insects is an effective, economical and environmentally friendly alternative that is poorly understood and largely unexploited among traditional leafy vegetables. A total of 35 amaranth accessions were evaluated for the expression of their antixenotic and antibiotic traits against S. recurvalis, focusing on their effects on the biology of the pest in comparison with a susceptible accession. The accession VI036227 was found to be highly resistant against the pest, exhibiting exemplary antibiosis by causing 100% larval mortality within the first 36 h, despite not being deterrent for oviposition. The accessions VI048076, VI056563 and VI047555-B demonstrated moderate resistance against the pest for specific parameters including low oviposition, moderate early stage larval mortality and reduced adult longevity. Total mortality and weight gain in these three accessions were, however, not significantly different from the susceptible control. Higher numbers of eggs were laid in no-choice compared to choice situations. The implications of these findings in the management of S. recurvalis on amaranths are discussed

Farmers' control practices against the invasive red spider mite, Tetranychus evansi Baker & Pritchard in Benin

In 2008, the invasive tomato red spider mite Tetranychus evansi (Acari: Tetranychidae), a pest of solanaceous crops, was identified for the first time as the cause of serious damage on tomato (Solanum lycopersicum L.; Solanaceae) crops in Benin. Since then, frequent outbreaks have been observed on Solanaceae and other leafy vegetables such as purple amaranth (Amaranthus cruentus L; Amaranthaceae) and bitter leaf (Vernonia amygdalina D.; Asteraceae) in all growing areas in southern Benin. The objective of this study was to evaluate the intensity of damage by this invasive pest and the impact of farmers' control practices on purple amaranth, African eggplant (Solanum macrocarpon L; Solanaceae) and tomato crops. A survey was carried out in January 2013 among 150 farmers in the three major growing areas in southern Benin: Seme-Kpodji, Grand-Popo and Pahou. Tetranychus evansi was the only mite observed, causing production losses estimated at 65% for African eggplant, 56% for tomato and 25% for purple amaranth. Previously encountered species such as Tetranychus urticae Koch, Tetranychus ludeni Zacher (Acari: Tetranychidae) and Polyphagotarsonemus lotus Banks (Acari: Tarsonemidae) were not observed in any of the 45 samples. To protect the infested crops, growers sprayed various synthetic pesticides at high frequencies according to crop phenology 3, 6 and 12 times per month, respectively, on purple amaranth, African eggplant and on tomato, on average. The most frequently used pesticides were pyrethroids and organophosphate compounds. Farmers reported that these compounds were largely ineffective against T evansi. The risks posed to human and environmental health, as well as existing alternatives to chemical pesticide use, are discussed

Survival curves for <i>Phaedrotoma scabriventris</i> adults parasitizing 2^nd and 3^rd instar <i>Liriomyza huidobrensis</i> larvae following exposure to <i>Vicia faba</i> plants endophytically-colonized by different fungal isolates of <i>Beauveria bassiana</i> (S4SU1, G1LU3 and ICIPE 279) and <i>Hypocrea lixii</i> F3ST1 after 40 days post-exposure.

<p>Survival curves for <i>Phaedrotoma scabriventris</i> adults parasitizing 2^nd and 3^rd instar <i>Liriomyza huidobrensis</i> larvae following exposure to <i>Vicia faba</i> plants endophytically-colonized by different fungal isolates of <i>Beauveria bassiana</i> (S4SU1, G1LU3 and ICIPE 279) and <i>Hypocrea lixii</i> F3ST1 after 40 days post-exposure.</p

Progeny survival curves of <i>Diglyphus isaea</i> emerging from <i>Vicia faba</i> plants endophytically-colonized by different fungal isolates of <i>Beauveria bassiana</i> (S4SU1, G1LU3 and ICIPE279) and <i>Hypocrea lixii</i> (F3ST1) and infested with 2^nd and 3^rd instar larvae of <i>Liriomyza huidobrensis</i>.

<p>Progeny survival curves of <i>Diglyphus isaea</i> emerging from <i>Vicia faba</i> plants endophytically-colonized by different fungal isolates of <i>Beauveria bassiana</i> (S4SU1, G1LU3 and ICIPE279) and <i>Hypocrea lixii</i> (F3ST1) and infested with 2^nd and 3^rd instar larvae of <i>Liriomyza huidobrensis</i>.</p

Progeny survival curves of <i>Phaedrotoma scabriventris</i> emerging from <i>Vicia faba</i> plants endophytically-colonized by different fungal isolates of <i>Beauveria bassiana</i> (S4SU1, G1LU3 and ICIPE279) and <i>Hypocrea lixii</i> (F3ST1) and infested with 2^nd and 3^rd instar larvae of <i>Liriomyza huidobrensis</i>.

<p>Progeny survival curves of <i>Phaedrotoma scabriventris</i> emerging from <i>Vicia faba</i> plants endophytically-colonized by different fungal isolates of <i>Beauveria bassiana</i> (S4SU1, G1LU3 and ICIPE279) and <i>Hypocrea lixii</i> (F3ST1) and infested with 2^nd and 3^rd instar larvae of <i>Liriomyza huidobrensis</i>.</p