2 p. / Originally published 2001. / The plants on this list represent plants less likely to be eaten by javelina. Reviewed 10/2016. Originally published 2001.

The banana weevil, Cosmopolites sordidus, is an economical pest of Musa, distributed to most areas where the crop is grown. The beetle larvae produce feeding tunnels in the pseudostem and rhizome, reducing bunch weight and causing toppling or snapping of plants. In developing an integrated pest management system for South Africa, specific aims of the study were to quantify the genetic diversity of the species around the world, investigate the population dynamics of the insect, determine the potential of semiochemical mass trapping, elucidate the efficacy of cultural and chemical control methods and establish economic thresholds for the banana weevil on Cavendish bananas in South Africa. Pest status of the insect is variable around the world, and may be influenced by genetically distinct populations of the weevil. Six populations from four countries were sampled: Australia, Costa Rica, South Africa (South Coast, North Coast and Tzaneen) and Uganda. DNA was isolated from 12 individuals per population and subjected to amplified fragment length polymorphism (AFLP) analysis. The AFLP analysis involved DNA restriction with EcoRI and PstI enzymes, ligation of adapters, and a pre-selective and five selective PCR amplifications. Empirical analysis of the AFLP fingerprints showed that, within populations, genetic diversity varied from 16-53%, with the South Coast and Tzaneen/Australian populations the least and most variable, respectively. The coefficient of gene differentiation showed that the Tzaneen population were the most differentiated from the South Coast population, while the South and North Coast populations were the most similar. All the populations showed statistically distinct marker frequencies, except for the Costa Rican and South and North Coast populations, which were similar. Based on the simple mismatch coefficient, a neighbour-joining tree showed the Australian, Ugandan and South African coastal populations produced monophyletic groups, while the South African Tzaneen population were removed from the other populations and presented an ancestral state. The population dynamics of the insect was investigated over two seasons and at three locations in the South Coast of KwaZulu-Natal. Adult activity was monitored with semiochemical (Cosmolure®) baited pitfall traps. Traps were moved monthly to a random independent location, or left in situ for the duration of the experiment. The ontogeny was determined by dissecting felled plants and toppled plants (up to 2-week-old fresh residues), and harvested plants visually classified as an early and a late rotting stage (decayed residues). Replicated, randomised block designs were used in the experiments. The adult beetles were sexed and the percentage females with eggs and the number of eggs per female were recorded. Larval head capsule widths were measured with an electronic caliper. Ambient temperature and precipitation (rainfall + irrigation) were measured on site. Weevils were active throughout the year and mainly collected in stationary traps, with a collection peak in May and high numbers in early spring and late autumn/early winter. The activity was usually a negative and a positive function of ambient temperature and corrected rainfall, respectively. Eggs per female and percentage females with eggs were reduced during winter and a positive function of ambient temperature. The beetles sampled from plant material represented an equal sex ratio, while the pheromone traps collected a female biased sex ratio during spring and autumn/early winter. The beetle had overlapping generations with a peak of adults and larvae in autumn and late summer, respectively. Adults were mainly associated with decayed residues while larvae were mostly found in freshly toppled plants. Adults were the main over-wintering stage. The earliest larval instars were usually sampled during autumn. The data suggested that the beetle is multivoltine in the study areas and provided valuable information for the optimal management of the insect pest. Semiochemical adult trapping methods were compared in field trials using a randomised block design. Pseudostem traps, pitfall traps containing a pheromone (either Cosmolure® (Pheromone A) or Cosmolure+® (Pheromone B)), and unbaited pitfall traps (control), were compared over 5 weeks during all seasons along the Southeast coast of South Africa. Pseudostem traps treated with an insecticide, and rhizome traps were included as additional treatments in autumn. In summer two treatments were also added: individual suspension of both pheromones above a pitfall trap either in combination with or without a pseudostem trap. The adult beetles were sexed, and the number of internal eggs noted. Pheromone A proved to be the most effective of the different traps. Grouping of the pheromones resulted in a synergistic response, while combining the pseudostem did not enhance trap efficacy. The different plant material traps and the control were usually equally effective in catching weevils. Plant material traps caught greater numbers of fecund females, but pheromone traps captured a higher proportion of females. Treatment effects were much less pronounced in summer, and compared to a pseudostem trap, pitfall traps were the most efficacious during spring. Compared to conventional pseudostem trapping, Pheromone A pitfall traps should be optimally applied during spring in South Africa. Cultural control methods were investigated over 2 years at an ongoing trial in the Southern KwaZulu Natal, South Africa. Harvesting at ground level and dissection of remnants, and covering of the mat with soil and moving debris to the inter-row, were compared to a positive control that involved treatment of plants with a registered pesticide, and a negative control that involved harvesting at approximately 150 cm with no soil or sanitation amendments. Yield, weevil damage and pseudostem girth of plants were measured from August to November annually, while adult beetle densities were assessed over 4 weeks in October/November and April. Nematode samples were analysed in October/November every year. Damage parameters included the Coefficient of Infestation, the Percentage Coefficient of Infestation (PCI) at two intervals, the summed PCI value, the percentage cross sectional damage of the central cylinder (XI) and cortex, and the mean cross sectional damage percentage (X mean). A replicated block design was used in the experiment. The parameters were similar before the onset of the trial. Fruit yield and plant girth, corrected by nematode densities, were not significantly different in any treatment, nor were the nematodes controlled. Soil cover and recession of remnants was the only effective treatment, significantly reducing the Coefficient of Infestation, but not the adult density or any other damage parameter. The former showed promise as a cultural control method because it only needs to be applied seasonally and reduced the XI, the damage parameter most closely related to yield, by 14.18%. The weevil is difficult to control, and chemical control arguably provides the best opportunity to manage the pest. The efficacy of injecting bifenthrin, chlorpyrifos, fipronil, imidacloprid, oxamyl and water (control) into residual banana plants was determined. The chemicals were administered every even numbered month over 2 years at two locations in Southern KwaZulu-Natal, South Africa. Yield, weevil damage and pseudostem girth of plants felled from August to October were measured, while adult beetle densities were assessed over 4 weeks in October and April. Nematode samples were analysed in October every year. Damage parameters included were similar to that of the cultural control trial. Replicated block designs were used in the experiments. The parameters were similar before the onset of the trial. Fruit yield and plant girth, corrected by nematode densities, were not significantly increased after chemical applications, nor were the nematodes controlled. Fipronil and imidacloprid were highly effective against C. sordidus, minimising damage to the periphery, cortex and central cylinder of the rhizome and significantly reduced adult density. Fipronil caused a 95% and imidacloprid a 100% reduction in the XI. Injection of fipronil and imidacloprid provides an optimal chemical strategy in an integrated pest management programme for the banana weevil. Economic thresholds of the insect were investigated on bananas at four locations in the South Coast of KwaZulu-Natal. Yield (bunch weights) and larval damage to felled plants were measured from August to October in 2003, while adult densities were assessed over 4 weeks in October 2003. Nematode samples were collected and analysed in October 2003. Damage parameters included were similar to that of the cultural control trial. Replicated block designs were used in the experiments. The economic-injury level (EIL) for chemical and cultural control was calculated. Nematode densities did not influence the yield of plants. The XI was the best predictor of yield, but under certain conditions X mean was the most important. Chemical control showed the lowest EIL, with more than 1 and 7% damage to the central cylinder when applying fipronil and imidacloprid, respectively. The EIL for cultural control was more than 11% damage to the central cylinder. A recommendation algorithm, considering all the findings of the individual studies, is provided for IPM of the banana weevil in the South Africa. The potential use of microbial and invertebrate (especially parasitoids) biological control and semiochemical mass trapping of the weevil requires further research. Long-term research should focus on host resistance, and weevil damage to the central cylinder can serve as indicator of susceptibility of Cavendish bananas. / Thesis (PhD (Entomology))--University of Pretoria, 2008. / Zoology and Entomology / unrestricted

Insecticidal neonicotinoid seed treatments in agriculture is a common insect pest management strategy. Seed treatments have systemic and residual toxicity, which are effective against target insect pests. However, effects on other arthropod pests is less straightforward. We evaluated the effects of a neonicotinoid seed treatment, thiamethoxam, on two soybean pests, herbivorous two-spotted spider mites (Tetranychus urticae Koch) and an omnivore and facultative predator of spider mite eggs, western flower thrips (Frankliniella occidentalis Pergande). We used greenhouse and laboratory experiments to evaluate thiamethoxam soybean seed treatments on spider mite densities and thrips omnivorous feeding behavior. Our results suggest seed treatment may encourage spider mite reproduction and influence thrips herbivory over egg predation when both resources are available. Implications of this study highlight the use of thiamethoxam soybean seed treatment as a potential contributor to increased spider mite populations, thrips reduced role as spider mite predator, and increased role as herbivorous pest.

The Virginia Integrated Pest Management Expert for Wheat was designed to combine the best available information regarding wheat pest management of disease pathogens, weeds, and insects into a decision support system that would provide potential outbreak risk and pest control information to the Comprehensive Resource Planning System (CROPS). In addition, the system stands alone as an educational tool for farmers and Extension personnel. This is a rule-based system developed on the Microsoft Windows platform. Knowledge about crops and pest management is represented in the form of IF/THEN rules, demons, and "when-changed" methods. The inference engine analyzes specific crop system information entered by the user to determine potential risks of outbreak for wheat crop pests common to Virginia. These potential outbreak risks are presented as low, medium, and high levels of risk and are presented for each of 15 pests of wheat in Virginia. The system was evaluated using thirty random cropping system scenarios. By comparing expert system output with output from human experts, it was shown that the expert system agreed with human expert opinions in 84 percent of the decisions made. Statistical analysis of the insect pest data showed that there was no significant statistical difference between the distribution of the human expert predictions and the expert system predictions. Statistical analysis of the disease pest data showed that there were some significant statistical differences between the distribution of the human expert predictions and the expert system predictions. / Master of Science

This study identifies the factors influencing adoption of IPM practices and number of pesticide applications in vegetable farmers in Kenya. The sample size for this study includes 263 vegetable farmers. The survey was conducted in four counties of Kenya: Nyeri, Tharka Nithi, Nakuru and Bomet. The vegetables considered in this study are tomato, cabbage and French beans. Different econometric tools are used to analyze adoption of IPM practices and pesticide application for vegetables. It is found that experience in vegetable cultivation and number of livestock owned have a positive impact on the adoption of IPM practices. However, distance to the nearest town has a negative impact on adoption. Moreover, the number of times pesticides are applied to vegetables also declines as distance of the household from the nearest town increases. Farmers whose crops face less stress from insects and disease tend to apply pesticides fewer times as well. Results from this study indicate that being close to town is important for agricultural activities in general. Being farther away not only reduces the probability of IPM adoption but also reduces pesticide application. / Master of Science

This study evaluates the adoption and impacts of Integrated Pest Management (IPM) adoption for rice in Cambodia. Extent of adoption and characteristics of adopters are discovered. Farmers are considered high adopters of IPM if they used two non-pesticide or minimal-pesticide practices to control rice insect, disease, weed, or rodent pests in the last twelve months; farmers are considered low adopters if they used one practice; farmers are considered non-adopters if they used zero practices. IPM practices include pest-resistant variety; stale seedbed (sequential harrowing or harrowing followed by a non-selective herbicide); apply Trichoderma on seeds or seedlings, no insecticide spray for the first 40 days; apply bio-pesticides such as neem, Bt, and metarhizium, and Beauvaria; Sarcocystis bait for rodents; hand weeding at recommended growth stage; and/or another practice specified by the farmer. Out of 394 farmers surveyed, 40 (10.15%) were found to be high adopters, 228 (57.86%) were found to be low adopters, and 126 (31.97%) were found to be non-adopters of IPM. IPM practices currently include mostly hand-weeding and no spray for 40 days; few other practices were adopted. Our study reveals a need for broader education on rice IPM throughout Cambodia. The high frequency of pesticide applications among rice farmers, the finding that adoption of IPM was not found to have a meaningful influence on the number of pesticide applications, and the finding that less than one-quarter of farmers in our study have received training on IPM reveal the need for increased knowledge of IPM in Cambodia, and the need for future education on IPM to focus on reducing pesticide use. / Master of Science

Improper pesticide use on crops causes adverse effects on humans, livestock, crops and the environment. Integrated pest management practices emphasize minimal use of pesticides in controlling pests, and their adoption by farmers can reduce the use of pesticides and their adverse impacts. The introduction of IPM CRSP activities in Uganda to institutionalize IPM methods focused on priority crops in the country. This study analyzed adoption of eight IPM technologies on cowpea, sorghum and groundnuts. Low levels of adoption (<25%) were found with five of these technologies while three technologies had high adoption levels (>75%). Results indicate that farmers' participation in on-farm trial demonstrations, accessing agricultural knowledge through researchers, and prior participation in pest training were associated with increased adoption of most IPM practices. Size of farmer's land holdings did not affect IPM adoption suggesting that IPM technologies are mostly scale neutral, implying that IPM dissemination may take place regardless of farmer's scale of operation. Farmers' perception of harmful effects of chemicals did not influence farmers' decisions in regard to IPM technology adoption despite their high knowledge of this issue, suggesting that these farmers did not consider environmental and health impacts important factors when choosing farming practices. Farmers' managerial capabilities were not important in explaining cowpea IPM technology adoption. / Master of Science

Doctor of Philosophy / Department of Entomology / Brian P. McCornack / Timely enactment of insect pest management and incursion mitigation protocols requires development of time-sensitive monitoring approaches. Numerous passive monitoring methods exist (e.g., insect traps), which offer an efficient solution to monitoring for pests across large geographic regions. However, given the number of different monitoring tools, from specific (e.g., pheromone lures) to general (e.g., sticky cards), there is a need to develop protocols for deploying methods to effectively and efficiently monitor for a multitude of potential pests. The non-random movement of the Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae), toward several visual, chemical, and tactile cues, makes it a suitable study organism to examine new sensor technologies and deployment strategies that can be tailored for monitoring specific pests. Therefore, the objective was to understand Hessian fly behavior toward new sensor technologies (i.e., light emitting diodes (LEDs) and laser displays) to develop monitoring and deployment strategies. A series of laboratory experiments and trials were conducted to understand how the Hessian fly reacts to the technologies and how environmental factors may affect the insect’s response. Hessian fly pupae distribution within commercial wheat fields was also analyzed to determine deployment of monitoring strategies. Laboratory experiments demonstrated Hessian fly attraction to green spectrum (502 and 525 nm) light (LEDs), that response increased with light intensity (16 W/m2), and that they responded in the presence of wheat odor and the Hessian fly female sex-pheromone, but, response was reduced under ambient light. These laboratory experiments can be used to build a more targeted approach for Hessian fly monitoring by utilizing the appropriate light wavelength and intensity with pheromone and wheat odor to attract both sexes, and mitigating exposure to ambient light. Together this information suggested that light could be used with natural cues to increase attraction. Therefore, a light source (green laser display) was applied to a wheat microcosm, which resulted in greater oviposition in wheat covered by the laser display. Examination of Hessian fly pupal distribution within commercial wheat fields showed that proportion of wheat within a 1 km buffer of the field affected distribution between fields. This helps to inform deployment of monitoring strategies as it identified fields with a lower proportion of wheat within a 1 km buffer to be at higher risk Hessian fly infestation, and therefore monitoring efforts should be focused on those fields. Together this work demonstrates Hessian fly behavior toward new sensor technologies, how those technologies interact with environmental cues, and how environmental composition affects pupal distribution. Collectively this information will enable cheaper, more accurate and more efficient monitoring of this destructive pest.

Doctor of Philosophy / Department of Entomology / Franklin Arthur / James R. Nechols / The Indianmeal moth, Plodia interpunctella Hubner, is capable of infesting a number of different commodities including a wide variety of grains, nuts and finished stored products. Therefore, control of the Indianmeal moth is especially needed in areas where food is being stored for human consumption. Increased concerns of consumers and producers regarding the impact of conventional insecticides on the environment and on human health has prompted scientists and the agricultural chemical industry to search for insecticides that do not affect mammalian nervous systems and have limited effects on non-target organisms. One group of insecticides with reduced risks is insect growth regulators (IGRs), which are substances that mimic insect hormones essential to normal development and reproduction. Currently methoprene, a juvenile hormone analog, is labeled for direct application to stored grains, as well as a contact insecticide and as an aerosol application inside mills, warehouses, and indoor food storage facilities. Surface treatments and aerosol space applications can be effective ways to treat the interior surfaces and storage areas of warehouses and food processing facilities. There is little recent research with large-scale aerosol applications in storage sites; furthermore, there are no published references in the scientific literature regarding efficacy of using methoprene alone in aerosol form. Therefore, the purpose of this research was to evaluate the use of surface and aerosol applications of methoprene on finished stored-product packaging materials and facilities for the control of P. interpunctella. Results of this research showed that while methoprene has good residual activity, and efficacy is unaffected by temperature, surface applications of methoprene on packaging materials is not as effective for control of P. interpunctella as aerosol applications of methoprene. Aerosol methoprene is highly effective alone and in combination with conventional chemicals for control of eggs and wandering-phase larvae. Simulations with a population growth model make it possible to estimate impact of insecticide treatments at different temperatures and application times on populations of P. interpunctella. Aerosol treatments are also economically viable as part of an overall integrated pest management program.

The near absence of bed bugs from human dwellings for fifty or more years has left us with limited knowledge of its biology and few answers to eliminate populations. I explored a diverse set of objectives to answer key questions concerning bed bug biology and control. Major objectives were studies of circadian rhythmicity, pyrethroid resistance, sublethal effects of insecticides, synergism of pyrethroids, and evaluation of a pyrrole insecticides, chlorfenapyr. Additional studies included persistence of Borrelia in bed bugs after ingestion, and aggregation factors from feces. In the absence of host stimuli, insects were much more active in the dark than in the light. Nocturnal activity was periodical under continuous light conditions, which indicates that locomotion is endogenously generated by a circadian clock. Circadian rhythm was entrained to reverse dark-light regimes. Short–term starved adults moved more frequently than long-starved adults. These results suggest that starved bugs reduce locomotor activity as a strategy to conserve metabolic reserves. Pyrethroid resistance in C. lectularius was documented for the first time. Extremely high levels of resistance to deltamethrin and λ-cyhalothrin, was detected in populations collected in Kentucky and Ohio. The resistance ratios reported are among the highest documented in any arthropod. Evaluations of more than 20 populations from across the United States indicate that resistance to pyrethroid insecticides is widespread. Bed bugs avoided resting on surfaces treated with deltamethrin but not with chlorfenapyr. Video recordings of bed bugs showed that insects increased their activity when they contacted sublethal doses of deltamethrin. However, harborages treated with a deltamethrin remained attractive. A nearby heat source overcame avoidance to deltamethrin. The P450 inhibitor piperonyl butoxide (PBO) enhanced toxicity of deltamethrin to resistant bed bugs. However, the residual resistance after PBO treatment indicated that other resistance mechanisms are involved. The effectiveness of combining PBO with pyrethroids varied among populations, which indicates that this synergist is not a comprehensive solution to pyrethroid resistance. Chlorfenapyr was effective against pyrethroid resistant strains. While it does not cause quick knockdown, long residual activity and no avoidance behavior to dry residues appears to make this insecticide a useful tool for bed bug control.