The insects that cause or transmit human and animal disease constitute a wide range of taxa sharing a similar feeding habit, but differing in most other aspects of their life histories, including oviposition. This chapter mainly deals with oviposition or larviposition behaviour within the Diptera, since the major groups that exhibit such behaviour and that constitute pests of major medical or veterinary importance are true flies. Aggregation behaviour in bloodsucking Hemiptera is discussed briefly. Bloodfeeding groups generally oviposit at sites remote from their vertebrate hosts: mosquitoes (Culicidae) and blackflies (Simuliidae) oviposit in aquatic environments, and sandflies (Psychodidae), tsetse flies (Glossinidae), bedbugs (Cimicidae) and kissing bugs (Reduviidae) oviposit in terrestrial environments. Facultative or obligatory carnivorous Diptera, where the immature stages can be saprotrophic or parasitic on the same animals on which the adult flies feed, also locate and select oviposition or larviposition sites using chemical cues. These include warble flies, bot flies (Oestridae), blowflies, screwworms (Calliphoridae) and flesh flies (Sarcophagidae). Not surprisingly, given the range of life histories of these diverse groups, the interaction of pheromones with visual cues, odours of environmental origin and the physical properties of the oviposition site, is wide-ranging in nature. Knowledge of the chemoecology of oviposition in these insects lags behind that on herbivorous and parasitic insects and attractant compounds have been identified in only a few cases. A number of plant species have evolved to mimic animal odour cues to attract carnivorous fly species as pollinators. Because of the importance of these insects as vectors of human and animal disease, interest in this field has been driven primarily by a search for chemically baited traps for monitoring and control. Odour baited oviposition traps are currently used in the surveillance of a number of important pest species. Odour baited trapping for the control of pest populations may be feasible for certain species. 5.

Chemoecology of insect eggs and egg deposition

Natural selection should favor females that avoid ovipositing where risk of predation is high for their progeny. Despite the large consequences of such oviposition behavior for individual fitness, population dynamics, and community structure, relatively few studies have tested for this behavior. Moreover, these studies have rarely assessed the mode of detection of predators, compared responses in prey species that vary in vulnerability to predators, or tested for the behavior in natural habitats. In an outdoor artificial pool experiment, we tested the oviposition responses of two dipteran species, Culiseta longiareolata (mosquito) and Chironomus riparius (midge), to the hemipteran predator, Notonecta maculata. Both dipteran species have similar life history characteristics, but Culiseta longiareolata larvae are highly vulnerable to predation by Notonecta, while Chironomus riparius larvae are not. As their vulnerabilities would suggest, Culiseta longiareolata, but not Chironomus riparius, strongly avoided ovipositing in pools containing Notonecta. An experiment in natural rock pools assessing oviposition by Culiseta longiareolata in response to Notonecta maculata yielded an oviposition pattern highly consistent with that of the artificial pool experiment. We also demonstrated that the cue for oviposition avoidance by Culiseta longiareolata was a predator-released chemical: Notonecta water (without Notonecta replenishment) repelled oviposition for 8 days. Oviposition avoidance and mode of detection of the predator have important implications for how to assess the true impact of predators and for the use of commercially produced kairomones for mosquito control.

Oviposition habitat selection in response to risk of predation in temporary pools: mode of detection and consistency across experimental venue

Mosquitoes are not only a nuisance, but also vector many important human and animal diseases Here, in opposition with the dogma that increased precipitation predicts mosquito abundance, we hypothesize that mosquitoes should show population outbreaks after drought years Specifically, we suggest that in wetlands that never dry (permanent), predators limit mosquito abundance, whereas in wetlands that dry yearly (temporary), competitors that are well adapted to predictable drying, limit mosquito abundance However, in wetlands that dry only during drought years (semi-permanent), mosquito predators and competitors are eliminated and must recolonize following a drought, and the abundance of wetland mosquitoes can skyrocket We present supportive evidence for this hypothesis from surveys of natural wetlands and from a controlled mesocosm experiment We conclude that this framework may provide a reliable way to predict and prepare for year-to-year variation in mosquito abundances at large spatial scales

Drought-induced mosquito outbreaks in wetlands

Malaria is one of the most common vector-borne diseases widespread in the tropical and subtropical regions. Despite considerable success of malaria control programs in the past, malaria still continues as a major public health problem in several countries. Vector control is an essential part for reducing malaria transmission and became less effective in recent years, due to many technical and administrative reasons, including poor or no adoption of alternative tools. Of the different strategies available for vector control, the most successful are indoor residual spraying and insecticide-treated nets (ITNs), including long-lasting ITNs and materials. Earlier DDT spray has shown spectacular success in decimating disease vectors but resulted in development of insecticide resistance, and to control the resistant mosquitoes, organophosphates, carbamates, and synthetic pyrethroids were introduced in indoor residual spraying with needed success but subsequently resulted in the development of widespread multiple insecticide resistance in vectors. Vector control in many countries still use insecticides in the absence of viable alternatives. Few developments for vector control, using ovitraps, space spray, biological control agents, etc., were encouraging when used in limited scale. Likewise, recent introduction of safer vector control agents, such as insect growth regulators, biocontrol agents, and natural plant products have yet to gain the needed scale of utility for vector control. Bacterial pesticides are promising and are effective in many countries. Environmental management has shown sufficient promise for vector control and disease management but still needs advocacy for inter-sectoral coordination and sometimes are very work-intensive. The more recent genetic manipulation and sterile insect techniques are under development and consideration for use in routine vector control and for these, standardized procedures and methods are available but need thorough understanding of biology, ethical considerations, and sufficiently trained manpower for implementation being technically intensive methods. All the methods mentioned in the review that are being implemented or proposed for implementation needs effective inter-sectoral coordination and community participation. The latest strategy is evolution-proof insecticides that include fungal biopesticides, Wolbachia, and Denso virus that essentially manipulate the life cycle of the mosquitoes were found effective but needs more research. However, for effective vector control, integrated vector management methods, involving use of combination of effective tools, is needed and is also suggested by Global Malaria Control Strategy. This review article raises issues associated with the present-day vector control strategies and state opportunities with a focus on ongoing research and recent advances to enable to sustain the gains achieved so far.

Malaria vector control: from past to future

Ram Kumar and Jiang-Shiou Hwang (2006) Larvicidal efficiency of aquatic predators: a perspective for mos- quito biocontrol. Zoological Studies 45(4): 447-466. Biological control of mosquito larvae with predators and other biocontrol agents would be a more-effective and eco-friendly approach, avoiding the use of synthetic chemicals and concomitant damage to the environment. Manipulating or introducing an auto-reproducing predator into the ecosystem may provide sustained biological control of pest populations. The selection of a biological control agent should be based on its self-replicating capacity, preference for the target pest popula- tion in the presence of alternate natural prey, adaptability to the introduced environment, and overall interaction with indigenous organisms. In order to achieve an acceptable range of control, a sound knowledge of various attributes of interactions between a pest population and the predator to be introduced is desirable. Herein, we qualitatively review a wide range of literature sources discussing the ability of different aquatic predators to con- trol mosquito larval populations in environments where mosquitoes naturally breed. Different predators of mos- quito larvae include amphibian tadpoles, fish, dragonfly larvae, aquatic bugs, mites, malacostracans, anostra- cans, cyclopoid copepods, and helminths. The most widely used biocontrol agents of mosquito populations are the western mosquito fish, Gambusia affinis, and the eastern mosquito fish, G. holbrooki. The effect of these fishes on native faunal composition and their inability to survive in small containers, tree holes etc., which are ideal breeding sites of vectorially important mosquitoes, make them inefficient in controlling mosquito popula- tions. On the basis of larvicidal efficiency, the ability to produce dormant eggs, the hatchability of dormant eggs after rehydration, faster developmental rates, and higher fecundity, various tadpole shrimp can be considered to

https://zoolstud.sinica.edu.tw/Journals/45.4/447.pdf

Larvicidal Efficiency of Aquatic Predators: A Perspective for Mosquito Biocontrol

1. The impact of the predator, Notonecta maculata, on invertebrate community structure was investigated by a combination of a natural pool survey, an outdoor artificial pool experiment, and a laboratory prey preference experiment.



2. In a survey of forty natural pools in the Negev Desert, Israel, pelagic/neustonic species richness and overall species richness, but not benthic species richness, were negatively associated with N. maculata density.



3. In the artificial pool experiment, in which the presence or absence of Notonecta was manipulated, Notonecta caused a reduction in the richness of species colonizing the pools. Notonecta strongly reduced densities of the pelagic dipterans, Culiseta longiareolata (often 100% reduction of later-instar larvae and pupae) and ephydrids. Fewer Culiseta egg rafts were found in Notonecta pools, indicating that part of the observed reduction of Culiseta is not due to consumption of Culiseta larvae by Notonecta, but to habitat selection by ovipositing Culiseta females in response to risk of predation by Notonecta. Notonecta did not affect densities of (benthic) chironomids or the small cladoceran, Ceriodaphnia cf. quadrangula. Laboratory assessments of selectivity by Notonecta for the various prey matched patterns found in the field experiment.



4. This work provides strong evidence that N. maculata is an important organizer of community structure: it strongly reduces or even eliminates larger pelagic or neustonic species, but does not affect densities of small or benthic species.

Blaustein Leon

Papers

Influence of the predatory backswimmer, Notonecta maculata, on invertebrate community structure